CN103296889A - Power supply conversion device - Google Patents

Abstract

The invention discloses a power conversion device, which comprises a transformer, a primary side circuit, a secondary side circuit and a power output unit. The primary side circuit is positioned on the primary side of the transformer and comprises a power input unit, a transistor switch, a first diode, a second diode, a first capacitor and a second capacitor; the secondary side circuit is located on the secondary side of the transformer and comprises a third diode, a fourth diode, a third capacitor and a fourth capacitor. The voltage of the power output unit electrically connected between the second capacitor and the fourth capacitor can be higher than the voltage of the power input unit by the control of the transistor switch; and by using the circuit structure, the leakage inductance energy of the secondary side can be recovered.

Description

power conversion device

technical field

The present invention relates to a conversion device, and in particular to a power conversion device.

Background technique

The traditional boost converter is a power converter whose output voltage is higher than the input voltage. When the output voltage gain is low, the circuit can achieve high conversion efficiency; conversely, when the output voltage gain is high, the circuit The parasitic elements will increase the circuit loss and reduce the conversion efficiency. Among them, in order to obtain a high voltage gain ratio of the traditional boost converter, the duty cycle must exceed 50%, and the excessive duty cycle will make the power conversion efficiency lower and lower.

Flyback converters can obtain high voltage gain through the ratio of the number of turns of the primary side (primary side) to the secondary side (secondary side). Therefore, in order to increase the voltage gain, the number of turns of the secondary side winding must be increased, which increases the leakage inductance and copper loss of the transformer. When the power switch is turned off, due to the leakage inductance of the transformer, a voltage spike (Spike) will be generated between the power switch drain (Drain) and the source (Source), which will cause circuit losses, and a high withstand voltage power switch must be selected. . In order to overcome the voltage surge caused by the leakage inductance, the design of the snubber circuit (Snubber Circuit) will be the focus of the flyback converter, and the snubber circuit will cause some conversion losses due to resistance.

Contents of the invention

In view of this, the present invention provides a power conversion device capable of reducing conversion loss.

To achieve the above object, the present invention provides a power conversion device, which includes a transformer, a primary side circuit, a secondary side circuit and a power output unit. The transformer has a primary side and a secondary side corresponding to the primary side, the primary side has a first terminal and a second terminal, and the secondary side has a third terminal and a fourth terminal. The primary side circuit includes a power input unit, a transistor switch, a first capacitor, a second capacitor, a first diode and a second diode. The power input unit includes a first electrode end and a second electrode end, the first electrode end is electrically connected to the first end, the transistor switch includes a drain end (drain end, Drain) and a source end, the drain end is electrically connected to the second end, and the source end is electrically connected to the second end. Connect to the second electrode terminal, one end of the first capacitor is electrically connected to the drain terminal, the other end of the first capacitor is electrically connected to the P-type junction end of the second diode, and the P-type junction end of the first diode is electrically connected to the first end , the N-type junction end of the first diode is electrically connected to the P-type junction end of the second diode, one end of the second capacitor is electrically connected to the source end, and the other end of the second capacitor is electrically connected to the N-type junction end of the second diode joint end. The secondary side circuit includes a third capacitor, a fourth capacitor, a third diode and a fourth diode. One end of the third capacitor is electrically connected to the third end, the other end of the third capacitor is electrically connected to the P-type junction end of the fourth diode, the P-type junction end of the third diode is electrically connected to the fourth end, and the third diode The N-type junction end of the tube is electrically connected to the P-type junction end of the fourth diode, one end of the fourth capacitor is electrically connected to the N-type junction end of the fourth diode, and the other end of the fourth capacitor is electrically connected to the fourth end and the fourth capacitor. The N-type junction end of the second diode; the power output unit is electrically connected to the second electrode end and the N-type junction end of the fourth diode.

It can be seen that the power conversion device provided by the present invention has the following features: high voltage gain, energy recovery from leakage inductance, simple circuit design and high conversion efficiency.

Description of drawings

1 is a circuit diagram of a power conversion device according to an embodiment of the present invention;

Fig. 2 is the schematic diagram of the circuit operation when the transistor switch of the circuit of Fig. 1 is turned on;

Fig. 3 is the schematic diagram of circuit action when its transistor switch of the circuit of Fig. 1 is cut off;

Fig. 4 is the action waveform diagram of Fig. 1 circuit;

Fig. 5 is a schematic diagram (1) of the detailed circuit operation of Fig. 1;

Fig. 6 is the schematic diagram (2) of the detailed circuit action of Fig. 1;

Fig. 7 is the schematic diagram (3) of the detailed circuit action of Fig. 1;

Fig. 8 is the schematic diagram (four) of the detailed circuit action of Fig. 1;

Fig. 9 is the schematic diagram (five) of the detailed circuit action of Fig. 1;

Fig. 10 is the schematic diagram (six) of the detailed circuit action of Fig. 1; and

Fig. 11 is a schematic diagram (7) of the detailed circuit operation in Fig. 1 .

Explanation of reference signs

1 Power conversion device

11 Primary side circuit

12 Secondary side circuit

C1 The first capacitor

C2 Second Capacitor

C3 The third capacitor

C4 The fourth capacitor

D1 first diode

D2 Second Diode

D3 The third diode

D4 Fourth diode

E1 first end

E2 Second end

E3 The third terminal

E4 Fourth end

Lm Exciting inductance

Lk1,Lk2 leakage inductance

S1 Transistor switch

D Drain terminal

G Gate terminal

_RL load

S source terminal

Tr Transformer

Vc1 The charging voltage of the first capacitor

Vc2 The charging voltage of the second capacitor

Vc3 The charging voltage of the third capacitor

Vc4 The charging voltage of the fourth capacitor

V ₁ power input unit

Vo Power output unit.

Detailed ways

In order to make the above objects, features and characteristics of the present invention more comprehensible, the relevant embodiments of the present invention will be described in detail as follows with reference to the accompanying drawings.

Please refer to FIG. 1 . FIG. 1 is a circuit diagram of a power conversion device according to an embodiment of the present invention.

It can be seen from FIG. 1 that the power conversion device 1 includes a transformer Tr, a primary side circuit 11 , a secondary side circuit 12 and a power output unit Vo.

The transformer Tr has a primary side and a secondary side corresponding to the primary side, wherein the voltage of the secondary side is induced by the primary side. The primary side has a first end E1 and a second end E2; the secondary side has a third end E3 and a fourth end E4.

The primary side circuit 11 includes a power input unit V _I , a transistor switch S1 (power switch), a first capacitor C1 , a second capacitor C2 , a first diode D1 and a second diode D2 .

The power input unit _VI includes a first electrode terminal and a second electrode terminal, and the first electrode terminal is electrically connected to the first terminal E1. The transistor switch S1 includes a drain terminal (drain terminal, Drain) D and a source terminal S, wherein the drain terminal D is electrically connected to the second terminal E2; the source terminal S is electrically connected to the second electrode terminal of the power input unit _VI .

One end of the first capacitor C1 is electrically connected to the drain terminal D; the other end of the first capacitor C1 is electrically connected to the P-type junction end of the second diode D2. The P-type junction end of the first diode D1 is electrically connected to the first end E1 ; the N-type junction end of the first diode D1 is electrically connected to the P-type junction end of the second diode D2 . One end of the second capacitor C2 is electrically connected to the source terminal S; the other end of the second capacitor C2 is electrically connected to the N-type junction end of the second diode D2.

The secondary side circuit 12 includes a third capacitor C3 , a fourth capacitor C4 , a third diode D3 and a fourth diode D4 .

One end of the third capacitor C3 is electrically connected to the third end E3; the other end of the third capacitor C3 is electrically connected to the P-type junction end of the fourth diode D4. The P-type junction end of the third diode D3 is electrically connected to the fourth end E4; the N-type junction end of the third diode D3 is electrically connected to the P-type junction end of the fourth diode D4.

One end of the fourth capacitor C4 is electrically connected to the N-type junction of the fourth diode D4; the other end of the fourth capacitor C4 is electrically connected to the fourth end E4 and the N-type junction of the second diode D2. The power output unit Vo is electrically connected between the second electrode end of the power input unit V _I and the N-type junction end of the fourth diode D4.

In detail, the transistor switch S1 is a metal-oxide-semiconductor field effect transistor (for example: MOS FET) further including a gate terminal G, but is not limited thereto.

And the first electrode end of the power input unit V _I can be a positive electrode end; the second electrode end of the power input unit V _I can be a negative electrode end. And, the power output unit Vo further includes a load _RL .

Please refer to FIG. 1 and FIG. 2 at the same time. FIG. 2 is a schematic diagram of the circuit operation when the transistor switch of the circuit in FIG. 1 is turned on.

It can be seen from Fig. 1 and Fig. 2 that the high voltage gain principle of the power conversion device 1 is as follows:

When the transistor switch S1 is turned ON (the second diode D2 and the fourth diode D4 are in a non-conductive state). The first diode D1 on the primary side of the transformer Tr starts to conduct, the first capacitor C1 starts to charge, and a magnetizing inductor Lm starts to store energy. Wherein, the charging voltage of the first capacitor C1 and the storage voltage of the magnetizing inductor Lm are the input power V _I .

And, when the transistor switch S1 is turned on (ON), the voltage on the secondary side of the transformer Tr is induced from the primary side to the secondary side, and charges the third capacitor C3 via the conduction path of the third diode D3 . The voltage on the secondary side of the transformer Tr and the charging voltage of the third capacitor C3 are n times the input voltage (n: turns ratio=N2/N1).

Please refer to FIG. 3 at the same time. FIG. 3 is a schematic diagram of the circuit operation when the transistor switch of the circuit in FIG. 1 is turned off.

When the transistor switch S1 is cut off (OFF) (the first diode D1 and the third diode D3 are cut off), the first diode D1 on the primary side of the transformer Tr is cut off; the second diode D2 start conduction. At this time, the charging voltage of the second capacitor C2 is equal to the sum of the charging voltage of the first capacitor C1, the energy storage voltage of the exciting inductor Lm, and the power input unit V _I (that is, the energy storage voltage of Vc2=Vc1+Lm+V _I ).

And, when the transistor switch S1 is turned off (OFF), the third diode D3 is turned off; the fourth diode D4 starts to turn on. At this moment, the charging voltage of the fourth capacitor C4 is equal to the sum of the charging voltage of the third capacitor C3 and the voltage of the secondary side of the transformer Tr (ie Vc4=Vc3+voltage of the secondary side of the transformer Tr).

Therefore, the voltage across the load _RL (that is, the voltage of the power output unit Vo) is the sum of the voltages of the second capacitor C2 on the primary side of the transformer Tr and the fourth capacitor C4 on the secondary side of the transformer Tr.

Please refer to Fig. 4 and Fig. 5 at the same time. Fig. 4 is an operation waveform diagram of the circuit in Fig. 1; Fig. 5 is a schematic diagram (1) of the detailed circuit operation in Fig. 1.

In detail, when in a working mode (such as time t ₀ ~ t ₁ in FIG. 4 , where Vgs is the input signal of the transistor switch S1), the transistor switch S1 starts to conduct, and the first diode D1 also starts to Forward conduction and the second diode D2 is reverse cut-off, the first capacitor C1 starts charging through the forward conduction of the first diode D1, and the excitation inductance Lm and leakage inductance Lk1 also start to store energy, and the secondary side is stored in The remaining leakage inductance energy of the air gap is still forward-conducting through the fourth diode D4 to send energy to the load _RL and the fourth capacitor C4 on the secondary side.

Please refer to FIG. 4 and FIG. 6 at the same time. FIG. 6 is a schematic diagram (2) of the detailed circuit operation in FIG. 1 .

When in a working mode 2 (for example, time t ₁ ~ t ₂ in FIG. 4 ), the transistor switch S1 is still in an on state. At this time, after the residual leakage inductance energy stored in the air gap on the secondary side is released, the fourth diode D4 starts to be in the cut-off state, and the third diode D3 starts to conduct forward, and the voltage V across the exciting inductor Lm _{The LM} induces energy to the secondary side through the ideal transformer Tr, and uses the forward conduction of the third diode D3 to charge the third capacitor C3. However, the first capacitor C1 is still in a charging state through the forward conduction of the first diode D1 , and the magnetizing inductance Lm and the leakage inductance Lk1 are still in an energy storage state.

Please refer to FIG. 4 and FIG. 7 at the same time. FIG. 7 is a schematic diagram (3) of the detailed circuit operation in FIG. 1 .

When in a working mode three (for example, time t ₂ ~ t ₃ in FIG. 4 ), the transistor switch S1 starts to be cut off, and the first diode D1 is also reversely cut off. When the voltage sum of the power input unit V _I , the cross-voltage V _LM of the magnetizing inductance Lm, the cross-voltage V _LK1 of the leakage inductance Lk1 and the voltage Vc1 of the first capacitor C1 is greater than the voltage Vc2 of the clamped second capacitor C2, the second The second diode D2 starts forward conduction, charges the second clamp capacitor C2 and discharges part of the current to the load _RL ; while the energy of the leakage inductance of the secondary side is still forward conduction through the third diode D3. Press the third capacitor C3 to charge.

Please refer to FIG. 4 and FIG. 8 at the same time. FIG. 8 is a schematic diagram (4) of the detailed circuit operation in FIG. 1 .

When in an operation mode 4 (for example, time t ₃ -t ₄ in FIG. 4 ), the transistor switch S1 is still in an off state. When the sum of the voltage Vc3 of the secondary side voltage doubling third capacitor C3, the cross-voltage V _LK2 of the leakage inductance Lk2, and the voltage V _N2 induced on the secondary side of the ideal transformer Tr is greater than the voltage Vc4 of the output fourth capacitor C4, the third The diode D3 starts to cut off in reverse and the fourth diode D4 starts to conduct forward, then the energy on the secondary side starts to release energy to the load _RL through the forward conduction path of the fourth diode D4, and the secondary side outputs The fourth capacitor C4 still continues to discharge the load _RL ; while the energy of the primary side is still forward-conducting through the second diode D2 and continues to charge the clamping second capacitor C2, and part of the current provides energy to the load _RL .

Please refer to FIG. 4 and FIG. 9 at the same time. FIG. 9 is a schematic diagram (5) of the detailed circuit operation in FIG. 1 .

When in a working mode five (for example, time t ₄ -t ₅ in FIG. 4 ), the transistor switch S1 is still in an off state. The energy on the primary side continues to charge the second clamping capacitor C2 forwardly through the second diode D2, and part of the current provides energy to the load _RL ; while the energy on the secondary side passes through the fourth diode D4 The forward conduction begins to charge the fourth output capacitor C4 on the secondary side, and part of the current provides energy to the load _RL . Therefore, the energy required to load _RL in this working interval is all provided by the main circuit.

Please refer to FIG. 4 and FIG. 10 at the same time. FIG. 10 is a schematic diagram (6) of the detailed circuit operation in FIG. 1 .

When in an operating mode six (for example, time t ₅ -t ₆ in FIG. 4 ), the transistor switch S1 is still in an off state. At this time, the energy on the primary side and the clamping second capacitor C2 begin to discharge to the load _RL ; while the energy on the secondary side continues to charge the fourth output capacitor C4 on the secondary side through the forward conduction of the fourth diode D4, And part of the current provides energy to the load _RL .

Please refer to FIG. 4 and FIG. 11 at the same time. FIG. 11 is a schematic diagram (7) of the detailed circuit operation in FIG. 1 .

When in an operation mode 7 (for example, time t ₆ ~ t ₀ in FIG. 4 ), the transistor switch S1 is still in an off state. When the energy on the primary side is released to be lower than the voltage Vc2 of the clamping second capacitor C2, the second diode D2 begins to cut off, and at this time the energy is provided to the load _RL by the clamping second capacitor C2; and the secondary side The energy still conducts forwardly through the fourth diode D4 and continues to charge the fourth output capacitor C4 on the secondary side, and part of the current provides energy to the load _RL .

From the above, it can be seen that the power conversion device of the present invention has the following features: high voltage gain, active clamping, low switching voltage stress, leakage inductance energy recovery, simple circuit design and high conversion efficiency.

To sum up, the present invention only describes the preferred implementation mode or example of the technical means adopted to solve the problems, and is not intended to limit the scope of the patent implementation of the present invention. That is, all changes and modifications that are consistent with the meaning of the scope of the patent application of the present invention, or made in accordance with the scope of the patent of the present invention, are covered by the scope of the patent of the present invention.

Claims (6)

1. A power conversion device, characterized in that it comprises: A transformer has a primary side and a secondary side corresponding to the primary side, the primary side has a first terminal and a second terminal, and the secondary side has a third terminal and a fourth terminal; A primary side circuit, including a power input unit, a transistor switch, a first capacitor, a second capacitor, a first diode and a second diode, the power input unit includes a first electrode terminal and a second electrode terminal, the first electrode terminal is electrically connected to the first terminal, the transistor switch includes a drain terminal and a source terminal, the drain terminal is electrically connected to the second terminal, and the source terminal is electrically connected to the second terminal One end of the first capacitor is electrically connected to the drain terminal, the other end of the first capacitor is electrically connected to a P-type junction end of the second diode, and a P-type junction end of the first diode is electrically connected to The first end, an N-type junction end of the first diode is electrically connected to the P-type junction end of the second diode, one end of the second capacitor is electrically connected to the source end, and the other end of the second capacitor One end is electrically connected to an N-type junction end of the second diode; A secondary side circuit includes a third capacitor, a fourth capacitor, a third diode and a fourth diode, one end of the third capacitor is electrically connected to the third end, and the other end of the third capacitor One end is electrically connected to a P-type junction end of the fourth diode, a P-type junction end of the third diode is electrically connected to the fourth end, and an N-type junction end of the third diode is electrically connected to the The P-type junction end of the fourth diode, one end of the fourth capacitor is electrically connected to an N-type junction end of the fourth diode, and the other end of the fourth capacitor is electrically connected to the fourth end and the second the N-junction of the diode; and A power output unit is electrically connected between the second electrode end and the N-type junction end of the fourth diode. 2. The power conversion device as claimed in claim 1, wherein the transistor switch further comprises a gate terminal. 3. The power conversion device according to claim 2, wherein the transistor switch is a metal oxide semiconductor field effect transistor. 4. The power conversion device according to claim 1, wherein the first electrode terminal is a positive electrode terminal. 5. The power conversion device according to claim 1, wherein the second electrode terminal is a negative electrode terminal. 6. The power conversion device according to claim 1, wherein the power output unit further comprises a load.

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