阅读说明：本技术 软开关ac-dc维也纳变换器拓扑结构及控制方法 (Soft switch AC-DC Vienna converter topological structure and control method ) 是由 曼苏乐 徐雅梅 于 2020-12-14 设计创作，主要内容包括：本发明涉及一种软开关AC-DC维也纳变换器拓扑结构及控制方法,该结构包括第一整流二极管D1、第二整流二极管D2、第一主开关S1、第二主开关S2、第一输出直流环节电容器C_(01)和第一输出直流环节电容器C_(01),该变换器还包括有源缓冲电路,该有源缓冲电路包括缓冲电感L_S、第一辅助有源开关S_(S1)、第一缓冲电容C_(S1)、第二辅助有源开关S_(S2)和第二缓冲电容C_(S2),所述的缓冲电感L_S依次通过第一辅助有源开关S_(S1)和第一缓冲电容C_(S1)与第一整流二极管D1的负极连接,并依次通过第二辅助有源开关S_(S2)和第二缓冲电容C_(S2)与第二整流二极管D2的负极连接,而且依次通过第一主开关S1和第二主开关S2接地。与现有技术相比,本发明具有降低整流二极管的反向恢复损耗、避免振铃问题等优点。(The invention relates to a soft switch AC-DC Vienna converter topological structure and a control method, the structure comprises a first rectifying diode D1, a second rectifying diode D2, a first main switch S1, a second main switch S2 and a first output direct current link capacitor C 01 And a first output DC link capacitor C 01 The converter further comprises an active snubber circuit including a snubber inductor L S First auxiliary active switch S S1 A first buffer capacitor C S1 A second auxiliary active switch S S2 And a second buffer capacitor C S2 Said buffer inductor L S Sequentially passes through the first auxiliary active switch S S1 And a first buffer capacitor C S1 Is connected with the cathode of the first rectifier diode D1 and passes through the second auxiliary active switch S in turn S2 And a second buffer capacitor C S2 The negative electrode of the second rectifying diode D2 is connected to ground via the first main switch S1 and the second main switch S2 in this order. Compared with the prior art, the invention has the advantages of reducing the reverse recovery loss of the rectifier diode, avoiding the ringing problem and the like.)

1. A soft switch AC-DC Vienna converter topological structure comprises a first rectifying diode D1, a second rectifying diode D2, a first main switch S1, a second main switch S2, and a first output direct current link capacitor C₀₁And a first output DC link capacitor C₀₁The structure is characterized by further comprising an active buffer circuit, wherein the active buffer circuit comprises a buffer inductor L_SFirst auxiliary active switch S_S1A first buffer capacitor C_S1A second auxiliary active switch S_S2And a second buffer capacitor C_S2Said buffer inductor L_SSequentially passes through the first auxiliary active switch S_S1And a first buffer capacitor C_S1Is connected with the cathode of the first rectifier diode D1 and passes through the second auxiliary active switch S in turn_S2And a second buffer capacitor C_S2The negative electrode of the second rectifying diode D2 is connected to ground via the first main switch S1 and the second main switch S2 in this order.

2. A soft switch according to claim 1AC-DC Vienna converter topology, characterized in that the first auxiliary active switch S_S1Using N-channel MOSFET, a first auxiliary active switch S_S1And a first buffer capacitor C_S1To provide a discharge path for the residual energy stored in the buffer inductance.

3. The soft-switched AC-DC vienna converter topology of claim 2, wherein the second active auxiliary switch S_S2Using N-channel MOSFET, a second auxiliary active switch S_S2And a second buffer capacitor C_S2To provide a discharge path for the residual energy stored in the buffer inductance.

4. A soft-switching AC-DC vienna converter topology as recited in claim 3, wherein said snubber inductor L_SAnd a first active auxiliary switch S_S1The source of the first buffer capacitor C is connected with the source of the second buffer capacitor C_S1Arranged at a first active auxiliary switch S_S1And the cathode of the first rectifying diode D1.

5. A soft-switching AC-DC vienna converter topology as recited in claim 3, wherein said snubber inductor L_SWith a second auxiliary active switch S_S2The source of the first buffer capacitor C is connected with the source of the second buffer capacitor C_S2Arranged at the second active auxiliary switch S_S2And the cathode of the second rectifying diode D2.

6. The soft-switched AC-DC Vienna converter topology of claim 4, wherein the first S1 and the second S2 switch are N-channel MOSFET switches, the source of the first S1 switch is connected to the source of the second S2 switch, and the drain of the second S2 switch is grounded.

7. A method for controlling a soft-switching AC-DC Vienna converter topology, during the positive half cycle of the input voltage, when the first rectifier diode D1 and the first auxiliary active switch Ss1 are closed, the current Is1 of the first main switch S1 Is equal to the input current Ii, and when the first main switch S1 Is open, the voltage increases linearly from zero to V0+ Vsc1, the voltage of the first auxiliary active switch Ss1 decreases from V0+ Vsc1 to zero, when the switching voltage across the rectifying diode D1 exceeds the conduction voltage V0 of the first rectifying diode D1, the first rectifying diode D1 starts to conduct, and the current of the snubber inductor Ls starts to decrease, when the voltage across the main switch S1 reaches V0+ Vs1, and the anti-parallel diode on the first active auxiliary switch Ss1 is turned on, the first active auxiliary switch Ss1 is turned on, and current starts to flow through the snubber inductor Ls.

8. The method of claim 7, wherein the method of controlling the soft-switched AC-DC Vienna converter topology is based on the input current I_iBuffer inductor current i_Ls+ the first rectifying diode D1 current i_D1At the buffer of the inductor current i_LsDuring the further decrease, the current i of the first rectifying diode D1_D1Continuing to increase at an equal rate, when the snubber inductor current iLs reaches a zero level, the anti-parallel diode of the first active auxiliary switch Ss1 stops conducting, and the snubber inductor current i_LsBefore reaching zero, the first active auxiliary switch Ss1 is opened, and after the first active auxiliary switch Ss1 is opened, the inductor current i is buffered_LsContinues to flow in the reverse direction through the first active auxiliary switch Ss1, at which time the current i of the first rectifier diode D1_D1Continue to increase at the same rate.

9. The method of claim 8, wherein the snubber inductor current i when the first active auxiliary switch Ss1 is turned off during the positive half cycle of the input voltage_LsThe voltage of the output capacitor of the main switch S1 is reduced from V0+ Vsc1 to zero, and the buffer inductor current i_LsIncreasing from a negative value to zero, the first rectifier diode D1 has a current i_D1Reduced to the input current level Ii, the energy stored in the buffer inductor Ls is greater thanThe energy required by the output capacitance of the first main switch S1.

10. The method of claim 9, wherein when the energy stored in the snubber inductor Ls is sufficient to discharge the output capacitor of the first main switch S1, the anti-parallel diode of the first main switch S1 begins to conduct and the snubber inductor current i, is sufficient to discharge the snubber inductor S1_LsIncreasing linearly to zero, the first main switch S1 turns on at ZVS when the anti-parallel diode turns on, and the snubber inductor current i when the first main switch S1 turns on_LsLinearly increasing, the current i of the first rectifying diode D1_D1Linearly decreasing at an equal rate, the current i of the first rectifying diode D1_D1The rate of decrease of (d) is determined by the value of the snubber inductance Ls, then:

where V0 is the on voltage.

Technical Field

The invention relates to a circuit topology technology, in particular to a soft switching AC-DC Vienna converter topology structure and a control method.

Background

In the prior art, there are a number of circuit topologies that employ active and passive snubber circuits to create soft switching conditions for the semiconductor devices and rectifier diodes. These snubber circuits are used to limit the rate of change of the diode current and create soft switching conditions for the semiconductor elements of the circuit.

The converter circuits of the prior art using active snubber circuits have the function of reducing the current and voltage stresses, in addition to the soft switches of switch-on and rectifier-off, whereas the auxiliary switches of the active snubber circuits have a higher current stress and operate in hard switching conditions, whereas in the boost topology described in the prior art both the main and auxiliary switches operate in soft switching conditions, but the voltage stress of their main switches is higher than in converter circuits using active snubber circuits (controlled by appropriate choice of the snubber inductance value and the switching frequency), and moreover the requirements of the gate drive circuit are complex and expensive.

Disclosure of Invention

The present invention is directed to a soft switching AC-DC vienna converter topology, a control method thereof, and a control method thereof, which overcome the above-mentioned drawbacks of the prior art.

The purpose of the invention can be realized by the following technical scheme:

a soft switch AC-DC Vienna converter topological structure comprises a first rectifying diode D1, a second rectifying diode D2, a first main switch S1, a second main switch S2, and a first output direct current link capacitor C₀₁And a first output DC link capacitor C₀₁The structure further comprises an active snubber circuit including a snubber inductor L_SFirst auxiliary active switch S_S1A first buffer capacitor C_S1A second auxiliary active switch S_S2And a second buffer capacitor C_S2Said buffer inductor L_SSequentially passes through the first auxiliary active switch S_S1And a first buffer capacitor C_S1Is connected with the cathode of the first rectifier diode D1 and passes through the second auxiliary active switch S in turn_S2And a second buffer capacitor C_S2Is connected with the cathode of the second rectifying diode D2 and passes through the first main switch S1 and the second main switchSwitch S2 is connected to ground.

The first auxiliary active switch S_S1Using N-channel MOSFET, a first auxiliary active switch S_S1And a first buffer capacitor C_S1To provide a discharge path for the residual energy stored in the buffer inductance.

The second active auxiliary switch S_S2Using N-channel MOSFET, a second auxiliary active switch S_S2And a second buffer capacitor C_S2To provide a discharge path for the residual energy stored in the buffer inductance.

The buffer inductor L_SAnd a first active auxiliary switch S_S1The source of the first buffer capacitor C is connected with the source of the second buffer capacitor C_S1Arranged at a first active auxiliary switch S_S1And the cathode of the first rectifying diode D1.

The buffer inductor L_SWith a second auxiliary active switch S_S2The source of the first buffer capacitor C is connected with the source of the second buffer capacitor C_S2Arranged at the second active auxiliary switch S_S2And the cathode of the second rectifying diode D2.

The first main switch S1 and the second main switch S2 both adopt N-channel MOSFET tubes, the source electrode of the first main switch S1 is connected with the source electrode of the second main switch S2, and the drain electrode of the second main switch S2 is grounded.

During the positive half cycle of the input voltage, when a first rectifying diode D1 and a first auxiliary active switch Ss1 are closed, the current Is1 of a first main switch S1 Is equal to the input current Ii, when the first main switch S1 Is opened, the voltage of the first auxiliary active switch Ss1 Is increased from zero to V0+ Vsc1, the voltage of the first auxiliary active switch Ss1 Is reduced from V0+ Vsc1 to zero, when the switching voltage across the rectifying diode D1 exceeds the conducting voltage V0 of the first rectifying diode D1, the first rectifying diode D1 starts to be conducted, the current of a buffer inductor Ls starts to be reduced, when the voltage across the main switch S1 reaches V0+ Vs1, and an anti-parallel diode on the first active auxiliary switch Ss1 Is conducted, the first active auxiliary switch Ss1 and the buffer inductor Ls start to be conducted.

According toInput current I_iBuffer inductor current i_Ls+ the first rectifying diode D1 current i_D1At the buffer of the inductor current i_LsDuring the further decrease, the current i of the first rectifying diode D1_D1Continuing to increase at an equal rate, when the snubber inductor current iLs reaches a zero level, the anti-parallel diode of the first active auxiliary switch Ss1 stops conducting, and the snubber inductor current i_LsBefore reaching zero, the first active auxiliary switch Ss1 is opened, and after the first active auxiliary switch Ss1 is opened, the inductor current i is buffered_LsContinues to flow in the reverse direction through the first active auxiliary switch Ss1, at which time the current i of the first rectifier diode D1_D1Continue to increase at the same rate.

During the positive half cycle of the input voltage, when the first active auxiliary switch Ss1 is turned off, the inductor current i is buffered_LsThe voltage of the output capacitor of the main switch S1 is reduced from V0+ Vsc1 to zero, and the buffer inductor current i_LsIncreasing from a negative value to zero, the first rectifier diode D1 has a current i_D1Decreasing to the input current level Ii, the energy stored in the buffer inductor Ls is larger than the energy required by the output capacitance of the first main switch S1.

When the energy stored in the snubber inductor Ls is sufficient to discharge the output capacitor of the first main switch S1, the anti-parallel diode of the first main switch S1 begins to conduct and the snubber inductor current i_LsIncreasing linearly to zero, the first main switch S1 turns on at ZVS when the anti-parallel diode turns on, and the snubber inductor current i when the first main switch S1 turns on_LsLinearly increasing, the current i of the first rectifying diode D1_D1Linearly decreasing at an equal rate, the current i of the first rectifying diode D1_D1The rate of decrease of (d) is determined by the value of the snubber inductance Ls, then:

where V0 is the on voltage.

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

in the circuit technology provided by the invention, the buffer inductor of the auxiliary switch reduces the reverse recovery loss of the rectifier diode by controlling the change rate of the current of the rectifier diode, in addition, the energy stored in the buffer inductor is used for discharging the output capacitor to zero before the main switch is opened, so that the zero capacitor conduction switch loss is generated, when the main switch is disconnected, the auxiliary switch and the buffer capacitor of the active buffer circuit provide a discharge path for the residual energy stored in the buffer inductor, and the circuit topological structure effectively solves the ringing problem caused by the interaction of the junction capacitor of the rectifier diode and the buffer inductor.

Drawings

FIG. 1 is a circuit diagram of the structure of the present invention.

Fig. 2 shows the operation stages of the AC-DC converter during the positive half cycle of the input voltage, where fig. 2a shows the first stage, fig. 2b shows the second stage, fig. 2c shows the third stage, fig. 2d shows the fourth stage, fig. 2e shows the fifth stage, fig. 2f shows the sixth stage, fig. 2g shows the seventh stage, and fig. 2h shows the eighth stage.

Fig. 3 is a control waveform diagram corresponding to the positive half cycle period of the input voltage.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

Examples

The present invention provides a circuit for reducing reverse recovery losses and switching losses associated with semiconductor elements of rectifier diodes by employing an active snubber circuit in a vienna rectifier circuit topology that does not impose any additional voltage stress on the rectifier diodes and that can be applied in high voltage high power ac to dc conversion systems.

As shown in fig. 1, fig. 1 is a circuit structure of a soft switching AC-DC vienna converter using an active snubber circuit, the active snubber reduces reverse recovery loss of a rectifier diode and realizes zero voltage switching of a semiconductor main switch, the active snubber circuit is composed of an auxiliary active switch, a snubber capacitor and a snubber inductor, soft switching conditions are created for the semiconductor main switch and the auxiliary active switch by controlling di/dt rate of the rectifier diode, the snubber inductor reduces reverse recovery loss by controlling change rate di/dt of a rectifier diode current, the snubber inductor is connected on a series path of the rectifier diode and the semiconductor main switch, energy stored in the snubber inductor is used for discharging an output capacitor of the semiconductor main switch before the switch rotates to prevent conduction loss of a capacitor thereof, the auxiliary active switch and the snubber capacitor are connected in series in the snubber circuit, when the switch is turned off, the energy stored in the snubber inductor is discharged to the output DC link capacitor.

To simplify the analysis, the line inductance L is replaced by a constant current source Ii and the output dc link capacitance is replaced by a dc voltage source. In addition, it is assumed that the on-state resistance of the semiconductor switch is zero, but the output capacitance and the reverse recovery charge of the rectifier diode are not zero. Fig. 2 shows the operation phases of the proposed AC-DC converter during the positive half cycle of the input voltage, and its corresponding key operating waveforms are shown in fig. 3.

When the rectifier diode D1 and the first auxiliary active switch Ss1 are turned off, the current of the main switch S1 is equal to the input current Ii, and the voltage V0 (the conduction voltage of the rectifier diode) and V0+ Vsc1 (the junction capacitance voltage) are blocked before the main switch S1 is turned off, respectively. When the main switch S1 turns off, its voltage increases linearly from zero to V0+ Vsc 1. The voltage of the auxiliary active switch Ss1 drops from V0+ Vsc1 to zero, the rectifier diode D1 begins to conduct when the switching voltage across the rectifier diode D1 exceeds the V0 level, and the current of the snubber inductor Ls begins to decrease, and Ss1 can conduct when the voltage across the main switch S1 reaches V0+ Vs1 and the anti-parallel diode of the active auxiliary switch Ss1 conducts, and current begins to flow through the snubber inductor Ls.

Due to input current I_i＝i_Ls+i_D1Buffer the inductor current i_LsContinues to decrease while the current i of the rectifier diode D1_D1Continuing to increase at an equal rate, when iLs reaches a zero level, the anti-parallel diode of active auxiliary switch Ss1 stops conducting, and therefore needs to be at i_LsBefore zero is reached active auxiliary switch Ss1 is opened, after active auxiliary switch Ss1 is opened, i_LsContinue to flow in reverse direction through the active auxiliary switchTherefore, the current i of the rectifying diode D1_D1Continues to increase at the same rate, the magnitude of which exceeds the input current I_iUnless the active auxiliary switch Ss1 is closed, the energy stored in the auxiliary capacitor Cs1 is returned to the auxiliary inductor Ls through the active auxiliary switch Ss 1.

When the active auxiliary switch Ss1 is closed, the inductor current i is buffered_LsFlows through the output capacitor of the main switch S1 to reduce the voltage from V0+ Vsc1 to zero, thereby buffering the inductor current i_LsIncreases from a negative value to zero, i_D1The input current level Iin will decrease and the energy stored in the snubber inductor Ls should be greater than the energy required to discharge the output capacitance of the main switch S1, otherwise the main switch voltage Vs1 will not return to zero completely and will oscillate unless the main switch S1 is turned on after the main switch voltage Vs1 reaches a minimum value.

When the snubber inductor energy is sufficient to discharge the output capacitor of S1, the anti-parallel diode of the main switch S1 begins to conduct and the snubber inductor current i_LsIncreasing linearly to zero, the main switch S1 may conduct at the zero voltage switch ZVS when the anti-parallel diode conducts. When the main switch S1 is turned on, the inductor current i is buffered_LsLinearly increases and the current i of the rectifier diode D1_D1Linearly decreasing at equal rates, rectifying the current i of diode D1_D1The rate of decrease of (d) is determined by the value of the snubber inductance Ls, then:

the higher the Ls value of the buffer inductor, the required di_D1The smaller the rate of/dt, and therefore the smaller the reverse recovery losses.

Linearly increasing buffer inductor current i_LsLinearly decreasing current i of rectifier diode D1 when Iin level is reached_D1A zero current value is reached and the reverse reduction continues due to the remaining stored charge, thereby creating an overshoot in the switching current that exceeds the level of the input current Ii, which overshoot is even greater and may damage the device if the appropriate snubber inductance Ls is not applied.

In addition to the residual charge that must be recovered before the rectifying diode blocks the voltage, it also has a junction capacitance SC1 that can resonate in series with the snubber inductance Ls, which can cause parasitic ringing and increase the voltage stress of the rectifying diode. This problem is solved by a heavy RCD snubber, the main switch S1 and the active auxiliary switch Ss1 have similar voltage stresses, equal to V0+ Vsc 1. In order to keep the voltage stress within a reasonable range, it is important to choose the voltage across Cs 1. The voltage on Cs1 depends on the load, line voltage V_inSwitching frequency f_sAnd buffer inductance value L_sAs shown below

For a given input current I₀Line voltage V_inAnd V₀By lowering L_sf_sThe voltage on Cs1 may be reduced.