阅读说明：本技术 一种辅助回路最低损耗的无桥双升软开关整流器 (Bridgeless double-boost soft switching rectifier with lowest loss of auxiliary loop ) 是由 安永泉 禹健 郝小聿 李晋华 王志斌 于 2020-07-08 设计创作，主要内容包括：本发明属于电力电子变流技术领域,具体涉及一种辅助回路最低损耗的无桥双升软开关整流器,包括主电路和辅助电路,所述主电路包括第一主开关管、第一主整流二极管,所述第一主开关管的漏极与第一主整流二极管的正极均连接在P点上,构成主回路左桥臂；所述第二主开关管的漏极与第二主整流二极管的正极均连接在Q点上,构成主回路右桥臂；所述第一主开关管的源极、第二主开关管的源极均与直流母线的负极连接,所述第一主整流二极管的负极、第二主整流二极管的负极均与直流母线的正极连接。本发明实现了主回路开关和辅助回路开关的零电压开通,吸收电容设计使得关断损耗减小,使整流器效率得到了大幅度提高。本发明用于整流。(The invention belongs to the technical field of power electronic converter, and particularly relates to a bridgeless double-boost soft switching rectifier with the lowest loss of an auxiliary loop, which comprises a main circuit and an auxiliary circuit, wherein the main circuit comprises a first main switching tube and a first main rectifying diode, and the drain electrode of the first main switching tube and the anode of the first main rectifying diode are connected to a point P to form a left bridge arm of the main loop; the drain electrode of the second main switching tube and the anode of the second main rectifying diode are connected to a Q point to form a right bridge arm of the main circuit; the source electrode of the first main switching tube and the source electrode of the second main switching tube are both connected with the negative electrode of the direct current bus, and the negative electrode of the first main rectifying diode and the negative electrode of the second main rectifying diode are both connected with the positive electrode of the direct current bus. The invention realizes zero voltage switching-on of the main loop switch and the auxiliary loop switch, reduces turn-off loss due to the design of the absorption capacitor, and greatly improves the efficiency of the rectifier. The invention is used for rectification.)

1. A bridge-free double-rising soft switching rectifier with lowest loss of an auxiliary loop is characterized in that: comprises a main circuit including a first main switching tube (S)₁) A first main rectifier diode (D)₁) A second main switch tube (S)₂) A second main rectifier diode (D)₂) DC bus (V)_DC) Said first main switching tube (S)₁) And a first main rectifying diode (D)₁) The positive electrodes of the two-way bridge are connected to a point P to form a main circuit left bridge arm; the second main switching tube (S)₂) And a second main rectifying diode (D)₂) The positive electrodes of the two-way bridge are connected to a Q point (Q) to form a main circuit right bridge arm; the first main switching tube (S)₁) Source electrode, second main switch tube (S)₂) All the source electrodes of (2) are connected with a direct current bus (V)_DC) Of said first main rectifier diode (D)₁) Negative pole of (D), second main rectifier diode (D)₂) With the negative electrode of the DC bus (V)_DC) The positive electrode of (1) is connected;

the auxiliary circuit comprises a first auxiliary switching tube (Q)_a1) A first absorption capacitor (C)₁) A second absorption capacitor (C)₂) A second auxiliary switch tube (Q)_a2) Auxiliary inductor (L)_AUX) A first auxiliary diode (D)_a1) A second auxiliary diode (D)_a2) A third auxiliary diode (D)_a3) And a fourth auxiliary diode (D)_a4) Alternating current (I)_AC) Said first auxiliary switching tube (Q)_a1) Source electrode and first absorption capacitor (C)₁) Are all connected at one endConnected to point P, the second absorption capacitance (C)₂) One end of (1), a second auxiliary switching tube (Q)_a2) Are all connected to a point Q, the first auxiliary switch tube (Q)_a1) Drain electrode of (1), second auxiliary switching tube (Q)_a2) Are respectively connected to the auxiliary inductors (L)_AUX) Said first auxiliary diode (D)_a1) Positive electrode of (D), third auxiliary diode (D)_a3) Negative electrode of (2), second absorption capacitor (C)₂) Are connected to point A, said second auxiliary diode (D)_a2) Positive electrode of (D), fourth auxiliary diode (D)_a4) Negative electrode of (1), first absorption capacitor (C)₁) Are connected to point B, said third auxiliary diode (D)_a3) Positive pole of (2) and first auxiliary switch tube (Q)_a1) The drain of the fourth auxiliary diode (D)_a4) Positive pole of (2) and second auxiliary switch tube (Q)_a2) The drain of the first auxiliary diode (D)_a1) Negative electrode of (D), second auxiliary diode (D)_a2) With the negative electrode of the DC bus (V)_DC) Of said alternating current (I)_AC) Connected between point P and point Q.

2. The bridgeless dual-buck soft-switching rectifier as claimed in claim 1, wherein the bridgeless dual-buck soft-switching rectifier further comprises: the first main switching tube (S)₁) A second main switch tube (S)₂) All adopt IPDD60R080G7, the first main switch tube (S)₁) A second main switch tube (S)₂) Is 650V, the first main switching tube (S)₁) A second main switch tube (S)₂) Is 83A, the first main switching tube (S)₁) A second main switch tube (S)₂) All resistances of 80m omega.

3. The bridgeless dual-buck soft-switching rectifier as claimed in claim 1, wherein the bridgeless dual-buck soft-switching rectifier further comprises: the first auxiliary switch tube (Q)_a1) A second auxiliary switch tube (Q)_a2) Is CSD17573Q5B, the first auxiliary switch tube (Q)_a1)、Second auxiliary switch tube (Q)_a2) Is 30V, the first auxiliary switch tube (Q)_a1) A second auxiliary switch tube (Q)_a2) Is 100A, the first auxiliary switch tube (Q)_a1) A second auxiliary switch tube (Q)_a2) The resistances of (2) were all 30m Ω.

4. The bridgeless dual-buck soft-switching rectifier as claimed in claim 1, wherein the bridgeless dual-buck soft-switching rectifier further comprises: the first auxiliary diode (D)_a1) A second auxiliary diode (D)_a2) A third auxiliary diode (D)_a3) And a fourth auxiliary diode (D)_a4) Is IDDD08G65C5, the first auxiliary diode (D)_a1) A second auxiliary diode (D)_a2) A third auxiliary diode (D)_a3) And a fourth auxiliary diode (D)_a4) Has a capacitance of 30 pF.

5. The bridgeless dual-buck soft-switching rectifier as claimed in claim 1, wherein the bridgeless dual-buck soft-switching rectifier further comprises: the first absorption capacitance (C)₁) A second absorption capacitor (C)₂) Is IDDD08G65C1, and the first absorption capacitor (C)₁) A second absorption capacitor (C)₂) Has a capacitance of 1000 pF.

6. A control method of a bridgeless double-boost soft switching rectifier with the lowest loss of an auxiliary loop is characterized by comprising the following steps: when the positive pole and the negative pole of the alternating current power supply Q are positive and negative, the circuit is in a stable state, and the first main switch tube S₁Conduction, AC supply current I_ACThrough a second main switch tube S₂The parasitic diode of (1) freewheeling, the first auxiliary switching tube Q_a1A second auxiliary switch tube Q_a2In an off state;

t₀at all times, the first main switch tube S is closed₁；

Delay D_A1Then, the second auxiliary switch tube Q is switched on_a2

Delay D_A2Then, the first main switch tube S is switched on₁Turning off the second auxiliary switch tube Q_a2

Delay D_A3Then, the next working cycle can be entered;

the delay D_A1～D_A3The parameters in (1) include input quantity and constrained quantity, and the input quantity comprises: the V is_DCFor inputting a DC voltage, C_m-ossParasitic capacitance of the main switching tube, C_a-ossTo assist the parasitic capacitance of the switching tube, C_NCapacitance as an auxiliary diode, said C₀To absorb capacitance, said_ACThe main switch tube is an alternating current and can meet the waiting time after zero voltage is turned on;

the constrained amount is: said L_AUXIs an auxiliary inductor.

Technical Field

The invention belongs to the technical field of power electronic converter, and particularly relates to a bridgeless double-boost soft-switching rectifier with the lowest loss of an auxiliary loop.

Background

Among many PFC circuits, Boost converters are widely used due to their simple structure, continuous input current, and strong uniformity of characteristics. The bridgeless Boost PFC reduces conduction loss by reducing the number of semiconductor devices on a working circuit, and achieves the purpose of improving efficiency. However, the problem of switching loss in the bridgeless PFC is prominent, and when the switching frequency is increased, the switching loss in the circuit is increased, and especially when the circuit operates in CCM, the reverse recovery current of the freewheeling diode increases the switching loss of the switching tube. In order to reduce the switching loss and dynamic switching stress and realize high switching frequency operation, the auxiliary resonant commutation ultra-soft switching topological structure does not influence the working mode of the original main loop and does not increase the switching stress, thereby gaining wide attention.

In 1990, R.De Doncker originally proposed a capacitance voltage division type auxiliary resonant pole topology, and the neutral point is gradually changed and replaced by an inductance voltage division type auxiliary resonant pole topology due to large volume. However, the inductance voltage division type auxiliary resonant pole topology has the problem of excitation current reset. The zero voltage conversion (ZVT) inverter (ZVT-2CI) realized based on the double-coupling inductor realizes the unidirectional reset of the exciting current, so that the transformer core of the auxiliary circuit is prevented from being saturated, and the direct current output current condition can work. However, three types of problems exist in the ZVT-2CI inverter family: 1) the switch ZCS of the auxiliary loop is switched on, only an IGBT device with smaller EOSS (equivalent output capacitor energy storage) can be used, and the conduction loss and EMI cannot be ignored; 2) the excitation current is reset in a single direction, so that the size of the magnetic core of the selected transformer is large, and two sets of auxiliary loops are needed to realize the auxiliary current conversion work of the main switch under the condition of bidirectional current output; 3) the auxiliary current conversion diode has no clamping measure, and the voltage stress and EMI are caused by overcharge and ringing. 4) In high-frequency application, under the condition of small duty ratio of a main loop, the commutation preparation time is insufficient.

Disclosure of Invention

Aiming at the technical problems, the invention provides a bridgeless double-boost soft-switching rectifier which has the advantages of reduced turn-off loss, high efficiency and lowest loss of an auxiliary loop of zero-voltage switching-on.

In order to solve the technical problems, the invention adopts the technical scheme that:

a bridgeless double-boost soft switching rectifier with the lowest loss of an auxiliary loop comprises a main circuit and an auxiliary circuit, wherein the main circuit comprises a first main switching tube, a first main rectifying diode, a second main switching tube, a second main rectifying diode and a direct current bus, and the drain electrode of the first main switching tube and the anode of the first main rectifying diode are connected to a point P to form a left bridge arm of the main loop; the drain electrode of the second main switching tube and the anode of the second main rectifying diode are connected to a Q point to form a right bridge arm of the main circuit; the source electrode of the first main switching tube and the source electrode of the second main switching tube are both connected with the negative electrode of the direct-current bus, and the negative electrode of the first main rectifying diode and the negative electrode of the second main rectifying diode are both connected with the positive electrode of the direct-current bus;

the auxiliary circuit comprises a first auxiliary switching tube, a first absorption capacitor, a second auxiliary switching tube, an auxiliary inductor, a first auxiliary diode, a second auxiliary diode, a third auxiliary diode, a fourth auxiliary diode and alternating current, wherein a source electrode of the first auxiliary switching tube and one end of the first absorption capacitor are connected to a point P, one end of the second absorption capacitor and a source electrode of the second auxiliary switching tube are connected to a point Q, a drain electrode of the first auxiliary switching tube and a drain electrode of the second auxiliary switching tube are respectively connected to two ends of the auxiliary inductor, an anode of the first auxiliary diode, a cathode of the third auxiliary diode and the other end of the second absorption capacitor are connected to a point A, an anode of the second auxiliary diode, a cathode of the fourth auxiliary diode and the other end of the first absorption capacitor are connected to a point B, the positive pole of the third auxiliary diode is connected with the drain electrode of the first auxiliary switch tube, the positive pole of the fourth auxiliary diode is connected with the drain electrode of the second auxiliary switch tube, the negative pole of the first auxiliary diode and the negative pole of the second auxiliary diode are both connected with the positive pole of the direct current bus, and the alternating current is connected between a point P and a point Q.

The first main switching tube and the second main switching tube both adopt IPDD60R080G7, the rated voltage of the first main switching tube and the rated voltage of the second main switching tube are both 650V, the rated current of the first main switching tube and the second main switching tube are both 83A, and the resistance of the first main switching tube and the resistance of the second main switching tube are both 80m omega.

The model of first auxiliary switch pipe, second auxiliary switch pipe are CSD17573Q5B, the rated voltage of first auxiliary switch pipe, second auxiliary switch pipe is 30V, the rated current of first auxiliary switch pipe, second auxiliary switch pipe is 100A, the resistance of first auxiliary switch pipe, second auxiliary switch pipe is 30m omega.

The types of the first auxiliary diode, the second auxiliary diode, the third auxiliary diode and the fourth auxiliary diode are all IDDD08G65C5, and the capacitances of the first auxiliary diode, the second auxiliary diode, the third auxiliary diode and the fourth auxiliary diode are 30 pF.

The type of the first absorption capacitor and the type of the second absorption capacitor are both IDDD08G65C1, and the capacitance of the first absorption capacitor and the capacitance of the second absorption capacitor are 1000 pF.

When the positive pole and the negative pole of the Q pole of the alternating-current power supply are negative, the working process and the switching time interval are as follows:

the circuit is in a stable state, and a first main switch tube S₁Conducting; AC supply current I_ACThrough a second main switch tube S₂The parasitic diode of (1) freewheeling, the first auxiliary switching tube Q_a1A second auxiliary switch tube Q_a2In an off state;

t₀at all times, the first main switch tube S is closed₁；

Delay D_A1Then, the second auxiliary switch tube Q is switched on_a2

Delay D_A2Then, the first main switch tube S is switched on₁Turning off the second auxiliary switch tube Q_a2

Delay D_A3Then, the next working cycle can be entered;

the delay D_A1～D_A3The parameters in (1) include input quantity and constrained quantity, and the input quantity comprises: the V is_DCFor inputting a DC voltage, C_m-ossParasitic capacitance of the main switching tube, C_a-ossTo assist the parasitic capacitance of the switching tube, C_NCapacitance as an auxiliary diode, said C₀To absorb capacitance, said_ACThe main switch tube is an alternating current and can meet the waiting time after zero voltage is turned on;

the constrained amount is: said L_AUXIs an auxiliary inductor.

Compared with the prior art, the invention has the following beneficial effects:

on the basis of the traditional bridgeless double-boost rectifier, the auxiliary circuit is designed, zero-voltage switching-on of the main loop switch and the auxiliary loop switch is realized, the turn-off loss is reduced due to the design of the absorption capacitor, and the efficiency of the rectifier is greatly improved by cooperating with the auxiliary inductor selection principle.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic diagram of the mode 1 operation of the present invention;

FIG. 3 is a schematic diagram of the mode 2 operation of the present invention;

FIG. 4 is a schematic diagram of the mode 3 operation of the present invention;

FIG. 5 is a schematic view of the mode 4 operation of the present invention;

FIG. 6 is a schematic view of the mode 5 operation of the present invention;

FIG. 7 is a schematic illustration of mode 6 operation of the present invention;

FIG. 8 is a schematic view of the mode 7 operation of the present invention;

FIG. 9 is a schematic diagram of a mode 4 equivalent circuit within a PWM switching cycle according to the present invention;

FIG. 10 is a schematic diagram of a mode 6 equivalent circuit within a PWM switching cycle according to the present invention;

FIG. 11 is a waveform diagram of the driving pulse signal, node voltage and branch current of each switch tube according to the present invention;

FIG. 12 shows the present invention t₁-t₄A time-interval loss analysis equivalent model;

FIG. 13 shows the present invention t₄-t₆A time-interval loss analysis equivalent model;

wherein: s₁Is a first main switching tube, D₁Is a first main rectifier diode, S₂Is a second main switching tube, D₂Is a second main rectifier diode, V_DCIs a DC bus, Q_a1Is a first auxiliary switch tube, C₁Is a first absorption capacitor, C₂Is a second absorption capacitor, Q_a2Is a second auxiliary switch tube, L_AUXAs an auxiliary inductor, D_a1Is a first auxiliary diode, D_a2Is a second auxiliary diode, D_a3Is a third auxiliary diode, D_a4Is a fourth auxiliary diode, I_ACIs an alternating current, Q is point Q, P is point P, A is point A, and B is point B.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A bridgeless double-boost soft-switching rectifier with the lowest loss of an auxiliary loop is shown in figure 1 and comprises a main circuit and an auxiliary loopThe main circuit comprises a first main switching tube S₁A first main rectifier diode D₁A second main switch tube S₂A second main rectifier diode D₂DC bus V_DCFirst main switch tube S₁And the first main rectifying diode D₁The positive electrodes of the two-way bridge are connected to a point P to form a main circuit left bridge arm; second main switch tube S₂And a second main rectifying diode D₂The positive electrodes of the two-way bridge are connected to a Q point Q to form a main circuit right bridge arm; first main switch tube S₁Source electrode and second main switch tube S₂Source electrodes of the two-way transistor are connected with a direct current bus V_DCIs connected to the negative pole of a first main rectifier diode D₁Negative pole of (1), second main rectifier diode D₂The negative electrode of the DC bus V is connected with the DC bus_DCThe positive electrode of (1) is connected;

further, the auxiliary circuit comprises a first auxiliary switch tube Q_a1A first absorption capacitor C₁A second absorption capacitor C₂A second auxiliary switch tube Q_a2Auxiliary inductor L_AUXA first auxiliary diode D_a1A second auxiliary diode D_a2A third auxiliary diode D_a3The fourth auxiliary diode D_a4AC current I_ACFirst auxiliary switch tube Q_a1Source electrode and first absorption capacitor C₁One end of the second absorption capacitor C is connected to the point P₂One end of (1), a second auxiliary switch tube Q_a2The source electrodes are connected to a Q point Q, and a first auxiliary switch tube Q_a1Drain electrode of the first auxiliary switch tube Q_a2Are respectively connected with the auxiliary inductors L_AUXTwo ends of the first auxiliary diode D_a1Anode of (2), third auxiliary diode D_a3Negative electrode of (1), and second absorption capacitor C₂The other end of the first auxiliary diode D is connected with the point A, and the second auxiliary diode D_a2Positive electrode of (2), fourth auxiliary diode D_a4Negative electrode of (1), first absorption capacitor C₁The other ends of the first and second auxiliary diodes D are connected to a point B and a third auxiliary diode D_a3Positive pole and first auxiliary switch tube Q_a1Is connected to the drain of the fourth auxiliary diode D_a4Positive pole of the first auxiliary switch tube Q_a2Is connected to the drain of the first auxiliary diode D_a1Negative electrode of (1), second auxiliary diode D_a2The negative electrode of the DC bus V is connected with the DC bus_DCIs connected to the positive pole of the alternating current I_ACConnected between the P point P and the Q point Q.

Further, preferably, the first main switching tube S₁A second main switch tube S₂All adopt IPDD60R080G7, the first main switch tube S₁A second main switch tube S₂The rated voltage of the first main switch tube S is 650V₁A second main switch tube S₂Is 83A, the first main switch tube S₁A second main switch tube S₂All resistances of 80m omega.

Further, preferably, the first auxiliary switch tube Q_a1A second auxiliary switch tube Q_a2The model of the first auxiliary switch tube Q is CSD17573Q5B_a1A second auxiliary switch tube Q_a2The rated voltage of the first auxiliary switch tube Q is 30V_a1A second auxiliary switch tube Q_a2The rated current of the first auxiliary switch tube Q is 100A_a1A second auxiliary switch tube Q_a2The resistances of (2) were all 30m Ω.

First auxiliary diode D_a1A second auxiliary diode D_a2A third auxiliary diode D_a3The fourth auxiliary diode D_a4Is IDDD08G65C5, a first auxiliary diode D_a1A second auxiliary diode D_a2A third auxiliary diode D_a3The fourth auxiliary diode D_a4Has a capacitance of 30 pF.

Further, preferably, the first absorption capacitor C₁A second absorption capacitor C₂Is IDDD08G65C1, and a first absorption capacitor C₁A second absorption capacitor C₂Has a capacitance of 1000 pF.

The circuit state diagrams of each phase in one PWM switching period are shown in fig. 2-8, and the waveforms of the driving pulse signal of each switching tube, the main node voltage and the branch current are shown in fig. 11.

The working process and the interval time of each stage in the positive half period of the alternating current power supply are as follows:

mode 1(t < t)₀) As shown in fig. 2: the circuit is in a stable state, and the main switch tube S₁Conducting; AC supply current I_ACThrough a main switch tube S₂The parasitic diode of (1) freewheeling, the auxiliary switch tube Q_a1、Q_a2In an off state.

Mode 2 (t)₀-t₁) As shown in fig. 3: t is t₀At all times, the main switch tube S is closed₁Current I of_ACThe inflow node P flows into the equivalent capacitor C_equ1In which it is charged. When the voltage at two ends of the capacitor cannot change suddenly in the process of closing the capacitor, the switch tube S₁Achieving ZVS turn-off. Equivalent capacitance C_equ1Is three capacitorsAnd C₁The parallel combination of (a): c_equ1＝C_m-oss+C_N+C₀. In the mode 1, the switch tube S₁The voltage at two ends increases linearly, and the expression of the voltage at two ends is as follows:

t₁time of day u_PThe two-terminal voltage is charged to V_DCSo the time for this mode is:

mode 3 (t)₁-t₂) As shown in fig. 4: t is t₁Time of day, diode D₁The voltage at both ends is greater than its own turn-on voltage, diode D₁And conducting. t is t₁At any moment, the auxiliary switch tube Q is switched on_a2Due to the flow through the auxiliary resonant inductor L_AUXCannot abruptly change, so Q_a2ZCS opening is realized. At this time, is applied to L_AUXElectricity at both endsPressure is V_DCCurrent flowing through the auxiliary resonant inductor

Linearly increasing, the expression for the current is:

the time required for this mode is:

mode 4 (t)₂-t₃) As shown in fig. 5: t is t₂Time of day, auxiliary inductance L_AUXMedium current up to I_ACDiode D₁And the medium-voltage power supply is free of current and is naturally turned off. Diode capacitor C_D1And a switching tube S₁Parasitic capacitance C of_S1The voltage at both ends cannot suddenly change and is clamped at V_DC. Both equivalent capacitances C_equ2＝C_N+C_m-oss. The energy stored therein will interact with the auxiliary resonant inductor L_AUXResonance occurs. The phase plan view of this mode is shown in fig. 9. Equivalent capacitance C_equ2Voltage across and auxiliary resonant inductor L_AUXThe current flowing in the middle is:

u_C＝V_DCcos ω₁t

wherein:

auxiliary resonance inductor L after resonance is finished_AUXThe maximum current flowing in the middle is:

the expression for the time required for this mode is:

mode 5 (t)₃-t₄) As shown in fig. 6: t is t₃At that time, the voltage at point P drops to zero. Main switch S₁The ZVS turn-on condition is reached.

D_A2＝T_1-2+T_2-3+

Mode 6 (t)₄-t₅) As shown in fig. 7: t is t₄At a time determined by PWM control, turn on S₁Turn off the auxiliary switch tube Q_a2. Auxiliary switch tube Q_a2Two-terminal parasitic capacitance C_Qa2The voltage at two ends can not suddenly change to assist the resonant inductor L_AUXWill be in resonance with the auxiliary resonance capacitor C₁And an auxiliary switching tube Q_a2Parasitic capacitance C_Qa2Resonance occurs. An equivalent capacitance value of C_equ3＝C₀+C_a-oss。t₅Time of day, C_equ3In the process, the equivalent capacitance C_equ3Voltage across and auxiliary resonant inductor L_AUXThe expressions for the currents in between are:

the voltage at two ends of the capacitor reaches V_DCThe back resonance ends.

Wherein:

the phase plan view of this mode is shown in fig. 10.

Mode 7 (t)₅-t₆) As shown in fig. 8: t is t₅At that moment, the resonance ends. Auxiliary inductor L_AUXThe remaining energy passes through the auxiliary diode D_a2And D_a4Feeding back to the output terminal. t is t₆And at the moment, finishing energy feedback. The circuit will return to the state of mode 1.

The aforementioned seven modes describe an AC power source I_ACIn the positive half period of Q pole positive pole P pole negative pole, main loop switch S₁The ZVS switching implementation of (1). Wherein the action is an auxiliary loop switch Q_a2. In an alternating current power supply I_ACIn the negative half period of P pole positive Q pole negative, the main switch S₂The ZVS of (1) is realized, and the action is to assist the switch Q_a1The workflow is completely symmetrical and the same, only the currents are opposite.

The principle of device type selection during operation is loss minimization for the additional auxiliary circuit for realizing soft switching. The modal phase with current in the auxiliary path is t₁-t₆。

Wherein t is₁-t₄The equivalent loss model of (2) is shown in fig. 12.

Auxiliary inductor currentLinear rising section t₁-t₂Loss:

auxiliary inductor currentResonant rising section t₂-t₃Loss:

auxiliary inductor current

Duration segment t₃-t₄Loss:

wherein t is₄-t₆The equivalent loss model of (2) is shown in fig. 13.

Auxiliary inductor currentResonance descending section t₄-t₅Loss:

auxiliary inductor currentLinear down section t₄-t₅Loss:

the total loss is:

although only the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art, and all changes are encompassed in the scope of the present invention.