A Zero-Crossing Resonance ZVS Control Circuit for a Four-Switch Buck-Boost Converter

Abstract

The present invention provides a zero-crossing resonance ZVS control circuit of a four-switch buck-boost converter, which enables some switches to work in a ZCS state to reduce the loss of circuit switch components. i >V o When the inductor current changes from negative to positive, Q4 is turned off, so that Q4 is turned off with zero current; when V i <V o When the inductor current changes from positive to negative, Q1 is turned off, so that Q1 is turned off with zero current. The present invention uses an inductor current zero-crossing control method for a four-switch buck-boost converter, breaking the limitation of the ZVS current. Under the same output current condition, the effective value of the inductor current can be reduced, and the circuit loss can be reduced; and a lower switching frequency can be obtained when the same power is output, which is beneficial to reducing the loss of the switching device; at the same time, the corresponding switching device can be turned off at the current zero-crossing point, which is beneficial to reducing the switching loss and voltage stress of the switching device, and further improving the conversion efficiency of the circuit.

Description

Technical Field

[0001] The invention relates to the technical field of space equipment energy, and in particular to a zero-crossing resonance ZVS control circuit of a four-switch buck-boost converter. Background Art

[0002] In recent years, my country's aerospace industry has accelerated its development, and the demand for power supply for space equipment such as space stations and large satellites has become increasingly high. The main way to obtain space energy is photovoltaic panels, and the main storage medium for space energy is batteries. The biggest problem in the application of photovoltaic panels and batteries is that the output voltage varies in a wide range during operation, which cannot meet the load's requirements for the stability of the supply voltage. Therefore, high-efficiency converters that are suitable for input voltages with a wide range of changes and can achieve buck-boost functions have received widespread attention. Among them, a topology called a four-switch buck-boost converter has the advantages of low voltage / current stress on switching devices, fewer passive components, and high efficiency, and has broad application prospects.

[0003] In order to give full play to the topological advantages of the four-switch buck-boost converter and improve the power density and efficiency of the power supply, domestic and foreign scholars and institutions have conducted in-depth research on the control strategy of this topology in recent years. It can be roughly divided into two categories: hard-switch multi-mode PWM modulation strategy and quadrilateral inductor current soft switching (ZVS) modulation strategy. The hard-switch control timing is relatively simple, but the loss of the switching device is high, which is not suitable for high-frequency and high-power density applications. Summary of the invention

[0004] The object of the present invention is to provide a zero-crossing resonance ZVS control circuit for a four-switch buck-boost converter to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A zero-crossing resonance ZVS control circuit of a four-switch buck-boost converter, the four-switch buck-boost converter comprising switch devices Q1, Q2, Q3, Q4 and an inductor L, the control circuit comprising a first comparator, a second comparator, a third comparator, a fourth comparator, a fifth comparator, a first multiplexer, a second multiplexer, a first trigger, a second trigger, a first dead zone counter, a second dead zone counter, a current reference unit, a delay unit and an inverter;

[0007] The negative terminal of the first comparator is the actual output voltage V of the four-switch buck-boost converter. o As input, the positive terminal is given an output voltage V o ' as input and connected to the positive terminal of the second comparator, and the output terminal is connected to the positive terminal of the third comparator;

[0008] The negative terminal of the second comparator is the input voltage V of the four-switch buck-boost converter. i As input, the output terminal is connected to the control terminal of the first multi-way selection switch and the control terminal of the second multi-way selection switch respectively;

[0009] The negative terminal of the third comparator, the positive terminal of the fourth comparator, and the positive terminal of the fifth comparator are connected and connected with the inductor current I L As input;

[0010] The output end of the third comparator is connected to the input end of the first multi-way selection switch, the first output end of the first multi-way selection switch is connected to the R pole of the first trigger, and the second output end is connected to the R pole of the second trigger;

[0011] The negative terminal of the fourth comparator is connected to a constant current source with an output current value of I0, and the output terminal is respectively connected to the S pole of the second trigger and the input terminal of the delay unit, and the output terminal of the delay unit is connected to the S pole of the first trigger;

[0012] The negative terminal of the fifth comparator is grounded and the input current is zero, the output terminal is connected to the input terminal of the second multi-way selection switch, the first output terminal of the second multi-way selection switch is connected to the R pole of the first trigger through the inverter, and the second output terminal is connected to the R pole of the second trigger;

[0013] The Q poles of the first trigger and the second trigger are connected to the input ends of the first dead zone counter and the second dead zone counter respectively;

[0014] The output end of the first dead zone counter is used to control the on and off of the switch devices Q1 and Q2, and the output end of the second dead zone counter is used to control the on and off of the switch devices Q3 and Q4.

[0015] Furthermore, the four-switch buck-boost converter also includes a power supply V S , capacitor C0 and resistor R L The drain of the switching device Q1 is connected to the power supply V S The positive terminal is connected to the positive terminal of the switch device Q2, the source is connected to the drain of the switch device Q2, and the source of the switch device Q2 is connected to the power supply V S The negative terminal of the switch device Q1 is connected to the source of the switch device Q4, the drain of the switch device Q4 is connected to the source of the switch device Q3, one end of the inductor L is connected to the common end of the switch devices Q1 and Q2, and the other end is connected to the common end of the switch devices Q3 and Q4, one end of the capacitor C0 is connected to the source of the switch device Q4, and the other end is connected to the drain of the switch device Q3, the resistor R L is connected in parallel with both ends of capacitor C0.

[0016] Furthermore, the first comparator compares the output voltage Vo and an error value of a given voltage V o ′ generates a peak inductor current reference signal and outputs it to the positive terminal of the third comparator;

[0017] The second comparator generates a multiplexer polarity selection signal by comparing the input voltage V i and the output voltage V o and outputs it to the control terminals of the first multiplexer and the second multiplexer.

[0018] Further, the third comparator is used to compare the inductor current I L with the peak inductor current reference signal value. When the inductor current I L is higher than the peak inductor current reference signal value, the third comparator outputs a high level; the specific control process is as follows:

[0019] When V i > V o the first multiplexer connects the output terminal of the third comparator to the R pole of the first flip-flop, thereby controlling the switching device Q1 to turn off;

[0020] When V i < V o the first multiplexer connects the output terminal of the first comparator to the R pole of the second flip-flop, thereby controlling the switching device Q4 to turn off.

[0021] Further, the fourth comparator is used to compare the inductor current I L with the current value I0 of the constant current source. When I L < I0, the fourth comparator outputs a high level to the S poles of the first flip-flop and the second flip-flop; the specific control process is as follows:

[0022] The S pole of the first flip-flop is connected to a delay unit. The high level output by the fourth comparator first passes through the second flip-flop and outputs to the second dead-time counter, and after inserting the dead time, controls the switching device Q4 to turn on; then after a delay of T time, the high level output by the fourth comparator passes through the first flip-flop and outputs to the first dead-time counter, and after inserting the dead time, controls the switching device Q1 to turn on.

[0023] Further, the fifth comparator is used to detect the zero-crossing point of the inductor current I L When I L > 0, the fifth comparator outputs a high level, otherwise outputs a low level; the specific control process is as follows:

[0024] When V i > V o the second multiplexer connects the output terminal of the fifth comparator to the R pole of the second flip-flop, and when the inductor current I LWhen it changes from negative to positive, the fifth comparator outputs a high level, controls the second trigger to output a low level, and then controls the switch device Q4 to turn off;

[0025] When V i <V o When the inductor current changes from positive to negative, the fifth comparator outputs a low level, controls the first trigger to output a low level, and then controls the switch device Q1 to turn off.

[0026] It can be seen from the above technical solutions that the present invention uses an inductor current zero-crossing control method for a four-switch buck-boost converter, breaking the limitation of the ZVS current. Under the same output current conditions, the effective value of the inductor current can be reduced, reducing circuit losses; and a lower switching frequency can be obtained for the same output power, which is beneficial to reducing the loss of switching devices; at the same time, the corresponding switching devices can be turned off at the current zero-crossing point, which is beneficial to reducing the switching loss and voltage stress of the switching devices, and further improving the conversion efficiency of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a topological diagram of a four-switch buck-boost converter of the present invention;

[0028] Figure 2 for Figure 1 The working timing waveform of the circuit shown;

[0029] Figure 3 for Figure 1 Commutation path diagram of the circuit shown;

[0030] Figure 4 and Figure 5 It is the linear relationship diagram between the effective value of current and the inductor current;

[0031] Figure 6 It is a connection diagram of the control circuit of the present invention;

[0032] Figure 7 V i >V o The switch operation timing diagram of the control circuit;

[0033] Figure 8 V i <V o The switch operation timing diagram of the control circuit;

[0034] Fig. 9 This is a comparison chart of the control effect of the present invention and the effect of the traditional method. DETAILED DESCRIPTION

[0035] A preferred embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific implementation disclosed below.

[0036] like Figure 1 The topology of the four-switch buck-boost converter shown in Figure 1 includes the power supply V S , capacitor C0, resistor R L , switch devices Q1, Q2, Q3, Q4 and an inductor L, specifically, the drain of the switch device Q1 is connected to the power supply V S The positive terminal is connected to the positive terminal of the switch device Q2, the source is connected to the drain of the switch device Q2, and the source of the switch device Q2 is connected to the power supply V S The negative terminal of the switch device Q1 is connected to the source of the switch device Q4, the drain of the switch device Q4 is connected to the source of the switch device Q3, one end of the inductor L is connected to the common end of the switch devices Q1 and Q2, and the other end is connected to the common end of the switch devices Q3 and Q4, one end of the capacitor C0 is connected to the source of the switch device Q4, and the other end is connected to the drain of the switch device Q3, the resistor R L further, the source and drain of the switching devices Q1, Q2, Q3, and Q4 described in this preferred embodiment are anti-parallel-connected with diodes and connected through parasitic capacitance.

[0037] Specifically, the working timing waveform and the commutation path of the topology circuit of the four-switch buck-boost converter under the control of the quadrilateral inductor current modulation strategy are respectively as follows: Figure 2 and Figure 3 As shown:

[0038] During the period t0-t1, the switch devices Q1 and Q4 are turned on, and the voltage across the inductor is the input power supply voltage V i , when the inductor current rises from I0 to I1, Q4 is turned off;

[0039] During the period t1-t2, the switch device Q4 is turned off, the inductor current charges the parasitic capacitance of Q4 and discharges the parasitic capacitance of the switch device Q3, thereby causing the voltage across Q3 to drop. When the voltage across Q3 drops to zero, the diode anti-parallel to Q3 is turned on, and the mode ends.

[0040] During the t2-t3 period, the switch device Q3 is turned on at zero voltage at t2, and the voltage across the inductor L is equal to the input power supply voltage V i and output voltage V o The difference, when V i >V oWhen V i <V o When , the inductor current decreases linearly;

[0041] During the period t3-t4, the switch device Q1 is turned off, the inductor current charges the parasitic capacitance of Q1 and discharges the parasitic capacitance of the switch device Q2, and the voltage across Q2 drops. When the voltage across Q2 drops to zero, the diode anti-parallel to Q2 is turned on, and the mode ends.

[0042] During the t4-t5 period, the switch device Q2 is turned on at zero voltage at t4, and the voltage across the inductor is equal to -V o , when the inductor current drops linearly to I0, the switch device Q3 is turned off;

[0043] During the period t5-t6, after the switch device Q3 is turned off, the inductor current charges the parasitic capacitance of Q3 and discharges the parasitic capacitance of the switch device Q4. When the voltage across Q4 drops to zero, the diode anti-parallel to Q4 is turned on.

[0044] During the period t6-t7, the switch device Q4 is turned on at zero voltage, the voltage across the inductor is zero, and the equivalent series resistance of the line is ignored, so the inductor current is always maintained at I0;

[0045] During the period t7-t8, the switching device Q2 is turned off, the inductor current discharges the parasitic capacitance of the switching device Q1 and charges the parasitic capacitance of Q2, and the voltage across Q1 decreases linearly. When the voltage across Q1 drops to zero, Q1 is turned on with zero voltage, starting a new switching cycle.

[0046] According to the above analysis, in order to achieve ZVS turn-on of switching devices Q1, Q2, Q3, and Q4, the inductor current should meet the following constraints:

[0047]

[0048] Where, t d is the dead time between Q1 and Q2 and between Q3 and Q4.

[0049] In addition, in this circuit, the same current can be output with a variety of different combinations of I1 and I2 current values. The principle is as follows Figure 4 As shown; through analysis, it can be seen that the current effective values ​​corresponding to different combinations of I1 and I2 are different. The smaller the effective value, the smaller the power loss of the circuit. Therefore, the minimum inductor current effective value control method is adopted in the prior art. Combined with the ZVS constraint conditions, it can be seen that: Figure 5 As shown, when the input voltage is higher than the output voltage and When the input voltage is lower than the output voltage and When , the corresponding inductor current effective value is the smallest.

[0050] Therefore, in V i >V o When the existing technology is limited by the ZVS constraint, the minimum I1 should be When Q4 is turned off when the inductor current is I1, Q4 will generate large turn-off loss and peak voltage. Similarly, when V i <V o When I2 is at its minimum When Q1 is turned off when the inductor current is equal to I2, Q1 will generate large turn-off loss and spike voltage; in addition, due to the limitation of the minimum value of I1 or I2, the effective value of the inductor current is large and the inductor loss is still high.

[0051] The zero-crossing resonance ZVS control circuit of the four-switch buck-boost converter of the present invention comprises a first comparator, a second comparator, a third comparator, a fourth comparator, a fifth comparator, a first multiplexer, a second multiplexer, a first trigger, a second trigger, a first dead zone counter, a second dead zone counter, a current reference unit, a delay unit and an inverter; the control circuit of this preferred embodiment is as follows Figure 6 As shown:

[0052] The negative terminal of the first comparator is the actual output voltage V of the four-switch buck-boost converter. o As input, the positive terminal is given an output voltage V o ' is used as input and connected to the positive terminal of the second comparator, and the output terminal is connected to the positive terminal of the third comparator; the negative terminal of the second comparator is connected to the input voltage V i As input, the output end is connected to the control end of the first multi-way selection switch and the control end of the second multi-way selection switch respectively; the negative end of the third comparator, the positive end of the fourth comparator, and the positive end of the fifth comparator are connected and the inductor current I Las input; the output end of the third comparator is connected to the input end of the first multi-way selection switch, the first output end of the first multi-way selection switch is connected to the R pole of the first trigger, and the second output end is connected to the R pole of the second trigger; the negative end of the fourth comparator is connected to a constant current source with an output current value of I0, and the output end is respectively connected to the S pole of the second trigger and the input end of the delay unit, and the output end of the delay unit is connected to the S pole of the first trigger; the negative end of the fifth comparator is grounded and the input current is zero, the output end is connected to the input end of the second multi-way selection switch, the first output end of the second multi-way selection switch is connected to the R pole of the first trigger through an inverter, and the second output end is connected to the R pole of the second trigger; the Q poles of the first trigger and the second trigger are respectively connected to the input ends of the first dead zone counter and the second dead zone counter; the output end of the first dead zone counter is used to control the on and off of the switch devices Q1 and Q2, and the output end of the second dead zone counter is used to control the on and off of the switch devices Q3 and Q4.

[0053] The specific working process of the above control circuit is:

[0054] (1) The first comparator compares the output voltage V o And a given voltage V o The error value of ′ generates an inductor current peak reference signal and outputs it to the positive terminal of the third comparator;

[0055] (2) The second comparator compares the input voltage V i and output voltage V o Generate a multi-way switch polarity selection signal and output it to the control end of the first multi-way selection switch and the second multi-way selection switch;

[0056] (3) The third comparator is used to compare the inductor current I L With the inductor current peak reference signal value, when the inductor current I L When the current is higher than the inductor current peak reference signal value, the third comparator outputs a high level; the specific control process is:

[0057] When V i >V o When , the first multi-way selection switch connects the output terminal of the third comparator to the R pole of the first trigger, thereby controlling the switch device Q1 to be turned off;

[0058] When V i <V o When , the first multi-way selection switch connects the output terminal of the first comparator to the R pole of the second trigger, thereby controlling the switch device Q4 to be turned off;

[0059] (4) The fourth comparator is used to compare the inductor current I LWith the current value I0 of the constant current source, when I L < I0, the fourth comparator outputs a high level to the S poles of the first flip-flop and the second flip-flop; the specific control process is as follows:

[0060] The S pole of the first flip-flop is connected with a delay unit. The high level output by the fourth comparator first passes through the second flip-flop and outputs to the second dead-time counter, and after inserting dead time, controls the switch device Q4 to turn on; then after delaying for T time, the high level output by the fourth comparator passes through the first flip-flop and outputs to the first dead-time counter, and after inserting dead time, controls the switch device Q1 to turn on;

[0061] (5) The fifth comparator is used to detect the zero-crossing point of the inductor current I L When I L > 0, the fifth comparator outputs a high level, otherwise outputs a low level; the specific control process is as follows:

[0062] When V i > V o At this time, the second multiplexer connects the output terminal of the fifth comparator to the R pole of the second flip-flop, and when the inductor current I L changes from negative to positive, the fifth comparator outputs a high level, controls the second flip-flop to output a low level, and further controls the switch device Q4 to turn off;

[0063] When V i < V o At this time, the second multiplexer connects the output of the fifth comparator to the R pole of the first flip-flop through an inverter, and when the inductor current changes from positive to negative, the fifth comparator outputs a low level, controls the first flip-flop to output a low level, and further controls the switch device Q1 to turn off.

[0064] The switching working principle of the inductor current zero-crossing resonance ZVS control circuit of the present invention is as follows:

[0065] (1) When V i > V o At this time, the working timing is as Figure 7 shown, and the specific process is as follows:

[0066] In the time period from t0 to t1, the switch devices Q1 and Q4 are turned on, the voltage across the inductor is the input power supply voltage V i , the inductor current rises from I0, and when the inductor current rises to zero, Q4 turns off, and it is zero-current turn-off (ZCS);

[0067] In the time period from t1 to t2, the inductor L and the parasitic capacitances of the switch devices Q3 and Q4 resonate under the input voltage V iResonance is generated under the drive of , the resonant current charges the parasitic capacitance of Q4, discharges the parasitic capacitance of Q3, and the voltage across Q3 drops. When the voltage across Q3 drops to zero, the diode anti-parallel to Q3 is turned on, and the voltage across Q3 is clamped to zero, after which Q3 is turned on.

[0068] During the t2-t3 period, the switch device Q3 is turned on at zero voltage at t2, and the voltage across the inductor is equal to the input power supply voltage V i and output voltage V o The difference due to V i >V o , the inductor current increases linearly;

[0069] During the period t3-t4, the switch device Q1 is turned off, the inductor current charges the parasitic capacitance of Q1 and discharges the parasitic capacitance of Q2, and the voltage across Q2 drops. When the voltage across Q2 drops to zero, the diode anti-parallel to Q2 is turned on, and the mode ends.

[0070] During the t4-t5 period, the switch device Q2 is turned on at zero voltage at t4, and the voltage across the inductor is equal to -V o , when the inductor current drops linearly to I0, Q3 is turned off.

[0071] During the period t5-t6, the switch device Q3 is turned off, the inductor current charges the parasitic capacitance of Q3 and discharges the parasitic capacitance of the switch device Q4. When the voltage across Q4 drops to zero, the diode anti-parallel to Q4 is turned on.

[0072] During the period t6-t7, the switch device Q4 is turned on at zero voltage, the voltage across the inductor is zero, and the equivalent series resistance of the line is ignored, so the inductor current is always maintained at I0;

[0073] During the period t7-t8, the switch device Q2 is turned off, the inductor current discharges the parasitic capacitance of the switch device Q1, charges the parasitic capacitance of Q2, and the voltage across Q1 decreases linearly. When the voltage across Q1 drops to zero, Q1 is turned on with zero voltage, and a new switching cycle begins.

[0074] (2) When V i <V o When the working sequence is Figure 8 As shown, the specific process is:

[0075] During the period t0-t1, the switch devices Q1 and Q4 are turned on, and the voltage across the inductor is the input power supply voltage V i , the inductor current rises from I0. When the inductor current rises to I1, Q4 is turned off;

[0076] During the period t1-t2, the inductor current charges the parasitic capacitance of the switch device Q4 and discharges the parasitic capacitance of the switch device Q3. The voltage across Q3 decreases. When the voltage across Q3 decreases to zero, the diode anti-parallel to Q3 turns on, and the voltage across Q3 is clamped to zero. Thereafter, Q3 turns on.

[0077] During the t2-t3 period, the switch device Q3 is turned on at zero voltage at t2, and the voltage across the inductor is equal to the input power supply voltage V i and output voltage V o The difference is due to V i <V o , the inductor current decreases linearly;

[0078] During the t3-t4 period, when the inductor current drops to zero, the switch device Q1 is turned off with zero current, and the parasitic capacitance between the inductor L and the switch devices Q1 and Q2 is proportional to the output voltage V o Resonance is generated under the drive of , the resonant current charges the parasitic capacitance of Q1 and discharges the parasitic capacitance of Q2, and the voltage across Q2 drops. When the voltage across Q2 drops to zero, the diode anti-parallel to Q2 is turned on, and the voltage across Q2 is clamped to zero. After that, Q2 is turned on and the mode ends;

[0079] During the t4-t5 period, the switch device Q2 is turned on at zero voltage at t4, and the voltage across the inductor is equal to -V o , when the inductor current drops linearly to I0, Q3 turns off;

[0080] During the period t5-t6, after the switch device Q3 is turned off, the inductor current charges the parasitic capacitance of Q3 and discharges the parasitic capacitance of the switch device Q4. When the voltage across Q4 drops to zero, the diode anti-parallel to Q4 is turned on, and then Q4 is turned on.

[0081] During the period t6-t7, the switch device Q4 is turned on at zero voltage, the voltage across the inductor is zero, and if the equivalent series resistance of the line is ignored, the inductor current is always maintained at I0.

[0082] During the period t7-t8, the switching device Q2 is turned off, the inductor current discharges the parasitic capacitance of the switching device Q1 and charges the parasitic capacitance of Q2, and the voltage across Q1 decreases linearly. When the voltage across Q1 drops to zero, Q1 is turned on with zero voltage, starting a new switching cycle.

[0083] By using the control circuit of the present invention, the following can be obtained: Fig. 9From the inductor current waveform shown in FIG. 1 , it can be seen that the present invention uses the inductor current zero-crossing control method, breaking the limitation of ZVS current. Under the same output current condition, the effective value of the inductor current can be reduced, and the circuit loss can be reduced. At the same time, when the output power is the same, the method of the present invention will obtain a lower switching frequency, which is conducive to reducing the loss of the switching device. In addition, from Figure 7 and 8 It can be seen that the method of the present invention can be used to turn off the corresponding switching device when the current crosses zero point, which is beneficial to reducing the switching loss and voltage stress of the switching device and further improving the conversion efficiency of the circuit.

[0084] The above-described embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A zero-crossing resonance ZVS control circuit of a four-switch buck-boost converter, the four-switch buck-boost converter comprising switch devices Q1, Q2, Q3, Q4 and an inductor L, characterized in that: The control circuit includes a first comparator, a second comparator, a third comparator, a fourth comparator, a fifth comparator, a first multiplexer, a second multiplexer, a first trigger, a second trigger, a first dead zone counter, a second dead zone counter, a current reference unit, a delay unit and an inverter; The negative terminal of the first comparator is the actual output voltage V of the four-switch buck-boost converter. o As input, the positive terminal is given an output voltage V o ´It is used as input and connected to the positive terminal of the second comparator, and its output is connected to the positive terminal of the third comparator; The negative terminal of the second comparator is the input voltage V of the four-switch buck-boost converter. i As input, the output terminal is connected to the control terminal of the first multi-way selection switch and the control terminal of the second multi-way selection switch respectively; The negative terminal of the third comparator, the positive terminal of the fourth comparator, and the positive terminal of the fifth comparator are connected and connected with the inductor current I L As input; The output end of the third comparator is connected to the input end of the first multi-way selection switch, the first output end of the first multi-way selection switch is connected to the R pole of the first trigger, and the second output end is connected to the R pole of the second trigger; The negative terminal of the fourth comparator is connected to a constant current source with an output current value of I0, and the output terminal is respectively connected to the S pole of the second trigger and the input terminal of the delay unit, and the output terminal of the delay unit is connected to the S pole of the first trigger; The negative terminal of the fifth comparator is grounded and the input current is zero, the output terminal is connected to the input terminal of the second multi-way selection switch, the first output terminal of the second multi-way selection switch is connected to the R pole of the first trigger through the inverter, and the second output terminal is connected to the R pole of the second trigger; The Q poles of the first trigger and the second trigger are connected to the input ends of the first dead zone counter and the second dead zone counter respectively; The output end of the first dead zone counter is used to control the on and off of the switch devices Q1 and Q2, and the output end of the second dead zone counter is used to control the on and off of the switch devices Q3 and Q4; The first comparator compares the output voltage V o And a given voltage V o The error value of ´ generates an inductor current peak reference signal and outputs it to the positive terminal of the third comparator; The second comparator compares the input voltage V i and output voltage V o Generate a multi-way switch polarity selection signal and output it to the control end of the first multi-way selection switch and the second multi-way selection switch; The third comparator is used to compare the inductor current I L With the inductor current peak reference signal value, when the inductor current I L When the current is higher than the inductor current peak reference signal value, the third comparator outputs a high level; the specific control process is: When V i >V o When , the first multi-way selection switch connects the output terminal of the third comparator to the R pole of the first trigger, thereby controlling the switch device Q1 to be turned off; When V i <V o When , the first multi-way selection switch connects the output terminal of the first comparator to the R pole of the second trigger, thereby controlling the switch device Q4 to be turned off.

2. The zero-crossing resonance ZVS control circuit of a four-switch buck-boost converter according to claim 1, characterized in that: The four-switch buck-boost converter also includes a power supply V S , capacitor C0 and resistor R L The drain of the switching device Q1 is connected to the power supply V S The positive terminal is connected to the positive terminal of the switch device Q2, the source is connected to the drain of the switch device Q2, and the source of the switch device Q2 is connected to the power supply V S The negative terminal of the switch device Q1 is connected to the source of the switch device Q4, the drain of the switch device Q4 is connected to the source of the switch device Q3, one end of the inductor L is connected to the common end of the switch devices Q1 and Q2, and the other end is connected to the common end of the switch devices Q3 and Q4, one end of the capacitor C0 is connected to the source of the switch device Q4, and the other end is connected to the drain of the switch device Q3, the resistor R L The two ends of are connected in parallel with the two ends of capacitor C0.

3. The zero-crossing resonance ZVS control circuit of a four-switch buck-boost converter according to claim 2, characterized in that: The sources and drains of the switch devices Q1 , Q2 , Q3 , and Q4 are anti-parallel connected with diodes and are connected via parasitic capacitances.

4. The zero-crossing resonance ZVS control circuit of a four-switch buck-boost converter according to claim 1, characterized in that: The fourth comparator is used to compare the inductor current I L With the current value of the constant current source I0, when I L < I0, the fourth comparator outputs a high level to the S poles of the first trigger and the second trigger; the specific control process is: The S pole of the first trigger is connected to a delay unit, and the high level output by the fourth comparator is first output to the second dead zone counter through the second trigger, and the switch device Q4 is controlled to be turned on after the dead zone is inserted; then after a delay of T time, the high level output by the fourth comparator is output to the first dead zone counter through the first trigger, and the switch device Q1 is controlled to be turned on after the dead zone is inserted.

5. The zero-crossing resonance ZVS control circuit of a four-switch buck-boost converter according to claim 1, characterized in that: The fifth comparator is used to detect the inductor current I L The zero crossing point of I L >0, the fifth comparator outputs a high level, otherwise it outputs a low level; the specific control process is: When V i >V o When the inductor current I L When it changes from negative to positive, the fifth comparator outputs a high level, controls the second trigger to output a low level, and then controls the switch device Q4 to turn off; When V i <V o When the inductor current changes from positive to negative, the fifth comparator outputs a low level, controls the first trigger to output a low level, and then controls the switch device Q1 to turn off.

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