PFC circuit consisting of soft-switching resonant boost converter

Abstract

The present invention relates to the field of switching power supplies. Provided is a PFC circuit consisting of a soft-switching resonant boost converter. The PFC circuit comprises: an input power supply module, which is configured to provide a direct-current power supply; a boost converter module, which is configured to increase an output voltage Vo under zero-voltage switching conditions; and a load module, which is configured to receive the output voltage Vo of the boost converter module, wherein the input power supply module is electrically connected to the boost converter module, and the boost converter module is electrically connected to the load module. The loss of a boost converter is reduced while power factor correction is implemented.

Description

PFC circuit composed of soft-switching resonant BOOST converter

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese Patent Application No. 2024106993562, filed May 31, 2024. The contents of the aforementioned application are hereby incorporated by reference. TECHNICAL FIELD

[0003] The present application relates to the field of switching power supply, in particular to a PFC circuit composed of soft-switching resonant BOOST converter. BACKGROUND

[0004] In the industrial field, power factor correction function is usually realized by using a boost (BOOST) circuit. 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 the realization of zero-current switching of the switching tube. However, whether it is a discontinuous mode or a critical continuous mode boost power factor correction circuit, the main switching tube used in most applications is a metal oxide semiconductor field effect transistor (MOSFET), which cannot eliminate the capacitive turn-on loss of the parasitic capacitor, increasing the loss of the boost converter, as shown in the circuit of FIG. 1.

[0005] SUMMARY

[0006] The purpose of the present application is to provide a PFC circuit composed of a soft-switching resonant BOOST converter, which can eliminate the capacitive turn-on loss of the switching tube parasitic capacitor and reduce the loss of the boost converter.

[0007] The present application provides a PFC circuit composed of a soft-switching resonant BOOST converter, comprising

[0008] an input power module for providing a direct current power supply,

[0009] a boost converter module for increasing the output voltage Vo under zero-voltage turn-on conditions,

[0010] a load module for receiving the output voltage Vo of the boost converter module,

[0011] 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.

[0012] Preferably, the boost converter module includes a resonance generating unit and a resonance interruption unit. The resonance generating unit is used to generate resonance, and the resonance interruption unit is used to interrupt the continuous resonance of the resonance generating unit. The resonance generating unit and the resonance interruption unit are electrically connected.

[0013] Preferably, the resonance generating unit includes a resonant capacitor Cr, an inductor L1, a switching transistor S1, and a switching transistor S2. The positive terminal of the input power module is electrically connected to one end of the inductor L1, and the other end of the inductor L1 is electrically connected to one end of the switching transistor S1. The other end of the switching transistor 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 terminal of the input power module. One end of the resonant capacitor Cr is electrically connected between the positive terminal of the input power module and the inductor L1, and the other end of the resonant capacitor Cr is electrically connected between the negative terminal of the input power module and the load module. One end of the switching transistor S2 is electrically connected between the inductor L1 and the switching transistor S1, and the other end of the switching transistor S2 is electrically connected between the resonant capacitor Cr and the load module. One end of the resonant interruption unit is electrically connected between the resonant capacitor Cr and the inductor L1, and the other end of the resonant interruption unit is electrically connected between the switching transistor S1 and the load module.

[0014] Preferably, the inductance value of the inductor L1 and the capacitance value of the resonant capacitor Cr satisfy the following relationship:

[0015] Wherein, L1 is the inductance value of the inductor L1, Cr is the capacitance value of the resonant capacitor Cr, CS2 is the parasitic capacitance value of the switching transistor S2, Vo is 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 across the switching transistor 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. Once the value of one is determined, the value of the other can be quickly determined according to this relationship, which facilitates the selection of components and further improves the efficiency of soft switching of the switching transistor.

[0016] Preferably, the resonant interruption unit is a unidirectional conduction device D5.

[0017] Preferably, the PFC circuit composed of a soft-switching resonant BOOST converter includes 10 operating modes, namely: Operating Mode 1, including: the switch S2 is turned on, and the forward current of the inductor L1 increases; Operating Mode 2, including: the switch S2 is turned off, the voltage across the switch S1 decreases, and the voltage across the switch S2 increases; Operating Mode 3, including: the parasitic diode of the switch S1 is turned on, and the forward current of the inductor L1 decreases; Operating Mode 4, including: the switch S1 is turned on, and the forward current of the inductor L1 decreases; Operating Mode 5, including: the switch S1 is turned on, the forward current of the inductor L1 drops 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; Operating Mode 6, including: the switch S1 is turned on, and the device is unidirectionally turned on. When D5 is turned on, the reverse current of inductor L1 stops rising and reaches its peak value; Operation mode 7 includes: the switch S1 is turned off, the unidirectional conducting device D5 is turned on, the voltage across the switch S1 decreases, and the voltage across the switch S2 increases; Operation mode 8 includes: the parasitic diode of the switch S2 is turned on, the unidirectional conducting device D5 is turned on, the voltage across the switch S1 increases, and the reverse current of inductor L1 decreases; Operation mode 9 includes: the switch S2 is turned on, the unidirectional conducting device D5 is turned on, and the reverse current of inductor L1 decreases; Operation mode 10 includes: the reverse current of inductor L1 decreases to zero, the unidirectional conducting device D5 is turned off, the forward current of inductor L1 rises from zero, and the voltage across the resonant capacitor Cr decreases; the current of inductor L1 with the same current direction as the input power module is defined as the forward current.

[0018] Preferably, in mode 6, the peak value of the reverse current of the inductor L1 satisfies the following relationship:

[0019] 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.

[0020] Preferably, the unidirectional conducting device D5 includes a diode D5.

[0021] Preferably, the input power module includes a rectifier unit composed of diodes D1, D2, D3 and D4 and an AC power supply Vin, wherein the rectifier unit is electrically connected to the AC power supply Vin.

[0022] Preferably, the system further includes a filtering module, which is connected in parallel with the load module.

[0023] Preferably, the types of the switching transistors S1 and S2 include metal-oxide-semiconductor field-effect transistors.

[0024] The beneficial effects of this invention are as follows:

[0025] This invention reduces the losses of the boost converter while achieving power factor correction by using an input power supply module to provide DC power, a boost converter module to increase the output voltage Vo under zero-voltage turn-on conditions, and a load module to receive the output voltage Vo of the boost converter module. The input power supply module is electrically connected to the boost converter module, and the boost converter module is electrically connected to the load module. Attached Figure Description

[0026] Figure 1 shows a power factor calibration circuit constructed from a conventional boost converter;

[0027] Figure 2 is a circuit diagram of the present invention;

[0028] Figure 3 shows the main operating waveforms of the power converter of the present invention;

[0029] Figure 4 is the circuit diagram for mode 1;

[0030] Figure 5 shows the circuit diagram for mode 2;

[0031] Figure 6 is the circuit diagram for mode 3;

[0032] Figure 7 shows the circuit diagram for mode 4;

[0033] Figure 8 is the circuit diagram of mode 5;

[0034] Figure 9 is the circuit diagram for mode 6;

[0035] Figure 10 is the circuit diagram of mode 7;

[0036] Figure 11 is the circuit diagram of mode 8;

[0037] Figure 12 is the circuit diagram of mode 9;

[0038] Figure 13 is the circuit diagram of mode 10. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, but do not exclude other elements or objects.

[0040] As shown in Figure 2, this embodiment provides a PFC circuit composed of a soft-switching resonant BOOST converter, an input power supply module for providing DC power, a boost converter module for increasing the output voltage Vo under zero-voltage turn-on conditions, and a load module for receiving the output voltage Vo of the boost converter module. The input power supply module is electrically connected to the boost converter module, and the boost converter module is electrically connected to the load module.

[0041] In this embodiment, the preferred input power module includes a rectifier unit composed of diodes D1, D2, D3, and D4, and an AC power supply Vin. The electrical connection between diodes D1, D2, D3, and D4 and the AC power supply Vin is as follows: the positive terminal of the AC power supply Vin is electrically connected to the positive terminal of diode D1, the negative terminal of diode D1 is electrically connected to the negative terminal of diode D2, the positive terminal of diode D2 is electrically connected to the negative terminal of the AC power supply Vin, the negative terminal of diode D3 is electrically connected to the positive terminal of the AC power supply Vin, the positive terminal of diode D3 is electrically connected to the positive terminal of diode D4, and the negative terminal of diode D4 is electrically connected to the positive terminal of the AC power supply Vin.

[0042] In this embodiment, the boost converter module includes a resonance generating unit and a resonance interruption unit. The resonance generating unit is used to generate resonance, and the resonance interruption unit is used to interrupt the continuous resonance of the resonance generating unit. The resonance generating unit and the resonance interruption unit are electrically connected. The components of the resonance generating unit include a resonant capacitor Cr, an inductor L1, a switching transistor S1, and a switching transistor S2. The component of the resonance interruption unit is a diode D5. The reason for using a resonance interruption unit in the boost converter module is that if the resonance phenomenon in the circuit continues, it will cause excessively high voltage and current in the circuit, which may damage the components in the circuit, cause distortion of the current and voltage waveforms, and make the circuit unable to work normally. In addition, it may also cause additional losses and heat in the circuit, further reducing the efficiency and lifespan of the circuit. It may also generate additional harmonic currents, pollute the power grid, and affect the stability of the power grid and the normal operation of other electrical equipment. Therefore, it is necessary to set up a resonance interruption unit to stop the circuit from continuing to resonate at a certain time.

[0043] In this embodiment, the load module is the load Rload, and the filter module is the filter capacitor Co. The function of the filter capacitor Co is to eliminate noise signals in the power supply and reduce 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:

[0044] The positive terminal of AC power supply Vin is electrically connected to the positive terminal of diode D1. The negative terminal of diode D1 is electrically connected to one end of inductor L1. The other end of inductor L1 is electrically connected to one end of switching transistor S1. The other end of switching transistor S1 is electrically connected to one end of load Rload. The other end of load Rload is electrically connected to the positive terminal of diode D4. The negative terminal of diode D4 is electrically connected to the negative terminal of AC power supply Vin. The positive terminal of diode D2 is electrically connected to the negative terminal of diode D4. The negative terminal of diode D2 is connected between the negative terminal of diode D1 and inductor L1. The positive terminal of diode D3 is electrically connected to the positive terminal of diode D4. The negative terminal of diode D3 is electrically connected to the positive terminal of diode D1. The positive terminal of diode D5 is connected between the negative terminal of diode D2 and inductor L1. The negative terminal of diode D5 is connected between switching transistor S1 and load Rload. Between these terminals, one end of the resonant capacitor Cr is electrically connected between the negative terminal of diode D2 and the positive terminal of diode D5, and the other end of the resonant capacitor Cr is electrically connected between the positive terminal of diode D4 and the load Rload. One end of the switching transistor S2 is electrically connected between the inductor L1 and the switching transistor S1, and the other end of the switching transistor 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 switching transistor S1 and the load Rload, and the other end of the filter capacitor Co is electrically connected between the load Rload and the switching transistor S2.

[0045] In this embodiment, the inductance value of inductor L1 and the capacitance value of resonant capacitor Cr satisfy the following relationship:

[0046] Where L1 is the inductance of inductor L1, Cr is the capacitance of resonant capacitor Cr, CS2 is the parasitic capacitance of switch S2, Vo is the output voltage Vo, Vin-pk is the peak voltage output of AC power supply Vin, and t is the time it takes for the voltage across switch S2 to drop from its peak value to zero, corresponding to the time between t5 and t6 in Figure 3. When selecting circuit components, this relationship allows for the rapid determination of the values ​​of either inductor L1 or resonant capacitor Cr. Once one value is determined, the other can be quickly determined using this relationship, facilitating component selection and further improving the efficiency of soft-switching of the switch. The time t for the voltage across switch S2 to drop to zero is related to the parasitic capacitance of switch S2, but independent of inductor L1 and resonant capacitor Cr, and can be calculated using relevant circuit principles.

[0047] In this embodiment, the switching transistors S1 and S2 are metal-oxide-semiconductor field-effect transistors (MOSFETs). A MOSFET has a source, a drain, and a gate. Therefore, one end of inductor L1 is electrically connected to the drain of switching transistor S1, the source of switching transistor S1 is electrically connected to the load Rload, the drain of switching transistor S2 is electrically connected between inductor L1 and the drain of switching transistor S1, the source of switching transistor S2 is electrically connected between resonant capacitor Cr and the load Rload, the negative terminal of diode D5 is electrically connected between the source of switching transistor S1 and the load Rload, one end of filter capacitor Co is electrically connected between the source of switching transistor S1 and the load Rload, and the other end of filter capacitor Co is electrically connected between the load Rload and the source of switching transistor S2.

[0048] This embodiment, based on the traditional boost power factor calibration circuit, as shown in Figure 1, requires replacing diode S1 in the boost circuit with switch S1. Simultaneously, using diode D5, resonant capacitor Cr, and inductor L1 from the traditional boost power factor calibration circuit, a resonant boost converter is constructed through specific parameter ratios. This provides soft-switching conditions for the boost switches S1 and S2, as well as diodes D1, D2, D3, D4, and D5, eliminating capacitive turn-on losses due to parasitic capacitance of the switches and reducing boost converter losses. Furthermore, since the resonant circuit only operates during the turn-on and turn-off moments of the boost converter switches S1 and S2, the boost converter can be controlled using a fixed-frequency pulse width modulation mode, making the control method mature and simple.

[0049] The operation method of a PFC circuit composed of a soft-switching resonant BOOST converter includes the following steps:

[0050] B1. The power factor calibration circuit is started, and a drive signal is input to the switch S2. The switch S2 is turned on. When the power factor calibration circuit is started, the current in the inductor L1 is defined as the forward current, and the current in the opposite direction of the forward current is defined as the reverse current. The start of the power factor calibration circuit and the input of the drive signal to the switch S2 are performed synchronously. This ensures that when the switch S2 is turned on, there is no voltage across the corresponding parasitic diode, and no turn-on capacitive loss of parasitic capacitance is generated, further reducing the loss of the converter.

[0051] B2. When the forward current of inductor L1 reaches its peak value, a turn-off signal is input to switch S2, and switch S2 is turned off.

[0052] B3. After the voltage across the switch S1 drops to zero and before the forward current of the inductor L1 drops to zero, a drive signal is input to the switch S1, and the switch S1 is turned on.

[0053] B4. At any time after the reverse current of inductor L1 reaches its peak value, input a turn-off signal to switch S1, and switch S1 will turn off. The reason for turning off switch S1 at any time after the reverse current of inductor L1 reaches its peak value is that after the reverse current of inductor L1 reaches its peak value, if the circuit state is not changed, the reverse current of inductor L1 will remain at its peak value and continue to continue, and the circuit state of other related devices will also continue to be maintained unless the circuit is turned off.

[0054] B5. After the voltage across the switch S2 drops to zero and before the reverse current of the inductor L1 drops to zero, a drive signal is input to the switch S2, and the switch S2 is turned on.

[0055] B6. Repeat steps B2 to B5 until the power factor calibration circuit is turned off.

[0056] In this embodiment, pulse width modulation (PWM) is used to control the on / off state of switching transistors S1 and S2. A fixed-frequency PWM method can be used, which is a mature, simple, and robust control scheme. If a non-fixed-frequency PWM method is used, the values ​​of inductor L1 and resonant capacitor Cr can be arbitrarily chosen. The resonant frequency at which resonance occurs can be calculated based on the values ​​of inductor L1 and resonant capacitor Cr, and the pulse width can be modulated according to this determined resonant frequency. If a fixed-frequency PWM method is used, the resonant frequencies of inductor L1 and resonant capacitor Cr must be determined based on the fixed frequency of the pulse width to establish the relationship between them. This relationship must satisfy the following equation:

[0057] In this embodiment, since the AC power supply Vin outputs an alternating AC voltage, when the AC power supply Vin is in the positive half-cycle, diodes D1 and D4 are conducting, while diodes D2 and D3 are always reverse-biased and cut off. When the AC power supply Vin is in the negative half-cycle, diodes D2 and D3 are conducting, while diodes D1 and D4 are reverse-biased and cut off. The positive and negative half-cycles operate in a dual manner, and the working principle is exactly the same. Therefore, this embodiment only describes the working principle of the positive half-cycle. According to the working waveform of the AC power supply Vin in the positive half-cycle shown in Figure 3, the power factor calibration circuit operates according to steps B1 to B5, including 10 operating modes. The circuit is divided into two modes: Mode 1: Before time t0, as shown in Figure 4, switch S2, diode D1, and diode D4 are turned on, and the current in inductor L1 increases linearly under the influence of AC power supply Vin; Mode 2: At time t0, as shown in Figure 5, switch S2 is turned off, the current in inductor L1 cannot change abruptly, and the current in inductor L1 charges the parasitic capacitance of switch S2, while the parasitic capacitance of switch S1 discharges (the parasitic capacitance of switch S1 does not discharge in the first cycle after the circuit is turned on, but it will discharge in the remaining cycles because the parasitic capacitance of switch S1 was not charged in the first cycle). Compared with inductor L1, switch S1 and... The parasitic capacitance of switch S2 is very small. The current change of inductor L1 during the discharge of the parasitic capacitance of switch S1 and the charging of the parasitic capacitance of switch S2 is negligible. Therefore, during this process, the voltage across switch S1 can be considered to decrease linearly, and the voltage across switch S2 can be considered to increase linearly until time t1. Mode 3: At time t1, as shown in Figure 6, the voltage across switch S1 drops to zero, and the parasitic diode of switch S1 conducts, clamping the voltage of switch S1 to zero. After the parasitic diode of switch S1 conducts, the current in inductor L1 flows through diode D1, diode D4, and switch S1. The parasitic diode of inductor L1 has a voltage of Vin-Vo across it. The current of inductor L1 decreases linearly under this voltage. Since the parasitic diode of switch S1 is conducting, the voltage across switch S1 is zero. Therefore, turning on switch S1 after time t1 results in zero-voltage switching (ZVS). Mode 4: At time t2, as shown in Figure 7, switch S1 is turned on. The current of inductor L1 flows through diode D1, diode D4, and switch S1. The voltage across inductor L1 is Vin-Vo. The current of inductor L1 decreases linearly under this voltage.Mode 5: At time t3, as shown in Figure 8, the current in inductor L1 drops to zero. Since switch S1 is still in the on state at this time, the voltage across inductor L1 is still Vin-Vo. The current in inductor L1 will increase in the reverse direction. Since diodes D1 and D4 are diodes, the current cannot reverse. Therefore, the current in inductor L1 will flow through the resonant capacitor Cr. Inductor L1 and resonant capacitor Cr work in resonance. The current in inductor L1 increases in the reverse resonance, and the voltage of resonant capacitor Cr rises from Vin resonance. Mode 6: At time t4 As shown in Figure 9, the voltage across the resonant capacitor Cr rises to Vo, diode D5 turns on, clamping the voltage across the resonant capacitor Cr at Vo. The resonant capacitor Cr and inductor L1 stop resonating, and the current in inductor L1 stops rising in the reverse direction. The current in inductor L1 flows through diode D5 and switch S1 for freewheeling. The resonance process ends, and it enters the freewheeling state. Ignoring the voltage drop across diode D5 and the impedance of switch S1, the current in inductor L1 remains constant during the freewheeling phase. Define this current as Ix, and this current Ix satisfies:

[0058] Where L1 is the inductance of inductor L1, Cr is the capacitance of resonant capacitor Cr, Vin is the output voltage of AC power supply Vin, and Vo is the output voltage Vo. Mode 7: At time t5, as shown in Figure 10, when switch S1 is turned off, the current of inductor L1 charges the parasitic capacitance of switch S1, and the parasitic capacitance of switch S2 discharges. Considering that the parasitic capacitances of switches S1 and S2 are very small, the change in the current of inductor L1 during this process is ignored. Then, the voltage across switch S2 decreases linearly, and the voltage across switch S1 increases linearly. Mode 8: At time t6, as shown in Figure 11, the voltage across switch S2 drops to zero, and after the voltage across switch S1 rises to Vo, the parasitic diode of switch S2 conducts, clamping the voltage across switch S2 to zero. The current of inductor L1 flows through diode D5 and the parasitic diode of switch S2. Under the action of voltage Vo, the current of inductor L1 flows in the reverse direction. Mode 9: At time t7, as shown in Figure 12, switch S2 is turned on with zero voltage. After switch S2 is turned on, the current of inductor L1 flows through diode D5 and switch S2. The current of inductor L1 decreases linearly in the reverse direction under the action of voltage Vo. Mode 10: At time t8, as shown in Figure 13, after the current of inductor L1 decreases to zero in the reverse direction, diode D5 is turned off. At this time, the voltage on resonant capacitor Cr is Vo. Under the action of voltage on resonant capacitor Cr, the current of inductor L1 increases in the resonant positive direction, and the voltage of resonant capacitor Cr decreases in the resonant direction. At time t9, after the voltage of resonant capacitor Cr decreases to Vin, diode D1 is turned on. The current of inductor L1 flows through diode D1, diode D4 and switch S2. The current of inductor L1 increases linearly under the action of AC power supply Vin, which is the same as mode 1 before time t0. The subsequent operation will repeat the above modes, which will not be described again here.

[0059] While embodiments of the present invention have been described in detail above, it will be apparent 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 fall within the scope and spirit of the invention as defined in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A PFC circuit composed of a soft-switching resonant BOOST converter, characterized by, The utility model relates to a kind of DC-DC converter, including Input power module for providing DC power supply, Boost converter module for improving output voltage Vo under zero voltage turn-on condition, Load module for receiving the output voltage Vo of the boost converter module, Wherein, the input power module is electrically connected with the boost converter module, and the boost converter module is electrically connected with 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 resonance generation unit and resonance interrupt unit, the resonance generation unit is used to generate resonance, and the resonance interrupt unit is used to interrupt the resonance generation unit to continue resonance, and the resonance generation unit is electrically connected with the resonance interrupt unit.

3. The PFC circuit composed of a soft-switching resonant BOOST converter according to claim 2, characterized in that, The resonance generation unit includes resonance capacitor Cr, inductance L1, switch tube S1 and switch tube S2, the positive pole of the input power module is electrically connected with one end of the inductance L1, the other end of the inductance L1 is electrically connected with one end of the switch tube S1, the other end of the switch tube S1 is electrically connected with one end of the load module, the other end of the load module is electrically connected with the negative pole of the input power module, one end of the resonance capacitor Cr is electrically connected between the positive pole of the input power module and the inductance L1, the other end of the resonance capacitor Cr is electrically connected between the negative pole of the input power module and the load module, one end of the switch tube S2 is electrically connected between the inductance L1 and the switch tube S1, the other end of the switch tube S2 is electrically connected between the resonance capacitor Cr and the load module, one end of the resonance interrupt unit is electrically connected between the resonance capacitor Cr and the inductance L1, and the other end of the resonance interrupt 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 resonance capacitor Cr satisfy the following relationship: Wherein, L1 is the inductance value of the inductance L1, Cr is the capacitance value of the resonance capacitor Cr, CS2 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 voltage peak value output by the input power module, and t is the time when the voltage across the switch tube S2 drops from 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 interrupt unit is a unidirectional conduction device D5.

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

7. The PFC circuit composed of a soft-switching resonant BOOST converter according to claim 6, characterized in that, In said mode 6, the peak value of the reverse current of said inductor LI 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 rectification unit composed of diodes D1, D2, D3 and D4, and an alternating current power Vin, and the rectification unit is electrically connected with the alternating current power Vin.

10. The PFC circuit composed of a soft-switching resonant BOOST converter according to claim 1, characterized in that, Further comprising a filtering module, which is connected in parallel with the load module.

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