WO1994006198A1 - Quasi square-wave back-emf permanent magnet ac machines with five or more phases - Google Patents
Quasi square-wave back-emf permanent magnet ac machines with five or more phases Download PDFInfo
- Publication number
- WO1994006198A1 WO1994006198A1 PCT/US1993/007154 US9307154W WO9406198A1 WO 1994006198 A1 WO1994006198 A1 WO 1994006198A1 US 9307154 W US9307154 W US 9307154W WO 9406198 A1 WO9406198 A1 WO 9406198A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- stator
- permanent magnet
- rotor
- magnet synchronous
- pitch
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K29/00—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices
- H02K29/06—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices with position sensing devices
- H02K29/12—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices with position sensing devices using detecting coils using the machine windings as detecting coil
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K21/00—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
- H02K21/12—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K21/00—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
- H02K21/12—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets
- H02K21/24—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets axially facing the armatures, e.g. hub-type cycle dynamos
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K29/00—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices
- H02K29/03—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K41/00—Propulsion systems in which a rigid body is moved along a path due to dynamo-electric interaction between the body and a magnetic field travelling along the path
- H02K41/02—Linear motors; Sectional motors
- H02K41/03—Synchronous motors; Motors moving step by step; Reluctance motors
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/08—Arrangements for controlling the speed or torque of a single motor
- H02P6/085—Arrangements for controlling the speed or torque of a single motor in a bridge configuration
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/10—Arrangements for controlling torque ripple, e.g. providing reduced torque ripple
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K3/00—Details of windings
- H02K3/04—Windings characterised by the conductor shape, form or construction, e.g. with bar conductors
- H02K3/28—Layout of windings or of connections between windings
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P2209/00—Indexing scheme relating to controlling arrangements characterised by the waveform of the supplied voltage or current
- H02P2209/07—Trapezoidal waveform
Definitions
- the present invention relates to permanent magnet (PM) synchronous machines and, more particularly, to a quasi square-wave brushless DC machine incorporating five or more phases for increased efficiency and/or torque density.
- FIG. 2 gives a simple example for a sinusoidally varying stator sheet current K sz (x) which is in-phase with a sinusoidally varying magnetic flux density B (x) at air gap 2.
- equation (1) can be solved as follows for the net force per pole F for the perfectly in-phase drive of FIG. 2: p s i p' It is known that single frequency sinusoidal line voltage and current machines do not fully utilize the available "active" regions at the air gap 2. More specifically, the driving stress at the stator surface peaks at the pole centers when the rotor magnets reach alignment with a stator current sheet, but towards the mid-pole regions of air gap 2, the drive stress falls to zero. Hence, the net force per pole F for a perfectly in-phase AC sinusoidal drive is unduly low in comparison to "square-wave" machines.
- Permanent magnet synchronous machines which operate from square-wave input signals make better use of the air gap 2 periphery.
- FIG. 3 gives an example for a three-phase machine operating from a quasi-square wave (a.k.a. trapezoidal) stator sheet current K sz (x) which is in-phase with a square-wave magnetic flux density B (x) at air gap 2.
- K sz a quasi-square wave
- B (x) a square-wave magnetic flux density
- the maximum square- wave stator excitation current must relate to the maximum sinusoidal stator excitation current as follows: Again solving equation (1) for a square-wave machine with square waves of magnetic flux and current drive, and for peak flux density B m and peak sheet current density K sG , the net force per pole F for a perfectly in-phase drive is -K sD B m m x . Thus, with equal I 2 r heating losses, the quasi-square wave machine generates a force per pole F which exceeds that of an otherwise equivalent sinusoidal AC machine by an improvement factor of V2m .
- the improvement factor can be elevated even further by constructing a quasi square-wave back emf PM machine with a greater number of phases. For instance, a five phase machine would have 4/5 of the rotor magnets active, and the improvement factor would equal V8/5 or 1.27. It should be noted that the incremental gain in the improvement factor falls off rapidly for phase orders exceeding five phases. For example, the improvement factors for 7, 9, and 11 phase machines are 1.31, 1.33, and 1.35, respectively.
- the ratio of inverter volt-amps to machine volt-amps is then 4n/(n - 1), which for 3, 5, 7, and 9 phase machines has values of 6, 5, 4.67, and 4.5, respectively. Again, we see better results as the phase order increases, and the largest incremental advantage occurs in the 5-phase machine.
- the present invention provides a new class of quasi square- wave (trapezoidal) back-emf permanent magnet AC machines with five or more phases.
- the subject matter of the invention conforms to the following document, said document herein being incorporated by reference: McCleer, Five Phase Trapezoidal Back EMF PM Synchronous Machines and Drives, presented at the European Power Conference, Florence, Italy, September 3, 1991.
- the subject matter of the invention includes a rotary permanent magnet synchronous machine which, in a radial embodiment, has a rotor with a cylindrical rotor core and a plurality of permanent magnets spaced at equal angular intervals around the rotor core. The pitch of each permanent magnet defines one rotor pole.
- the machine also includes a stator and a plurality of stator windings forming n stator phases, where n must be an odd number > 5.
- the stator may be formed with a plurality of salient teeth spaced at equal angular intervals around a central axis, and each stator winding is wound around a group of stator teeth to define a stator pole having a pitch substantially equal to the pitch of the rotor poles (permanent magnets) .
- the stator teeth may be omitted, and the stator windings are wound directly within the air gap between the stator and rotor to likewise define stator poles having a pitch substantially equal to the pitch of the rotor poles (permanent magnets) .
- the invention in an axial embodiment, includes a rotor having a rotor core with a plurality of pie-shaped permanent magnet wedges arranged at equal angular intervals around a central axis to define a disk. The pitch of each permanent magnet defines one rotor pole.
- the axial embodiment also includes a stator for exciting the rotor to move, the stator being provided with a plurality of stator windings forming n stator phases, where n is an odd number :> 5.
- the stator includes at least one stator disk facing the rotor, and depending on the particular application, a pair of stator disks may be provided on opposing sides of the rotor.
- Each stator disk may be formed with a plurality of salient teeth extending radially along the disk and projecting inwardly toward the rotor. This way, the stator windings are each wound around a group of the stator teeth to define a stator pole having a pitch substantially equal to the pitch of the rotor permanent magnets.
- the stator teeth may be omitted, and the stator windings wound directly within the air gap between the stator and rotor to likewise define stator poles having a pitch substantially equal to the pitch of the rotor poles (permanent magnets) .
- a linear embodiment of the invention which includes a secondary having a linear secondary core, and a plurality of permanent magnets spaced at equal intervals along a surface of the secondary core.
- the pitch of each permanent magnet defines one secondary pole.
- a primary is also provided for exciting the secondary to move.
- the primary further comprises a linear primary core having a plurality of primary windings forming n primary phases, where n is an odd number > 5.
- the primary may be formed with a plurality of salient teeth spaced at equal angular intervals along a surface thereof and facing the secondary permanent magnets. This way, the primary windings are each wound around a group of primary teeth to define a primary pole having a pitch substantially equal to the pitch of the secondary permanent magnets.
- stator teeth may be omitted, and the stator windings wound directly within the air gap between the stator and rotor to likewise define stator poles having a pitch substantially equal to the pitch of the rotor poles (permanent magnets) .
- the number n of stator phases may be 5, 7, 9...etc.
- the invention also provides a switched voltage source inverter drive circuit and commutation sequence for commutating any of the rotary or linear embodiments.
- the drive circuit includes 2n gated switch devices arranged in n parallely-connected switch legs for connection to an input voltage source. Each switch leg has an upper switch device coupled to one of the motor phase windings for driving the phase winding according to a first polarity, and a lower switch device coupled to the one motor phase winding for driving said phase winding according to a second polarity.
- the switch devices of the drive circuit are gated according to a predetermined commutation sequence at angular intervals of ((n-1) x 180°)/n.
- FIG. 1 is a cross-section of generic permanent magnet synchronous machine pole pair which, for illustrative purposes, is shown in linear form;
- FIG. 2 is a graphical illustration of a sinusoidally varying AC stator sheet current K sz (x) for the machine of FIG. 1, along with a graph of sinusoidally varying in-phase magnetic flux density B- ⁇ fx) across air gap 2;
- FIG. 3 is a graphical perspective for a three-phase machine operating from a quasi-square wave stator sheet current K sz (x) as shown in the lower graph, said current being in phase with the air gap 2 magnetic flux density B ⁇ fx) shown in the middle graph;
- FIG. 4 illustrates a cross-section of a quasi square-wave back-emf permanent magnet machine having five phases in accordance with one embodiment of the present invention, the section being shown in linear form for ease of illustration;
- FIG. 5 is a bar graph illustrating the calculated efficiency of the above-described lOhp embodiment as a function of both the percentage of rated speed and the percentage of rated torque;
- FIG. 6 is a graphical illustration showing the variation of the radial component of gap flux density B sr at the effective inside distance r sid of the stator laminations 20 of FIG. 1, the illustration being broken into four graphs covering four possible magnet angular widths a m of permanent magnets 14;
- FIG. 7 is a perspective drawing showing an axial rotary PM synchronous machine according to a second embodiment of the present invention.
- FIG. 8 is a schematic diagram of a voltage source inverter (VSI) drive circuit for use in driving a five phase quasi square-wave back emf machine according to the present invention
- FIG. 9 is a side-by-side graphical illustration of a suitable switching sequence for switch devices S, - S 10 of FIG. 7 and the corresponding quasi square-wave back emfs for each of the five phase windings;
- VSI voltage source inverter
- FIG. 10 is a graph of a simulated waveshape of the terminal current in any one of the five phases for the 144° square wave drive of FIG. 8 applied to a 10 hp rotary embodiment of the invention.
- FIG. 11 is a graph of the simulated instantaneous variation of drive torque (torque ripple) in the 10 hp rotary embodiment due to all the winding currents when the machine is driven at 38.6% of its rated speed (1390 rpm) and the terminal current is maintained at 13.4 A.
- FIG. 4 illustrates a linearized section of a quasi square-wave (a.k.a. trapezoidal) back-e f permanent magnet machine having five phases in accordance with one embodiment of the present invention.
- An exemplary five-phase stator winding distribution is shown above for perspective.
- FIG. 4 may be used to explain linear embodiments of the invention (having a primary and secondary) as well as both radial and axial rotary embodiments (having stators and rotors) .
- the machine includes a secondary (or rotor) 10 having a core 12 and a plurality of permanent magnets 14 mounted along the surface in a facing relation to a primary (or stator) 20.
- the secondary (rotor) core 12 and primary (stator) core 20 are formed in a conventional manner from a plurality of discrete laminations which are stacked along a length L.
- the primary (stator) 20 laminations are slotted to define a plurality of salient teeth 22 opposing permanent magnets 14, and the faces of teeth 22 are separated from the faces of magnets 14 by an air gap g of extent R .
- the phase windings are situated in the slots between stator teeth 22.
- the effect of the relative dimensions of the slots and the extent R of air gap g on the strength of the magnetic flux B (x) within the air gap g may be calculated in a conventional manner such as shown and described in M.G. Say, Alternating Current
- stator teeth 22 can be eliminated if the permanent magnets 14 are strong enough, and the phase windings can be situated in the air gap g itself if the application so permits. Such a variation is considered to be within the scope of the invention.
- the permanent magnets 14 of the rotor 10 are uniform, have full pole pitches p r , and a constant thickness ⁇ r m and are uniformly magnetized in the y (or radial) direction.
- the permanent secondary (rotor) magnets 14 may also be formed from a plurality of stacked laminations, and permanent magnets 14 likewise have an axial extent L. Torque production is considered to be uniform along the stack length L of the radial machine.
- r sid is the actual inside radius of the stator laminations.
- N # number of phases in stator windings.
- N number of magnetic poles.
- N number of parallel wires which form "one" conductor.
- N c the number of conductors per slot (equal to two times the number of turns per coil in any one full pitch coil) .
- AWG the type (AWG number) of wire used in the stator windings.
- R y resistance at a given temperature per unit length of the wire used in the stator windings.
- N u number of wires which can be packed (wound) in a unit cross-sectional area.
- R is the radius of the air gap and N is the number of magnetic poles.
- the middle term is the air gap enclosed volume which depends upon the radius of the air gap R . This can be rearranged in terms of the air gap diameter D to give:
- the base/rated speed of the machine is specified to be 3600 rpm, and the switched drive system is powered from a full wave, 6-pulse diode bridge rectifier connected to a 240 volt three phase input main.
- the machine line-to-line back emf must be slightly lower than the DC-bus voltage (approximately 339V for a 240V system) .
- the detailed machine dimensions of the above-described 10 horsepower five-phase radial rotary embodiment may be determined using equation (4) above, with
- FIG. 5 is a bar graph illustrating the calculated efficiency of the above-described lOhp embodiment as a function of both the percentage of rated speed and the percentage of rated torque. Note that these predicted efficiency values do not include the effects of any high frequency loss components due to continuous pulse width modulation (PWM) control of the machine current by a PWM switched drive system.
- PWM pulse width modulation
- the magnetic losses quoted here are calculated by the method set forth in Slemon et al.. Core Losses in Permanent Magnet Motors. IEEE Transactions on Magnetics, Vol. 26, No. 5, pp. 1653-1655 (Sept., 1990).
- the variation of the radial component of gap flux density B sr at the effective inside distance r sjd of the stator laminations 20 is shown in FIG.
- FIG. 6 is broken into four graphs covering four possible magnet angular widths a m of permanent magnets 14.
- the magnetic flux density B sr is almost constant at its peak value over 7/9 of a pole arc, and falls to approximately 94% of its peak value at an angle of 80 electrical degrees off pole center. Since the concentrated phase windings within one slot extend an angle of approximately 17 electrical degrees (given uniform slots and stator teeth 22, the waveform of the back emf will nearly match the flux density B sr waveform of FIG. 6(c). The drop-off of the back emf waveform may be somewhat more rounded due to the randomness of the windings within any one slot. However, this is insignificant since nearly all of the radial flux B sr through the gap g will be occur through the stator teeth 22, and this tends to lessen the effect of the current within a slot.
- FIG. 7 is a perspective drawing of an axial embodiment of a PM synchronous machine according to the present invention.
- the illustrated axial embodiment includes two diametric stator disks 120 each having a plurality of salient pie-shaped wedge teeth 122 projecting inwardly toward an interposed cylindrical rotor 110.
- an axial machine could be constructed in accordance with the present invention using only one of the two stator disks 120.
- the cylindrical rotor 110 is formed from a plurality of pie-shaped wedge permanent magnets 114 which are equally spaced and alternately arranged by polarity around a central axis of the machine.
- the relation between each stator disk 120 and the rotor 110 of the embodiment of FIG. 7 is essentially similar to the above-described radial embodiment, and can likewise be explained with reference to FIG. 4.
- Permanent magnets 114 of the rotor 110 are uniform, have full pole pitches p r , are wedge-shaped, and are uniformly magnetized in the y (or axial) direction along the radial extent L.
- the following table 2 shows the design results for an axial air gap 6-pole, five phase, 10 hp, 3600 rpm machine which utilizes rare earth (SmCo) wedge-shaped permanent magnets 114 and concentrated, full pitch stator windings to obtain quasi square-wave (trapezoidal) back emf waveforms.
- SmCo rare earth
- FIG. 8 illustrates a basic voltage source inverter (VSI) drive circuit for a five-phase quasi square-wave back emf machine according to the present invention which utilizes ten (10) active switch devices S, - S 10 .
- Switch devices S, - S 10 may be any suitable gated solid- state switching elements such as bi-polar transistors, insulated-gate bi-polar transistors, field effect transistors, or gate turn-off thyristors.
- Ten wheeling diodes D, - D 10 provide conduction paths for phase winding (inductive) currents whenever a corresponding switch device S 1 - S 10 on the same inverter leg is gated off.
- Switch devices S, - S 10 are sequentially gated according to the switching sequence shown in FIG. 9.
- Switching occurs in 144 electrical degree periods which are synchronized to the stator winding back emfs of the rotor (or secondary) magnets 6, i.e., in synchronism with the secondary (or rotor) position.
- the DC source voltage E 0 must be varied with machine speed to maintain control of the magnitude of the stator winding currents.
- E 0 can be fixed and within the correct (144°) periods (as determined by rotor position) , the switching devices S 1 - S 10 can be gated in a conventional pulse width modulated (PWM) mode to attain current control.
- PWM pulse width modulated
- FIGS. 10 and 11 Simulation results for the above-described 144° square wave drive applied to the 10 hp rotary embodiment described above are given in FIGS. 10 and 11.
- FIG. 10 shows the waveshape of the terminal current in any one phase and
- FIG. 11 shows the instantaneous variation of the drive torque due to all the winding currents.
- the machine is being driven at 38.6% of its rated speed (1390 rpm), and the DC drive voltage E 0 is such that the flat top value of the terminal current is 13.4 A (103% of the design rated value).
- the fast rise of fall spike-like deviations in the terminal current and thus the notch-like deviations in the drive torque are due to commutation transients in the incoming and outgoing phase at switch device/phase switching points.
- L 8 is the self inductance of any one stator winding.
Abstract
A new class of higher phase-order (five or more) quasi square-wavbe back emf permanent magnet machines including radial, axial and linear embodiments which employ a greater number of active phase windings located in the slots between the stator teeth (22) during continuous operation, the secondary or rotor includes a core (10) having permanent magnets (14) thereby utilizing more of the machine copper and magnet material.
Description
QUASI SQUARE-WAVE BACK-EMF PERMANENT MAGNET AC MACHINES WITH FIVE OR MORE PHASES
BACKGROUND OF THE INVENTION
1. Field of the invention The present invention relates to permanent magnet (PM) synchronous machines and, more particularly, to a quasi square-wave brushless DC machine incorporating five or more phases for increased efficiency and/or torque density.
2. Description of the Background Consider a pole pair of a generic permanent magnet synchronous linear machine as shown in FIG. 1. The direction of rotor movement is along the x-axis, and this is perpendicular to the y-directed magnetic flux flow across air gap 2. The current I through the phase windings of the stator can be represented by an equivalent z-directed sheet current Ksz(x) at point 4 because the sheet current Ksz(x) produces the same fields as those which would otherwise be produced by actual stator windings. At the position 4 of the equivalent sheet current Ks2(x), the tangential (or x-directed) component of surface force density (or stress) fz is given by:
fz(x) = -Ksz(x)B(ny(x) (N/m2)
where B (x) is the normal or y-directed component of magnetic flux density through the air gap 2 due to the rotor magnet 6. The net instantaneous force per pole F per unit active width of the machine of FIG. 1 is then given by:
, where the distance x is a pole pitch.
It is obvious from equation (1) that for maximum motoring (or generating) force per ampere of stator current we must have the stator sheet current Ksz(x) and air gap 2 magnetic
flux density B (x) spatially and temporally in phase (anti¬ phase for generation) .
FIG. 2 gives a simple example for a sinusoidally varying stator sheet current Ksz(x) which is in-phase with a sinusoidally varying magnetic flux density B (x) at air gap 2. For peak flux density Bm and peak sheet current density K8, equation (1) can be solved as follows for the net force per pole F for the perfectly in-phase drive of FIG. 2: p s i p' It is known that single frequency sinusoidal line voltage and current machines do not fully utilize the available "active" regions at the air gap 2. More specifically, the driving stress at the stator surface peaks at the pole centers when the rotor magnets reach alignment with a stator current sheet, but towards the mid-pole regions of air gap 2, the drive stress falls to zero. Hence, the net force per pole F for a perfectly in-phase AC sinusoidal drive is unduly low in comparison to "square-wave" machines.
Permanent magnet synchronous machines which operate from square-wave input signals make better use of the air gap 2 periphery.
FIG. 3 gives an example for a three-phase machine operating from a quasi-square wave (a.k.a. trapezoidal) stator sheet current Ksz(x) which is in-phase with a square-wave magnetic flux density B (x) at air gap 2. For square-wave machines, let the fraction m equal that portion of a full pole pitch which, at any one time, has full stator sheet current excitation at maximum value KsD. For the same RMS heating as in the above-described sinusoidal drive and for equal amounts and even distribution of stator copper, the maximum square- wave stator excitation current must relate to the maximum sinusoidal stator excitation current as follows:
Again solving equation (1) for a square-wave machine with square waves of magnetic flux and current drive, and for peak
flux density Bm and peak sheet current density KsG, the net force per pole F for a perfectly in-phase drive is -KsDBmm x . Thus, with equal I2r heating losses, the quasi-square wave machine generates a force per pole F which exceeds that of an otherwise equivalent sinusoidal AC machine by an improvement factor of V2m . Since three-phase quasi square-wave (trapezoidal) back emf machines have approximately constant current flow in two of the three stator phase windings at any one time, the fraction of rotor magnet use m equals 2/3, and the above-described improvement factor under ideal conditions equals V4/3, or 1.16.
The improvement factor can be elevated even further by constructing a quasi square-wave back emf PM machine with a greater number of phases. For instance, a five phase machine would have 4/5 of the rotor magnets active, and the improvement factor would equal V8/5 or 1.27. It should be noted that the incremental gain in the improvement factor falls off rapidly for phase orders exceeding five phases. For example, the improvement factors for 7, 9, and 11 phase machines are 1.31, 1.33, and 1.35, respectively.
Higher phase order square wave PM machines also make better use of the solid-state switching devices in their switched drive systems (relative to their three-phase counter parts) . Specifically, if the machine peak stator phase winding current has value I , and the peak machine line-to- line back emf has value Em, then the required peak volt-amp performance for an n-phase machine is (n - l)E|_I(n/2. Moreover, an n-phase machine requires 2n switching devices in the accompanying solid state inverter drive system, and each switch must be capable of blocking at least Em volts and conducting at least Im amps. The total volt-amp rating of the inverter is thus 2nE|nIffl. The ratio of inverter volt-amps to machine volt-amps is then 4n/(n - 1), which for 3, 5, 7, and 9 phase machines has values of 6, 5, 4.67, and 4.5, respectively. Again, we see better results as the phase order
increases, and the largest incremental advantage occurs in the 5-phase machine.
Consequently, it would be greatly advantageous to provide a higher phase-order (five or more) quasi square-wave back emf permanent magnet machine which capitalizes on the above- described efficiencies.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a higher phase-order (five or more) permanent magnet machine to increase the number of active phase windings during continuous operation, thereby utilizing more of the machine copper and magnet material.
It is another object to increase the efficiency of the above-described machines by employing a quasi square-wave (trapezoidal) drive.
It is a specific object to employ five phase windings in a quasi square-wave back emf PM machine in order to maintain 4 active phases, thereby utilizing 4/5 of the machine copper and magnet material. Likewise, it is an object to employ seven, nine, eleven and more phase windings to respectively maintain 6, S, 10, etc. active phases, thereby maximizing the use of the machine copper and magnet material.
It is another object to provide a solid state inverter drive circuit for an n-phase quasi square-wave back emf PM machine as described above, said drive circuit requiring only 2n switching devices.
In accordance with the above-described and other objects, the present invention provides a new class of quasi square- wave (trapezoidal) back-emf permanent magnet AC machines with five or more phases. The subject matter of the invention conforms to the following document, said document herein being incorporated by reference: McCleer, Five Phase Trapezoidal Back EMF PM Synchronous Machines and Drives, presented at the European Power Conference, Florence, Italy, September 3, 1991.
In particular, the subject matter of the invention includes a rotary permanent magnet synchronous machine which, in a radial embodiment, has a rotor with a cylindrical rotor core and a plurality of permanent magnets spaced at equal angular intervals around the rotor core. The pitch of each permanent magnet defines one rotor pole. The machine also includes a stator and a plurality of stator windings forming n stator phases, where n must be an odd number > 5. The stator may be formed with a plurality of salient teeth spaced at equal angular intervals around a central axis, and each stator winding is wound around a group of stator teeth to define a stator pole having a pitch substantially equal to the pitch of the rotor poles (permanent magnets) . Alternatively, the stator teeth may be omitted, and the stator windings are wound directly within the air gap between the stator and rotor to likewise define stator poles having a pitch substantially equal to the pitch of the rotor poles (permanent magnets) .
In an axial embodiment, the invention includes a rotor having a rotor core with a plurality of pie-shaped permanent magnet wedges arranged at equal angular intervals around a central axis to define a disk. The pitch of each permanent magnet defines one rotor pole. The axial embodiment also includes a stator for exciting the rotor to move, the stator being provided with a plurality of stator windings forming n stator phases, where n is an odd number :> 5. The stator includes at least one stator disk facing the rotor, and depending on the particular application, a pair of stator disks may be provided on opposing sides of the rotor. Each stator disk may be formed with a plurality of salient teeth extending radially along the disk and projecting inwardly toward the rotor. This way, the stator windings are each wound around a group of the stator teeth to define a stator pole having a pitch substantially equal to the pitch of the rotor permanent magnets. Alternatively, the stator teeth may be omitted, and the stator windings wound directly within the
air gap between the stator and rotor to likewise define stator poles having a pitch substantially equal to the pitch of the rotor poles (permanent magnets) .
Further, a linear embodiment of the invention is disclosed which includes a secondary having a linear secondary core, and a plurality of permanent magnets spaced at equal intervals along a surface of the secondary core. The pitch of each permanent magnet defines one secondary pole. A primary is also provided for exciting the secondary to move. The primary further comprises a linear primary core having a plurality of primary windings forming n primary phases, where n is an odd number > 5. The primary may be formed with a plurality of salient teeth spaced at equal angular intervals along a surface thereof and facing the secondary permanent magnets. This way, the primary windings are each wound around a group of primary teeth to define a primary pole having a pitch substantially equal to the pitch of the secondary permanent magnets. Alternatively, the stator teeth may be omitted, and the stator windings wound directly within the air gap between the stator and rotor to likewise define stator poles having a pitch substantially equal to the pitch of the rotor poles (permanent magnets) .
In any of the rotary (axial or radial) or linear embodiments, the number n of stator phases may be 5, 7, 9...etc.
The invention also provides a switched voltage source inverter drive circuit and commutation sequence for commutating any of the rotary or linear embodiments. The drive circuit includes 2n gated switch devices arranged in n parallely-connected switch legs for connection to an input voltage source. Each switch leg has an upper switch device coupled to one of the motor phase windings for driving the phase winding according to a first polarity, and a lower switch device coupled to the one motor phase winding for driving said phase winding according to a second polarity.
The switch devices of the drive circuit are gated according to a predetermined commutation sequence at angular intervals of ((n-1) x 180°)/n.
BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features, and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments and certain modifications thereof when taken together with the accompanying drawings in which: FIG. 1 is a cross-section of generic permanent magnet synchronous machine pole pair which, for illustrative purposes, is shown in linear form;
FIG. 2 is a graphical illustration of a sinusoidally varying AC stator sheet current Ksz(x) for the machine of FIG. 1, along with a graph of sinusoidally varying in-phase magnetic flux density B-^fx) across air gap 2;
FIG. 3 is a graphical perspective for a three-phase machine operating from a quasi-square wave stator sheet current Ksz(x) as shown in the lower graph, said current being in phase with the air gap 2 magnetic flux density B^fx) shown in the middle graph;
FIG. 4 illustrates a cross-section of a quasi square-wave back-emf permanent magnet machine having five phases in accordance with one embodiment of the present invention, the section being shown in linear form for ease of illustration; FIG. 5 is a bar graph illustrating the calculated efficiency of the above-described lOhp embodiment as a function of both the percentage of rated speed and the percentage of rated torque; FIG. 6 is a graphical illustration showing the variation of the radial component of gap flux density Bsr at the effective inside distance rsid of the stator laminations 20 of FIG. 1, the illustration being broken into four graphs
covering four possible magnet angular widths am of permanent magnets 14;
FIG. 7 is a perspective drawing showing an axial rotary PM synchronous machine according to a second embodiment of the present invention;
FIG. 8 is a schematic diagram of a voltage source inverter (VSI) drive circuit for use in driving a five phase quasi square-wave back emf machine according to the present invention; FIG. 9 is a side-by-side graphical illustration of a suitable switching sequence for switch devices S, - S10 of FIG. 7 and the corresponding quasi square-wave back emfs for each of the five phase windings;
FIG. 10 is a graph of a simulated waveshape of the terminal current in any one of the five phases for the 144° square wave drive of FIG. 8 applied to a 10 hp rotary embodiment of the invention; and
FIG. 11 is a graph of the simulated instantaneous variation of drive torque (torque ripple) in the 10 hp rotary embodiment due to all the winding currents when the machine is driven at 38.6% of its rated speed (1390 rpm) and the terminal current is maintained at 13.4 A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 4 illustrates a linearized section of a quasi square-wave (a.k.a. trapezoidal) back-e f permanent magnet machine having five phases in accordance with one embodiment of the present invention. An exemplary five-phase stator winding distribution is shown above for perspective. Although the illustration of FIG. 4 extends linearly in the x- direction, this is merely to better describe dimensions along the y-axis. Hence, FIG. 4 may be used to explain linear embodiments of the invention (having a primary and secondary) as well as both radial and axial rotary embodiments (having stators and rotors) .
The machine includes a secondary (or rotor) 10 having a core 12 and a plurality of permanent magnets 14 mounted along the surface in a facing relation to a primary (or stator) 20. The secondary (rotor) core 12 and primary (stator) core 20 are formed in a conventional manner from a plurality of discrete laminations which are stacked along a length L. The primary (stator) 20 laminations are slotted to define a plurality of salient teeth 22 opposing permanent magnets 14, and the faces of teeth 22 are separated from the faces of magnets 14 by an air gap g of extent R . The phase windings are situated in the slots between stator teeth 22. The effect of the relative dimensions of the slots and the extent R of air gap g on the strength of the magnetic flux B (x) within the air gap g may be calculated in a conventional manner such as shown and described in M.G. Say, Alternating Current
Machines, Halsted Press, John Wiley & Sons, New York, pp. 37- 39 (5th Ed., 1983) .
It should be apparent to those skilled in the art that the stator teeth 22 can be eliminated if the permanent magnets 14 are strong enough, and the phase windings can be situated in the air gap g itself if the application so permits. Such a variation is considered to be within the scope of the invention.
A radial air-gap embodiment of the invention will now be described with reference to FIG. 4. The permanent magnets 14 of the rotor 10 are uniform, have full pole pitches pr, and a constant thickness Δrm and are uniformly magnetized in the y (or radial) direction. The permanent secondary (rotor) magnets 14 may also be formed from a plurality of stacked laminations, and permanent magnets 14 likewise have an axial extent L. Torque production is considered to be uniform along the stack length L of the radial machine.
In accordance with elementary electromagnetic theory, we will view the radial rotary embodiment under the following two assumptions:
(1) The torque Te on the stator 20 due to a single stator conductor carrying current I, when said conductor is positioned in a slot directly over a rotor magnet 14, and the rotor magnet 14 produces a y-directed (or radial) component of magnetic flux density B8r at the effective inside distance rsid of the stator laminations 20, is given by the following equation:
T„e = s_,iαM x Bcsrr x I x L;'
In a rotary embodiment, rsid is the actual inside radius of the stator laminations.
(2) A voltage ee which is induced in a single stator conductor as described in (1) above, and which is subject to the y-directed (or radial) component of magnetic flux density Bsr at the effective inside distance r8Ϊd of the stator laminations 20 and which is rotating at angular velocity bm is given by the equation:
e«e = BsCfr. x L x resϊiα x hm.
It is important to note that the torque Te and voltage ee of relations (1) and (2) remain at their peak values over approximately the full pitch a permanent magnet 14. In contrast, the torque Te and voltage ee of relations (1) and (2) are at their peak values for only a single instance (the center of a magnetic pole) for a sinusoidal machine. Taking relations (1) and (2) in the context of the above- described general structure of the rotary machine, the remaining detailed machine design requires devising a magnetic field excitation structure, a set of stator windings, and the connections of said stator windings which will produce the required total torque and total winding voltage needed to satisfy a given set of predetermined specifications.
The specifications which must be provided to begin the detailed design are as follows:
1. PR, rated machine shaft power.
2. foR, rated machine shaft speed, the lowest speed at which the machine is to attain its rated power.
3. rsod, outside radius of stator laminations.
4. rm, outside radius of rotor magnet segments.
5. Δrm, radial thickness of rotor magnet segments.
6. Bm, residual magnetic flux density of the rotor PM material.
7. μra, relative magnetic permeability of rotor PM material. 8. g, air gap length.
9. L, active axial length of machine.
10. N#, number of phases in stator windings.
11. N , number of magnetic poles.
12. N / number of parallel coil sets per phase in stator windings.
13. N , number of parallel wires which form "one" conductor.
14. Nc, the number of conductors per slot (equal to two times the number of turns per coil in any one full pitch coil) .
15. AWG, the type (AWG number) of wire used in the stator windings.
16. Ry, resistance at a given temperature per unit length of the wire used in the stator windings. 17. Nu, number of wires which can be packed (wound) in a unit cross-sectional area.
18. tj, thickness of slot insulation material.
19. Sj, slot fill factor, the fraction of available slot cross-sectional area to be "filled" with wire at the density N .
We can derive the total torque T for a square-wave input by adding the total torque contributions from all of the stator conductors as determined in relation (1) , as follows:
T~κ n;RgNp KsBa^
where R is the radius of the air gap and N is the number of magnetic poles.
Since we also know that Np,xp„ = 2rR a„ ( •where R9„ is the approximate diameter of the air gap g region) , the expression for total torque becomes:
Note that the middle term is the air gap enclosed volume which depends upon the radius of the air gap R . This can be rearranged in terms of the air gap diameter D to give:
Knowing that the machine will have five phases, we know that the fraction of rotor magnet 6 use m equals 4/5. In addition, the choice of permanent magnet 14 material determines the peak flux density Bm. Hence, given an initial choice of permanent magnet material, and setting D /L to l to minimize potential dynamic problems such as hoop stress at high speeds and low critical speeds, we can now calculate the length L of the machine using equation (4) above for a given peak value of sheet current density Ks
As one example of a radial rotary embodiment according to the present invention, we will consider a 10 horsepower five- phase machine which employs inexpensive conventional ceramic permanent magnets 14 which are to be fabricated with ceramic
material equivalent to commercially available Hitachi" grade YBM-2BB, with a B^ = 0.42 Tesla, and a relative permeability of μm = 1.05. The base/rated speed of the machine is specified to be 3600 rpm, and the switched drive system is powered from a full wave, 6-pulse diode bridge rectifier connected to a 240 volt three phase input main.
At the rated 3600 rpm speed, the machine line-to-line back emf must be slightly lower than the DC-bus voltage (approximately 339V for a 240V system) . The detailed machine dimensions of the above-described 10 horsepower five-phase radial rotary embodiment may be determined using equation (4) above, with
T = TR = PR/)R = 20.2 N - m Dg/L = 1.0 «/2mp = 1.27
Ks = 20,000 A/m and
B = 0.75B . where it is assumed that we can attain at least 75% of the residual induction of the magnet in the air gap and a relatively low Ks compared to standard AC machinery in order to lessen i2R losses.
Evaluation of equation (4) with the above-specified parameters yields length L = D = 148 mm - 6 inches. Further consideration of standard commercially available rotary frames approximating such dimensions leads to an initial choice of the National Electrical Manufacturer's Association (NEMA) standard 182T frame, which has a total outer diameter (including small fins) of 9.0 inches. We can estimate a stator 20 lamination outside radius at 4.25 inches. The choice of pole order for the machine results in a trade-off between operation at a lower electrical frequency (hence, lower magnetic losses) for low pole order machines versus a reduced radial thickness of the primary (or stator) 20 for higher pole order machines.
All remaining design parameters may be easily determined by common and conventional design principles, or by trial and error.
The following Table 1 sets forth a completed design for the 10 hp radial rotary machine.
TABLE 1
The calculated performance results given in Table 1 are very encouraging; assuming worst case, an efficiency of greater than 95% may be expected at rated output conditions. The efficiency values are most impressive over a range of torque and speed below machine ratings.
FIG. 5 is a bar graph illustrating the calculated efficiency of the above-described lOhp embodiment as a
function of both the percentage of rated speed and the percentage of rated torque. Note that these predicted efficiency values do not include the effects of any high frequency loss components due to continuous pulse width modulation (PWM) control of the machine current by a PWM switched drive system. The magnetic losses quoted here are calculated by the method set forth in Slemon et al.. Core Losses in Permanent Magnet Motors. IEEE Transactions on Magnetics, Vol. 26, No. 5, pp. 1653-1655 (Sept., 1990). The variation of the radial component of gap flux density Bsr at the effective inside distance rsjd of the stator laminations 20 is shown in FIG. 6 (as determined by the analytic method set forth in Boules, Prediction of No-load Flux Density Distribution in Permanent Magnet Machines". IEEE Transactions on Industry Applications, Vol. IA-21, No. 3, pp. 633-645 (May/June 1985)). FIG. 6 is broken into four graphs covering four possible magnet angular widths am of permanent magnets 14.
FIG. 6(c) illustrates a nominal design case wherein affl=95% of a full pole pitch. In this case, the magnetic flux density Bsr is almost constant at its peak value over 7/9 of a pole arc, and falls to approximately 94% of its peak value at an angle of 80 electrical degrees off pole center. Since the concentrated phase windings within one slot extend an angle of approximately 17 electrical degrees (given uniform slots and stator teeth 22, the waveform of the back emf will nearly match the flux density Bsr waveform of FIG. 6(c). The drop-off of the back emf waveform may be somewhat more rounded due to the randomness of the windings within any one slot. However, this is insignificant since nearly all of the radial flux Bsr through the gap g will be occur through the stator teeth 22, and this tends to lessen the effect of the current within a slot.
Experimental results for the three phase quasi square- wave (trapezoidal) PM synchronous machine according to the
present invention confirm that the actual back emf waveforms have sharper corners than would be expected if only averaging over a slot arc was considered.
The above-described description has been limited to a rotary embodiment of the invention having a radial air gap. However, those skilled in the art would consider the counterpart axial air gap rotary embodiment to be equivalent in all material respects and clearly within the scope of the invention. FIG. 7 is a perspective drawing of an axial embodiment of a PM synchronous machine according to the present invention. The illustrated axial embodiment includes two diametric stator disks 120 each having a plurality of salient pie-shaped wedge teeth 122 projecting inwardly toward an interposed cylindrical rotor 110. However, it should be apparent that an axial machine could be constructed in accordance with the present invention using only one of the two stator disks 120. The cylindrical rotor 110 is formed from a plurality of pie-shaped wedge permanent magnets 114 which are equally spaced and alternately arranged by polarity around a central axis of the machine. The relation between each stator disk 120 and the rotor 110 of the embodiment of FIG. 7 is essentially similar to the above-described radial embodiment, and can likewise be explained with reference to FIG. 4. Permanent magnets 114 of the rotor 110 are uniform, have full pole pitches pr, are wedge-shaped, and are uniformly magnetized in the y (or axial) direction along the radial extent L. The foregoing design calculations and performance evaluations for the radial embodiment would be exactly the same for an axial embodiment (having an axial air gap g) if one redefines the axial dimensions (in the z-direction) of FIG. 4 as radial and the radial dimensions (in the y-direction, including variables rm, rsid' rsiot an~- rsod of FIG.4) as aχial dimensions which are constant along a circular cut of constant radius from the center axis of the machine. In this perspective, the circumferentially-
directed surface force density (or stress) f becomes the product of a radial sheet current density K and an axial flux density B.
In addition, one must further impose the equivalence Rg = (r80a - r8ia)/2, e.g., the equivalent air gap radius Rg being equal to the average radius for the stator conductors, where r„s„oa0 is the outside axial dimension of the stator conductors and r81- is the inside axial dimension. The "length" of the stator conductors rsoa - rsia is then equivalent to the axial length L in the radial gap equations.
The following table 2 shows the design results for an axial air gap 6-pole, five phase, 10 hp, 3600 rpm machine which utilizes rare earth (SmCo) wedge-shaped permanent magnets 114 and concentrated, full pitch stator windings to obtain quasi square-wave (trapezoidal) back emf waveforms.
TABLE 2
In addition to both axial and radial embodiments of the rotary machine, those skilled in the art would consider the counterpart linear embodiment to be equivalent in all material respects and also within the scope of the invention.
FIG. 8 illustrates a basic voltage source inverter (VSI) drive circuit for a five-phase quasi square-wave back emf machine according to the present invention which utilizes ten (10) active switch devices S, - S10. Switch devices S, - S10 may be any suitable gated solid- state switching elements such as bi-polar transistors, insulated-gate bi-polar transistors, field effect transistors, or gate turn-off thyristors.
Ten wheeling diodes D, - D10 provide conduction paths for phase winding (inductive) currents whenever a corresponding switch device S1 - S10 on the same inverter leg is gated off. Switch devices S, - S10 are sequentially gated according to the switching sequence shown in FIG. 9. Switching occurs in 144 electrical degree periods which are synchronized to the stator winding back emfs of the rotor (or secondary) magnets 6, i.e., in synchronism with the secondary (or rotor) position. For the illustrated 144° square wave drive, the DC source voltage E0 must be varied with machine speed to maintain control of the magnitude of the stator winding currents. Alternatively, E0 can be fixed and within the correct (144°) periods (as determined by rotor position) , the switching devices S1 - S10 can be gated in a conventional pulse width modulated (PWM) mode to attain current control.
Simulation results for the above-described 144° square wave drive applied to the 10 hp rotary embodiment described above are given in FIGS. 10 and 11. FIG. 10 shows the waveshape of the terminal current in any one phase and FIG. 11
shows the instantaneous variation of the drive torque due to all the winding currents. The machine is being driven at 38.6% of its rated speed (1390 rpm), and the DC drive voltage E0 is such that the flat top value of the terminal current is 13.4 A (103% of the design rated value). The fast rise of fall spike-like deviations in the terminal current and thus the notch-like deviations in the drive torque are due to commutation transients in the incoming and outgoing phase at switch device/phase switching points. Current in the outgoing (turned-off) phase falls rapidly, being driven to zero by back emf voltages approximately to E0. However, current in the incoming phase is driven to its flat top value by only the small difference between E0 and the sum of two back emf voltages. Current in each phase is affected due to the common connection at the isolated neutral point and the mutual inductances between the stator windings. Since the secondary (or rotor) magnets have approximately air-like values of relative permeability (μm - 1) and are mounted on the (round) secondary (or rotor) surface, the mutual inductances between the stator windings are not functions of the secondary (or rotor) instantaneous position. For the concentrated winding five phase machine, the inductance matrix representing the self and mutual inductances of the five stator windings can be easily shown to be:
where L8 is the self inductance of any one stator winding.
For applications requiring smooth drive torque, such as machine tools, the torque ripple produced by the simple 144° square wave drive is unacceptable. The torque ripple shown in FIG. 11, approximately 15%, is typical for five phase machines at rated torque output. This ripple value will decrease somewhat at very low speeds and increase somewhat at speeds close to the rated value. There are several known strategies for PWM control of the switching devices during the commutation periods which may be employed to mitigate the magnitude of the torque ripple component.
The above-described results show that five-phase (or more) versions of quasi square-wave back emf PM synchronous machines can better utilize given amounts of machine copper and iron and drive silicon. A potential 27% improvement may be realized in torque/volume performance of a five phase quasi square-wave back emf machine according to the present invention relative to a similarly sized prior art sinusoidal machine. Having now fully set forth the preferred embodiments and certain modifications of the concept underlying the present invention, various other embodiments as well as certain variations and modifications of the embodiment herein shown
and described will obviously occur to those skilled in the art upon becoming familiar with said underlying concept. It is to be understood, therefore, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically set forth herein.
Claims
1. A permanent magnet radial air gap synchronous machine comprising: a rotor, said rotor further comprising, a cylindrical rotor core, and a plurality of permanent magnets spaced at equal angular intervals around the periphery of said rotor core, a pitch of each of said permanent magnets defining one rotor pole; and a stator for exciting said rotor to move, said stator further comprising, a stator core, and a plurality of stator windings forming N stator phases, N being an odd number > 5, said stator windings each being wound around said stator core to define a plurality of stator poles each having a pitch substantially equal to a pitch of said rotor permanent magnets.
2. The permanent magnet synchronous machine according to claim 1, wherein said number N equals 5.
3. The permanent magnet synchronous machine according to claim 1, wherein said number N equals 7.
4. The permanent magnet synchronous machine according to claim 1, wherein said number N equals 9.
5. The permanent magnet synchronous machine according to claim 1, wherein said stator core further comprises a plurality of salient teeth spaced at equal angular intervals around a central axis, and said stator windings are each wound around a group of said stator teeth to define a stator pole having a pitch substantially equal to a pitch of said rotor permanent magnets.
6. The permanent magnet synchronous machine according to claim 1, wherein said stator windings are each wound within an air gap formed between said stator and said rotor.
7. A permanent magnet axial air gap synchronous machine comprising: a rotor, said rotor further comprising, a rotor core including a plurality of pie- shaped permanent magnet wedges arranged at equal angular intervals around a central axis to define a disk, a pitch of each of said permanent magnets defining one rotor pole; and a stator for exciting said rotor to move, said stator further comprising, at least one stator disk concentrically facing said rotor, and a plurality of stator windings wound around each stator disk to form N stator phases, N being an odd number > 5, and said stator windings being wound around each stator disk to define stator poles having a pitch substantially equal to a pitch of said rotor permanent magnets.
8. The permanent magnet synchronous machine according to claim 7, wherein said number N equals 5.
9. The permanent magnet synchronous machine according to claim 7, wherein said number N equals 7.
10. The permanent magnet synchronous machine according to claim 7, wherein said number N equals 9.
11. The permanent magnet synchronous machine according to claim 7, wherein each stator disk further comprises a plurality of salient teeth extending radially along said stator disk and projecting inwardly toward said rotor, said stator windings each being wound around a group of said stator teeth to define a stator pole having a pitch substantially equal to a pitch of said rotor permanent magnets.
12. The permanent magnet synchronous machine according to claim 7, wherein said stator windings are wound around each stator disk within an air gap formed between said stator disk and said rotor.
13. A permanent magnet synchronous drive system comprising: a permanent magnet back emf radial air gap quasi square- wave motor, said motor further comprising, a rotor having a cylindrical rotor core, and a plurality of permanent magnets spaced at equal angular intervals around the periphery of said rotor core, a pitch of each of said permanent magnets defining one rotor pole, and a stator for exciting said rotor to move, said stator including a stator core and a plurality of stator windings forming N stator phases, N being an odd number ^ 5, said stator windings each being wound around said stator core to define a plurality of stator poles each having a pitch substantially equal to a pitch of said rotor permanent magnets; and a switched voltage source inverter drive circuit for commutating said phases of said stator according to a predetermined commutation sequence, said drive circuit further comprising 2N gated switch devices arranged in N parallely- connected switch legs for connection to an input voltage source, each switch leg having an upper switch device coupled to one of said motor phase windings for driving said phase winding according to a first polarity, and a lower switch device coupled to the one motor phase winding for driving said phase winding according to a second polarity.
14. The permanent magnet synchronous drive system according to claim 13, wherein said number N equals 5.
15. The permanent magnet synchronous drive system according to claim 13, wherein said number N equals 7.
16. The permanent magnet synchronous drive system according to claim 13, wherein said number N equals 9.
17. The permanent magnet synchronous drive system according to claim 14, wherein each of said switch devices of said drive circuit are gated on for an angular intervals of
((N-l) x 180°)/N during said predetermined commutation sequence.
18. The permanent magnet synchronous drive system according to claim 14, wherein each of said switch devices of said drive circuit are gated in a regulated switching pattern for angular intervals of ((N-l) x 180°)/N during said predetermined commutation sequence.
19. The permanent magnet synchronous drive system according to claim 18, wherein said regulated switching pattern is for pulse width modulation (PWM) .
20. The permanent magnet synchronous machine according to claim 14, wherein said stator core further comprises a plurality of salient teeth spaced at equal angular intervals around a central axis, said stator windings each being wound around a group of said stator teeth to define a stator pole having a pitch substantially equal to a pitch of said rotor permanent magnets.
21. The permanent magnet synchronous machine according to claim 14, wherein said stator windings are each wound within an air gap formed between said stator and said rotor.
22. A permanent magnet synchronous drive system comprising: a permanent magnet axial air gap synchronous machine including, a rotor having a rotor core formed of a plurality of pie-shaped permanent magnet wedges arranged at equal angular intervals around a central axis to define a disk, a pitch of each of said permanent magnets defining one rotor pole, and a stator for exciting said rotor to move, said stator further comprising at least one stator disk concentrically facing said rotor and a plurality of stator windings wound around each stator disk to form N stator phases, N being an odd number > 5, and said stator windings being wound around each stator disk to define stator poles having a pitch substantially equal to a pitch of said rotor permanent magnets; and a switched voltage source inverter drive circuit for commutating said phases of said stator according to a predetermined commutation sequence, said drive circuit further comprising 2N gated switch devices arranged in N parallely- connected switch legs for connection to an input voltage source, each switch leg having an upper switch device coupled to one of said motor phase windings for driving said phase winding according to a first polarity, and a lower switch device coupled to the one motor phase winding for driving said phase winding according to a second polarity.
23. The permanent magnet synchronous drive system according to claim 22, wherein said number N equals 5.
24. The permanent magnet synchronous drive system according to claim 22, wherein said number N equals 7.
25. The permanent magnet synchronous drive system according to claim 22, wherein said number N equals 9.
26. The permanent magnet synchronous drive system according to claim 23, wherein each of said switch devices of said drive circuit are gated on for an angular intervals of ((N-l) x 180°)/N during said predetermined commutation sequence.
27. The permanent magnet synchronous drive system according to claim 23, wherein each of said switch devices of said drive circuit are gated in a regulated switching pattern for angular intervals of ((N-l) x 180°)/N during said predetermined commutation sequence.
28. The permanent magnet synchronous drive system according to claim 27, wherein said regulated switching pattern is for pulse width modulation (PWM) .
29. The permanent magnet synchronous machine according to claim 23, wherein each stator disk further comprises a plurality of salient teeth extending radially along said stator disk and projecting inwardly toward said rotor, said stator windings each being wound around a group of said stator disk teeth to define a stator pole having a pitch substantially equal to a pitch of said rotor permanent magnets.
30. The permanent magnet synchronous machine according to claim 23, wherein said stator windings are wound around each stator disk within an air gap formed between said stator disk and said rotor.
31. A linear permanent magnet synchronous machine comprising: a secondary, said secondary further comprising, a linear secondary core, and a plurality of permanent magnets spaced at equal intervals along a surface of said secondary core, a pitch of each of said permanent magnets defining one secondary pole; and a primary for exciting said secondary to move, said primary further comprising, a linear primary core, and a plurality of primary windings forming N primary phases, N being an odd number > 5, said primary windings each being wound around said primary core to define a plurality of primary poles each having a pitch substantially equal to a pitch of said secondary permanent magnets.
32. The permanent magnet synchronous machine according to claim 31, wherein said number N equals 5.
33. The permanent magnet synchronous machine according to claim 31, wherein said number N equals 7.
34. The permanent magnet synchronous machine according to claim 31, wherein said number N equals 9.
35. The permanent magnet synchronous machine according to claim 31, wherein said primary core further comprises a plurality of salient teeth spaced at equal angular intervals along its length, said primary windings each being wound around a group of said primary teeth to define a primary pole having a pitch substantially equal to a pitch of said secondary permanent magnets.
36. The permanent magnet synchronous machine according to claim 31, wherein said primary windings are each wound within an air gap formed between said primary and said secondary.
37. A linear permanent magnet synchronous drive system, comprising: a secondary, said secondary further comprising, a linear secondary core, and a plurality of permanent magnets spaced at equal intervals along a surface of said secondary core, a pitch of each of said permanent magnets defining one secondary pole; a primary for exciting said secondary to move, said primary further comprising, a linear primary core, and a plurality of primary windings forming N primary phases, N being an odd number :> 5, said primary windings each being wound around said primary core to define a plurality of primary poles each having a pitch substantially equal to a pitch of said secondary permanent magnets; and a switched voltage source inverter drive circuit for commutating said phases of said primary according to a predetermined commutation sequence, said drive circuit further comprising 2N gated switch devices arranged in N parallely- connected switch legs for connection to an input voltage source, each switch leg having an upper switch device coupled to one of said motor phase windings for driving said phase winding according to a first polarity, and a lower switch device coupled to the one motor phase winding for driving said phase winding according to a second polarity.
38. The permanent magnet synchronous drive system according to claim 37, wherein said number N equals 5.
39. The permanent magnet synchronous drive system according to claim 37, wherein said number N equals 7.
40. The permanent magnet synchronous drive system according to claim 37, wherein said number N equals 9.
41. The permanent magnet synchronous drive system according to claim 38, wherein each of said switch devices of said drive circuit are gated on for an angular intervals of ((N-l) x 180°)/N during said predetermined commutation sequence.
42. The permanent magnet synchronous drive system according to claim 38, wherein each of said switch devices of said drive circuit are gated in a regulated switching pattern for angular intervals of ((N-l) x 180°)/N during said predetermined commutation sequence.
43. The permanent magnet synchronous drive system according to claim 42, wherein said regulated switching pattern is for pulse width modulation (PWM) .
44. The permanent magnet synchronous machine according to claim 37, wherein each stator disk further comprises a plurality of salient teeth extending radially along said stator disk and projecting inwardly toward said rotor, said stator windings each being wound around a group of said stator disk teeth to define a stator pole having a pitch substantially equal to a pitch of said rotor permanent magnets.
45. The permanent magnet synchronous machine according to claim 37, wherein said stator windings are wound around each stator disk within an air gap formed between said stator disk and said rotor.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU47931/93A AU4793193A (en) | 1992-09-02 | 1993-07-29 | Quasi square-wave back-emf permanent magnet ac machines with five or more phases |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US07/939,123 | 1992-09-02 | ||
US07/939,123 US5394321A (en) | 1992-09-02 | 1992-09-02 | Quasi square-wave back-EMF permanent magnet AC machines with five or more phases |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1994006198A1 true WO1994006198A1 (en) | 1994-03-17 |
Family
ID=25472581
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1993/007154 WO1994006198A1 (en) | 1992-09-02 | 1993-07-29 | Quasi square-wave back-emf permanent magnet ac machines with five or more phases |
Country Status (3)
Country | Link |
---|---|
US (2) | US5394321A (en) |
AU (1) | AU4793193A (en) |
WO (1) | WO1994006198A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2744855A1 (en) * | 1996-02-14 | 1997-08-14 | Koehler Gerard | VARIABLE HYBRID VARIABLE RELUCTANCE DYNAMOELECTRIC MACHINE WITH A VERNER EFFECT AND METHOD OF MANUFACTURE AND CALCULATION |
US6113901A (en) * | 1989-10-27 | 2000-09-05 | Arch Development Corporation | Methods of stimulating or enhancing the immune system with anti-CD3 antibodies |
Families Citing this family (97)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5394321A (en) * | 1992-09-02 | 1995-02-28 | Electric Power Research Institute, Inc. | Quasi square-wave back-EMF permanent magnet AC machines with five or more phases |
US6054837A (en) * | 1994-06-28 | 2000-04-25 | Borealis Technical Limited | Polyphase induction electrical rotating machine |
US5828200A (en) * | 1995-11-21 | 1998-10-27 | Phase Iii | Motor control system for variable speed induction motors |
JP2000504196A (en) * | 1996-01-22 | 2000-04-04 | イリノイ トゥール ワークス インコーポレイティド | Magnetic pole shaft motor |
US5907205A (en) * | 1996-07-08 | 1999-05-25 | Herman; Robert Wayne | Constant reluctance rotating magnetic field devices with laminationless stator |
US6570361B1 (en) | 1999-02-22 | 2003-05-27 | Borealis Technical Limited | Rotating induction apparatus |
US6348751B1 (en) * | 1997-12-12 | 2002-02-19 | New Generation Motors Corporation | Electric motor with active hysteresis-based control of winding currents and/or having an efficient stator winding arrangement and/or adjustable air gap |
KR19990013313A (en) * | 1998-02-11 | 1999-02-25 | 이이수 | Variable Voltage Outputless Rectifier DC Motor |
US6793167B2 (en) | 1999-01-12 | 2004-09-21 | Island Oasis Cocktail Company, Inc. | Food processing apparatus including magnetic drive |
CN100490279C (en) * | 1999-02-10 | 2009-05-20 | 维斯塔斯风力系统公司 | An electric multipole motor/generator with axial magnetic flux |
US6864661B2 (en) * | 1999-02-22 | 2005-03-08 | Borealis Technical Limited | Rotating induction apparatus |
US6922037B2 (en) * | 1999-02-22 | 2005-07-26 | Borealis Technical Limited | Rotating induction apparatus |
US6049149A (en) * | 1999-03-23 | 2000-04-11 | Lin; Shou-Mei | Brushless DC motor having opposed pairs of axial magnetic field type permanent magnets and control system therefor |
US20060038516A1 (en) * | 2001-02-20 | 2006-02-23 | Burse Ronald O | Segmented switched reluctance electric machine with interdigitated disk-type rotor and stator construction |
JP3668938B2 (en) * | 2001-12-11 | 2005-07-06 | 三菱電機株式会社 | Rotating electric machine |
US6930426B2 (en) * | 2003-11-26 | 2005-08-16 | Visteon Global Technologies, Inc. | Alternator stator having a multiple filar construction to improve convective cooling |
US6882077B2 (en) * | 2002-12-19 | 2005-04-19 | Visteon Global Technologies, Inc. | Stator winding having cascaded end loops |
AU2002244205A1 (en) * | 2002-02-25 | 2003-09-09 | Borealis Technical Limited | Polyphase induction electrical rotating machine |
US7982352B2 (en) * | 2002-09-18 | 2011-07-19 | Vestas Wind Systems A/S | Electrical motor/generator having a number of stator pole cores being larger than a number of rotor pole shoes |
JP3582789B2 (en) * | 2002-10-01 | 2004-10-27 | セイコーインスツルメンツ株式会社 | Permanent magnet for motor device, motor device, and magnetization method |
US6995494B2 (en) * | 2002-10-14 | 2006-02-07 | Deere & Company | Axial gap brushless DC motor |
JP2004201487A (en) * | 2002-11-28 | 2004-07-15 | Nsk Ltd | Motor and its drive controlling apparatus |
US20040119359A1 (en) * | 2002-12-19 | 2004-06-24 | Visteon Global Technologies, Inc. | Automotive alternator stator assembly with odd number of electrical turns |
US7190101B2 (en) * | 2003-11-03 | 2007-03-13 | Light Engineering, Inc. | Stator coil arrangement for an axial airgap electric device including low-loss materials |
JP4349089B2 (en) * | 2003-11-10 | 2009-10-21 | 株式会社エクォス・リサーチ | Axial gap rotating electric machine |
US7514833B2 (en) * | 2004-09-03 | 2009-04-07 | Ut-Battelle Llc | Axial gap permanent-magnet machine with reluctance poles and PM element covers |
US7982350B2 (en) | 2004-10-25 | 2011-07-19 | Novatorque, Inc. | Conical magnets and rotor-stator structures for electrodynamic machines |
US8543365B1 (en) | 2004-10-25 | 2013-09-24 | Novatorque, Inc. | Computer-readable medium, a method and an apparatus for designing and simulating electrodynamic machines implementing conical and cylindrical magnets |
US9093874B2 (en) | 2004-10-25 | 2015-07-28 | Novatorque, Inc. | Sculpted field pole members and methods of forming the same for electrodynamic machines |
US8471425B2 (en) | 2011-03-09 | 2013-06-25 | Novatorque, Inc. | Rotor-stator structures including boost magnet structures for magnetic regions having angled confronting surfaces in rotor assemblies |
US8330316B2 (en) | 2011-03-09 | 2012-12-11 | Novatorque, Inc. | Rotor-stator structures including boost magnet structures for magnetic regions in rotor assemblies disposed external to boundaries of conically-shaped spaces |
US8283832B2 (en) | 2004-10-25 | 2012-10-09 | Novatorque, Inc. | Sculpted field pole members and methods of forming the same for electrodynamic machines |
WO2006057317A1 (en) * | 2004-11-24 | 2006-06-01 | Nsk Ltd. | Non-connection motor, its drive control device and mortorized power steering device using drive control device of non-connection motor |
FI118448B (en) * | 2004-12-13 | 2007-11-15 | Kone Corp | Reducing harmonics in an electric motor |
DE102005018323A1 (en) * | 2005-04-20 | 2006-10-26 | Siemens Ag | Ceramic green body, as a piezo stack for sintering by microwaves, has a susceptor at least partially within it to absorb and conduct microwave energy to give shorter sintering times at lower temperatures |
FR2901073B1 (en) * | 2006-05-09 | 2008-07-18 | Gerard Koehler | METHOD FOR PRODUCING A GLOBAL WINDING WITH POLES CONSEQUENT IN WIRE, FOR A ROTARY DYNAMO-ELECTRIC ROTATING MACHINE WITH PLANE AND ANGULARLY DISTRIBUTED PHASE INTERFERS |
FR2901925B1 (en) * | 2006-06-06 | 2008-08-29 | Gerard Koehler | PROCESS FOR PRODUCING A GLOBAL WINDING WITH EFFECTIVE WIRE POLES, FOR AN ANGULAR SECTOR OF A STATOR OF A RELUCTANCE MACHINE WITH CYLINDRICAL AND ANGULARLY DISTRIBUTED PHASE BREAKERS |
WO2007141948A1 (en) * | 2006-06-06 | 2007-12-13 | Honda Motor Co., Ltd. | Motor and motor control device |
JP4169055B2 (en) * | 2006-07-14 | 2008-10-22 | ダイキン工業株式会社 | Rotating electric machine |
US7557482B2 (en) * | 2006-07-31 | 2009-07-07 | Caterpillar Inc. | Axial-flux electric machine |
US20080024035A1 (en) * | 2006-07-31 | 2008-01-31 | Caterpillar Inc. | Power system |
US7710081B2 (en) * | 2006-10-27 | 2010-05-04 | Direct Drive Systems, Inc. | Electromechanical energy conversion systems |
EP2096735A4 (en) * | 2006-12-06 | 2014-07-30 | Honda Motor Co Ltd | Axial gap motor |
JP4394115B2 (en) * | 2006-12-26 | 2010-01-06 | 本田技研工業株式会社 | Axial gap type motor |
JP2008271640A (en) * | 2007-04-17 | 2008-11-06 | Honda Motor Co Ltd | Axial gap motor |
JP4707696B2 (en) * | 2007-06-26 | 2011-06-22 | 本田技研工業株式会社 | Axial gap type motor |
JP4961302B2 (en) * | 2007-08-29 | 2012-06-27 | 本田技研工業株式会社 | Axial gap type motor |
JP4729551B2 (en) | 2007-10-04 | 2011-07-20 | 本田技研工業株式会社 | Axial gap type motor |
US7977843B2 (en) * | 2007-10-04 | 2011-07-12 | Honda Motor Co., Ltd. | Axial gap type motor |
US7906883B2 (en) * | 2008-06-02 | 2011-03-15 | Honda Motor Co., Ltd. | Axial gap motor |
US8049389B2 (en) * | 2008-06-02 | 2011-11-01 | Honda Motor Co., Ltd. | Axial gap motor |
JP4678549B2 (en) | 2008-10-09 | 2011-04-27 | 本田技研工業株式会社 | Axial gap type motor |
US9377061B2 (en) | 2010-12-10 | 2016-06-28 | Means Industries, Inc. | Electromagnetic system for controlling the operating mode of an overrunning coupling assembly and overrunning coupling and control assembly including the system |
US8813929B2 (en) | 2010-12-10 | 2014-08-26 | Means Industries, Inc. | Controllable coupling assembly |
US9638266B2 (en) | 2010-12-10 | 2017-05-02 | Means Industries, Inc. | Electronic vehicular transmission including a sensor and coupling and control assembly for use therein |
US9234552B2 (en) | 2010-12-10 | 2016-01-12 | Means Industries, Inc. | Magnetic system for controlling the operating mode of an overrunning coupling assembly and overrunning coupling and magnetic control assembly having same |
US9435387B2 (en) | 2010-12-10 | 2016-09-06 | Means Industries, Inc. | Device and apparatus for controlling the operating mode of a coupling assembly, coupling and control assembly and electric motor disconnect and pass through assemblies |
US10677296B2 (en) | 2010-12-10 | 2020-06-09 | Means Industries, Inc. | Electronic, high-efficiency vehicular transmission, overrunning, non-friction coupling and control assembly and switchable linear actuator device for use therein |
US9874252B2 (en) | 2010-12-10 | 2018-01-23 | Means Industries, Inc. | Electronic, high-efficiency vehicular transmission, overrunning, non-friction coupling and control assembly and switchable linear actuator device for use therein |
US8888637B2 (en) | 2010-12-10 | 2014-11-18 | Means Industries, Inc. | Vehicle drive system including a transmission |
US9541141B2 (en) | 2010-12-10 | 2017-01-10 | Means Industries, Inc. | Electronic vehicular transmission, controllable coupling assembly and coupling member for use in the assembly |
JP5885214B2 (en) | 2010-12-10 | 2016-03-15 | ミーンズ インダストリーズ,インク. | Electromechanical drive coupler and control assembly |
US9255614B2 (en) | 2010-12-10 | 2016-02-09 | Means Industries, Inc. | Electronic vehicular transmission and coupling and control assembly for use therein |
US8646587B2 (en) | 2010-12-10 | 2014-02-11 | Means Industries, Inc. | Strut for a controllable one-way clutch |
US9186977B2 (en) | 2011-08-26 | 2015-11-17 | Means Industries, Inc. | Drive system including a transmission for a hybrid electric vehicle |
US9441708B2 (en) | 2010-12-10 | 2016-09-13 | Means Industries, Inc. | High-efficiency drive system including a transmission for a hybrid electric vehicle |
US9303699B2 (en) | 2010-12-10 | 2016-04-05 | Means Industries, Inc. | Electromechanical assembly to control the operating mode of a coupling apparatus |
US9127724B2 (en) | 2010-12-10 | 2015-09-08 | Means Industries, Inc. | Electromechanical apparatus for use with a coupling assembly and controllable coupling assembly including such apparatus |
DE202012012653U1 (en) * | 2011-01-25 | 2013-07-26 | Coriolis Power Systems Ltd. | Electric axial flow machine |
US9933049B2 (en) | 2012-10-04 | 2018-04-03 | Means Industries, Inc. | Vehicle drive system including a transmission |
US9371868B2 (en) | 2013-08-27 | 2016-06-21 | Means Industries, Inc. | Coupling member subassembly for use in controllable coupling assembly and electromechanical apparatus having a pair of simultaneously actuated elements for use in the subassembly |
US10533618B2 (en) | 2013-09-26 | 2020-01-14 | Means Industries, Inc. | Overrunning, non-friction coupling and control assembly, engageable coupling assembly and locking member for use in the assemblies |
US9562574B2 (en) | 2014-02-19 | 2017-02-07 | Means Industries, Inc. | Controllable coupling assembly and coupling member for use in the assembly |
US9482294B2 (en) | 2014-02-19 | 2016-11-01 | Means Industries, Inc. | Coupling and control assembly including a sensor |
DE102014203550A1 (en) * | 2014-02-27 | 2015-08-27 | Robert Bosch Gmbh | Electric drive system |
US10619681B2 (en) | 2014-09-16 | 2020-04-14 | Means Industries, Inc. | Overrunning, non-friction coupling and control assemblies and switchable linear actuator device and reciprocating electromechanical apparatus for use therein |
US9482297B2 (en) | 2015-04-01 | 2016-11-01 | Means Industries, Inc. | Controllable coupling assembly having forward and reverse backlash |
JP2018529302A (en) | 2015-08-11 | 2018-10-04 | ジェネシス ロボティクス エルエルピー | Electric machine |
US11139707B2 (en) | 2015-08-11 | 2021-10-05 | Genesis Robotics And Motion Technologies Canada, Ulc | Axial gap electric machine with permanent magnets arranged between posts |
US11043885B2 (en) | 2016-07-15 | 2021-06-22 | Genesis Robotics And Motion Technologies Canada, Ulc | Rotary actuator |
EP3577362B1 (en) | 2017-02-02 | 2023-07-12 | Means Industries, Inc. | Reciprocating electromechanical apparatus |
US11035423B2 (en) | 2017-02-02 | 2021-06-15 | Means Industries, Inc. | Non-friction coupling and control assembly, engageable coupling assembly and locking member for use in the assemblies |
US10590999B2 (en) | 2017-06-01 | 2020-03-17 | Means Industries, Inc. | Overrunning, non-friction, radial coupling and control assembly and switchable linear actuator device for use in the assembly |
JP2020524477A (en) * | 2017-06-30 | 2020-08-13 | 広東美芝制冷設備有限公司 | Permanent magnet motor, compressor and refrigeration system |
US10651770B2 (en) | 2018-08-29 | 2020-05-12 | Hamilton Sundstrand Corporation | Direct current voltage regulation of a six-phase permanent magnet generator |
US10778127B2 (en) * | 2018-09-10 | 2020-09-15 | Hamilton Sundstrand Corporation | Direct current voltage regulation of permanent magnet generator |
US10855216B2 (en) | 2018-09-10 | 2020-12-01 | Hamilton Sundstrand Corporation | Voltage regulation of multi-phase permanent magnet generator |
CN112888871B (en) | 2018-10-04 | 2022-11-15 | 敏思工业公司 | Coupler and controller assembly with internal latching mechanism |
US11646618B2 (en) | 2018-10-31 | 2023-05-09 | Optiphase Drive Systems, Inc. | Electric machine with permanent magnet rotor |
US10995803B2 (en) | 2018-12-04 | 2021-05-04 | Means Industries, Inc. | Electromagnetic system for controlling the operating mode of a non friction coupling assembly and coupling and magnetic control assembly having same |
WO2020163686A1 (en) | 2019-02-08 | 2020-08-13 | Means Industries, Inc. | Non-friction coupling and control assembly, engageable coupling assembly and locking member for use in the assemblies |
US11215245B2 (en) | 2019-12-03 | 2022-01-04 | Means Industries, Inc. | Coupling and control assembly including controllable coupling assembly having speed sensor and methods of controlling the controllable coupling assembly using information from the speed sensor for park/hill-hold operations |
US11286996B2 (en) | 2020-02-12 | 2022-03-29 | Means Industries, Inc. | Electro-dynamic coupling and control assembly and switchable linear actuator device for use therein |
DE102021107969A1 (en) | 2020-03-31 | 2021-09-30 | Means Industries, Inc. | COUPLING AND CONTROL UNIT WITH A CONTACTLESS, INDUCTIVE POSITION SENSOR |
DE102021104228A1 (en) | 2020-03-31 | 2021-09-30 | Means Industries, Inc. | Coupling and control arrangement with a non-contact, linear inductive position sensor |
US11542992B2 (en) | 2020-03-31 | 2023-01-03 | Means Industries, Inc. | Coupling and control assembly including a non-contact, linear inductive position sensor |
US11874142B2 (en) | 2020-03-31 | 2024-01-16 | Means Industries, Inc. | Coupling and control assembly including a position sensor |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4918346A (en) * | 1987-06-26 | 1990-04-17 | Hitachi, Ltd. | Low ripple-torque permanent magnet brushless motor |
US5019766A (en) * | 1986-07-22 | 1991-05-28 | University Of Texas | Method and apparatus for improving performance of AC machines |
US5023495A (en) * | 1990-04-17 | 1991-06-11 | Hitachi Metals & Shicoh Engine | Moving-magnet type linear d.c. brushless motor having plural moving elements |
US5023496A (en) * | 1985-10-28 | 1991-06-11 | Sony Corporation | Linear motor |
US5128570A (en) * | 1991-06-24 | 1992-07-07 | Japan Servo Co., Ltd. | Permanent magnet type stepping motor |
Family Cites Families (29)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3860843A (en) * | 1970-06-26 | 1975-01-14 | Matsushita Electric Ind Co Ltd | Rotating electric machine with reduced cogging |
US3809936A (en) * | 1972-05-18 | 1974-05-07 | E Klein | Brushless generator |
DE2337905A1 (en) * | 1973-07-26 | 1975-02-13 | Gerhard Berger Fabrikation Ele | SELF-STARTING SYNCHRONOUS MOTOR WITH PERMANENT MAGNETIC RUNNING |
DE2342994A1 (en) * | 1973-08-25 | 1975-03-20 | Gerhard Berger Fabrikation Ele | FIVE PHASE STEPPER MOTOR |
DE2526564C2 (en) * | 1975-06-13 | 1985-03-07 | Gerhard Berger GmbH & Co KG Fabrik elektrischer Geräte, 7630 Lahr | Stepper motor with five stator windings |
US4025810A (en) * | 1975-08-29 | 1977-05-24 | Sigma Instruments, Inc. | Low noise synchronous motors |
US4190779A (en) * | 1976-05-04 | 1980-02-26 | Ernest Schaeffer | Step motors |
JPS5378011A (en) * | 1976-12-21 | 1978-07-11 | Mitsubishi Electric Corp | Electric valve feeding motor apparatus commutated by internal electromotive force |
US4363988A (en) * | 1978-06-12 | 1982-12-14 | General Electric Company | Induction disk motor with metal tape components |
DE2940637A1 (en) * | 1979-10-06 | 1981-04-16 | Philips Patentverwaltung Gmbh, 2000 Hamburg | DC MOTOR WITH ELECTRONIC COMMUTATION CIRCUIT |
US4321495A (en) * | 1980-04-21 | 1982-03-23 | Veeder Industries, Inc. | Rotary pulse generator |
US4361791A (en) * | 1981-05-12 | 1982-11-30 | General Electric Company | Apparatus for controlling a PWM inverter-permanent magnet synchronous motor drive |
US4645961A (en) * | 1983-04-05 | 1987-02-24 | The Charles Stark Draper Laboratory, Inc. | Dynamoelectric machine having a large magnetic gap and flexible printed circuit phase winding |
DE3476497D1 (en) * | 1983-05-02 | 1989-03-02 | Weh Herbert | Electric drive |
JPH0667257B2 (en) * | 1984-04-16 | 1994-08-24 | ファナック株式会社 | Synchronous motor control method |
US4874975A (en) * | 1984-11-13 | 1989-10-17 | Digital Equipment Corporation | Brushless DC motor |
GB8501215D0 (en) * | 1985-01-17 | 1985-02-20 | Dowty Fuel Syst Ltd | Alternating-current electrical generator |
US4745312A (en) * | 1986-01-09 | 1988-05-17 | Kabushiki Kaisha Yaskawa Denki Seisakusho | Stepping motor |
US4928042A (en) * | 1986-03-22 | 1990-05-22 | Robert Bosch Gmbh | Circuit arrangement for operating a multi-phase synchronous motor on a direct-voltage system |
JPS633638A (en) * | 1986-06-23 | 1988-01-08 | Tamagawa Seiki Co Ltd | Brushless dc motor |
US4739239A (en) * | 1986-11-10 | 1988-04-19 | Seagate Technology, Inc. | Bipolar motor control |
KR890004099B1 (en) * | 1987-04-22 | 1989-10-20 | 이이수 | D.c. multi-phase bi-polar brushless motor |
JP2645655B2 (en) * | 1987-11-14 | 1997-08-25 | 株式会社日立ビルシステム | Control device for permanent magnet synchronous motor |
IT1233424B (en) * | 1987-12-14 | 1992-03-31 | Sgs Microelettronica Spa | BOOSTER CIRCUIT FOR DIGITAL CIRCUITS. |
GB8817760D0 (en) * | 1988-07-26 | 1988-09-01 | Rolls Royce Plc | Electrical power generator |
US5059883A (en) * | 1989-06-29 | 1991-10-22 | Kabushiki Kaisha Toshiba | Method and apparatus for driving stepping motor |
US5280209A (en) * | 1989-11-14 | 1994-01-18 | The United States Of America As Represented By The Secretary Of The Army | Permanent magnet structure for use in electric machinery |
SE9002420L (en) * | 1990-07-12 | 1992-01-13 | Skf Ab | CONVERTER 3 |
US5394321A (en) * | 1992-09-02 | 1995-02-28 | Electric Power Research Institute, Inc. | Quasi square-wave back-EMF permanent magnet AC machines with five or more phases |
-
1992
- 1992-09-02 US US07/939,123 patent/US5394321A/en not_active Expired - Fee Related
-
1993
- 1993-07-29 AU AU47931/93A patent/AU4793193A/en not_active Abandoned
- 1993-07-29 WO PCT/US1993/007154 patent/WO1994006198A1/en active Application Filing
-
1994
- 1994-07-27 US US08/281,232 patent/US5642009A/en not_active Expired - Fee Related
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5023496A (en) * | 1985-10-28 | 1991-06-11 | Sony Corporation | Linear motor |
US5019766A (en) * | 1986-07-22 | 1991-05-28 | University Of Texas | Method and apparatus for improving performance of AC machines |
US4918346A (en) * | 1987-06-26 | 1990-04-17 | Hitachi, Ltd. | Low ripple-torque permanent magnet brushless motor |
US5023495A (en) * | 1990-04-17 | 1991-06-11 | Hitachi Metals & Shicoh Engine | Moving-magnet type linear d.c. brushless motor having plural moving elements |
US5128570A (en) * | 1991-06-24 | 1992-07-07 | Japan Servo Co., Ltd. | Permanent magnet type stepping motor |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6113901A (en) * | 1989-10-27 | 2000-09-05 | Arch Development Corporation | Methods of stimulating or enhancing the immune system with anti-CD3 antibodies |
FR2744855A1 (en) * | 1996-02-14 | 1997-08-14 | Koehler Gerard | VARIABLE HYBRID VARIABLE RELUCTANCE DYNAMOELECTRIC MACHINE WITH A VERNER EFFECT AND METHOD OF MANUFACTURE AND CALCULATION |
EP0790695A1 (en) * | 1996-02-14 | 1997-08-20 | KOEHLER, Gérard | Hybrid dynamo-electric variable reluctance machine and manufacturing and calculation method |
Also Published As
Publication number | Publication date |
---|---|
AU4793193A (en) | 1994-03-29 |
US5394321A (en) | 1995-02-28 |
US5642009A (en) | 1997-06-24 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US5394321A (en) | Quasi square-wave back-EMF permanent magnet AC machines with five or more phases | |
RU2313880C1 (en) | Motor with constant magnets | |
Toliyat et al. | Analysis of a concentrated winding induction machine for adjustable speed drive applications. I. Motor analysis | |
Wang et al. | Three-phase flux reversal machine (FRM) | |
EP2412091B1 (en) | Electric motor system | |
JP3212310B2 (en) | Multi-phase switching type reluctance motor | |
US5825112A (en) | Doubly salient motor with stationary permanent magnets | |
US6078122A (en) | Reluctance machine with fractional pitch winding and drive therefore | |
US4161680A (en) | AC rotary machine apparatus | |
KR101781382B1 (en) | Design improvements for flux switching machines | |
JPH09500517A (en) | Torque notch minimization method for quasi-square wave back-EMF permanent magnet synchronous machine with voltage source drive | |
US6787958B1 (en) | Electrical machines | |
EP0959555A2 (en) | Operation of switched reluctance machines | |
JP2015509697A (en) | Synchronous electrical machine | |
Lipo et al. | Comparison of AC motors to an ideal machine part II—non-sinusoidal AC machines | |
US4218646A (en) | AC Feeding apparatus and rotating field apparatus having AC feeding apparatus | |
Goplarathnam et al. | Development of low cost multi-phase brushless DC (BLDC) motors with unipolar current excitations | |
JPH08182280A (en) | Generator | |
Moghbelli et al. | Performance review of ac adjustable drives | |
Ooi et al. | Optimal winding design of a permanent magnet motor for self-controlled inverter operation | |
JP2518206B2 (en) | Winding method of brushless DC linear motor | |
US10469003B2 (en) | Rotating electric machine | |
Boldea et al. | Low-speed flux-reversal machines: Pole-face versus inset PM stators | |
Gray et al. | GTO thyristor commutation of DC machine | |
De Buck | Design adaptation of inverter-supplied induction motors |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): AU CA JP |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE |
|
DFPE | Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101) | ||
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
122 | Ep: pct application non-entry in european phase | ||
NENP | Non-entry into the national phase |
Ref country code: CA |