Reconfigurable DC-DC converter soft switching circuit

Abstract

The invention provides a transformer-free and coupling-inductor-free resonant soft switching circuit based on a reconfigurable secondary / semi-secondary DC-DC converter, according to the characteristics of the reconfiguration circuit, a designed auxiliary soft switching network does not influence the operation of each original circuit, and the original functions of the reconfiguration circuit are ensured; the number of the designed auxiliary soft switching networks is four, and the auxiliary soft switching networks comprise two single-capacitor auxiliary soft switching circuits and two multi-element networks containing auxiliary active switches. The two single-capacitor auxiliary soft switching circuits are used for a pre-stage circuit of the reconfigurable secondary / semi-secondary DC-DC converter; auxiliary soft switching networks are respectively designed around each main switching tube branch circuit of the reconfigurable secondary / semi-secondary DC-DC converter, and the soft switching function of a main switching tube and a post-stage fly-wheel diode is met on the basis that the functions of respective secondary step-down / semi-secondary step-up and step-down circuits are not influenced by each other; based on the design of the resonance type auxiliary soft switching network, three power diodes and two main switching tubes in the reconfigurable conversion main circuit can achieve the functions of conducting and turning off complete soft switching, and meanwhile auxiliary power devices of the auxiliary soft switching network assembly can also achieve the functions of conducting and turning off complete soft switching. The auxiliary soft switching network is suitable for a reconfigurable converter with more power diodes or main switches and high-frequency working conditions, can effectively improve the efficiency of the converter, and has a wide voltage regulation range and a load range.

Description

Technical Field

[0001] The present invention relates to the technical field of soft switching circuits of reconfigurable secondary / semi-secondary DC-DC converters, and in particular to a transformerless resonant soft switching circuit of a reconfigurable secondary / semi-secondary DC-DC converter, which maintains the original working characteristics of each converter in the reconfigurable circuit, and the resonant network circuits do not affect each other. All power devices in the main circuit of the converter and all power devices in the auxiliary resonant network are fully soft switches. Background Art

[0002] The design of hydrogen production power supply for water electrolysis hydrogen production system in new energy scenarios must not only meet the working characteristics of large current and low ripple on the hydrogen production side of the electrolyzer, but also take into account the strong volatility of the power of new energy hydrogen production. The continuity of the electrolyzer power supply has an impact on the service life of the electrolyzer. Therefore, the DC-DC converter used for new energy water electrolysis hydrogen production should meet the requirements of high step-down conversion ratio, low output current ripple, high fault tolerance, high efficiency, low electromagnetic interference and low cost. Based on the above hydrogen production power supply requirements, the secondary buck and semi-secondary buck-boost reconfigurable topologies as hydrogen production converters are suitable for new energy hydrogen production scenarios.

[0003] In order to reduce the weight and size of the hydrogen production converter and meet the technical requirements of high power density, it is necessary to increase the switching frequency of the converter. However, the increase in switching frequency leads to an increase in switching losses, thereby reducing the transmission efficiency of the traditional pulse width modulation (PWM) switch mode converter. For the reconfigurable secondary / semi-secondary DC-DC converter, although each reconfigurable circuit has only one active power switch tube, there are three power diodes. Under high-frequency working conditions, the switching losses of the four tubes will increase significantly. Therefore, the overall efficiency of the converter can be improved by reducing the switching losses of the power devices. Soft switching technology is to control the conduction and shutdown of the switching device under zero voltage and zero current conditions, which effectively reduces the switching loss and switching noise of the circuit and is widely used in power electronic devices. However, there is a lack of literature and information on the soft switching design of reconfigurable secondary / semi-secondary DC-DC converters. The present invention proposes a resonant soft switching circuit based on a reconfigurable secondary / semi-secondary DC-DC converter, so that all power devices in each converter have soft switching functions, and full soft switching capabilities for conduction and shutdown, and the characteristics of large PWM adjustment range, wide output voltage range, high switching frequency and high power density. Summary of the invention

[0004] A transformerless resonant soft switching circuit of a reconfigurable secondary / semi-secondary DC-DC converter, characterized in that it comprises: a DC voltage source, a main circuit component, a load, and an auxiliary soft switching network component;

[0005] The auxiliary soft switch network includes four groups of circuits, namely, two single capacitor soft switch networks and a resonant network containing an auxiliary active switch. The auxiliary soft switch capacitor connected in parallel with the second diode of the front stage of the main circuit is the auxiliary soft switch network 1; the auxiliary soft switch capacitor connected in parallel with the output end of the front stage of the main circuit is the auxiliary soft switch network 2; the auxiliary soft switch network of the secondary buck-type main switch tube in the reconfigurable circuit is the auxiliary soft switch network 3; the auxiliary soft switch network of the semi-secondary buck-boost type main switch tube in the reconfigurable circuit is the auxiliary soft switch network 4.

[0006] Preferably, the positive electrode of the DC voltage source is connected to the first end of the auxiliary capacitor of the auxiliary soft switch network 1, and the midpoint of the first and second diodes in series in the front stage of the main circuit is connected to the second end of the capacitor of the auxiliary switch network 1. The negative electrode of the DC power supply is connected to the second end of the auxiliary capacitor of the auxiliary soft switch network 2, and the first end of the main switch tube of the secondary buck type / semi-secondary buck-boost type of the main circuit is connected to the first end of the capacitor of the soft switch network 2.

[0007] Preferably, the positive electrode of the DC voltage source is connected to the first end of the auxiliary soft switch capacitor of the auxiliary soft switch network 1, and the midpoint of the first and second diodes connected in series in the front stage of the main circuit is connected to the second end of the auxiliary soft switch capacitor of the auxiliary switch network 1. The negative electrode of the DC power supply is connected to the second end of the auxiliary soft switch capacitor of the auxiliary soft switch network 2, and the first end of each main switch of the secondary buck type / semi-secondary buck-boost type of the main circuit, the second end of the front stage energy storage inductor, and the first end of the auxiliary soft switch network 4-1 are connected to the first end of the auxiliary soft switch capacitor of the soft switch network 2.

[0008] Preferably, the second end of the secondary buck type main switch in the main circuit is connected to the first end of the auxiliary network component 3, and the cathode of the output freewheeling diode of the rear stage in the main circuit is connected to the first end of the auxiliary resonant inductor of the auxiliary soft switch network component 3. The negative electrode of the DC voltage source is connected to the second end of the auxiliary soft switch network 3. The control end of the main circuit component and the control end of the auxiliary soft switch network component 3 are connected to the controller.

[0009] Preferably, the auxiliary soft switch network 3 component includes an auxiliary switch tube, a first auxiliary diode, a second auxiliary diode, a resonant inductor, and a first auxiliary resonant capacitor and a second auxiliary resonant capacitor, wherein the control end of the auxiliary switch tube is connected to the controller, the first end of the auxiliary switch tube is electrically connected to the first end of the first auxiliary resonant capacitor, and the second end of the auxiliary switch tube is electrically connected to the second end of the auxiliary resonant inductor. The first end of the auxiliary resonant inductor is electrically connected to the second end of the main switch in the main circuit. The second end of the first auxiliary resonant capacitor is electrically connected to the first end of the second auxiliary resonant capacitor, the first and second auxiliary resonant capacitors are connected in series, and the second end of the second auxiliary resonant capacitor is the second end of the auxiliary soft switch network 3. The second auxiliary diode is connected in parallel with the second auxiliary resonant capacitor, the first auxiliary diode is connected in series with the second auxiliary diode, the anode of the first auxiliary diode is connected to the cathode of the second auxiliary diode, and the cathode of the first auxiliary diode is connected to the first end of the auxiliary resonant inductor.

[0010] Preferably, a first end of the semi-secondary buck-boost main switch in the main circuit is connected to a first end of the auxiliary network component 4, and a second end of the semi-secondary buck-boost main switch is connected to a second end of the resonant soft switch network of the auxiliary network 4. A first end of the current limiting inductor of the auxiliary soft switch network 4 is connected to a second end of the semi-secondary buck-boost main switch, and a second end of the current limiting inductor of the auxiliary network 4 is connected to a first end of a subsequent energy storage inductor.

[0011] Preferably, the auxiliary soft switch network 4 components include an auxiliary switch tube, a first auxiliary diode, a second auxiliary diode, an auxiliary resonant inductor, an auxiliary resonant capacitor, and a current limiting inductor. The control end of the auxiliary switch tube is connected to the controller. The first end of the auxiliary resonant capacitor is connected to the first end of the main switch, the second end of the auxiliary resonant capacitor is connected to the anode of the first auxiliary diode, and the cathode of the first auxiliary diode is connected to the second end of the main switch, forming a series branch 1 in the soft switch circuit network. The cathode of the second auxiliary diode is connected to the first end of the main switch, the anode of the second auxiliary diode is connected to the first end of the auxiliary resonant inductor, and the second end of the auxiliary resonant inductor is connected to the second end of the main switch, forming a series branch 2 in the soft switch circuit network. The second end of the auxiliary resonant capacitor is connected to the anode of the first auxiliary diode, and the connection point is the midpoint of the series branch 1; the anode of the second auxiliary diode is connected to the first end of the auxiliary resonant inductor, and the connection point is the midpoint of the series branch 2. The first end of the auxiliary switch tube is connected to the midpoint of the series branch 2, and the second end of the auxiliary switch tube is connected to the midpoint of the series branch 1. The first end of the auxiliary current limiting inductor is connected to the second end of the main switch tube and the second end of the resonant network component in the auxiliary soft switch network 3, and the second end of the auxiliary current limiting inductor is connected to the first end of the subsequent energy storage inductor.

[0012] The main circuit assembly includes a front-stage circuit and a rear-stage circuit, and the components include: a secondary buck-type main switch, a semi-secondary buck-boost main switch, a front-stage first main diode, a front-stage second main diode, a front-stage energy storage inductor, a front-stage energy storage capacitor, a rear-stage freewheeling diode, a rear-stage filter inductor and a filter capacitor, each main switch tube connects the front stage with the rear stage, wherein the control end of each main switch tube is connected to the controller;

[0013] The first main diode of the front stage of the reconfigurable secondary / semi-secondary DC-DC converter is connected in series with the second main diode of the front stage, the anode of the first main diode of the front stage is connected to the negative electrode of the DC voltage source, the cathode of the second main diode of the front stage is connected to the positive electrode of the DC voltage source, the first end of the front energy storage inductor is connected to the cathode of the second main diode of the front stage, the second end of the front energy storage inductor is connected to the first end of the front energy storage capacitor, and is also connected to the first end of each main switch tube of the secondary / semi-secondary DC-DC converter, and the second end of the front energy storage capacitor is connected to the midpoint of the first main diode of the front stage and the second main diode of the front stage in series. The cathode of the rear-stage freewheeling diode is connected to the second end of the resonant inductor of the auxiliary soft switch network 3 component, and is also connected to the first end of the rear-stage filter inductor, the second end of the rear-stage filter inductor is connected to the first end of the rear-stage filter capacitor, and the second end of the rear-stage filter capacitor is connected to the anode of the rear-stage freewheeling diode and the negative electrode of the DC voltage source. The load is connected in parallel with the rear-stage filter capacitor.

[0014] According to a resonant soft switching circuit of a reconfigurable quadratic / semi-quadratic DC-DC converter according to claim 1, it is characterized in that the auxiliary switch tube is an NMOS tube or an IGBT tube, the control end of the auxiliary switch tube is the gate of the NMOS tube or the IGBT tube, the first end of the auxiliary switch tube is the drain of the NMOS tube or the collector of the IGBT tube, and the second end of the auxiliary switch tube is the source of the NMOS tube or the emitter of the IGBT tube.

[0015] According to a resonant soft switching circuit of a reconfigurable quadratic / semi-quadratic DC-DC converter according to claim 1, it is characterized in that the main switch tube is an NMOS tube or an IGBT tube, the control end of the main switch tube is the gate of the NMOS tube or the IGBT tube, the first end of the main switch tube is the drain of the NMOS tube or the collector of the IGBT tube, and the second end of the main switch tube is the source of the NMOS tube or the emitter of the IGBT tube.

[0016] A resonant soft switching circuit of a reconfigurable secondary / semi-quadratic DC-DC converter, characterized in that it comprises a controller and a resonant soft switching circuit of a reconfigurable secondary / semi-quadratic DC-DC converter according to any one of claims 1 to 3, wherein the control end of the main circuit component and the control end of the auxiliary soft switching network component are electrically connected to the output end of the controller;

[0017] Wherein, the reconfigurable secondary / semi-secondary DC-DC converter operates in the secondary buck mode, and the controller is configured to control the opening and closing of the secondary buck main switch tube and the auxiliary switch tube in the auxiliary soft switch network 3. After the secondary buck main switch tube is turned on, after the zero current conduction of the main switch tube, the auxiliary soft switch in the auxiliary soft switch network 3 is used to create conditions for zero voltage shutdown. After controlling the zero voltage shutdown of the main switch tube, the auxiliary switch tube is turned on, and the auxiliary switch tube is turned on with zero current. After the auxiliary resonant capacitor in the auxiliary soft switch network 3 is discharged to zero, and after the current flowing through the auxiliary switch tube is zero, the auxiliary switch tube is turned off, and the auxiliary switch tube is turned off with zero current. It operates in the semi-secondary buck-boost mode and is not affected by the auxiliary soft switch network component 4.

[0018] Wherein, the reconfigurable secondary / semi-secondary DC-DC converter operates in the semi-secondary buck-boost mode, and the controller is configured to control the switching operation of the main switch tube and the auxiliary switch tube of the semi-secondary buck-boost. In the semi-secondary buck-boost, the main switch tube is turned on and the auxiliary switch tube in the auxiliary soft switch network 4 is turned on at the same time. After the main switch tube and the auxiliary switch tube are both turned on with zero current, the electric energy stored in the auxiliary resonant capacitor in the auxiliary soft switch network 4 is transmitted to the auxiliary resonant inductor in the auxiliary soft switch network 4 through resonance, creating conditions for zero voltage shutdown. After controlling the main switch tube and the auxiliary switch tube to be turned off with zero voltage, the electric energy stored in the auxiliary resonant inductor in the auxiliary soft switch network 4 is transmitted to the auxiliary resonant capacitor in the auxiliary soft switch network 4 through resonance, creating conditions for zero voltage-zero current shutdown. In the entire switching cycle, all diodes and main switches in the secondary buck-boost main circuit, as well as all auxiliary diodes and auxiliary switches in the auxiliary soft switch network component 4 are soft switches, and the overall circuit adjusts the output voltage by controlling the duty cycle of the main switch tube. It operates in semi-quadratic buck-boost mode and is not affected by the auxiliary soft switch network component 4. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a circuit diagram of a reconfigurable quadratic / semi-quadratic DC-DC converter;

[0020] Figure 21 is a circuit diagram of a reconfigurable quadratic / semi-quadratic DC-DC converter based on resonant soft switching provided by an embodiment of the present invention;

[0021] Figure 3 1 is a circuit diagram of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention;

[0022] Figure 4 It is a schematic diagram of the circuit principle waveform of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention;

[0023] Figure 5 It is a schematic diagram of equivalent circuits of each stage of a circuit of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention; Figure 5 (a) is a schematic diagram of an equivalent circuit of the first stage of a circuit of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention;

[0024] Figure 5 (b) is a schematic diagram of a second-stage equivalent circuit of a circuit of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention;

[0025] Figure 5 (c) is a schematic diagram of a third-stage equivalent circuit of a circuit of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention;

[0026] Figure 5 (d) is a schematic diagram of an equivalent circuit of the fourth stage of a circuit of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention;

[0027] Figure 5 (e) is a schematic diagram of a fifth-stage equivalent circuit of a circuit of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention;

[0028] Figure 5 (f) is a schematic diagram of a sixth-stage equivalent circuit of a circuit of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention;

[0029] Figure 5 (g) is a schematic diagram of an equivalent circuit of the seventh stage of a circuit of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention;

[0030] Figure 5 (h) is a schematic diagram of an eighth-stage equivalent circuit of a circuit of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention;

[0031] Figure 5(i) is a schematic diagram of a ninth-stage equivalent circuit of a circuit of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention;

[0032] Figure 5 (j) is a schematic diagram of a tenth stage equivalent circuit of a circuit of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention;

[0033] Figure 5 (k) is a schematic diagram of an eleventh stage equivalent circuit of a circuit of a secondary buck converter based on resonant soft switching provided by an embodiment of the present invention;

[0034] Figure 6 It is a semi-quadratic buck-boost circuit diagram in a reconfigurable quadratic / semi-quadratic DC-DC converter based on resonant soft switching provided by an embodiment of the present invention;

[0035] Figure 7 It is a circuit principle waveform diagram of a semi-quadratic buck-boost DC-DC converter based on resonant soft switching provided by an embodiment of the present invention;

[0036] Figure 8 It is a schematic diagram of equivalent circuits of each stage of a semi-quadratic buck-boost mode in a reconfigurable quadratic / semi-quadratic DC-DC converter based on resonant soft switching provided by an embodiment of the present invention;

[0037] Figure 8 (a) is a schematic diagram of the first stage equivalent circuit of a semi-quadratic buck-boost converter based on resonant soft switching provided by an embodiment of the present invention;

[0038] Figure 8 (b) is a schematic diagram of a second-stage equivalent circuit of a circuit of a semi-quadratic buck-boost converter based on resonant soft switching provided by an embodiment of the present invention;

[0039] Figure 8 (c) is a schematic diagram of a third-stage equivalent circuit of a semi-quadratic buck-boost converter based on resonant soft switching provided by an embodiment of the present invention;

[0040] Figure 8 (d) is a schematic diagram of a fourth-stage equivalent circuit of a semi-quadratic buck-boost converter based on resonant soft switching provided by an embodiment of the present invention;

[0041] Figure 8 (e) is a schematic diagram of a fifth-stage equivalent circuit of a circuit of a semi-quadratic buck-boost converter based on resonant soft switching provided by an embodiment of the present invention;

[0042] Figure 8(f) is a schematic diagram of the sixth stage equivalent circuit of a circuit of a semi-quadratic buck-boost converter based on resonant soft switching provided by an embodiment of the present invention;

[0043] Figure 8 (g) is a schematic diagram of the seventh stage equivalent circuit of a circuit of a semi-quadratic buck-boost converter based on resonant soft switching provided by an embodiment of the present invention;

[0044] Figure 8 (h) is a schematic diagram of an eighth-stage equivalent circuit of a circuit of a semi-quadratic buck-boost converter based on resonant soft switching provided by an embodiment of the present invention;

[0045] Figure 8 (i) is a schematic diagram of the ninth stage equivalent circuit of a circuit of a semi-quadratic buck-boost converter based on resonant soft switching provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention.

[0047] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0048] See also Figure 2 The first embodiment of the present invention provides a reconfigurable secondary / semi-secondary DC-DC converter based on a transformerless resonant soft switching circuit, comprising: a DC voltage source V in , a main circuit component, a load R, and an auxiliary soft switch network component; wherein the auxiliary soft switch network includes: four groups of circuits, namely two single-capacitor soft switch networks and a resonant network containing an auxiliary switch. The reconfigurable secondary / semi-secondary DC-DC converter main circuit includes a front-stage circuit and a rear-stage circuit. The auxiliary soft switch capacitor C connected in parallel with the second diode D2 of the front stage D2 , the auxiliary soft switching capacitor C D2It is the auxiliary soft switch network 1; the auxiliary soft switch capacitor C3 connected in parallel to the front-stage output end of the main circuit, and the auxiliary soft switch capacitor C3 is the auxiliary soft switch network 2; the auxiliary soft switch network of the main switch tube Q1 of the secondary buck circuit is the auxiliary soft switch network 3; the auxiliary soft switch network of the main switch tube Q2 of the semi-secondary buck-boost circuit is the auxiliary soft switch network 4.

[0049] Preferably, the auxiliary soft switch capacitor C of the auxiliary soft switch network 1 D2 The first end is connected to the DC voltage source V in The anode of the front stage second diode D2 is connected to the cathode of the auxiliary soft switching capacitor C D2 The second end of the auxiliary soft switch capacitor C is connected to the anode of the second diode D2 in the front stage of the main circuit. D2 The first end of the auxiliary soft switch capacitor C3 of the auxiliary soft switch network 2 is connected to the second end of the front-stage energy storage inductor L1 of the main circuit and the second end of the front-stage energy storage inductor C1, and the second end of C3 is connected to the DC voltage source V in The cathode of the first diode D1 in the previous stage is connected.

[0050] Preferably, the auxiliary soft switch network 3 component includes an auxiliary switch tube Q r , the first auxiliary diode D r1 , the second auxiliary diode D r2 , resonant inductor L r , and the first auxiliary resonant capacitor C r1 , the second auxiliary resonant capacitor C r2 Among them, the auxiliary switch tube Q r The control end is connected to the controller, and the auxiliary switch tube Q r The first end of the auxiliary resonant capacitor C r1 The first end is electrically connected to the auxiliary switch tube Q r The second end of the auxiliary resonant inductor L r The second end of the auxiliary resonant inductor L is electrically connected to r The first end of the auxiliary resonant capacitor C is electrically connected to the second end of the main switch Q1 in the main circuit. r1 The second terminal is connected to the second auxiliary resonant capacitor C r2 The first end of the auxiliary resonant capacitor C r1 , C r2 The second auxiliary resonant capacitor C r2 The second end of the auxiliary soft switch network 3 is the second end of the input port and the output port, and is connected to the negative electrode of the DC voltage source. r2 The second auxiliary resonant capacitor C r2In parallel, the first auxiliary diode D r1 With the second auxiliary diode D r2 In series, the first auxiliary diode D r1 The anode of the second auxiliary diode D r2 Cathode connection, first auxiliary diode D r1 The cathode and auxiliary resonant inductor L r The first end of the connection.

[0051] Preferably, the auxiliary soft switch network 4 components include an auxiliary switch tube Qsn, a first auxiliary diode D sn1 , the second auxiliary diode D sn2 , resonant inductor L sn , auxiliary resonant capacitor C sn , is the auxiliary soft switching network 4-1, and the current limiting inductor L σ , is the auxiliary soft switch network 4-2. Wherein, the auxiliary switch tube Q sn The control end of the auxiliary soft switch network 4-1 is connected to the controller. sn The first end of the auxiliary resonant capacitor C is connected to the first end of the main switch Q2. sn The second end of the first auxiliary diode D sn1 The anode of the first auxiliary diode D sn1 The cathode of the auxiliary soft switch network 4-1 is connected to the second end of the main switch Q2 to form a series branch 1 in the soft switch circuit network. sn2 The cathode of the second auxiliary diode D is connected to the first end of the main switch Q2. sn2 The anode and resonant inductor L sn The first end is connected to the resonant inductor L sn The second end is connected to the second end of the main switch Q2 to form a series branch 2 in the soft switching circuit network. sn The second end of the first auxiliary diode D sn1 The anode of the second auxiliary diode D is connected, and its connection point is the midpoint of the series branch 1; sn2 The anode and resonant inductor L sn The first end is connected, and the connection point is the midpoint of the series branch 2. Auxiliary switch tube Q sn The first end is connected to the midpoint of the series branch 2, and the auxiliary switch tube Q sn The second end of the auxiliary soft switch network 4-1 is connected to the midpoint of the series branch 1. The first end of the auxiliary resonant capacitor C sn The first terminal and the second auxiliary diode D sn2 The second end of the auxiliary soft switch network 4-2 is a resonant inductor L sn The second terminal and the first auxiliary diode D sn1The resonant inductor L in the auxiliary soft switch network 4-2 σ The first end of the resonant inductor L is connected to the second end of the main switch tube Q2 and the second end of the auxiliary soft switch network 4-1. σ The second end of is connected to the load ground terminal and the second end of the subsequent energy storage inductor L2.

[0052] Preferably, the main circuit assembly includes a front-stage circuit and a rear-stage circuit, and the components included are: a secondary buck main switch tube Q1, a semi-secondary buck-boost main switch tube Q2, a front-stage first main diode D1, a front-stage second main diode D2, a front-stage energy storage inductor L1, a front-stage energy storage capacitor C1, a rear-stage freewheeling diode D3, a rear-stage filter inductor L2 and a filter capacitor C2, and the load is connected in parallel with the filter capacitor C2. Among them, the control end of the secondary main switch tube Q2 is connected to the controller, and the main switch tube connects the front stage with the rear stage, wherein the control end of the secondary buck main switch tube Q1 and the semi-secondary buck-boost main switch tube Q2 are connected to the controller. The front-stage first main diode D1 is connected in series with the front-stage second main diode D2, and the anode of the front-stage first main diode D1 is connected to the DC voltage source V in The cathode of the second main diode D2 of the front stage is connected to the DC voltage source V in The first end of the front-stage energy storage inductor L1 is connected to the cathode of the front-stage second main diode D2 and the DC voltage source V in The anode of the front-stage energy storage inductor L1 is connected to the second end of the front-stage energy storage capacitor C1 and the first end of the secondary / semi-secondary main switch tubes Q1 and Q2. The first end of the front-stage energy storage capacitor C1 is connected to the midpoint of the first main diode D1 and the second main diode D2 in series. The cathode of the rear-stage freewheeling diode D3 is connected to the first end of the rear-stage filter capacitor C2, the resonant inductor L of the auxiliary soft switch network 3 component, and the resonant inductor L r The anode of the post-stage freewheeling diode D3 is connected to the first end of the post-stage filter inductor L2 and the DC voltage source V in The negative electrode of the post-stage filter capacitor C2 is electrically connected to the second end of the post-stage filter inductor L2 and the resonant inductor L in the auxiliary soft switch network 4. σ The load R is connected in parallel with the post-stage filter capacitor C2.

[0053] The first end of the secondary buck main switch tube Q1 is electrically connected to the second end of the main circuit front-stage energy storage inductor L1, the first end of the semi-secondary buck-boost main switch tube Q2, and the first end of the auxiliary soft switch network 4-1. The second end of the secondary buck main switch tube Q1 is electrically connected to the resonant inductor L1 in the auxiliary soft switch network 3 component. r The first end of the connection.

[0054] The first end of the semi-secondary buck-boost main switch tube Q2 is electrically connected to the second end of the main circuit front-stage energy storage inductor L1, the first end of the secondary buck main switch tube Q1, and the first end of the auxiliary soft switch network 4-1. The second end of the semi-secondary buck-boost main switch tube Q2 is electrically connected to the second end of the auxiliary soft switch network 4-1, the resonant inductor L1 of the auxiliary soft switch network 4-2, and the ... σ The first end is electrically connected.

[0055] When the reconfigurable circuit operates in a secondary step-down conversion circuit, such as Figure 3 As shown, in the stable working state, please refer to the circuit state change timing Figure 4 The soft-switching secondary buck converter circuit based on the resonant network can be divided into 11 working modes, and the circuit diagrams of each stage are as follows: Figure 5 shown.

[0056] Mode 1 [t0, t1]: The circuit working state in this mode is as follows Figure 5 (a) As shown. Before t0, that is, before the end of mode 11, the main switch tube Q1 and the auxiliary switch tube Q r are both in the off state, the output filter inductor current Through D3, the load current I o The output filter inductor L2 provides the current i1. L1 The capacitor C3 voltage is maintained at V in (1+D). At t0, Q1 is turned on, connecting the front and back stages of the circuit, and the power supply is included in the loop that transmits energy to the load. The transmission circuit contains an auxiliary resonant inductor L with zero current. r , the power supply output current is equal to the auxiliary resonant inductor L r Current And gradually increase, the front stage energy storage inductor L1 and the rear stage filter inductor L2 are relatively large, and their corresponding inductor currents are still flowing in the original loop, therefore, together with the auxiliary resonant inductor L r The series main switch Q1 uses an inductor to reduce the current rise rate, achieving zero current turn-on (ZCS-on) of Q1.

[0057] As the power supply output current increases, until time t1, the auxiliary resonant inductor current i Lr and the previous inductor current i L1 equal, the charging current of the front-stage inductor L1 to the front-stage capacitor C1 drops to zero, so that the front-stage power diode D2 is turned off with zero current. Lr o , there is still some output current in the D3 branch.

[0058] Mode 2 [t1, t2]: The circuit working state in this mode is as follows​ Figure 5 (b) At t1, the auxiliary capacitor C connected in parallel at the moment when the front diode D2 is turned off with zero current D2 The voltage is zero, and the current i flows through the front-stage inductor L1 There is no increase, while the power supply V in In order to meet the demand of the subsequent circuit for increased current, the power supply V in To the auxiliary capacitor C D2 It is charged and discharged through the front capacitor C1. At the same time, it forms a voltage loop with the auxiliary capacitor C3. Under the constraint of the loop KVL, the voltage of C3 is V in (1+D) discharges to the next stage, so that the previous stage inductor branch and auxiliary capacitor C D2 The front-stage capacitor C1 branch and the auxiliary capacitor C3 branch circuit all flow to the back-stage circuit through the main switch Q1. D2 Voltage is At t2, the polarity of the front-stage inductor changes and begins to absorb the power supply energy for storage. D2 Charge to V in At the same time, the discharge voltage of auxiliary capacitor C3 is V in D, the mode ends. In this state, the auxiliary resonant inductor L r With the previous auxiliary capacitor C3, auxiliary capacitor C D2 The series branches with the previous capacitor C1 resonate respectively to realize the transfer of capacitor energy to the next stage.

[0059] Mode 3 [t2, t3]: The circuit working state in this mode is as follows Figure 5 (c) At t2, the voltage of auxiliary capacitor C3 is V in D has the same voltage as the front-stage capacitor C1, the front-stage diode D1 is turned on at zero voltage, the front-stage capacitor C1 resonates with the auxiliary resonant inductor L, and C1 continues to be discharged. As the current flowing through the main switch tube Q1 gradually increases, the current of the rear-stage freewheeling diode D3 decreases, and this mode continues until the resonant inductor current Rise to I o , that is, the current of the freewheeling diode D3 is reduced to zero. The clamping effect of the freewheeling diode D3 makes the current of the auxiliary switch Qr branch zero, and the resonant capacitor voltage is zero.

[0060] Mode 4 [t3, t4]: The circuit working state in this mode is as follows Figure 5 (d) As shown. At time t3, The voltage of the auxiliary switch tube Q r The body diode is forward biased and conducts, forming L r With C r1 , C r2Series resonant branch. After half a resonant cycle, the current Once again to I o When the resonant capacitor C r1 , C r2 The current is zero, and the resonant capacitor voltage Reaching the maximum value, the resonant capacitor voltage is then r The body diode of the diode is clamped. The resonance ends. At this time, Q r The body diode zero current

[0061] (ZCS-off) shutdown.

[0062] Mode 5 [t4, t5]: The circuit working state in this mode is as follows Figure 5 (e) As shown. Auxiliary switch tube Q r After the body diode is turned off, L r , C r1 , C r2 The series resonant capacitor voltage is kept constant and the series resonant capacitor voltage is kept constant. constant, That is V cr1 =V cr2 =V in D, the resonant inductor current is In this mode, the voltage of the front-stage auxiliary capacitor C3 connected to the drain of Q1 (MOSFET is the drain, IGBT is the collector) is V in D, the subsequent auxiliary diode D connected to the source of Q1 (MOSFET is the source, IGBT is the emitter) r1 (The voltage is zero at this time) and its series connection C r1 The capacitor voltage is V in D, provides the condition for the zero voltage shutdown of the main switch Q1. This state continues until the shutdown signal of the main switch Q1 arrives.

[0063] Mode 6 [t5, t6]: The circuit working state in this mode is as follows Figure 5 At t5, the main switch Q1 is turned off. At this time, the voltage of the front-stage auxiliary capacitor C3 connected to the drain of Q1 (MOSFET is the drain, IGBT is the collector) is V in D, the subsequent auxiliary diode D connected to the source of Q1 (MOSFET is the source, IGBT is the emitter) r1 (The voltage is zero at this time) and its series connection C r1 The capacitor voltage is V in D, Q1 zero voltage off. After the main switch tube Q1 is turned off, the front stage forms two charging and discharging circuits, one is composed of L1 and C1, C D2 The composition of C1 charging, C D2The circuit for discharging and charging L1 is composed of L1, C3, and power supply V in The circuit formed by the C3 and L1 charging circuit. The subsequent circuit forms a resonant inductor L and a resonant series capacitor C r2 , the discharge circuit of the output filter inductor L2. In this circuit, D r1 It is turned on at zero voltage. At t6, the resonant series capacitor C r2 When the voltage discharges to zero, it enters the next mode.

[0064] Mode 7 [t6, t7]: The circuit working state in this mode is as follows Figure 5 (g) As shown. At t6, the subsequent resonant series capacitor C r2 When the voltage discharges to zero, there is still a resonant inductor freewheeling current i Lr =I o At this time, the auxiliary diode D r2 Zero voltage turn-on (ZVS-on), D r2 , D r1 , L r , L2, R L loop, maintaining the load current I o The front stage circuit has a relatively slow charging and discharging speed due to the large L1. The circuit state of mode 6 is still maintained. At t7, the front stage auxiliary capacitor C D2 Voltage At the same time, the voltage of the front-stage auxiliary capacitor C3 is charged to V C3 =V in (1+D), enter the next mode.

[0065] Mode 8 [t7, t8]: The circuit working state in this mode is as follows Figure 5 At t7, after the front stage circuit is charged and discharged, the front stage auxiliary capacitor C D2 Voltage The front-stage diode D2 is turned on at zero voltage, forming a loop in which the front-stage inductor L1 charges the front-stage capacitor C1. The rear-stage circuit maintains the state of mode 7. Until time t8, the auxiliary switch Q r When the on signal arrives, enter the next mode.

[0066] Mode 9 [t8, t9]: The circuit working state in this mode is as follows Figure 5 (i) At t8, the auxiliary switch Q r The auxiliary resonant capacitor C r1 Access to the circuit of the subsequent energy transmission. r1 Capacitor and filter inductor L r Forming a resonant circuit, C r1 The capacitor discharge current gradually increases, and the resonant inductor L r The freewheeling current iLr Gradually decreases. At t9, C r1 Capacitor discharge branch current i Cr1 Increase to I o When the resonant inductor L r Current i Lr When it decreases to zero, the mode ends.

[0067] Mode 10[t9,t 10 ]: The circuit working status in this mode is as follows Figure 5 (j) At t9, the capacitor C of the subsequent circuit r1 The discharge continues to provide load current. The previous circuit still maintains the state of mode 9. This mode is at t 10 At the moment, the subsequent capacitor C r1 The discharge voltage is zero and the mode ends.

[0068] Mode 11[t 10 , t 11 ]: The circuit working state in this mode is as follows Figure 5 (k) is shown. The state of the front stage circuit in this mode remains unchanged, the front stage inductor L1 resonates with the front stage capacitor C1, the inductor L1 discharges, and the capacitor C1 charges. r1 The voltage discharges to zero, and the load current I o The freewheeling diode D3 conducts zero voltage turn-on (ZVS-on). At the same time, the auxiliary switch Q r Zero voltage and zero current shutdown (ZVS / ZCS-off) is achieved. Mode 11 ends. Before the next switching cycle arrives, the auxiliary resonant inductor L r Current Auxiliary resonant capacitor voltage

[0069] When the reconfigurable circuit operates in a semi-quadratic buck-boost converter circuit, such as Figure 6 As shown, in the stable working state, please refer to the circuit state change timing Figure 7 The soft-switching semi-quadratic buck-boost converter circuit based on the resonant network can be divided into 9 working modes. The circuit diagrams of each stage are as follows: Figure 8 shown.

[0070] Mode 1 to Mode 4, that is, the time period t0-t1 is divided into 4 time-segment modes. Figure 7 Mode 1 [t0, t'0]: The circuit working state in this mode is as follows Figure 8 As shown in (a). Before time t0, the main switch tube Q2 and the auxiliary switch tube Q sn are both in the off state, the auxiliary resonant inductor L sn Current And the subsequent inductor L σ Current is zero, the resonant capacitor C sn The voltage is maintained at the resonance peak. The front-stage inductor L1 resonates with the front-stage capacitor C1, and the unidirectional resonant current is i L1 The voltage of the front-stage auxiliary capacitor C3 is maintained at V in (1+D). The current of the output filter inductor L2 of the rear stage flows through D3, and the load current I o The output filter inductor L2 provides the output filter. At time t0, the main switch tube Q2 and the auxiliary switch tube Q sn At the same time, Q2 connects the front and rear stages of the conversion circuit, and incorporates the power supply into the loop that transmits energy to the load. σ The DC voltage source V in Under the excitation of σ The series-connected Q2 gradually increases from zero current, thus achieving zero current turn-on (ZCS-on) of Q2.

[0071] In the auxiliary resonant network 3-1 connected in parallel with the main switch tube Q2, the resonant capacitor C sn With the resonant inductor L sn The main switch tube and the auxiliary switch tube form a resonant circuit, and the resonant capacitor C sn Discharge, resonant inductance L sn Charging, flowing through the resonant inductor L sn Current The auxiliary switch Q sn Also known as zero current switch-on (ZCS-on).

[0072] At the same time, the front-stage energy storage inductor L1 charges the front-stage energy storage capacitor C1 with a current i L1 Gradually decreases until t1, when the DC voltage source positive output current is equal to i L1 The charging current of the front-stage capacitor C1 drops to zero, so that the power diode D2 is turned off with zero current (ZCS-off). At the same time, the current flowing through the diode D3 in the rear-stage circuit Start descending from I2.

[0073] Mode 2 [t'0, t"'0]: The circuit working state in this mode is as follows Figure 8 (b) At t1, the auxiliary capacitor C connected in parallel at the moment when the front diode D2 is turned off with zero current D2 The voltage is zero, and the current i flows through the front-stage inductor L1 There is no increase, while the power supply V in In order to meet the demand of the subsequent circuit for increased current, the power supply V in To the auxiliary capacitor C D2It is charged and discharged through the front capacitor C1. At the same time, it forms a voltage loop with the auxiliary capacitor C3. Under the constraint of the loop KVL, the voltage of C3 is V in (1+D) discharges to the next stage, so that the previous stage inductor branch and auxiliary capacitor C D2 The currents of the front-stage capacitor C1 branch and the auxiliary capacitor C3 branch flow to the rear-stage circuit through the main switch tube Q1. D2 Voltage is At t2, the polarity of the front-stage inductor changes and begins to absorb the power supply energy for storage. The auxiliary resonant network connected in parallel with the main switch tube Q2 and the subsequent circuit mode remain in the previous mode. At t2, the auxiliary capacitor C D2 Charge to V in At the same time, the discharge voltage of auxiliary capacitor C3 is V in D, the mode ends. In this state, the auxiliary resonant inductor L σ With the previous auxiliary capacitor C3, auxiliary capacitor C D2 The series branches with the previous capacitor C1 resonate respectively to realize the transfer of capacitor energy to the next stage.

[0074] Mode 3 [t”0, t”'0]: The circuit working state in this mode is as follows Figure 8 (c) At t2, the voltage of auxiliary capacitor C3 is V in D has the same voltage as the front-stage capacitor C1, the front-stage diode D1 is turned on at zero voltage, the front-stage capacitor C1 resonates with the auxiliary resonant inductor L, and continues to maintain the discharge state of C1. The circuit mode of the auxiliary resonant soft switch network 3-1 connected in parallel with the main switch tube Q2 still maintains the previous mode. As the current flowing through the rear-stage energy storage inductor L2 gradually increases, the current of the rear-stage freewheeling diode D3 gradually decreases. This mode continues until the inductor current Rise to I L2 , that is, the current of D3 decreases to zero, that is, zero current shutdown (ZCS-off). In this mode, the diode D3 clamps the load current, and the load current is provided by the post-stage filter capacitor C2.

[0075] Mode 4 [t”’0, t1]: The circuit working state in this mode is as follows Figure 8 (d) The resonant capacitor C in this mode sn The energy is completely transferred to the resonant inductor L sn , and continues until the resonant capacitor voltage until.

[0076] Mode 5 [t1, t2]: The circuit working state in this mode is as follows Figure 8 (e) At time t4, the resonant capacitor C in the auxiliary resonant network 3-1 sn The voltage discharges to zero, and the auxiliary diode D sn1 and Dsn2 To achieve zero voltage turn-on (ZVS-on), the resonant inductor L sn Part of the current flows through the freewheeling diode D sn2 The freewheeling circuit formed by the main switch tube Q2, part of which passes through the freewheeling diode D sn1 and auxiliary switch tube Q sn The freewheeling circuit is formed. The working status of other devices is consistent with the previous mode. In this mode, the main switch tube Q2 and the auxiliary switch tube Q sn The voltage across the two ends is zero, providing conditions for the zero voltage turn-off (ZVS-off) of the two switch tubes. This stage continues until the main switch tube Q2 and the auxiliary switch tube Q sn The shutdown signal arrives.

[0077] Mode 6 [t2, t3]: The circuit working state in this mode is as follows Figure 8 (f) At t5, the main switch tube Q2 and the auxiliary switch tube Q sn The shutdown signal arrives. At this moment, the auxiliary resonant inductor L sn Through the auxiliary diode D sn1 and D sn2 With the resonant capacitor C sn A resonant circuit is formed. sn Resonance voltage Charging starts from zero, so Q2, Q sn Zero voltage shutdown (ZVS-off). After Q2 is turned off, the auxiliary inductor L σ The current flows through the resonant capacitor C sn and diode D sn1 There is conduction loss in the auxiliary switch tube and auxiliary diode in the auxiliary resonant network 3-1, so the resonant capacitor C sn The stored energy comes from two parts: one part is the resonant inductor L sn The other part is provided by the front stage circuit. The auxiliary inductor L of the rear stage circuit σ The current gradually decreases Part of the current of L2 is transferred to the load through D3. The current flowing through diode D3 starts to rise from zero, and diode D3 achieves zero current conduction (ZCS-on). , the mode ends.

[0078] Mode 7 [t3, t4]: The circuit working state in this mode is as follows Figure 8 (g) At t6, the auxiliary inductor L of the subsequent circuit σ The current drops to zero, and the load current I o The output filter capacitor C2 and the output inductor L2 provide the freewheeling current. The front stage forms two charging and discharging circuits, one of which is composed of L1 and C1, CD2 The composition of C1 charging, C D2 The circuit for discharging and charging L1 is composed of L1, C3, and power supply V in The circuit formed by charging C3 and L1. The resonant inductor in the resonant circuit continues to charge the resonant capacitor. At t7, the front stage auxiliary capacitor C D2 Discharge voltage At the same time, the voltage of the front-stage auxiliary capacitor C3 is charged to V C3 =V in (1+D), enter the next mode.

[0079] Mode 8 [t4, t5]: The circuit working state in this mode is as follows Figure 8 At t7, after the front stage circuit is charged and discharged, the front stage auxiliary capacitor C D2 Voltage The front-stage diode D2 is turned on at zero voltage (ZVS-on), forming a loop for the front-stage inductor L1 to charge the front-stage capacitor C1. The rear-stage circuit maintains the previous mode unchanged. sn Through the diode D sn1 and D sn2 Continue to give the resonant capacitor C sn The resonant capacitor voltage continues to increase while charging. This stage continues until the auxiliary resonant inductor current discharges to zero.

[0080] Mode 9 [t5, t6]: The circuit working state in this mode is as follows Figure 8 (i) At t8, the resonant inductor L in the auxiliary resonant network sn Current Discharge to zero. Resonant capacitor C sn The voltage reaches a maximum value of Auxiliary diode D sn1 and D sn2 Achieve zero current shutdown (ZCS-off). At this time, the load current I o Provided by the output filter inductor L2. The front-stage inductor L1 continues to charge the front-stage capacitor C1. This mode continues until the main switch tube conduction signal of the next cycle arrives.

Claims

1. A transformerless resonant soft switching circuit of a reconfigurable quadratic / semi-quadratic DC-DC converter, characterized in that: include: DC voltage source, main circuit components, load, and auxiliary soft switching network components; Among them, the auxiliary soft switch network includes: four groups of circuits, namely two single capacitor soft switch networks and two resonant networks containing auxiliary active switches. The power supply side of the power switch in the reconfigurable secondary / semi-secondary DC-DC converter is the front stage of the main circuit, and the load side is the back stage of the main circuit. The auxiliary soft switch capacitor connected in parallel with the second main diode of the front stage is the auxiliary soft switch network 1; the auxiliary soft switch capacitor connected in parallel with the output end of the front stage of the main circuit is the auxiliary soft switch network 2; the auxiliary soft switch network of the secondary buck type about the main switch tube in the reconfigurable circuit is the auxiliary soft switch network 3; the auxiliary soft switch network of the semi-secondary buck-boost type about the main switch tube in the reconfigurable circuit is the auxiliary soft switch network 4. The positive electrode of the DC voltage source is connected to the first end of the auxiliary capacitor of the auxiliary soft switch network 1, and the midpoint of the series connection of the first and second diodes of the front stage of the main circuit is electrically connected to the second end of the capacitor of the auxiliary switch network 1. The negative electrode of the DC power supply is electrically connected to the second end of the capacitor of the auxiliary soft switch network 2, and the first end of the main switch tube of the secondary buck type / semi-secondary buck-boost type of the main circuit is electrically connected to the first end of the capacitor of the soft switch network 2. The positive electrode of the DC voltage source is connected to the first end of the auxiliary soft switch capacitor of the auxiliary soft switch network 1, and the midpoint of the first and second diodes connected in series in the front stage of the main circuit is connected to the second end of the auxiliary soft switch capacitor of the auxiliary switch network 1. The negative electrode of the DC power supply is connected to the second end of the auxiliary soft switch capacitor of the auxiliary soft switch network 2, and the first end of each main switch of the secondary buck type / semi-secondary buck-boost type of the main circuit, the second end of the front stage energy storage inductor, and the first end of the auxiliary soft switch network 4 are connected to the first end of the auxiliary soft switch capacitor of the soft switch network 2. The auxiliary network component 3 is a dual-port circuit. The source of the main switch in the main circuit is connected to the first end of the input port of the auxiliary network component 3, and the negative electrode of the DC voltage source is connected to the second end of the input port of the auxiliary network component 3. The cathode of the rear-stage freewheeling diode of the main circuit is connected to the first end of the output port of the auxiliary network component 3, and the anode of the rear-stage freewheeling diode of the main circuit is connected to the second end of the output port of the auxiliary network component 3. The control end of the main circuit component and the control end of the auxiliary soft switch network component are connected to the controller. The auxiliary soft switch network 3 components include an auxiliary switch tube, a first auxiliary diode, a second auxiliary diode, a resonant inductor, and a first auxiliary resonant capacitor and a second auxiliary resonant capacitor. The control end of the auxiliary switch tube is connected to the controller, the first end of the auxiliary switch tube is electrically connected to the first end of the first auxiliary resonant capacitor, and the second end of the auxiliary switch tube is electrically connected to the second end of the auxiliary resonant inductor. The first end of the auxiliary resonant inductor is electrically connected to the second end (source) of the main switch in the main circuit. The second end of the first auxiliary resonant capacitor is electrically connected to the first end of the second auxiliary resonant capacitor, the first and second auxiliary resonant capacitors are connected in series, and the second end of the second auxiliary resonant capacitor is electrically connected to the second input end of the input port of the auxiliary soft switch network 3 and the second output end of the output port. The second auxiliary diode is connected in parallel to the second auxiliary resonant capacitor, the first auxiliary diode is connected in series to the second auxiliary diode, the anode of the first auxiliary diode is connected to the cathode of the second auxiliary diode, and the cathode of the first auxiliary diode is the first input end of the input port of the auxiliary soft switch network 3 connected to the first end of the auxiliary resonant inductor. The anode of the second auxiliary diode is the second input end of the input port of the auxiliary soft switch network 3 connected to the second end of the auxiliary second resonant capacitor. The auxiliary soft switch network 4 includes two parts, one part of the soft switch network component is connected in parallel with the main switch, which is the soft switch network 4-1, and the other part is the resonant inductor connected in series with the main switch, which is the soft switch network 4-2. The first end (drain) of the main switch in the main circuit is electrically connected to the first end of the auxiliary soft switch network component 4-1, and the second end (source) of the main switch in the main circuit is electrically connected to the second end of the auxiliary soft switch network component 4-1 or to the first end of the resonant inductor of the auxiliary soft switch network component 4-2. The cathode of the output freewheeling diode of the rear stage in the main circuit is electrically connected to the second end of the auxiliary soft switch network component 4-2. The control end of the main circuit component and the control end of the auxiliary soft switch network component are connected to the controller. The auxiliary soft switch network 4 component includes an auxiliary switch tube, a first auxiliary diode, a second auxiliary diode, an auxiliary resonant capacitor, and a second auxiliary resonant inductor to form an auxiliary soft switch network component 4-1, and the first auxiliary resonant inductor constitutes an auxiliary soft switch network component 4-2. Among them, the control end of the auxiliary switch tube is connected to the controller, the first end of the auxiliary switch tube is electrically connected to the connection point between the anode of the second end of the second auxiliary diode and the first end of the second auxiliary resonant inductor, and the second end of the auxiliary switch tube is electrically connected to the connection point between the second end of the resonant capacitor and the anode of the first end of the first auxiliary diode. The first end of the first auxiliary resonant inductor is electrically connected to the second end (source) of the main switch in the main circuit or to the second end of the auxiliary soft switch network 4-1, and the second end of the first auxiliary resonant inductor is electrically connected to the load grounding end. The first end of the first auxiliary resonant capacitor and the first end cathode of the second auxiliary diode are jointly the first end of the auxiliary soft switch network 4-1. The second end of the second auxiliary resonant inductor and the first end cathode of the first auxiliary diode are jointly the second end of the auxiliary soft switch network 4-1. The first end of the first auxiliary resonant inductor is the first end of the auxiliary soft switch network component 4 - 2 , and the second end of the first auxiliary resonant inductor is the second end of the auxiliary soft switch network component 4 - 2 . The main circuit assembly includes a front-stage circuit and a rear-stage circuit, and the components included are: a secondary step-down main switch, a semi-secondary step-up and step-down main switch, a front-stage first main diode, a front-stage second main diode, a front-stage energy storage inductor, a front-stage energy storage capacitor, a rear-stage freewheeling diode, a rear-stage filter inductor and a filter capacitor. Each main switch tube connects the front stage with the rear stage, wherein the control end of each main switch tube is connected to the controller. The first main diode of the front stage of the reconfigurable secondary / semi-secondary DC-DC converter is connected in series with the second main diode of the front stage, the anode of the first main diode of the front stage is connected to the negative electrode of the DC voltage source, the cathode of the second main diode of the front stage is connected to the positive electrode of the DC voltage source, the first end of the front energy storage inductor is connected to the cathode of the second main diode of the front stage, the second end of the front energy storage inductor is connected to the second end of the front energy storage capacitor, and is also connected to the first end of each main switch tube of the secondary / semi-secondary DC-DC converter, and the first end of the front energy storage capacitor is connected to the midpoint of the first main diode of the front stage and the second main diode of the front stage in series. The cathode of the rear-stage freewheeling diode is connected to the second end of the resonant inductor of the auxiliary soft switch network 3-2 component, and is also connected to the first end of the rear-stage filter inductor, the second end of the rear-stage filter inductor is connected to the first end of the rear-stage filter capacitor, and the second end of the rear-stage filter capacitor is connected to the anode of the rear-stage freewheeling diode and the negative electrode of the DC voltage source. The load is connected in parallel with the rear-stage filter capacitor.

2. The resonant soft switching circuit of a secondary buck converter according to claim 1, characterized in that: The auxiliary switch tube is an NMOS tube or an IGBT tube, the control end of the auxiliary switch tube is the gate of the NMOS tube or the gate of the IGBT tube, the first end of the auxiliary switch tube is the drain of the NMOS tube or the collector of the IGBT tube, and the second end of the auxiliary switch tube is the source of the NMOS tube or the emitter of the IGBT tube.

3. The resonant soft switching circuit of a secondary buck converter according to claim 1, characterized in that: The main switch tube is an NMOS tube or an IGBT tube, the control end of the main switch tube is the gate of the NMOS tube or the IGBT tube, the first end of the main switch tube is the drain of the NMOS tube or the collector of the IGBT tube, and the second end of the main switch tube is the source of the NMOS tube or the emitter of the IGBT tube.

4. A resonant soft-switching circuit of a reconfigurable quadratic / semi-quadratic DC-DC converter, characterized in that: A resonant soft-switching circuit comprising a controller and a reconfigurable quadratic / semi-quadratic DC-DC converter according to any one of claims 1 to 3, wherein the control end of the main circuit component and the control end of the auxiliary soft-switching network component are electrically connected to the output end of the controller; Wherein, the reconfigurable secondary / semi-secondary DC-DC converter operates in the secondary buck mode, and the controller is configured to control the opening and closing of the secondary buck main switch tube and the auxiliary switch tube in the auxiliary soft switch network 3. After the secondary buck main switch tube is turned on, after the zero current conduction of the main switch tube, the auxiliary soft switch in the auxiliary soft switch network 3 is used to create conditions for zero voltage shutdown. After controlling the zero voltage shutdown of the main switch tube, the auxiliary switch tube is turned on, and the auxiliary switch tube is turned on with zero current. After the auxiliary resonant capacitor in the auxiliary soft switch network 3 is discharged to zero, and after the current flowing through the auxiliary switch tube is zero, the auxiliary switch tube is turned off, and the auxiliary switch tube is turned off with zero current. It operates in the semi-secondary buck-boost mode and is not affected by the auxiliary soft switch network component 4. Wherein, the reconfigurable secondary / semi-secondary DC-DC converter operates in the semi-secondary buck-boost mode, and the controller is configured to control the switching operation of the main switch tube and the auxiliary switch tube of the semi-secondary buck-boost. In the semi-secondary buck-boost, the main switch tube is turned on and the auxiliary switch tube in the auxiliary soft switch network 4 is turned on at the same time. After the main switch tube and the auxiliary switch tube are both turned on with zero current, the electric energy stored in the auxiliary resonant capacitor in the auxiliary soft switch network 4 is transmitted to the auxiliary resonant inductor in the auxiliary soft switch network 4 through resonance, creating conditions for zero voltage shutdown. After controlling the main switch tube and the auxiliary switch tube to be turned off with zero voltage, the electric energy stored in the auxiliary resonant inductor in the auxiliary soft switch network 4 is transmitted to the auxiliary resonant capacitor in the auxiliary soft switch network 4 through resonance, creating conditions for zero voltage-zero current shutdown. In the entire switching cycle, all diodes and main switches in the secondary buck-boost main circuit, as well as all auxiliary diodes and auxiliary switches in the auxiliary soft switch network component 4 are soft switches, and the overall circuit adjusts the output voltage by controlling the duty cycle of the main switch tube. It operates in semi-quadratic buck-boost mode and is not affected by the auxiliary soft switch network component 4. During the entire switching cycle of the reconfigurable secondary / semi-secondary DC-DC converter working in each mode, all diodes and main switch tubes in the main circuit of the reconfigurable secondary / semi-secondary DC-DC converter, as well as all auxiliary diodes and auxiliary switch tubes in the auxiliary soft switch network components 3 and 4 are soft switches, and the overall circuit adjusts the output voltage by controlling the duty cycle of the main switch tube in each circuit mode. It has a wide voltage regulation range and load range.

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