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For a three-winding motor, a starting capacitor bank provides balanced currents in the windings, a high starting torque, and unity power-factor current in the single-phase supply line. A run-capacitor bank provides full-load balanced currents and a leading power-factor in the single-phase supply line. The method is applicable to a star or wye winding connection, to a delta winding connection, and to a Semihex.TM. winding connection.

Inventor: Otto J. M. Smith
Current U.S. Classification: 318/786; 318/781; 318/794
International Classification: H02P 142

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Citations

Cited PatentFiling dateIssue dateOriginal AssigneeTitle
US4066937Jan 13, 1976Jan 3, 1978Lennox Industries, Inc.Control circuit for a two speed single phase motor
US4378520Feb 9, 1981Mar 29, 1983D-C Relay relief control for A-C electric motor
US4642545Sep 13, 1985Feb 10, 1987Static phase conversion circuits for three-phase motors
US4675565Jun 2, 1986Jun 23, 1987Capacitor-start parallel resonant motor
US4792740Aug 14, 1987Dec 20, 1988Three-phase induction motor with single phase power supply
US4862053Aug 7, 1987Aug 29, 1989Reliance Electric CompanyMotor starting circuit
US5017853Feb 27, 1990May 21, 1991Rexnord CorporationSpikeless motor starting circuit
US5252904Nov 2, 1992Oct 12, 1993General Binding CorporationAuto reverse circuit
US5300870Apr 10, 1992Apr 5, 1994Three-phase motor control
US5545965Jul 25, 1994Aug 13, 1996Three phase motor operated from a single phase power supply and phase converter

Referenced by

Citing PatentFiling dateIssue dateOriginal AssigneeTitle
US6788031Jan 24, 2002Sep 7, 2004Induction generator system and method
US6894455Apr 30, 2003May 17, 2005Remy Inc.Performance improvement of integrated starter alternator by changing stator winding connection
US7023167May 2, 2002Apr 4, 2006Control arrangement for an induction motor compressor having at least three windings, a torque-augmentation circuit a starting capacitor and a resistive element
US7408321Jan 20, 2006Aug 5, 2008Control arrangement for an induction motor compressor having at least three windings, a torque-augmentation circuit, a starting capacitor and a resistive element
US7612519Jan 20, 2006Nov 3, 2009Control arrangement for an induction motor compressor having at least three windings, a torque-augmentation circuit, a starting capacitor and a resistive element
US7821146Dec 14, 2005Oct 26, 2010Robert Bosch GmbHParallel starting system having a low wiring expenditure
US7843166Jun 23, 2009Nov 30, 2010MERSTech, Inc.Alternating-current power supply device recovering magnetic energy
US7874788Feb 24, 2005Jan 25, 2011Clean Current Limited PartnershipFlow enhancement for underwater turbine
US8022567Dec 4, 2008Sep 20, 2011Clean Current Limited PartnershipUnderwater ducted turbine
US8222792Feb 7, 2007Jul 17, 2012Clean Current Limited PartnershipAxial air gap machine having stator and rotor discs formed of multiple detachable segments

Claims

1. In an electrical alternating-current motor driven by a single phase power supply and having at least three motor windings of different phases, a multipole starting contactor and a plurality of starting capacitors including switching means operable during the starting sequence where a first starting capacitor is connected in parallel with a first motor winding, and a second starting capacitor is connected in parallel with a second motor winding.

2. A three-winding electrical motor as in claim 1, with a plurality of motor terminals, said single-phase power supply having two supply terminals, a transformer with three transformer terminals, means to connect a first supply terminal to a first motor terminal, means to connect a second supply terminal to a second motor terminal, a first transformer terminal connected to said second motor terminal, a second transformer terminal connected to a third motor terminal wherein said first starting capacitor is connected between said first motor terminal and said third motor terminal and wherein said second starting capacitor is connected between said second motor terminal and said third motor terminal, and a motor-run capacitor connected between said first motor terminal and a third transformer terminal.

3. A three-winding electrical motor as in claim 2, a third starting capacitor connected between said second motor terminal and said first motor terminal.

4. An electrical motor as in claim 1, with a third starting capacitor which is connected in parallel with a third motor winding.

5. A motor as in claim 4, with a plurality of motor terminals, said single phase power supply having two lines, there being six of the said motor windings, at least three motor windings of different voltage phases, means to connect four of the said windings in series, a first winding connected between a first terminal and a second terminal, a second winding connected between said second terminal and a third terminal, a third winding connected between said third terminal and a fourth terminal, a fourth winding connected between said fourth terminal and a fifth terminal, said first starting capacitor connected between said first terminal and said second terminal, said second starting capacitor connected between said fourth terminal and said fifth terminal, means for said third starting capacitor to be connected between said second terminal and said fourth terminal, one line of said single-phase power supply connected to said first terminal, and the other line of said single-phase power supply connected to said fifth terminal.

6. A motor as in claim 4, wherein said motor has four terminals, a first motor winding connected between a first and a second terminal, a second motor winding connected between said second terminal and a third terminal, a third motor winding connected between said third terminal and a fourth terminal, where said first starting capacitor is connected between said first terminal and said third terminal, said second starting capacitor is connected between said third terminal and said second terminal, said third starting capacitor is connected between said second terminal and said third terminal, one line of said single-phase power supply is connected to said second terminal, and electrical circuit means between said other line of said single-phase power supply and said fourth terminal.

7. An alternating-current motor starter as in claim 6 for a three-winding motor including a series capacitor, said motor windings connected in series with 120.degree. phase differences with the said four sequential motor terminals 1, 2, 3 and 4, said series capacitor being the said electrical circuit means between said other line of said single-phase power supply and said terminal four.

8. A starter as in claim 7, with third and fourth starting capacitors, said third starting capacitor connected between motor terminals 2 and 4, and said fourth starting capacitor connected between motor terminals 3 and 4.

9. A starter as in claim 8, with a fifth starting capacitor connected between motor terminals 2 and 1.

10. A starter as in claim 8, wherein said third starting capacitor capacitance is selected to make the impedance between motor terminals 2 and 4 resistive.

11. A starter as in claim 7, wherein the capacitance of said series capacitor is chosen so that the voltage between motor terminals 1 and 3 is less than the voltage between the two lines of the said power supply.

12. A motor as in claim 4, wherein one terminal of said first capacitor is connected to one terminal of said second capacitor, the other terminal of said first capacitor is called "one available" terminal, the other terminal of said second capacitor is called "another available" terminal and wherein a fourth starting capacitor is connected between the said one and another available terminals of the series circuit formed by the said first capacitor and the said second capacitor.

13. An electrical motor as in claim 1 having a reduced-voltage starting circuit wherein said three motor windings are connected in series, a first motor winding being connected between a first and a second terminal, a second motor winding being connected between said second terminal and a third terminal, a third motor winding being connected between said third terminal and a fourth terminal, said single-phase power supply having two lines, where said first capacitor is connected between said first terminal and said second terminal, a third capacitor is connected between said first terminal and said third terminal, a fourth capacitor is connected between said second terminal and said fourth terminal, said second capacitor is connected between said third terminal and said fourth terminal, one line of the said supply is connected to said first terminal, and the other line of the said supply is connected to said fourth terminal.

14. A motor as in claim 13, including a first motor-run capacitor connected between said first terminal and said fourth terminal, and a second motor-run capacitor connected between said second terminal and said third terminal.

15. A motor as in claim 1, wherein said second motor winding is a series circuit of a plurality of motor windings.

16. In an electrical alternating-current motor as in claim 1, wherein said motor has three motor terminals, a first individual motor winding connected between a first motor terminal and a second motor terminal, a second individual motor winding connected between the said second motor terminal and a third motor terminal, said first starting capacitor being a switchable temporarily-connected intermittent-duty capacitor connected between said first and said second motor terminals, and said second starting capacitor being a switchable temporarily-connected intermittent-duty capacitor connected between said first motor terminal and said third motor terminal.

17. An electrical motor as in claim 16, with a third switchable temporarily-connected intermittent-duty starting capacitor connected between said second motor terminal and said third motor terminal.

18. An electrical motor as in claim 16, with a fourth motor terminal, a third individual motor winding connected between said fourth motor terminal and one of the other said motor terminals, with a third switchable temporarily-connected intermittent-duty starting capacitor connected between said fourth motor terminal and one of the other said motor terminals.

19. An electrical motor as in claim 16, said single-phase power supply having two supply terminals, means to connect one of said motor terminals to a first supply terminal, a fourth motor terminal, a third individual motor winding connected between said fourth motor terminal and one of the other said motor terminals, means to connect said fourth motor terminal to a second supply terminal, and means to connect said third switchable temporarily-connected intermittent-duty starting capacitor between said fourth motor terminal and one of the other said motor terminals.

20. An electrical motor as in claim 17, with a third individual motor winding connected between said third motor terminal and a fourth motor terminal, with a fourth starting capacitor connected between said first terminal and said fourth terminal.

21. An electrical motor as in claim 16, with a third individual motor winding connected between said third motor terminal and a fourth motor terminal, with a third starting capacitor connected between said fourth motor terminal and one of the other said motor terminals.

22. An electrical motor as in claim 16, with a plurality of motor terminals, said single-phase power supply having two supply terminals, a transformer with three transformer terminals, means to connect a first supply terminal to said third motor terminal, means to connect a second supply terminal to said second motor terminal, a first transformer terminal connected to said first motor terminal, a second transformer terminal connected to said second motor terminal, and a third capacitor connected between said third motor terminal and a third transformer terminal.

23. An electrical motor as in claim 16, with a plurality of motor terminals, said single-phase power supply having three terminals, a transformer with three transformer terminals, means to connect a first supply terminal to said first motor terminal, means to connect a second supply terminal to said second motor terminal, means to connect a third capacitor between said third motor terminal and a third supply terminal, means to connect a first transformer terminal to said second motor terminal, means to connect a second transformer terminal to said third motor terminal, and means to connect a fourth capacitor between said first motor terminal and said third transformer terminal.

24. An electrical motor as in claim 17, with a third individual motor winding connected between said third motor terminal and a fourth motor terminal, with a fourth starting capacitor connected between said fourth motor terminal and one of the other said motor terminals.

25. An electrical alternating-current motor as in claim 16 driven by a grounded center-tap single phase power supply including a fourth motor terminal said single-phase power supply having three supply terminals, means to connect a first motor terminal to a first supply terminal, means to connect a second motor terminal to a second supply terminal, and means to connect a third starting capacitor between said fourth motor terminal and said third supply terminal.

26. A motor as in claim 25, with a fourth starting capacitor connected between said second motor terminal and said fourth motor terminal.

27. A motor as in claim 1, including a single-phase power supply with a grounded center-tap and two other lines, three individual motor windings being connected in series forming a sequence of four motor terminals, a first individual motor winding connected between the first and second motor terminals, a second individual motor winding connected between the said second motor terminal and the third motor terminal, a third individual motor winding connected between the said third motor terminal and a fourth motor terminal, said first motor winding being identical to the said second individual motor winding, said second motor winding being the series connection of said first individual motor winding and said second individual motor winding, a first inductor connected between said first motor terminal and said second motor terminal, and a second inductor connected between said third motor terminal and said grounded center-tap.

28. A motor as in claim 27, including a first motor-run capacitor connected between said first motor terminal and said fourth motor terminal, and a second motor-run capacitor connected between said second motor terminal and said third motor terminal.

29. A motor as in claim 28, including a third switchable temporarily-connected intermittent-duty starting capacitor connected between said first motor terminal and said third motor terminal.

30. In an a-c electrical motor driven by a grounded center-tap single phase power supply and having at least three motor windings of different phases with four motor terminals, said single-phase supply having three terminals, means to connect a first capacitor between a first motor terminal and a second motor terminal, means to connect a first supply terminal to said first motor terminal, means to connect a second capacitor between said second motor terminal and a third motor terminal, means to connect a third capacitor between said third motor terminal and a second supply terminal which is said center-tap, and means to connect a fourth motor terminal to a third supply terminal.

31. A motor as in claim 30, wherein a fourth capacitor is connected between said fourth motor terminal and said first motor terminal.

32. A motor as in claim 30, wherein the supply voltage magnitude between said third supply terminal and said second supply terminal is approximately equal to the supply voltage magnitude between said second supply terminal and said first supply terminal.

33. In an a-c electrical motor driven by a single phase power supply and having at least three motor windings of different phases, said single-phase supply having two terminals, an inductor and a capacitor, a first winding terminal connected to a first supply terminal, a second winding terminal connected to a second supply terminal, the inductor connected between a third winding terminal and said first supply terminal, and the capacitor connected between said second winding terminal and said third winding terminal.

34. An electrical motor as in claim 33, including a second capacitor and a second inductor, a three-terminal single-phase supply, said second capacitor connected between said first winding terminal and a fourth winding terminal, and said second inductor connected between said fourth winding terminal and a third terminal of the single-phase supply.

35. An alternating-current motor having a two-line single-phase power supply, the motor having at least three motor windings of different phases, said motor windings connected in series with four sequential motor terminals 1, 2, 3 and 4, means to connect a first line of said power supply to the first motor terminal 1, means to connect the second line of said power supply to motor terminal 3, means to connect a first capacitor between motor terminal 1 and motor terminal 4, and switchable means to temporarily connect a starting capacitor during starting between motor terminal 3 and motor terminal 4.

36. A motor as in claim 35, wherein said means to connect a starting capacitor is a switchable means which connects said starting capacitor only during the starting transient.

37. A motor as in claim 35, including a timer, wherein said means to connect a starting capacitor is a switchable means which disconnects said starting capacitor after a preselected time interval.

38. A motor as in claim 31, wherein said means to connect a starting capacitor is a switchable means to disconnect said starting capacitor when the motor shaft speed exceeds a preselected value.

39. A motor as in claim 35, a current-sensing means, wherein said means to connect a starting capacitor is a switchable means to disconnect said starting capacitor when the magnitude of the current sensed in one of the windings is less than a preselected value.

40. A motor as in claim 35, with a second starting capacitor, and means to connect said second starting capacitor between motor terminal 3 and one other motor terminal.

41. A motor as in claim 35, with a second starting capacitor, and means to connect said second starting capacitor between motor terminal 2 and one other motor terminal.

42. A motor as in claim 35, wherein the phase of the phasor voltage from terminal 1 to terminal 2 leads the phase of the phasor voltage from terminal 2 to terminal 3 by more than 20 degrees.

43. A motor as in claim 35, wherein the phase of the phasor voltage from terminal 2 to terminal 3 leads the phase of the phasor voltage from terminal 3 to terminal 4 by less than 75 degrees.

44. An alternating-current motor with three motor windings with different voltage phases, three motor terminals, a three-terminal autotransformer, a single-phase supply with at least two lines, a first line connected to a first motor terminal, a second line connected to a second motor terminal, one terminal of said autotransformer connected to said second motor terminal, a second terminal of said autotransformer connected to a third motor terminal, a motor-run capacitor connected between the third terminal of said autotransformer and the said first motor terminal, and a plurality of switchable temporarily-connected intermittent-duty starting capacitors, one of said starting capacitors connected between said first and said third motor terminals.

45. A motor as in claim 44, including a second starting capacitor connected between said second and said third motor terminals.

46. A motor as in claim 44, including a second starting capacitor connected between said first and said second motor terminals.

47. A motor as in claim 45, including a third starting capacitor connected between said first and said second motor terminals.

48. An alternating-current motor as in claim 44, said single-phase supply having a grounded center-tap in addition to the other said two lines, and a second starting capacitor connected between said third motor terminal and said grounded center-tap.

49. A motor as in claim 48, including a third starting capacitor connected between said first motor terminal and said second motor terminal.

50. A motor as in claim 49, wherein each of said starting capacitors is a switchable temporarily-connected intermittent-duty starting capacitor.

Drawings