A soft switching circuit of a half-quadratic voltage-lifting DC-DC converter

Abstract

The application provides a resonant soft switching circuit of a half-second boost-buck DC-DC converter, and an auxiliary soft switching network is designed on the basis of a traditional half-second boost-buck DC-DC converter circuit; the auxiliary soft switching network is designed according to the circuit structure of the front stage and the rear stage of the half-second boost-buck DC-DC converter, and there are three auxiliary soft switching networks in total, including two single-capacitor auxiliary soft switching circuits of the front stage and a multi-element network containing an auxiliary switch in parallel with a main switch tube device; the half-second boost-buck DC-DC converter circuit based on the resonant soft switching includes three power diodes and one main switch tube in the main circuit, and the power diodes and the main switch tube can all realize complete soft switching functions of conduction and turn-off; meanwhile, the power devices of the auxiliary soft switching network components include two auxiliary power diodes and one auxiliary power switch tube, and the auxiliary power diodes and the auxiliary power switch tube can all realize complete soft switching functions of conduction and turn-off; the auxiliary soft switching network is suitable for converters with more power diodes or main switch tubes and high-frequency working conditions, can effectively improve the efficiency of the converter, and has a wide voltage regulation range and a wide load range.

Description

Technical Field

[0001] This invention relates to the field of soft-switching circuit technology for semi-secondary buck-boost DC-DC converters, specifically to a resonant soft-switching circuit for a semi-secondary buck-boost DC-DC converter and a semi-secondary buck-boost converter device with all power devices fully soft-switched. Background Technology

[0002] DC-DC converters have a wide range of applications, including data centers, communication equipment, the automotive industry, industrial control, and solar energy applications. Among them, a semi-secondary buck-boost DC-DC converter with an active switching device features high buck-boost capability, a wide input / output voltage range, stability, reliability, fast response, and high precision.

[0003] To reduce the weight and size of converters and meet the technical requirements of high-power-density devices, it is necessary to increase the switching frequency. However, increasing the switching frequency leads to increased switching losses, thereby reducing the transmission efficiency of traditional pulse-width modulation (PWM) switching-mode converters. Although a semi-secondary buck-boost DC-DC converter has only one active power switch, it contains three power diodes. Under high-frequency operating conditions, the switching losses of the four diodes increase significantly. Therefore, improving the overall efficiency of the converter can be achieved by reducing the switching losses of the power devices. Soft-switching technology utilizes the control of switching devices under zero-voltage and zero-current conditions to effectively reduce circuit switching losses and switching noise, and is widely used in power electronic devices. However, current literature and information on soft-switching design for semi-secondary DC-DC converter circuits are lacking. This invention proposes a resonant soft-switching circuit for a semi-secondary buck-boost DC-DC converter, featuring soft-switching functionality for all power devices, full soft-switching capability, a large PWM adjustment range, a high buck-boost ratio, and a high switching frequency. Summary of the Invention

[0004] A resonant soft-switching circuit for a secondary buck DC-DC converter, characterized in that it includes: a DC voltage source, a main circuit assembly, a load, and an auxiliary soft-switching network assembly;

[0005] The auxiliary soft-switching network component includes three circuits: two single-capacitor auxiliary soft-switching networks and one resonant network containing an auxiliary switch. The auxiliary soft-switching capacitor connected in parallel with the diodes in the front stage of the main circuit component constitutes auxiliary soft-switching network component 1; the auxiliary soft-switching capacitor connected in parallel with the output terminal of the front stage of the main circuit component constitutes auxiliary soft-switching network component 2; and the auxiliary soft-switching network related to the main switch in the main circuit component constitutes auxiliary soft-switching network component 3. The positive terminal of the DC voltage source is connected to the first terminal of auxiliary soft-switching network component 1, and the midpoint of the diodes connected in series in the front stage of the main circuit component is connected to the second terminal of auxiliary soft-switching network component 1. The negative terminal of the DC voltage source is connected to the second terminal of auxiliary soft-switching network component 2, and the first terminal of the main switch in the main circuit component is connected to the first terminal of the capacitor in soft-switching network component 2. Auxiliary soft-switching network component 3 comprises two parts: one part, a soft-switching network component connected in parallel with the main switch, is auxiliary soft-switching network component 3-1; the other part, an auxiliary resonant inductor connected in series with the main switch, is auxiliary soft-switching network component 3-2. In the main circuit assembly, the first terminal of the main switching transistor is electrically connected to the first terminal of the auxiliary soft-switching network assembly 3-1. The second terminal of the main switching transistor is electrically connected to the second terminal of the auxiliary soft-switching network assembly 3-1 and the first terminal of the auxiliary soft-switching network assembly 3-2. The second terminal of the output filter inductor, the second terminal of the filter capacitor, and the load ground terminal of the subsequent stage in the main circuit assembly are electrically connected to the second terminal of the auxiliary soft-switching network assembly 3-2. The control terminals of the main circuit assembly and the auxiliary soft-switching network assembly are connected to a controller.

[0006] The auxiliary soft-switching network component 3 comprises an auxiliary switching transistor, a first auxiliary diode, a second auxiliary diode, an auxiliary resonant capacitor, and a second auxiliary resonant inductor, forming auxiliary soft-switching network component 3-1. The first auxiliary resonant inductor forms auxiliary soft-switching network component 3-2. The control terminal of the auxiliary switching transistor is connected to the controller. The first terminal of the auxiliary switching transistor is electrically connected to the connection point between the anode of the second terminal of the second auxiliary diode and the first terminal of the second auxiliary resonant inductor. The second terminal of the auxiliary switching transistor is electrically connected to the connection point between the second terminal of the resonant capacitor and the anode of the first terminal of the first auxiliary diode. The first terminal of the first auxiliary resonant inductor is electrically connected to the second terminal of the main switching transistor in the main circuit assembly and the second terminal of the auxiliary soft-switching network component 3-1. The second terminal of the first auxiliary resonant inductor is electrically connected to the load ground terminal. The first terminal of the first auxiliary resonant capacitor and the cathode of the first terminal of the second auxiliary diode together constitute the first terminal of the auxiliary soft-switching network component 3-1. The second terminal of the second auxiliary resonant inductor and the cathode of the first terminal of the first auxiliary diode together constitute the second terminal of the auxiliary soft-switching network component 3-1. The first terminal of the first auxiliary resonant inductor is the first terminal of the auxiliary soft-switching network component 3-2, and the second terminal of the first auxiliary resonant inductor is the second terminal of the auxiliary soft-switching network component 3-2.

[0007] The main circuit assembly includes a front-end circuit and a rear-end circuit, containing the following components: a main switching transistor, a first front-end main diode, a second front-end main diode, a front-end energy storage inductor, a front-end energy storage capacitor, a rear-end freewheeling diode, a rear-end filter inductor, and a filter capacitor. The main switching transistor connects the front-end and rear-end circuits. The control terminal of the main switching transistor is connected to a controller. The first terminal of the main switching transistor is electrically connected to the second terminal of the front-end energy storage inductor and the second terminal of the front-end energy storage capacitor. The second terminal of the main switching transistor is electrically connected to the second terminal of auxiliary soft-switching network component 3-1 and the first terminal of auxiliary soft-switching network component 3-2. The first and second front-end main diodes are connected in series. The anode of the first front-end main diode is connected to the cathode of the DC voltage source, and the cathode of the second front-end main diode is connected to the anode of the DC voltage source. The first terminal of the front-end energy storage capacitor is connected to the cathode of the first front-end main diode and the anode of the second front-end main diode. The first terminal of the front-end energy storage inductor is electrically connected to the cathode of the second front-end main diode and the anode of the DC voltage source. The second terminal of the pre-stage energy storage inductor is connected to the second terminal of the pre-stage energy storage capacitor, and simultaneously connected to the first terminal of the main switching transistor. The first terminal of the pre-stage energy storage capacitor is connected to the midpoint of the pre-stage first main diode and the pre-stage second main diode, which are connected in series. The cathode of the post-stage freewheeling diode is connected to the positive terminal of the load and electrically connected to the first terminal of the post-stage filter capacitor. The anode of the post-stage freewheeling diode is electrically connected to the first terminal of the post-stage filter inductor and the cathode of the DC voltage source. The second terminal of the post-stage filter capacitor is electrically connected to the second terminal of the post-stage filter inductor and the load ground terminal.

[0008] The resonant soft-switching circuit of a semi-secondary buck-boost DC-DC converter is characterized in that the auxiliary switch is an NMOS transistor or an IGBT transistor, the control terminal of the auxiliary switch is the gate of the NMOS transistor or the gate of the IGBT transistor, the first terminal of the auxiliary switch is the drain of the NMOS transistor or the collector of the IGBT transistor, and the second terminal of the auxiliary switch is the source of the NMOS transistor or the emitter of the IGBT transistor.

[0009] The resonant soft-switching circuit of a semi-secondary buck-boost DC-DC converter is characterized in that the main switch is an NMOS transistor or an IGBT transistor, the control terminal of the main switch is the gate of the NMOS transistor or the IGBT transistor, the first terminal of the main switch is the drain of the NMOS transistor or the collector of the IGBT transistor, and the second terminal of the main switch is the source of the NMOS transistor or the emitter of the IGBT transistor.

[0010] A resonant soft-switching circuit for a semi-double step-up / step-down DC-DC converter is characterized in that it includes a controller and the resonant soft-switching circuit of the semi-double step-up / step-down DC-DC converter, wherein the control terminal of the main circuit component, the control terminal of the auxiliary soft-switching network component, and the output terminal of the controller are electrically connected.

[0011] The controller is configured to control the switching operation of the auxiliary switch and the main switch. When the main switch and the auxiliary switch are simultaneously turned on and off, the main switch is turned on with zero current. The auxiliary soft-switching network component creates conditions for the zero-voltage turn-off of the main switch and the auxiliary switch. After the auxiliary resonant capacitor discharges to zero, the main switch and the auxiliary switch are turned off with zero voltage. Throughout the switching cycle, all diodes and the main switch in the main circuit component, as well as all auxiliary diodes and the auxiliary switch in the auxiliary soft-switching network component, are soft-switched. The overall circuit adjusts the output voltage by controlling the duty cycle of the main switch. It has a wide voltage regulation range and load capacity. Attached Figure Description

[0012] Figure 1 This is a circuit diagram of a secondary step-down DC-DC converter;

[0013] Figure 2 This is a circuit diagram of a semi-secondary buck-boost DC-DC converter based on resonant soft switching provided in an embodiment of the present invention;

[0014] Figure 3 This is a schematic diagram of the circuit principle waveform of a semi-secondary buck-boost DC-DC converter based on resonant soft switching provided in an embodiment of the present invention;

[0015] Figure 4 This is a schematic diagram of the equivalent circuit of each stage of a semi-secondary buck-boost DC-DC converter based on resonant soft switching provided in an embodiment of the present invention.

[0016] Figure 4 (a) is a schematic diagram of the first stage of a semi-secondary buck-boost DC-DC converter based on resonant soft switching provided in an embodiment of the present invention.

[0017] Figure 4 (b) is a schematic diagram of the second stage of a circuit of a semi-secondary buck-boost DC-DC converter based on resonant soft switching provided in an embodiment of the present invention;

[0018] Figure 4 (c) is a schematic diagram of the third stage of a circuit of a semi-secondary buck-boost DC-DC converter based on resonant soft switching provided in an embodiment of the present invention.

[0019] Figure 4 (d) is a schematic diagram of the fourth stage of a circuit of a semi-secondary buck-boost DC-DC converter based on resonant soft switching provided in an embodiment of the present invention.

[0020] Figure 4 (e) is a schematic diagram of the fifth stage of a circuit of a semi-secondary buck-boost DC-DC converter based on resonant soft switching provided in an embodiment of the present invention.

[0021] Figure 4 (f) is a schematic diagram of the sixth stage of a circuit of a semi-secondary buck-boost DC-DC converter based on resonant soft switching provided in an embodiment of the present invention.

[0022] Figure 4 (g) is a schematic diagram of the seventh stage of a circuit of a semi-secondary buck-boost DC-DC converter based on resonant soft switching provided in an embodiment of the present invention.

[0023] Figure 4 (h) is the eighth-stage equivalent circuit diagram of a semi-secondary buck-boost DC-DC converter based on resonant soft switching provided in an embodiment of the present invention.

[0024] Figure 4 (i) is a schematic diagram of the ninth stage of a circuit of a semi-secondary buck-boost DC-DC converter based on resonant soft switching provided in an embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort 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 accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] Please see Figure 2 The first embodiment of the present invention provides a resonant soft-switching circuit for a semi-secondary buck-boost DC-DC converter, comprising: a DC voltage source V in The main circuit assembly includes a main circuit component, a load R, and an auxiliary soft-switching network component. The auxiliary soft-switching network comprises three circuits: two single-capacitor auxiliary soft-switching networks and a resonant network containing an auxiliary switch. The main circuit assembly of the semi-secondary buck-boost DC-DC converter includes a front-end circuit and a rear-end circuit. The auxiliary soft-switching capacitor C is connected in parallel with the second diode D2 in the front-end stage. D2 The auxiliary soft-switching capacitor C D2 The auxiliary soft-switching network component 1; the auxiliary soft-switching capacitor C3 connected in parallel to the output of the main circuit component is the auxiliary soft-switching network component 2; the auxiliary soft-switching network component 3 includes an auxiliary soft-switching network component 3-1 connected in parallel with the main switching transistor Q2 and an auxiliary soft-switching network component 3-1 connected in series with the main switching transistor Q2, namely the auxiliary resonant inductor L. σ The DC voltage source V in The positive electrode and the auxiliary soft-switching network component 1, i.e., C D2 The first terminal is connected to the midpoint of the first and second diodes D1 and D2, which are connected in series in the front stage of the main circuit component, and the auxiliary soft-switching network component 1C. D2 The second terminal is connected. The DC voltage source V... inThe negative terminal is connected to the second terminal of the auxiliary soft-switching network component 2, i.e., D3. The first terminal of the main switch transistor in the main circuit component, the first terminal of the auxiliary soft-switching network component 3-1, and the first terminal of the capacitor C3 in the auxiliary soft-switching network component 2 are connected. The first terminal of the main switch transistor Q2 in the main circuit component is connected to the first terminal of the auxiliary soft-switching network component 3-1, and the second terminal of the main switch transistor Q2 in the main circuit component is connected to the second terminal of the auxiliary soft-switching network component 3-1. The current-limiting inductor L of the auxiliary soft-switching network component 3-2... σ The first terminal is connected to the second terminal of the main switch Q2, and the current-limiting inductor L of the auxiliary soft-switching network component 3-2 is... σ The second terminal is connected to the second terminal of the subsequent energy storage inductor L2 and the load ground terminal. The control terminal of the main circuit component and the control terminal of the auxiliary soft-switching network component are connected to the controller.

[0028] Preferably, the auxiliary soft-switching capacitor C of the auxiliary soft-switching network component 1 D2 The first terminal is connected to the DC voltage source V in The anode of the capacitor is connected to the cathode of the second diode D2 in the pre-amplifier stage, and the auxiliary soft-switching capacitor C is connected to the cathode of the second diode D2 in the pre-amplifier stage. D2 The second terminal is connected to the anode of the second diode D2 in the main circuit assembly, i.e., the auxiliary soft-switching capacitor C. D2 It is connected in parallel with the second diode D2 of the preceding stage. The first terminal of the auxiliary soft-switching capacitor C3 of the auxiliary soft-switching network component 2 is connected to the second terminal of the preceding stage energy storage inductor L1 of the main circuit component and the first terminal of the preceding stage energy storage inductor C1. The second terminal of C3 is connected to the DC voltage source V. in The cathode and the anode of the first diode D1 in the front stage are connected.

[0029] Preferably, the auxiliary soft-switching network component 3 includes an auxiliary switch Q. sn First auxiliary diode D sn1 Second auxiliary diode D sn2 Second auxiliary resonant inductor L sn Auxiliary resonant capacitor C sn This constitutes the auxiliary soft-switching network component 3-1, and the first auxiliary resonant inductor L. σ This constitutes the auxiliary soft-switching network component 3-2. The auxiliary switch Q... sn The control terminal is connected to the controller. Auxiliary resonant capacitor C sn The first terminal is connected to the first terminal of the main switch Q2, and the auxiliary resonant capacitor C sn The second terminal is connected to the first auxiliary diode D sn1 Anode connection, first auxiliary diode D sn1 The cathode of the second auxiliary diode is connected to the second terminal of the main switch Q2, forming series branch 1 in the soft-switching circuit network.sn2 The cathode is connected to the first terminal of the main switch Q2, and the second auxiliary diode D... sn2 anode and auxiliary resonant inductor L sn The first connection is made to the auxiliary resonant inductor L. sn The second terminal is connected to the second terminal of the main switch Q2, forming series branch 2 in the soft-switching circuit network. Resonant capacitor C sn With the first auxiliary diode D sn1 The anode connection is at the midpoint of the series branch 1; the second auxiliary diode D sn2 anode and auxiliary resonant inductor L sn The first connection point is the midpoint of this series branch 2. Auxiliary switch Q sn The first terminal is connected to the midpoint of the series branch 2, and the auxiliary switch Q is connected to the midpoint of the series branch 2. sn The second end is connected to the midpoint of series branch 1. Auxiliary resonant inductor L σ The first terminal is connected to the second terminal of the main switch Q2 and the second terminal of the auxiliary soft-switching network component 3-1, and the auxiliary resonant inductor L σ The second terminal is electrically connected to the second terminal of the subsequent energy storage inductor L2 and the load ground terminal.

[0030] Preferably, the main circuit assembly includes a front-end circuit and a rear-end circuit, comprising the following components: a main switch transistor Q2, a first main diode D1, a second main diode D2, a front-end energy storage inductor L1, a front-end energy storage capacitor C1, a rear-end freewheeling diode D3, a rear-end filter inductor L2, and a filter capacitor C2. The load is connected in parallel with the filter capacitor C2. The main switch transistor Q2 connects the front-end and rear-end circuits. The control terminal of the main switch transistor Q2 is connected to a controller. The first terminal of the main switch transistor Q2 is electrically connected to the second terminal of the front-end energy storage inductor L1 and the first terminal of the auxiliary soft-switching network assembly 3-1. The second terminal of the main switch transistor Q2 is connected to the second terminal of the auxiliary soft-switching network assembly 3-1 and the auxiliary resonant inductor L1 in the auxiliary soft-switching network assembly 3-2. σ The first terminal is connected. The cathode of the first diode D1 is connected to the anode of the second diode D2, and the anode of the first diode is connected to the DC voltage source V. in The negative terminal of the first-stage second diode D2 is connected to the DC voltage source V. in The anode of the first stage energy storage inductor L1 is connected to the cathode of the second stage diode D2, the second stage energy storage inductor L1 is connected to the second stage energy storage capacitor C1 and the first stage of the main switch Q1, and the first stage energy storage capacitor C1 is connected to the midpoint of the first stage diode D1 and the second stage diode D2 connected in series.

[0031] The cathode of the subsequent freewheeling diode D3 is connected to the first terminal of the subsequent filter capacitor C2, and the anode of the subsequent freewheeling diode D3 is connected to the negative terminal of the DC voltage source and the first terminal of the subsequent filter inductor L2. The second terminal of the subsequent filter capacitor C2 is electrically connected to the second terminal of the subsequent filter inductor L2 and the load ground terminal. The load R is connected in parallel with the subsequent filter capacitor C2.

[0032] Please see Figure 3 During steady-state operation, the soft-switching semi-secondary buck-boost DC-DC converter circuit based on the resonant network can be divided into 9 operating modes. The circuit diagrams for each stage are as follows: Figure 4 As shown.

[0033] Modes 1-4, i.e., the time interval t0-t1, are divided into four time segments. Due to their short duration, they are considered time-series modes. Figure 3 Not marked in the text. Mode 1 [t0, t'0]: The circuit operating state in this mode is as follows. Figure 4 As shown in (a). Before time t0, the main switch Q2 and the auxiliary switch Q... sn Both are in the off state, and the auxiliary resonant inductor L sn Current and the subsequent inductor L σ Current The resonant capacitance C is zero. sn The voltage remains at the resonant peak. The preceding inductor L1 and capacitor C1 resonate, and the unidirectional resonant current is i. L1 The voltage of the auxiliary capacitor C3 in the preamplifier stage is maintained at V. in (1+D). The current in the output filter inductor L2 of the subsequent stage flows through D3, and the load current I... o The output filter inductor L2 provides all the necessary power. At time t0, the main switch Q2 and the auxiliary switch Q... sn Simultaneously activated, Q2 connects the pre- and post-conversion stages of the circuit, integrating the power supply into the energy transfer loop to the load. The auxiliary inductor L in the loop... σ In DC voltage source V in Under the excitation, the current gradually increases from zero, and L σ The current of Q2 in series gradually increases from zero, thus achieving zero-current turn-on (ZCS-on) of Q2.

[0034] In the auxiliary resonant network 3-1 connected in parallel with the main switch Q2, the resonant capacitor C sn With auxiliary resonant inductor L sn A resonant circuit is formed by the main switch and the auxiliary switch, and the resonant capacitor C... sn Discharge, auxiliary resonant inductor L sn Charging occurs as current flows through the auxiliary resonant inductor L. sn current It starts rising from zero in a sine wave. Therefore, the auxiliary switch Q...sn It is also known as zero-current turn-on (ZCS-on).

[0035] At the same time, the front-stage energy storage inductor L1 provides a charging current i to the front-stage energy storage capacitor C1. L1 Gradually decrease until time t1, the positive output current of the DC voltage source is equal to i L1 When the current is equal to the current flowing through the capacitor C1, the charging current drops to zero, causing the power diode D2 to turn off with zero current (ZCS-off). Simultaneously, the current flowing through diode D3 in the subsequent circuit... It starts to decline from I2.

[0036] Mode 2 [t'0, t”0]: The circuit operating state in this mode is as follows Figure 4 As shown in (b). At time t1, the auxiliary capacitor C connected in parallel at the instant the preceding diode D2 turns off with zero current. D2 The voltage is zero, and the current i flowing through the preceding inductor is... L1 There was no increase, while the power supply V in To meet the increased current requirements of the subsequent circuit, the power supply V in Give auxiliary capacitor C D2 The capacitor is charged and discharged through the preceding capacitor C1. Simultaneously, it forms a voltage loop with the auxiliary capacitor C3. Under the KVL constraint of the loop, the voltage of C3 changes from V... in (1+D) discharges to the next stage, thus the inductor branch of the previous stage and the auxiliary capacitor C... D2 The current in both the branch circuit with the preceding capacitor C1 and the branch circuit with the auxiliary capacitor C3 flows to the subsequent circuit through the main switch Q1. When the auxiliary capacitor C... D2 Voltage is At time t2, the polarity of the front-stage inductor changes, and it begins to absorb and store energy from the power supply. The auxiliary resonant network connected in parallel with the main switch Q2, and the subsequent circuit modes, maintain the previous mode. At time t2, the auxiliary capacitor C... D2 Charge to V in Meanwhile, the discharge voltage of auxiliary capacitor C3 is V. in D, this mode ends. In this state, the auxiliary resonant inductor L... σ With the pre-amplifier auxiliary capacitor C3, auxiliary capacitor C D2 The circuit resonates with the preceding capacitor C1 in series, enabling the transfer of capacitor energy to the subsequent stage.

[0037] Mode 3 [t”0, t”'0]: The circuit operating state in this mode is as follows Figure 4 As shown in (c), at time t2, the voltage across the auxiliary capacitor C3 is V. in The voltage across diode D1 is the same as that of the preceding capacitor C1. Diode D1 conducts with zero voltage. The preceding capacitor C1 and the auxiliary resonant inductor L... σResonance is achieved, and the discharge state of C1 continues. The circuit mode of the auxiliary soft-switching network component 3-1, connected in parallel with the main switch Q2, remains the previous mode. As the current flowing through the subsequent energy storage inductor L2 gradually increases, the current in the subsequent freewheeling diode D3 gradually decreases. This mode continues until the inductor current... Rise to I L2 This means that the current in D3 decreases to zero, i.e., zero-current turn-off (ZCS-off). The clamping effect of this mode diode D3 means that the load current is provided by the subsequent filter capacitor C2.

[0038] Mode 4[t”'0,t1]: The circuit operating state in this mode is as follows Figure 4 As shown in (d), the resonant capacitance C in this mode is... sn The energy is completely transferred to the auxiliary resonant inductor L. sn This continues until the resonant capacitor voltage... until.

[0039] Mode 5 [t1, t2]: The circuit operating state in this mode is as follows Figure 4 As shown in (e). At time t4, the resonant capacitance C in the auxiliary resonant network 3-1 is... sn Voltage discharged to zero, auxiliary diode D sn1 and D sn2 Achieving zero-voltage turn-on (ZVS-on) with auxiliary resonant inductor L sn Part of the current flows through the freewheeling diode D sn2 The freewheeling circuit formed by the main switch Q2 partially passes through the freewheeling diode D. sn1 and auxiliary switching transistor Q sn This forms a freewheeling circuit. The operating states of other devices remain consistent with the previous mode. In this mode, the main switch Q2 and the auxiliary switch Q... sn The voltage across the terminals is zero, providing the conditions for zero-voltage turn-off (ZVS-off) of both switches. This stage continues until the main switch Q2 and the auxiliary switch Q... sn The arrival of the shutdown signal.

[0040] Mode 6 [t2, t3]: The circuit operating state in this mode is as follows Figure 4 As shown in (f). At time t5, the main switch Q2 and the auxiliary switch Q... sn The shutdown signal arrives. At this moment, the auxiliary resonant inductor L... sn Through auxiliary diode D sn1 and D sn2 With resonant capacitor C sn This forms a resonant circuit. Because C sn Resonant voltage Starting from zero, therefore Q2, Q snZero-voltage turn-off (ZVS-off). After Q2 turns off, the auxiliary inductor L of the subsequent stage... σ Current flows through resonant capacitor C sn and diode D sn1 Branch freewheeling. In the auxiliary resonant network 3-1, the auxiliary switch and auxiliary diode have conduction losses, therefore, the resonant capacitor C at this stage... sn The stored energy comes from two parts: one part is from the auxiliary resonant inductor L sn One part is supplied by the discharge circuit, and the other part is supplied by the preceding stage circuit. The auxiliary inductor L of the following stage circuit... σ The current gradually decreases Part of the current from L2 is transferred to the load through D3. The current flowing through diode D3 rises from zero, achieving zero-current conduction (ZCS-on) for diode D3. Freewheeling current. When that happens, the mode ends.

[0041] Mode 7 [t3, t4]: The circuit operating state in this mode is as follows Figure 4 As shown in (g). At time t6, the auxiliary inductor L of the subsequent circuit... σ The current drops to zero, and the load current I of the subsequent circuit... o The current is supplied by the output filter capacitor C2 and the output inductor L2 freewheeling. The preamplifier forms two charging and discharging circuits: one connected to L1 and C1, C2... D2 The C1 charging and C configurations are as follows: D2 One circuit is for discharging and charging L1; the other is a circuit consisting of L1, C3, and power supply V. in This forms a charging circuit for C3 and L1. The auxiliary resonant inductor in the resonant circuit continues to charge the resonant capacitor. At time t7, the front-stage auxiliary capacitor C... D2 Discharge voltage At the same time, the voltage of the front-end auxiliary capacitor C3 is charged to V. C3 =V in When (1+D), the next mode is entered.

[0042] Mode 8 [t4, t5]: The circuit operating state in this mode is as follows Figure 4 As shown in (h). At time t7, after the preceding circuit has charged and discharged, the preceding auxiliary capacitor C... D2 voltage The front-stage diode D2 conducts at zero voltage (ZVS-on), forming a circuit for the front-stage inductor L1 to charge the front-stage capacitor C1. The subsequent circuit maintains the previous mode unchanged. The auxiliary resonant inductor L... sn Through diode D sn1 and D sn2 Continue to supply resonant capacitor C sn As the capacitor charges, the voltage across the resonant capacitor continues to rise. This phase continues until the current in the auxiliary resonant inductor discharges to zero.

[0043] Mode 9 [t5, t6]: The circuit operating state in this mode is as follows Figure 4 As shown in (i). At time t8, the auxiliary resonant inductor L in the auxiliary resonant network sn current Discharge to zero. Resonant capacitor C sn The voltage reaches its maximum value. Auxiliary diode D sn1 and D sn2 Achieve zero-current turn-off (ZCS-off). At this point, the load current I during this stage... o This is provided by the output filter inductor L2. The preceding inductor L1 continues to charge the preceding capacitor C1. This mode continues until the main switch transistor turns on in the next cycle.

Claims

1. A resonant soft-switching circuit for a semi-secondary buck-boost DC-DC converter, characterized in that, include: DC voltage source, main circuit components, load, and auxiliary soft-switching network components; The auxiliary soft-switching network component includes three circuits: two single-capacitor soft-switching networks and a resonant network containing an auxiliary switch. The auxiliary soft-switching capacitor connected in parallel with the second main diode in the front stage of the main circuit component is auxiliary soft-switching network component 1. The auxiliary soft-switching capacitor connected in parallel with the output terminal of the front stage of the main circuit component is auxiliary soft-switching network component 2. The auxiliary soft-switching network related to the main switch in the main circuit component is auxiliary soft-switching network component 3. The positive terminal of the DC voltage source is connected to the first terminal of auxiliary soft-switching network component 1. The midpoint of the main diode connected in series in the front stage of the main circuit component is connected to the second terminal of auxiliary soft-switching network component 1. The negative terminal of the DC voltage source is connected to the second terminal of auxiliary soft-switching network component 2. The first terminal of the main switch in the main circuit component is connected to the first terminal of auxiliary soft-switching network component 2. The auxiliary soft-switching network component 3 comprises two parts: one part, which is connected in parallel with the main switch transistor, is the auxiliary soft-switching network component 3-1; the other part, which is connected in series with the main switch transistor, is the first auxiliary resonant inductor, is the auxiliary soft-switching network component 3-2. The first terminal of the main switch transistor in the main circuit component is electrically connected to the first terminal of the auxiliary soft-switching network component 3-1. The second terminal of the main switch transistor in the main circuit component is electrically connected to the second terminal of the auxiliary soft-switching network component 3-1 and the first terminal of the auxiliary soft-switching network component 3-2. The second terminal of the filter inductor, the second terminal of the filter capacitor, and the load ground terminal in the main circuit component are electrically connected to the second terminal of the auxiliary soft-switching network component 3-2. The control terminal of the main circuit component and the control terminal of the auxiliary soft-switching network component are connected to the controller. The auxiliary soft-switching network component 3 comprises an auxiliary switching transistor, a first auxiliary diode, a second auxiliary diode, a first auxiliary resonant capacitor, and a second auxiliary resonant inductor, forming auxiliary soft-switching network component 3-1. The first auxiliary resonant inductor forms auxiliary soft-switching network component 3-2. The control terminal of the auxiliary switching transistor is connected to the controller. The first terminal of the auxiliary switching transistor is electrically connected to the connection point between the anode of the second terminal of the second auxiliary diode and the first terminal of the second auxiliary resonant inductor. The second terminal of the auxiliary switching transistor is electrically connected to the connection point between the second terminal of the resonant capacitor and the anode of the first terminal of the first auxiliary diode. The first terminal of the first auxiliary resonant inductor... The second terminal of the main switch in the main circuit assembly and the second terminal of the auxiliary soft-switching network assembly 3-1 are electrically connected. The second terminal of the first auxiliary resonant inductor is electrically connected to the load ground terminal. The first terminal of the first auxiliary resonant capacitor and the first cathode of the second auxiliary diode together form the first terminal of the auxiliary soft-switching network assembly 3-1. The second terminal of the second auxiliary resonant inductor and the first cathode of the first auxiliary diode together form the second terminal of the auxiliary soft-switching network assembly 3-1. The first terminal of the first auxiliary resonant inductor is the first terminal of the auxiliary soft-switching network assembly 3-2. The second terminal of the first auxiliary resonant inductor is the second terminal of the auxiliary soft-switching network assembly 3-2. The main circuit assembly includes a front-end circuit and a rear-end circuit, containing the following components: a main switching transistor, a first front-end main diode, a second front-end main diode, a front-end energy storage inductor, a front-end energy storage capacitor, a rear-end freewheeling diode, a rear-end filter inductor, and a filter capacitor. The main switching transistor connects the front-end and rear-end circuits. The control terminal of the main switching transistor is connected to a controller. The first terminal of the main switching transistor is electrically connected to the second terminal of the front-end energy storage inductor and the second terminal of the front-end energy storage capacitor. The second terminal of the main switching transistor is electrically connected to the second terminal of the auxiliary soft-switching network 3-1 component and the first terminal of the auxiliary soft-switching network 3-2 component. The first front-end main diode and the second front-end main diode are connected in series. The anode of the first front-end main diode is connected to the cathode of the DC voltage source. The second front-end main diode... The cathode is connected to the anode of the DC voltage source. The first terminal of the pre-stage energy storage capacitor is connected to the cathode of the first pre-stage main diode and the anode of the second pre-stage main diode. The first terminal of the pre-stage energy storage inductor is electrically connected to the cathode of the second main diode and the anode of the DC voltage source. The second terminal of the pre-stage energy storage inductor is connected to the second terminal of the pre-stage energy storage capacitor and also to the first terminal of the main switching transistor. The first terminal of the pre-stage energy storage capacitor is connected to the midpoint of the series-connected first and second pre-stage main diodes. The cathode of the subsequent freewheeling diode is connected to the positive terminal of the load and electrically connected to the first terminal of the subsequent filter capacitor. The anode of the subsequent freewheeling diode is electrically connected to the first terminal of the subsequent filter inductor and the cathode of the DC voltage source. The second terminal of the subsequent filter capacitor is electrically connected to the second terminal of the subsequent filter inductor and the load ground terminal.

2. The resonant soft-switching circuit of a semi-secondary buck-boost DC-DC converter according to claim 1, characterized in that, The auxiliary switch is an NMOS transistor or an IGBT transistor. The control terminal of the auxiliary switch is the gate of the NMOS transistor or the gate of the IGBT transistor. The first terminal of the auxiliary switch is the drain of the NMOS transistor or the collector of the IGBT transistor. The second terminal of the auxiliary switch is the source of the NMOS transistor or the emitter of the IGBT transistor.

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

4. A resonant soft-switching circuit for a semi-secondary buck-boost DC-DC converter, characterized in that, Includes a controller and a resonant soft-switching circuit for a semi-secondary buck-boost DC-DC converter as described in any one of claims 1 to 3, wherein the control terminal of the main circuit component and the control terminal of the auxiliary soft-switching network component are electrically connected to the output terminal of the controller; The controller is configured to control the switching operation of the auxiliary switch and the main switch. When the main switch and the auxiliary switch are simultaneously turned on and off, the main switch is turned on with zero current. Then, the auxiliary soft-switching network creates conditions for the main switch and the auxiliary switch to turn off with zero voltage. After the auxiliary resonant capacitor discharges to zero, the main switch and the auxiliary switch are turned off with zero voltage. Throughout the switching cycle, all diodes and the main switch in the main circuit assembly, as well as all auxiliary diodes and the auxiliary switch in the auxiliary soft-switching network assembly, are soft-switched. The overall circuit adjusts the output voltage by controlling the duty cycle of the main switch, and has a wide voltage adjustment range and load range.

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