WO2011160383A1

WO2011160383A1 - Dc-dc converting circuit

Info

Publication number: WO2011160383A1
Application number: PCT/CN2010/078763
Authority: WO
Inventors: 姚晓莉; 葛良安
Original assignee: 英飞特电子（杭州）有限公司
Priority date: 2010-06-24
Filing date: 2010-11-16
Publication date: 2011-12-29
Also published as: CN102299633A; CN102299633B

Abstract

A DC-DC converting circuit includes a switch (S1), a transformer (Ta), a first capacitor (C1), a first diode (D1), a second diode (D2), a third diode (D3), a fourth diode (D4), a first inductor (L1) and a filtering capacitor (C2). The dotted terminal of the primary winding of the transformer (Ta) is connected to a positive terminal of a power supply (Vdc). The synonym terminal of the primary winding of the transformer (Ta) is connected to the negative terminal of the power supply (Vdc) through the switch (S1). The dotted terminal of the secondary winding of the transformer (Ta) is connected to the synonym terminal of the secondary winding of the transformer (Ta) through the first capacitor (C1), the third diode (D3), the first inductor (L1), the filtering capacitor (C2) and the second diode (D2) which are sequentially connected in series. The synonym terminal of the secondary winding of the transformer (Ta) is connected to the dotted terminal of the secondary winding of the transformer (Ta) through the first diode (D1), the filtering capacitor (C2), the fourth diode (D4) and the first capacitor (C1) which are sequentially connected in series. The circuit benefits the reduction of the volume of the transformer and the capacitance of the filtering capacitor. By the presence of the first capacitor, the volt-second balance of the transformer and the equalization of the average value of the forward current and the backward current of the secondary winding in the transformer are guaranteed.

Description

DC-DC conversion circuit The present application claims priority to Chinese Patent Application No. 201010213644.0, entitled "DC-DC Conversion Circuit", filed on June 24, 2010, the entire contents of which is hereby incorporated by reference. This is incorporated herein by reference.

Technical field

The present invention relates to the field of power electronics, and in particular, to a DC-DC conversion circuit.

Background technique

A DC-DC converter circuit is used to power the DC load. The DC-DC conversion circuit of the prior art will be described in detail below with reference to the accompanying drawings.

Referring to Fig. 1, there is shown a block diagram of a DC-DC conversion circuit in the prior art.

The DC-DC conversion circuit is a paper published in the second issue of "Electronic Electronic Technology" in 1998. The primary side flyback circuit includes a forward transformer T2, a flyback transformer T1, a switching transistor VI, a first diode VD1, a second diode VD2, a capacitor Co and a resistor Ro, and also includes a third diode The circuit composed of the tube VD3, the fourth diode VD4, the inductor Ls, and the capacitor Cs constitutes a reset circuit of the forward transformer T2.

When the switch VI is turned on, the forward transformer T2 supplies power to the load through the second diode VD2 and the capacitor Co. When the switch VI is turned off, the flyback transformer T1 passes through the first diode VD1 and the capacitor Co as a load. powered by. The advantage of this circuit is that it can utilize the function of realizing the forward flyback circuit. During the turn-on and turn-off of the switch, energy is output to the load, thereby providing energy utilization. However, this circuit also has disadvantages. This circuit requires two transformers and a reset circuit of the forward transformer T2. Therefore, the circuit structure is complicated and the cost is high.

Referring to Figure 2, there is shown a block diagram of another DC-DC conversion circuit in the prior art.

The circuit shown in Figure 2 is in the paper published in the second issue of Power Electronics Technology in 2000. The circuit includes a switching transistor VS, a transformer, a first diode VD1, a second diode VD2, and a third diode. VD3, fourth diode VD4, inductor Lo and capacitor Co.

When the switch VS is turned on, the first diode VD1, the fourth diode VD4, the inductor Lo, and the capacitor Co supply power to the load, and the circuit operates in the forward mode. When the switch VS is turned off, the second diode VD2, the third diode VD3, and the capacitor Co supply power to the load, and the circuit operates in the flyback mode. The circuit Only one transformer can be used to output energy to the load when the switch is turned on and off, achieving two-way utilization of energy. The current of the inductor Lo in the circuit is in the discontinuous mode, and the relationship between the output voltage and the input voltage is: Vo=DVin/[n(lD)], and D is the duty ratio of the switching transistor VS. The disadvantage of this circuit is that the current of the inductor Lo can only work in the discontinuous mode. If the transformer is in continuous mode, the transformer will be unbalanced in volts, causing the core to deviate and cannot be reset. The average current in the positive and negative directions of the secondary winding of the transformer cannot be guaranteed. The values are equal.

Summary of the invention

The technical problem to be solved by the present invention is to provide a DC-DC conversion circuit capable of ensuring the volt-second balance of the transformer and the average values of the currents in the positive and negative directions of the secondary winding of the transformer are equal.

The present invention provides a DC-DC conversion circuit, including: a switching transistor, a transformer, a first capacitor, a first diode, a second diode, a third diode, a fourth diode, a first inductor, and a filter capacitor; the same name end of the primary winding of the transformer is connected to the positive pole of the power source, and the opposite end is connected to the negative pole of the power source through the switch tube;

The same-name end of the secondary winding of the transformer is sequentially connected to the different end of the secondary winding through the first capacitor, the third diode, the first inductor, the filter capacitor and the second diode connected in series;

The different end of the secondary winding of the transformer is sequentially connected to the same name end of the secondary winding through the first diode, the filter capacitor, the fourth diode and the first capacitor connected in series.

Preferably, the method includes: a switch tube, a transformer, a first capacitor, a first diode, a second diode, a third diode, a fourth diode, a first inductor, and a filter capacitor;

The same name end of the primary winding of the transformer is connected to the positive pole of the power source, and the opposite end is connected to the negative pole of the power supply through the switch tube;

The same-name end of the secondary winding of the transformer is sequentially connected to the different-name end of the secondary winding through the third diode, the first inductor, the filter capacitor, the second diode and the first capacitor connected in series;

The opposite end of the secondary winding of the transformer is sequentially connected to the same end of the secondary winding through the first capacitor, the first diode, the filter capacitor and the fourth diode connected in series.

The first diode, the second diode, the third diode, and the fourth diode are connected to form a rectifier bridge; the filter capacitor is connected in parallel at an output end of the rectifier bridge; The first capacitor is connected in series between the secondary winding of the transformer and the rectifier bridge; the primary winding of the transformer is connected in series with the switching transistor, and the first inductor is connected in series to the transformer. The primary winding circuit is connected in series or in series between the secondary winding of the transformer and the rectifier bridge.

Preferably, an absorption circuit is further included, and the absorption circuit is connected in parallel with the switching tube.

Preferably, the absorption circuit is an absorption capacitor, and the absorption capacitance is connected in parallel across the switch tube. The present invention also provides a DC-DC conversion circuit, comprising: a switching transistor, a transformer, a first capacitor, a first diode, a second diode, a third diode, a fourth diode, and a filter capacitor;

The first diode, the second diode, the third diode, and the fourth diode are connected to form a rectifier bridge; the filter capacitor is connected in parallel at an output end of the rectifier bridge;

The first capacitor is connected in series between the secondary winding of the transformer and the rectifier bridge;

The primary winding of the transformer is connected in series with the switching tube and connected to a power source.

The present invention also provides a DC-DC conversion circuit, comprising: a first switching transistor, a second switching transistor, a transformer, a first capacitor, a first diode, a second diode, a third diode, and a fourth a diode, a fifth diode, a sixth diode, a first inductor, and a filter capacitor;

The same end of the primary winding of the transformer is connected to the positive end of the power supply through the second switching tube, and connected to the negative end of the power supply through the sixth diode; the different end of the primary winding of the transformer passes the first switch The tube is connected to the negative end of the power supply, and is connected to the positive end of the power supply through the fifth diode;

The same name end of the secondary winding of the transformer sequentially passes through the third diode, the first inductor, a filter capacitor, a second diode, and a first capacitor connected to the opposite end of the secondary winding;

The different end of the secondary winding of the transformer is sequentially connected to the same name end of the secondary winding through the first capacitor, the first diode, the filter capacitor, the fourth diode and the first capacitor connected in series.

The first capacitor is connected in series between the secondary winding of the transformer and the rectifier bridge; the first inductor is connected in series at a different name end of the primary winding of the transformer, and the first switching transistor and the fifth diode Between the common ends of the tubes, or in series between the same-named end of the primary winding and the common end of the second switching diode and the sixth diode, or in series between the secondary winding of the transformer and the rectifier bridge.

The first capacitor is connected in series between the secondary winding of the transformer and the rectifier bridge; the first inductor is connected in series in a primary winding loop of the transformer, or is connected in series with a secondary winding of the transformer Between the rectifier bridges.

Compared with the prior art, the present invention has the following advantages:

In the DC-DC conversion circuit provided by this embodiment, when the switch tube is turned on and off, the secondary winding of the transformer Ta always has current, and the load is supplied through two different rectifier circuits, and the transformer can be realized. The two-way use of Ta helps to reduce the size of the transformer and the capacity of the filter capacitor. Moreover, the presence of the first capacitor can ensure the volt-second balance of the transformer, and the average value of the current in the positive and negative directions of the secondary winding of the transformer is equal.

DRAWINGS

1 is a structural diagram of a DC-DC conversion circuit in the prior art;

2 is a structural diagram of another DC-DC conversion circuit in the prior art;

3 is a structural diagram of Embodiment 1 of a DC-DC conversion circuit provided by the present invention;

4 is still another structural diagram of Embodiment 1 of the DC-DC conversion circuit provided by the present invention;

5 is a structural diagram of Embodiment 2 of a DC-DC conversion circuit provided by the present invention;

6 is still another structural diagram of Embodiment 2 of the DC-DC conversion circuit provided by the present invention;

Fig. 7 is a structural diagram showing the third embodiment of the DC-DC conversion circuit provided by the present invention.

8 is a structural diagram of a fourth embodiment of a DC-DC conversion circuit provided by the present invention;

9 is a structural diagram of a fifth embodiment of a DC-DC conversion circuit provided by the present invention;

10 is a structural diagram of a sixth embodiment of a DC-DC conversion circuit provided by the present invention;

Figure 11 is a block diagram showing the seventh embodiment of the DC-DC conversion circuit provided by the present invention.

detailed description

The above described objects, features and advantages of the present invention will become more apparent from the aspects of the appended claims.

Referring to FIG. 3, the figure is a structural diagram of a first embodiment of a DC-DC conversion circuit provided by the present invention.

The DC-DC conversion circuit provided in this embodiment includes: a switch tube S1, a transformer Ta, a first capacitor C1, a first diode D1, a second diode D2, a third diode D3, and a fourth diode a tube D4, a first inductor L1 and a filter capacitor C2;

The same name end of the primary winding of the transformer Ta is connected to the positive pole of the power supply Vdc, and the opposite end is connected to the negative pole of the power supply Vdc through the switch tube S1;

The same-name end of the secondary winding of the transformer Ta is sequentially connected to the different-name end of the secondary winding through the first capacitor C1, the third diode D3, the first inductor L1, the filter capacitor C2 and the second diode D2 connected in series. ;

The different end of the secondary winding of the transformer Ta is sequentially connected to the same-named end of the secondary winding through the first diode D1, the filter capacitor C2, the fourth diode D4, and the first capacitor C1 connected in series. The working principle of the DC-DC conversion circuit provided by this embodiment will be described in detail below with reference to FIG. When the switch S1 is turned on, the current flow of the secondary winding of the transformer Ta is: sequentially passing through the first capacitor C1, the third diode D3, the first inductor L1, the filter capacitor C2, and the second diode connected in series

D2, at this time, the transformer Ta stores energy.

When the switch S1 is turned off, the transformer Ta releases energy, and the current flow of the secondary winding of the transformer Ta is: sequentially passing through the first diode D1, the filter capacitor C2, the fourth diode D4, and the first capacitor connected in series Cl.

The load A1 is connected in parallel across the filter capacitor C2.

The relationship between the input voltage and the output voltage of the conversion circuit provided by this embodiment is: Uo=Vdc/[2n(lD)], where D is the on-duty of the switching transistor SI, and n is the primary winding of the transformer Ta. The ratio to the secondary winding. The relationship between the above input voltage and the output voltage is suitable when the first inductor L1 is small; when the first inductor L1 is large, the current on the first inductor L1 passes through the third diode during the off period of the switch S1 D3, the fourth diode D4 and the load are freewheeling. At this time, the relationship between the input voltage and the output voltage is: Uo=DVdc/[n(l+D)(lD)].

In this embodiment, the leakage inductance of the first capacitor C1, the first inductor L1 and the transformer Ta constitute a resonant circuit, and selecting a suitable value enables the rectifier circuit composed of the second diode D2 and the third diode D3 to realize zero current switching. This can reduce the reverse recovery loss of the diode and reduce the EMI of the circuit.

In the DC-DC conversion circuit provided in this embodiment, when the switch tube is turned on and off, the secondary winding of the transformer Ta always has a current, and the load is supplied through two different rectifier circuits, so that the two-way utilization of the transformer Ta can be realized. It is beneficial to reduce the volume of the transformer and the capacity of the filter capacitor. Moreover, the presence of the first capacitor ensures the volt-second balance of the transformer and the average of the currents in the positive and negative directions of the secondary winding of the transformer are equal.

It should be noted that, in the conversion circuit shown in FIG. 3, the first capacitor C1 is connected between the common end of the third diode D3 and the fourth diode D4 and the same end of the secondary winding, it being understood that The first capacitor C1 may also be connected between the common end of the first diode D1 and the second diode D2 and the opposite end of the secondary winding, as shown in FIG. 4, the connection and the other parts in FIG. The same in 3, will not be described here.

Referring to FIG. 5, the figure is a structural diagram of a second embodiment of a DC-DC conversion circuit provided by the present invention.

The DC-DC conversion circuit provided in this embodiment includes: a switch tube S1, a transformer Ta, and a first a capacitor C1, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first inductor L1 and a filter capacitor C2;

The same name end of the primary winding of the transformer Ta is connected to the positive pole of the power source, and the opposite end is connected to the negative pole of the power supply through the switch tube S1;

The same-name end of the secondary winding of the transformer Ta is sequentially connected to the different-name end of the secondary winding through the first capacitor C1, the first diode D1, the first inductor L1, the filter capacitor C2 and the fourth diode D4 connected in series. ;

The opposite end of the secondary winding of the transformer Ta is sequentially connected to the same-named end of the secondary winding through the third diode D3, the filter capacitor C2, the second diode D2, and the first capacitor C1 connected in series.

It should be noted that, in this embodiment, unlike the embodiment shown in FIG. 3, the position of the same-name end of the secondary winding changes, the position of the first inductor L1 also changes, and the connection relationship of other components does not change, and the working principle The same as the first embodiment, and details are not described herein again.

The first capacitor C1 in FIG. 5 is connected between the common terminal of the first diode D1 and the second diode D2 and the opposite end of the secondary winding. It can be understood that the first capacitor C1 is connected to the third. Between the common end of the diode D3 and the fourth diode D4 and the same-named end of the secondary winding, as shown in FIG. 6, the connections of the other portions in FIG. 6 are the same as those in FIG. 5, and details are not described herein again.

The first inductor in the conversion circuit provided by the above embodiment is connected to the rectifying and filtering circuit portion. It should be noted that the first inductor may also be directly connected in series with the winding of the transformer, that is, the main circuit portion connected to the transformer winding, and the transformer The primary windings are connected in series and can also be connected in series with the secondary winding of the transformer. The details will be described below with reference to the accompanying drawings.

Referring to FIG. 7, the figure is a structural diagram of a third embodiment of a DC-DC conversion circuit provided by the present invention.

The first diode D1, the second diode D2, the third diode D3 and the fourth diode D4 are connected as a rectifier bridge;

The filter capacitor C2 is connected in parallel at the output end of the rectifier bridge;

The first capacitor C1 is connected in series between the secondary winding of the transformer Ta and the rectifier bridge; the primary winding of the transformer Ta is connected in series with the switch S1, and the power is connected to the first power. The sense LI is connected in series in the primary winding loop of the transformer.

It should be noted that, referring to FIG. 8, the first inductor L1 may also be connected in series between the secondary winding of the transformer Ta and the rectifier bridge.

In the embodiment provided by FIG. 7 and FIG. 8 , the voltage stress of the switch S1 is increased due to the presence of the first inductor L1. Therefore, in order to reduce the voltage stress of the switch S1, an absorbing circuit may be added to the switch S1. In the embodiment, it is preferable to connect the absorption capacitor Ca in parallel at both ends of the switching transistor S1 as an absorption circuit, as shown in FIG.

It should be noted that the first inductor L1 shown in FIG. 7-9 can also be realized by the leakage inductance of the primary winding of the transformer and the leakage inductance of the secondary winding. As shown in FIG. 10, Lp is the primary side of the transformer. The leakage inductance of the winding, Ls is the leakage inductance of the secondary winding of the transformer.

It should be noted that the first capacitor C1 in FIG. 7-10 is connected between the common end of the third diode D3 and the fourth diode D4 and the same end of the secondary winding. It can be understood that A capacitor C1 can also be connected between the common terminal of the first diode D1 and the second diode D2 and the opposite end of the secondary winding.

The embodiment of the present invention further provides a DC-DC conversion circuit. The difference from FIG. 3 to FIG. 6 is that the circuit topology of the primary winding of the transformer in the DC-DC conversion circuit provided in this embodiment is shown in FIG. In the difference of FIG. 6, there is only one switching tube in the circuit topology of the primary winding in FIGS. 3-6, and there are two switching tubes in the circuit topology of the primary winding in the circuit provided in this embodiment. Referring to FIG. 11, FIG. 11 is a schematic diagram of still another DC-DC conversion circuit provided by the present invention, that is, Embodiment 7.

The DC-DC conversion circuit includes: a first switch S1, a second switch S2, a transformer Ta, a first capacitor C1, a first diode D1, a second diode D2, a third diode D3, and a a diode D4, a fifth diode D5, a sixth diode D6, a first inductor L1 and a filter capacitor C2; the same name end of the primary winding of the transformer is connected to the power supply through the second switch S2 The positive terminal is connected to the negative terminal of the power supply Vdc through the sixth diode D6; the opposite end of the primary winding of the transformer Ta is connected to the negative terminal of the power supply Vdc through the first switching transistor S1, and is connected through the fifth diode D5. The positive end of the power supply Vdc;

The same-name end of the secondary winding of the transformer Ta is sequentially connected to the different-name end of the secondary winding through the first capacitor C1, the third diode D3, the first inductor L1, the filter capacitor C2 and the second diode D2 connected in series. ; The different end of the secondary winding of the transformer Ta is sequentially connected to the same-named end of the secondary winding through the first diode D1, the filter capacitor C2, the fourth diode D4, and the first capacitor C1 connected in series.

It should be noted that the present invention also includes: The embodiment shown in FIG. 7 to FIG. 10 replaces the primary side topology with the primary side topology shown in FIG. 11, and details are not described herein again.

It should be noted that the circuit shown in Figs. 3 to 11 in the above embodiment can be used as a power factor correction circuit.

The above description is only a preferred embodiment of the invention and is not intended to limit the invention in any way. Although the present invention has been disclosed above in the preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above, or modify the equivalents of equivalent changes without departing from the scope of the technical solutions of the present invention. Example. Therefore, any modification, equivalent changes, and modifications made to the above embodiments in accordance with the technical spirit of the present invention are still within the scope of the technical solutions of the present invention.

Claims

Rights request

A DC-DC conversion circuit, comprising: a switch tube, a transformer, a first capacitor, a first diode, a second diode, a third diode, a fourth diode, and a An inductor and filter electric valley,

2. A DC-DC conversion circuit, comprising: a switch tube, a transformer, a first capacitor, a first diode, a second diode, a third diode, a fourth diode, and a An inductor and filter electric valley,

3. A DC-DC conversion circuit, comprising: a switch tube, a transformer, a first capacitor, a first diode, a second diode, a third diode, a fourth diode, and a An inductor and filter electric valley,

The first capacitor is connected in series between the secondary winding of the transformer and the rectifier bridge; the primary winding of the transformer is connected in series with the switching transistor, and the first inductor is connected in series to the transformer. The primary winding circuit is connected in series or in series between the secondary winding of the transformer and the rectifier bridge.

A DC-DC conversion circuit according to claim 3, further comprising an absorption power The absorbing circuit is connected in parallel with the switching tube.

The DC-DC converter circuit according to claim 4, wherein the absorbing circuit is an absorbing capacitor, and the absorbing capacitor is connected in parallel across the switching tube.

6. A DC-DC conversion circuit, comprising: a switching transistor, a transformer, a first capacitor, a first diode, a second diode, a third diode, a fourth diode, and a filter Capacitor

A DC-DC conversion circuit, comprising: a first switching transistor, a second switching transistor, a transformer, a first capacitor, a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a sixth diode, a first inductor, and a filter capacitor;

The first inductor is connected in series between the different end of the primary winding of the transformer and the common end of the first switching transistor and the fifth diode, or in series with the same name end of the primary winding and the second switching transistor and Between the common ends of the six diodes, or in series between the secondary winding of the transformer and the rectifier bridge.

A DC-DC conversion circuit, comprising: a first switching transistor, a second switching transistor, a transformer, a first capacitor, a first diode, a second diode, and a third diode, a fourth diode, a fifth diode, a sixth diode, and a filter capacitor;

The first capacitor is connected in series between the secondary winding of the transformer and the rectifier bridge.