PFC circuit formed by soft switching resonance BOOST converter

Abstract

The utility model relates to the switching power supply field, and provides a PFC circuit formed by a soft switching resonance BOOST converter, comprising an input power supply module used for providing a DC power supply, a boost converter module used for increasing an output voltage Vo under a zero-voltage turn-on condition, and a load module used for receiving the output voltage Vo of the boost converter module, the input power supply module is electrically connected with the boost converter module, and the boost converter module is electrically connected with the load module. And the loss of the boost converter on the premise of realizing power factor correction is reduced.

Description

Technical Field

[0001] The utility model relates to the field of switching power supplies, in particular to a PFC circuit composed of a soft-switching resonant BOOST converter. Background Art

[0002] In the industrial field, the power factor correction function is mostly realized by boost circuit. The discontinuous mode and critical continuous mode boost power factor correction (BOOST PFC) circuits are widely used in small and medium power applications because of their simple circuit structure, easy control, and zero current switching of the switch tube. However, whether it is the discontinuous mode or critical continuous mode boost power factor correction circuit, in most applications, the main switch tube uses a metal oxide semiconductor field effect transistor (MOSFET), which cannot eliminate the capacitive turn-on loss of the parasitic capacitance, increasing the loss of the boost converter, such as Figure 1 The circuit shown. Utility Model Content

[0003] The purpose of the utility model is to provide a PFC circuit composed of a soft-switching resonant BOOST converter, which is used to eliminate the capacitive turn-on loss of the parasitic capacitance of the switch tube and reduce the loss of the boost converter. The utility model provides a PFC circuit composed of a soft-switching resonant BOOST converter, including an input power module for providing a DC power supply,

[0004] The boost converter module is used to increase the output voltage Vo under zero voltage turn-on conditions.

[0005] A load module, used to receive the output voltage Vo of the boost converter module,

[0006] The input power module is electrically connected to the boost converter module, and the boost converter module is electrically connected to the load module.

[0007] Preferably, the boost converter module comprises a resonance generating unit and a resonance interrupting unit, the resonance generating unit is used to generate resonance, the resonance interrupting unit is used to interrupt the resonance generating unit from continuing to resonate, and the resonance generating unit is electrically connected to the resonance interrupting unit.

[0008] Preferably, the resonance generating unit includes a resonant capacitor Cr, an inductor L1, a switch tube S1 and a switch tube S2, the positive electrode of the input power module is electrically connected to one end of the inductor L1, the other end of the inductor L1 is electrically connected to one end of the switch tube S1, the other end of the switch tube S1 is electrically connected to one end of the load module, and the other end of the load module is electrically connected to the negative electrode of the input power module, one end of the resonant capacitor Cr is electrically connected between the positive electrode of the input power module and the inductor L1, the other end of the resonant capacitor Cr is electrically connected between the negative electrode of the input power module and the load module, one end of the switch tube S2 is electrically connected between the inductor L1 and the switch tube S1, and the other end of the switch tube S2 is electrically connected between the resonant capacitor Cr and the load module, one end of the resonance interruption unit is electrically connected between the resonant capacitor Cr and the inductor L1, and the other end of the resonance interruption unit is electrically connected between the switch tube S1 and the load module.

[0009] Preferably, the inductance value of the inductor L1 and the capacitance value of the resonant capacitor Cr satisfy the following relationship:

[0010]

[0011] Wherein, L1 is the inductance value of the inductor L1, Cr is the capacitance value of the resonant capacitor Cr, C S2 is the value of the parasitic capacitance of the switch tube S2, Vo is the value of the output voltage Vo, Vin-pk is the peak voltage output by the input power module, and t is the time for the voltage across the switch tube S2 to drop from the peak value to zero. When selecting circuit components, the value of the inductor L1 or the resonant capacitor Cr can be quickly determined according to this relationship. As long as the value of one of them is determined, the value of the other can be quickly determined according to this relationship, which brings convenience to the selection of components and further improves the efficiency of realizing soft switching of the switch tube.

[0012] Preferably, the resonance interruption unit is a unidirectional conducting device D5.

[0013] Preferably, the PFC circuit composed of the soft-switching resonant BOOST converter includes 10 operating modes, which are respectively operating mode 1, including: the switch tube S2 is turned on, and the forward current of the inductor L1 increases; operating mode 2, including: the switch tube S2 is turned off, the voltage across the switch tube S1 decreases, and the voltage across the switch tube S2 increases; operating mode 3, including: the parasitic diode of the switch tube S1 is turned on, and the forward current of the inductor L1 decreases; operating mode 4, including: the switch tube S1 is turned on, and the forward current of the inductor L1 decreases; operating mode 5, including: the switch tube S1 is turned on, the forward current of the inductor L1 drops to zero, the inductor L1 and the resonant capacitor Cr work in resonance, the reverse current of the inductor L1 increases from zero, and the voltage across the resonant capacitor Cr increases; operating mode 6, including: the switch tube S1 is turned on, the unidirectional conductive device D5 is turned on, and the reverse current of the inductor L1 stops rising and reaches a peak value; operation mode 7 includes: the switch tube S1 is turned off, the unidirectional conduction device D5 is turned on, the voltage across the switch tube S1 decreases, and the voltage across the switch tube S2 increases; operation mode 8 includes: the parasitic diode of the switch tube S2 is turned on, the unidirectional conduction device D5 is turned on, the voltage across the switch tube S1 increases, and the reverse current of the inductor L1 decreases; operation mode 9 includes: the switch tube S2 is turned on, the unidirectional conduction device D5 is turned on, and the reverse current of the inductor L1 decreases; operation mode 10 includes: the reverse current of the inductor L1 decreases to zero, the unidirectional conduction device D5 is turned off, the forward current of the inductor L1 increases from zero, and the voltage across the resonant capacitor Cr decreases; the current of the inductor L1 having the same direction as the current of the input power module is defined as the forward current.

[0014] Preferably, in the mode 6, the peak value of the reverse current of the inductor L1 satisfies the following relationship:

[0015]

[0016] Wherein, Ix is the peak value of the reverse current of the inductor L1, L1 is the inductance value of the inductor L1, Cr is the capacitance value of the resonant capacitor Cr, Vin is the voltage value output by the input power module, and Vo is the value of the output voltage Vo.

[0017] Preferably, the type of the unidirectional conducting device D5 includes a diode D5.

[0018] Preferably, the input power module comprises a rectifier unit consisting of a diode D1 , a diode D2 , a diode D3 and a diode D4 and an AC power source Vin, and the rectifier unit is electrically connected to the AC power source Vin.

[0019] Preferably, it further comprises a filter module, and the filter module is connected in parallel with the load module.

[0020] Preferably, the switch tube S1 and the switch tube S2 are made of metal oxide semiconductor field effect transistors.

[0021] The beneficial effects of the utility model are:

[0022] The utility model uses an input power module for providing a DC power supply, a boost converter module for increasing an output voltage Vo under a zero voltage switching condition, and a load module for receiving the output voltage Vo of the boost converter module. The input power module is electrically connected to the boost converter module, and the boost converter module is electrically connected to the load module, thereby reducing the loss of the boost converter under the premise of achieving power factor correction. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A power factor calibration circuit for a conventional boost converter;

[0024] Figure 2 It is a circuit diagram of the utility model;

[0025] Figure 3 This is the main working waveform diagram of the power converter of the utility model;

[0026] Figure 4 This is the circuit diagram of mode 1;

[0027] Figure 5 This is the circuit diagram of mode 2;

[0028] Figure 6 This is the circuit diagram of mode 3;

[0029] Figure 7 This is the circuit diagram of mode 4;

[0030] Figure 8 This is the circuit diagram of mode 5;

[0031] Fig. 9 This is the circuit diagram of mode 6;

[0032] Fig.10 This is the circuit diagram of mode 7;

[0033] Fig.11 This is the circuit diagram of mode 8;

[0034] Fig.12 This is the circuit diagram of mode 9;

[0035] Fig.13 This is the circuit diagram of mode 10. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the utility model belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0037] like Figure 2 As shown, this embodiment provides a PFC circuit composed of a soft-switching resonant BOOST converter, an input power module for providing a DC power supply, a boost converter module for increasing the output voltage Vo under a zero voltage turn-on condition, and a load module for receiving the output voltage Vo of the boost converter module, wherein the input power module is electrically connected to the boost converter module, and the boost converter module is electrically connected to the load module.

[0038] In this embodiment, the input power module preferably includes a rectifier unit composed of a diode D1, a diode D2, a diode D3 and a diode D4 and an AC power supply Vin. The diode D1, the diode D2, the diode D3 and the diode D4 are electrically connected to the AC power supply Vin as follows: the positive electrode of the AC power supply Vin is electrically connected to the positive electrode of the diode D1, the negative electrode of the diode D1 is electrically connected to the negative electrode of the diode D2, the positive electrode of the diode D2 is electrically connected to the negative electrode of the AC power supply Vin, the negative electrode of the diode D3 is electrically connected to the positive electrode of the AC power supply Vin, the positive electrode of the diode D3 is electrically connected to the positive electrode of the diode D4, and the negative electrode of the diode D4 is electrically connected to the positive electrode of the AC power supply Vin.

[0039] In this embodiment, the boost converter module includes a resonance generating unit and a resonance interrupting unit. The resonance generating unit is used to generate resonance, and the resonance interrupting unit is used to interrupt the resonance generating unit from continuing to resonate. The resonance generating unit is electrically connected to the resonance interrupting unit. The components of the resonance generating unit include a resonance capacitor Cr, an inductor L1, a switch tube S1 and a switch tube S2. The component of the resonance interrupting unit is a diode D5. The reason for using the resonance interrupting unit in the boost converter module is that if the resonance phenomenon in the circuit continues, excessive voltage and current will be generated in the circuit, which may damage the components in the circuit, may cause distortion of the current and voltage waveforms, and make the circuit unable to work normally. In addition, it may also cause the circuit to generate additional loss and heat, further reduce the efficiency and service life of the circuit, and may generate additional harmonic current, pollute the power grid, affect the stability of the power grid and the normal operation of other electrical equipment. Therefore, it is necessary to set the resonance interrupting unit to stop the circuit from continuing to resonate at a certain time.

[0040] In this embodiment, the load module is a load Rload, the filter module is a filter capacitor Co, and the filter capacitor Co is used to eliminate the clutter signal in the power supply and weaken the fluctuation amplitude of the load voltage, thereby ensuring the stability and purity of the power supply output. The specific circuit connection relationship is as follows:

[0041] The positive electrode of the AC power source Vin is electrically connected to the positive end of the diode D1, the negative end of the diode D1 is electrically connected to one end of the inductor L1, the other end of the inductor L1 is electrically connected to one end of the switch tube S1, the other end of the switch tube S1 is electrically connected to one end of the load Rload, the other end of the load Rload is electrically connected to the positive end of the diode D4, the negative end of the diode D4 is electrically connected to the negative electrode of the AC power source Vin, the positive end of the diode D2 is electrically connected to the negative end of the diode D4, the negative end of the diode D2 is electrically connected between the negative end of the diode D1 and the inductor L1, the positive end of the diode D3 is electrically connected to the positive end of the diode D4, the negative end of the diode D3 is electrically connected to the positive end of the diode D1, and the diode D5 is electrically connected to the positive end of the diode D4. The positive end of is electrically connected between the negative end of the diode D2 and the inductor L1, the negative end of the diode D5 is electrically connected between the switch tube S1 and the load Rload, one end of the resonant capacitor Cr is electrically connected between the negative end of the diode D2 and the positive end of the diode D5, the other end of the resonant capacitor Cr is electrically connected between the positive end of the diode D4 and the load Rload, one end of the switch tube S2 is electrically connected between the inductor L1 and the switch tube S1, the other end of the switch tube S2 is electrically connected between the resonant capacitor Cr and the load Rload, one end of the filter capacitor Co is electrically connected between the switch tube S1 and the load Rload, and the other end of the filter capacitor Co is electrically connected between the load Rload and the switch tube S2.

[0042] In this embodiment, the inductance value of the inductor L1 and the capacitance value of the resonant capacitor Cr satisfy the following relationship:

[0043]

[0044] Among them, L1 is the inductance value of inductor L1, Cr is the capacitance value of resonant capacitor Cr, C S2 is the value of the parasitic capacitance of the switch tube S2, Vo is the value of the output voltage Vo, Vin-pk is the peak voltage output by the AC power supply Vin, and t is the time for the voltage across the switch tube S2 to drop from the peak value to zero, corresponding to Figure 3 The time between t5 and t6 in . When selecting circuit components, the value of the inductor L1 or the resonant capacitor Cr can be quickly determined according to this relationship. As long as the value of one of them is determined, the value of the other can be quickly determined according to this relationship, which brings convenience to the selection of components and further improves the efficiency of realizing soft switching of the switch tube. The time t when the voltage across the switch tube S2 drops to zero is related to the parasitic capacitance of the switch tube S2, and has nothing to do with the inductor L1 and the resonant capacitor Cr, and can be calculated through relevant circuit principles.

[0045] In the present embodiment, the types of the switch tube S1 and the switch tube S2 include metal oxide semiconductor field effect transistors, and the metal oxide semiconductor field effect transistor has a source, a drain and a gate. Therefore, one end of the inductor L1 is electrically connected to the drain of the switch tube S1, the source of the switch tube S1 is electrically connected to the load Rload, the drain of the switch tube S2 is electrically connected between the inductor L1 and the drain of the switch tube S1, the source of the switch tube S2 is electrically connected between the resonant capacitor Cr and the load Rload, the negative end of the diode D5 is electrically connected between the source of the switch tube S1 and the load Rload, one end of the filter capacitor Co is electrically connected between the source of the switch tube S1 and the load Rload, and the other end of the filter capacitor Co is electrically connected between the load Rload and the source of the switch tube S2.

[0046] This embodiment is based on the traditional boost power factor calibration circuit. Figure 1 As shown, the diode S1 in the boost circuit needs to be replaced with the switch tube S1, and the diode D5, the resonant capacitor Cr, and the inductor L1 in the traditional boost power factor calibration circuit are used to form a resonant boost converter through a specific parameter ratio, which provides soft switching conditions for the boost switch tubes S1 and S2 and the diodes D1, D2, D3, D4, and D5, eliminates the capacitive turn-on loss of the parasitic capacitance of the switch tube, and reduces the loss of the boost converter. Moreover, since the resonant circuit only works at the moment when the switch tubes S1 and S2 of the boost converter are turned on and off, the boost converter can be controlled by a fixed-frequency pulse width modulation mode, and the control method is mature and simple.

[0047] The operating method of the PFC circuit composed of a soft-switching resonant BOOST converter includes the following steps: B1. Starting the power factor calibration circuit and inputting a driving signal to the switch tube S2, the switch tube S2 is turned on, and it is defined that when the power factor calibration circuit is started, the current of the inductor L1 is a forward current, and the current opposite to the forward current is a reverse current; starting the power factor calibration circuit and inputting the driving signal to the switch tube S2 are performed synchronously, so that when the switch tube S2 is turned on, there is no voltage at both ends of the corresponding parasitic diode, and no turn-on capacitive loss of the parasitic capacitor is generated, thereby further reducing the loss of the converter;

[0048] B2. When the forward current of the inductor L1 reaches a peak value, a shutdown signal is input to the switch tube S2, and the switch tube S2 is turned off;

[0049] B3. After the voltage across the switch tube S1 drops to zero and before the forward current of the inductor L1 drops to zero, a driving signal is input to the switch tube S1, and the switch tube S1 is turned on;

[0050] B4. At any time after the reverse current of the inductor L1 reaches the peak value, a shutdown signal is input to the switch tube S1, and the switch tube S1 is turned off; the switch tube S1 is turned off at any time after the reverse current of the inductor L1 reaches the peak value because after the reverse current of the inductor L1 reaches the peak value, if the circuit state is not changed, the reverse current of the inductor L1 will continue to remain at the peak value, and the circuit states of other related devices will also continue to remain, unless the circuit is turned off;

[0051] B5. After the voltage across the switch tube S2 drops to zero and before the reverse current of the inductor L1 drops to zero, a driving signal is input to the switch tube S2, and the switch tube S2 is turned on;

[0052] B6. Repeat steps B2 to B5 until the power factor calibration circuit is turned off.

[0053] In this embodiment, a pulse width modulation method is used to control the on and off of the switch tube S1 and the switch tube S2. It can be a fixed-frequency pulse width modulation method. The control scheme is mature, simple and robust. If a non-fixed-frequency pulse width modulation method is used, the values ​​of the inductor L1 and the resonant capacitor Cr can be arbitrarily selected. The resonant frequency when resonance occurs can be calculated according to the values ​​of the inductor L1 and the resonant capacitor Cr. The frequency of the pulse width can be modulated according to the determined resonant frequency. If a fixed-frequency pulse width modulation method is used, the resonant frequency of the inductor L1 and the resonant capacitor Cr needs to be determined according to the fixed frequency of the pulse width. The relationship between the inductor L1 and the resonant capacitor Cr needs to be determined, that is, the following relationship needs to be satisfied:

[0054]

[0055] In this embodiment, since the AC power source Vin outputs an AC alternating voltage, when the AC power source Vin is in the positive half cycle, the diodes D1 and D4 are turned on and work, and the diodes D2 and D3 are always reverse biased and cut off; when the AC power source Vin is in the negative half cycle, the diodes D2 and D3 are turned on and work, and the diodes D1 and D4 are reverse biased and cut off. The positive and negative half cycles work in pairs, and the working principles are exactly the same. Therefore, this embodiment only describes the working principle of the positive half cycle. Figure 3 As shown in the working waveform of the positive half cycle of the AC power supply Vin, when the power factor calibration circuit operates according to steps B1 to B5, it includes 10 operating modes, which are mode 1: before time t0, such as Figure 4 As shown, the switch tube S2, diode D1 and diode D4 are turned on, and the current of the inductor L1 increases linearly under the action of the AC power supply Vin; Mode 2: At t0, as shown Figure 5 As shown, when the switch tube S2 is turned off, the current of the inductor L1 cannot change suddenly. The current of the inductor L1 charges the parasitic capacitance of the switch tube S2, and the parasitic capacitance of the switch tube S1 is discharged (the parasitic capacitance of the switch tube S1 is not discharged in the first cycle after the circuit is turned on, and it will be discharged in the remaining cycles because the parasitic capacitance of the switch tube S1 is not charged at this time in the first cycle). Compared with the inductor L1, the parasitic capacitance of the switch tube S1 and the switch tube S2 is very small. The current change of the inductor L1 in the process of discharging the parasitic capacitance of the switch tube S1 and charging the parasitic capacitance of the switch tube S2 can be ignored. Therefore, in this process, it can be considered that the voltage across the switch tube S1 decreases linearly and the voltage across the switch tube S2 increases linearly until the moment t1; Mode 3: At the moment t1, as Figure 6 As shown, the voltage across the switch tube S1 drops to zero, and then the parasitic diode of the switch tube S1 is turned on, clamping the voltage of the switch tube S1 at zero. After the parasitic diode of the switch tube S1 is turned on, the current of the inductor L1 flows through the diode D1, the diode D4 and the parasitic diode of the switch tube S1. The voltage across the inductor L1 is Vin-Vo, and the current of the inductor L1 decreases linearly under this voltage. Since the parasitic diode of the switch tube S1 is turned on, the voltage across the switch tube S1 is zero. Therefore, turning on the switch tube S1 after time t1 is zero voltage switching (Zero-Voltage-Switching, ZVS); Mode 4: At time t2, as Figure 7 As shown, the switch tube S1 is turned on, and the current of the inductor L1 flows through the diode D1, the diode D4 and the switch tube S1. The voltage across the inductor L1 is Vin-Vo, and the current of the inductor L1 decreases linearly under the action of this voltage; Mode 5: At t3, as Figure 8As shown, the current of the inductor L1 drops to zero. Since the switch tube S1 is still in the on state at this moment, the voltage across the inductor L1 is still Vin-Vo, and the current of the inductor L1 will increase in the reverse direction. Since the diode D1 and the diode D4 are diodes, the current cannot be reversed, so the current of the inductor L1 will flow through the resonant capacitor Cr. The inductor L1 and the resonant capacitor Cr work in resonance, and the reverse resonance of the inductor L1 current increases, and the voltage of the resonant capacitor Cr rises from the resonance of Vin; Mode 6: At t4, as Fig. 9 As shown, the voltage of the resonant capacitor Cr rises to Vo through resonance, and the diode D5 is turned on, clamping the voltage of the resonant capacitor Cr at Vo. The resonant capacitor Cr and the inductor L1 stop resonating, and the current of the inductor L1 stops rising in the reverse direction. The current of the inductor L1 flows through the diode D5 and the switch tube S1 for freewheeling. The resonance process ends and enters the freewheeling state. Ignoring the tube voltage drop of the diode D5 and the impedance of the switch tube S1, the current of the inductor L1 remains unchanged in the freewheeling stage. This current is defined as Ix, and this current Ix satisfies:

[0056]

[0057] Wherein, L1 is the inductance value of the inductor L1, Cr is the capacitance value of the resonant capacitor Cr, Vin is the voltage value output by the AC power supply Vin, and Vo is the value of the output voltage Vo; Mode 7: At t5, Fig.10 As shown, the switch S1 is turned off, the current of the inductor L1 charges the parasitic capacitance of the switch S1, and the parasitic capacitance of the switch S2 is discharged. Considering that the parasitic capacitances of the switch S1 and the switch S2 are very small, the change of the current of the inductor L1 in this process is ignored, and the voltage across the switch S2 decreases linearly, and the voltage across the switch S1 increases linearly; Mode 8: At time t6, as Fig.11 As shown, the voltage across the switch tube S2 drops to zero, and after the voltage across the switch tube S1 rises to Vo, the parasitic diode of the switch tube S2 is turned on, clamping the voltage across the switch tube S2 at zero, and the current of the inductor L1 flows through the diode D5 and the parasitic diode of the switch tube S2. The current of the inductor L1 decreases linearly in the reverse direction under the action of the voltage value Vo; Mode 9: At t7, as Fig.12 As shown, the switch tube S2 is turned on, and the switch tube S2 is turned on with zero voltage. After the switch tube S2 is turned on, the current of the inductor L1 flows through the diode D5 and the switch tube S2. The current of the inductor L1 decreases linearly in the reverse direction under the action of the voltage value Vo; Mode 10: At t8, as Fig.13As shown, after the current of the inductor L1 drops to zero in the reverse direction, the diode D5 is turned off. At this time, the voltage on the resonant capacitor Cr is Vo. Under the action of the voltage on the resonant capacitor Cr, the current of the inductor L1 resonates positively and increases, and the voltage of the resonant capacitor Cr resonates and drops. At time t9, after the voltage of the resonant capacitor Cr drops to Vin, the diode D1 is turned on, and the current of the inductor L1 flows through the diode D1, the diode D4 and the switch tube S2. The current of the inductor L1 rises linearly under the action of the voltage of the AC power supply Vin, which is the same as mode 1 before time t0. The subsequent operation mode will repeat the above modes, which will not be repeated here.

[0058] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A PFC circuit consisting of a soft-switching resonant BOOST converter, characterized in that: include Input power module, used to provide DC power, The boost converter module is used to increase the output voltage Vo under zero voltage turn-on conditions. A load module, used to receive the output voltage Vo of the boost converter module, The input power module is electrically connected to the boost converter module, and the boost converter module is electrically connected to the load module.

2. The PFC circuit composed of a soft-switching resonant BOOST converter according to claim 1, characterized in that: The boost converter module includes a resonance generating unit and a resonance interrupting unit. The resonance generating unit is used to generate resonance. The resonance interrupting unit is used to interrupt the resonance generating unit from continuing to resonate. The resonance generating unit is electrically connected to the resonance interrupting unit.

3. The PFC circuit composed of a soft-switching resonant BOOST converter according to claim 2, characterized in that: The resonance generating unit includes a resonant capacitor Cr, an inductor L1, a switch tube S1 and a switch tube S2. The positive electrode of the input power module is electrically connected to one end of the inductor L1, the other end of the inductor L1 is electrically connected to one end of the switch tube S1, the other end of the switch tube S1 is electrically connected to one end of the load module, and the other end of the load module is electrically connected to the negative electrode of the input power module. One end of the resonant capacitor Cr is electrically connected between the positive electrode of the input power module and the inductor L1, the other end of the resonant capacitor Cr is electrically connected between the negative electrode of the input power module and the load module, one end of the switch tube S2 is electrically connected between the inductor L1 and the switch tube S1, and the other end of the switch tube S2 is electrically connected between the resonant capacitor Cr and the load module. One end of the resonance interruption unit is electrically connected between the resonant capacitor Cr and the inductor L1, and the other end of the resonance interruption unit is electrically connected between the switch tube S1 and the load module.

4. The PFC circuit composed of a soft-switching resonant BOOST converter according to claim 3, characterized in that: The inductance value of the inductor L1 and the capacitance value of the resonant capacitor Cr satisfy the following relationship: Wherein, L1 is the inductance value of the inductor L1, Cr is the capacitance value of the resonant capacitor Cr, C S2 is the value of the parasitic capacitance of the switch tube S2, Vo is the value of the output voltage Vo, Vin-pk is the peak voltage output by the input power module, and t is the time it takes for the voltage at both ends of the switch tube S2 to drop from the peak value to zero.

5. The PFC circuit composed of a soft-switching resonant BOOST converter according to claim 3, characterized in that: The resonance interruption unit is a unidirectional conducting device D5.

6. The PFC circuit composed of a soft-switching resonant BOOST converter according to claim 5, characterized in that: The invention comprises 10 operation modes, which are operation mode 1, comprising: the switch tube S2 is turned on, and the forward current of the inductor L1 increases; operation mode 2, comprising: the switch tube S2 is turned off, the voltage across the switch tube S1 decreases, and the voltage across the switch tube S2 increases; operation mode 3, comprising: the parasitic diode of the switch tube S1 is turned on, and the forward current of the inductor L1 decreases; operation mode 4, comprising: the switch tube S1 is turned on, and the forward current of the inductor L1 decreases; operation mode 5, comprising: the switch tube S1 is turned on, the forward current of the inductor L1 decreases to zero, the inductor L1 resonates with the resonant capacitor Cr, the reverse current of the inductor L1 increases from zero, and the voltage across the resonant capacitor Cr increases; operation mode 6, comprising: the switch tube S1 is turned on, the unidirectional conduction device D5 is turned on, the reverse current of the inductor L1 decreases, and the reverse current of the inductor L1 decreases. The current stops rising and reaches a peak value; operation mode 7 includes: the switch tube S1 is turned off, the unidirectional conduction device D5 is turned on, the voltage across the switch tube S1 decreases, and the voltage across the switch tube S2 increases; operation mode 8 includes: the parasitic diode of the switch tube S2 is turned on, the unidirectional conduction device D5 is turned on, the voltage across the switch tube S1 increases, and the reverse current of the inductor L1 decreases; operation mode 9 includes: the switch tube S2 is turned on, the unidirectional conduction device D5 is turned on, and the reverse current of the inductor L1 decreases; operation mode 10 includes: the reverse current of the inductor L1 decreases to zero, the unidirectional conduction device D5 is turned off, the forward current of the inductor L1 increases from zero, and the voltage across the resonant capacitor Cr decreases; the current of the inductor L1 having the same direction as the current of the input power module is defined as the forward current.

7. The PFC circuit composed of a soft-switching resonant BOOST converter according to claim 6, characterized in that: In the mode 6, the peak value of the reverse current of the inductor L1 satisfies the following relationship: Wherein, Ix is the peak value of the reverse current of the inductor L1, L1 is the inductance value of the inductor L1, Cr is the capacitance value of the resonant capacitor Cr, Vin is the voltage value output by the input power module, and Vo is the value of the output voltage Vo.

8. The PFC circuit composed of a soft-switching resonant BOOST converter according to claim 5, characterized in that: The type of the unidirectional conducting device D5 includes a diode D5.

9. The PFC circuit composed of a soft-switching resonant BOOST converter according to claim 1, characterized in that: The input power module includes a rectifier unit composed of a diode D1 , a diode D2 , a diode D3 and a diode D4 and an AC power source Vin, and the rectifier unit is electrically connected to the AC power source Vin.

10. The PFC circuit composed of a soft-switching resonant BOOST converter according to claim 1, characterized in that: It also includes a filter module, which is connected in parallel with the load module.

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