阅读说明：本技术 一种功率因素校正控制电路及驱动电源 (Power factor correction control circuit and driving power supply ) 是由 宋祖梅 陈圣伦 于 2020-11-02 设计创作，主要内容包括：本发明公开了一种功率因素校正控制电路及驱动电源,该电路包括电网输入Vin、整流桥DB1、电容C1、电容C2、开关管S1、开关管S2、开关管S3、二极管D1、电感L1、电阻R1、变压器T1、第一输出整流电路、输出电容Co、功率因素校正控制电路及谐振控制驱动电路。有益效果：本发明能够防止电路器件过应力,实现了功率因素校正功能；本发明的功率因素校正控制电路及驱动电源,电路简单,控制方便,相比于两级电路,电路成本较低,相比于无源电荷泵PFC,可以很好地兼顾母线容电压和功率因素,可以适用于较宽的输入和输出负载范围。(The invention discloses a power factor correction control circuit and a driving power supply, wherein the circuit comprises a power grid input Vin, a rectifier bridge DB1, a capacitor C1, a capacitor C2, a switch tube S1, a switch tube S2, a switch tube S3, a diode D1, an inductor L1, a resistor R1, a transformer T1, a first output rectifying circuit, an output capacitor Co, a power factor correction control circuit and a resonance control driving circuit. Has the advantages that: the invention can prevent the overstress of the circuit device and realize the function of correcting the power factor; the power factor correction control circuit and the driving power supply have the advantages of simple circuit and convenience in control, and compared with a two-stage circuit, the circuit cost is lower, and compared with a passive charge pump PFC, the power factor correction control circuit and the driving power supply can well give consideration to bus capacitance voltage and power factors, and can be suitable for wider input and output load ranges.)

1. A power factor correction control circuit is characterized by comprising a power grid input Vin, a rectifier bridge DB1, a capacitor C1, a capacitor C2, a switch tube S1, a switch tube S2, a switch tube S3, a diode D1, an inductor L1, a resistor R1, a transformer T1, a first output rectifying circuit, an output capacitor Co, a power factor correction control circuit and a resonance control drive circuit;

wherein, the grid input Vin is connected to the first end and the third end of the rectifier bridge DB1, the second end of the rectifier bridge DB1 is sequentially connected to the positive electrode of the capacitor C1 and the first end of the switch tube S1, the second end of the switch tube S1 is sequentially connected to one end of the resistor R1 and the first end of the switch tube S2, the other end of the resistor R1 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to the first input end of the transformer T1, the second input end of the transformer T1 is connected to one end of the capacitor C2, the output end of the transformer T1 is connected to the first output rectifying circuit in parallel, the first output rectifying circuit is connected to the output capacitor Co in parallel, and the other end of the capacitor C2 is sequentially connected to the first end of the switch tube S3, the negative electrode of the diode D1 and the fourth end of the rectifier bridge DB1, the anode of the diode D1 is sequentially connected to the cathode of the capacitor C1, the second terminal of the switching tube S3, and the second terminal of the switching tube S2, and is grounded, the power factor correction control circuit is connected to the third terminal of the switching tube S3, the first terminal of the resonance control driving circuit is connected to the third terminal of the switching tube S1, and the second terminal of the resonance control driving circuit is connected to the third terminal of the switching tube S2;

the power factor correction control circuit controls the conduction time of the switch tube S3, and can limit and stabilize the voltage of the capacitor C1; when the current of the inductor L1 flows in the positive half cycle, the conduction time of the switch tube S3 is controlled, the current which is supplied to the capacitor C1 through the rectifier bridge DB1 and the input power grid Vin can be controlled, the longer the conduction time of the switch tube S3 is, the smaller the current which is charged to the capacitor C1 is, and on the contrary, the shorter the conduction time of the switch tube S3 is, the larger the current which is charged to the capacitor C1 is; when the on-time of the switch tube S3 is at a certain value, the charging and discharging currents of the capacitor C1 are equal, and the voltage of the capacitor C1 is at a steady state;

the power factor correction control circuit controls and modulates the conduction time and the conduction duty ratio of the switching tube S3 according to the input power grid voltage, so that the average value of the current flowing through the rectifier bridge DB1 and the power grid tracks the input power grid voltage in a power frequency period, and the power factor correction function is realized;

the power factor correction control circuit samples a Vir signal, a steamed bread wave voltage Vin _ rec signal obtained by rectifying the power grid Vin, and a bus capacitor voltage Vbus, and realizes the limiting and stable control of the bus voltage C1 and the power factor correction function of the power grid by adopting a double-loop control mode of average current control of an outer loop and an inner loop of a voltage loop.

2. The pfc control circuit of claim 1, wherein the capacitor C1 is a polar capacitor.

3. The power factor correction control circuit of claim 1, wherein the capacitor Co is a polar capacitor.

4. A power factor correction control circuit according to claim 1, wherein the resonance control drive circuit feedback-controls to obtain a desired output voltage Vo and current Io; the power factor correction control circuit controls the voltage of the stabilizing capacitor C1 in a feedback mode, and the power factor correction function is achieved.

5. The pfc control circuit of claim 1, wherein when the inductor L1 is conducting current from right to left and flowing in the negative half cycle, the diode D1 is conducting, the bridge rectifier DB1 is cut off, and the current does not pass through the input grid Vin.

6. The pfc control circuit of claim 1, wherein when the inductor L1 is flowing from left to right in a positive half cycle, if the switch S3 is turned on, the rectifier bridge DB1 is turned off, and the current does not pass through the input grid Vin.

7. The pfc control circuit of claim 1, wherein when the inductor L1 is flowing from left to right in a positive half cycle, if the switch S3 is turned off, the rectifier bridge DB1 is turned on, and the current passes through the input grid Vin.

8. The power factor correction control circuit of claim 1, wherein the resonant control drive circuit supplies energy to the output capacitor and the load through the transformer via the first output rectifying circuit.

9. The power factor correction control circuit of claim 1, wherein the resonant control driving circuit employs frequency feedback control of the output voltage and the output current, which is similar to the control of the general series resonant and series-parallel resonant circuit, and the switching tube S1 and the switching tube S2 are driven symmetrically and complementarily, and the set output voltage Vo and output current Io are obtained by frequency control.

10. A driving power supply comprising the power factor correction control circuit as claimed in any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of circuits and driving power supplies, in particular to a power factor correction control circuit and a driving power supply.

Background

In the field of power supplies, a driving power supply with high power density, high efficiency and low cost is more competitive. Usually, the driving power source selects a resonant circuit to achieve the objectives of high power density and high efficiency. The resonant circuit can realize zero voltage switching-on of two or more switching tubes on the primary side and zero current switching-off of the secondary side rectifier diode, can reduce the switching loss of a power supply, and improves the efficiency and the power density of the power converter. Meanwhile, in order to improve the power factor, a primary active PFC power factor correction circuit is often added at a front stage of the resonant circuit, but this results in a complex circuit and high cost.

Therefore, in the prior art, a charge pump circuit replaces a PFC (Power Factor Correction) circuit, so that a single-stage resonant circuit meets the Power Factor requirement. However, the resonant circuit having the charge pump has the following problems: when the circuit is under the working condition that the amplitude of the input voltage is changed within a certain range, when the amplitude of the input voltage is increased and the energy required by the resonance main circuit is unchanged, the voltage on the bus capacitor is immediately increased; or, when the output power of the resonant main circuit changes within a certain range (i.e. the power required by the resonant main circuit changes within a certain range), the output power decreases and the input voltage does not change, and the voltage on the bus capacitor increases immediately. If the voltage on the bus capacitor is at a higher amplitude level, the related devices of the later stage resonant main circuit need to bear higher voltage stress. Therefore, when designing the circuit, these devices of the resonant main circuit need to select the withstand voltage performance according to the bus capacitor voltage of the highest magnitude. The devices with high voltage resistance are expensive, and for circuits which work under low-amplitude bus capacitor voltage for a long time and occasionally work under high-amplitude bus capacitor voltage, the devices with high voltage resistance are selected to be too wasteful and must be selected, otherwise, the devices can be damaged due to voltage resistance under the high-amplitude bus capacitor voltage.

Meanwhile, the charge pump PFC is used as a passive measure, so that ideal power factor correction is difficult to realize in a wider input and load range, and the power factor and harmonic effect are not ideal.

In view of this, a technical problem to be solved by those skilled in the art is to stably limit the voltage of the bus capacitor to a certain voltage value, to avoid voltage stress on the device due to the overhigh voltage of the bus capacitor, and to achieve better power factor correction in a wider input and load range.

An effective solution to the problems in the related art has not been proposed yet.

Disclosure of Invention

The present invention provides a power factor correction control circuit and a driving power supply for solving the above-mentioned problems of the related art.

Therefore, the invention adopts the following specific technical scheme:

according to an aspect of the present invention, there is provided a power factor correction control circuit, including a grid input Vin, a rectifier bridge DB1, a capacitor C1, a capacitor C2, a switching tube S1, a switching tube S2, a switching tube S3, a diode D1, an inductor L1, a resistor R1, a transformer T1, a first output rectification circuit, an output capacitor Co, a power factor correction control circuit, and a resonance control driving circuit; the grid input Vin is connected to the first end and the third end of the rectifier bridge DB1, the second end of the rectifier bridge DB1 is sequentially connected to the positive electrode of the capacitor C1 and the first end of the switch tube S1, the second end of the switch tube S1 is sequentially connected to one end of the resistor R1 and the first end of the switch tube S2, the other end of the resistor R1 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to the first input end of the transformer T1, the second input end of the transformer T1 is connected to one end of the capacitor C2, the output end of the transformer T1 is connected to the first output rectifying circuit in parallel, the first output rectifying circuit is connected to the output capacitor Co in parallel, the other end of the capacitor C2 is sequentially connected to the first end of the switch tube S3, the negative electrode of the diode D1 and the fourth end of the rectifier bridge DB1, and the positive electrode of the diode D1 is sequentially connected to the negative electrode of the capacitor C1, The second end of the switch tube S3 and the second end of the switch tube S2 are connected and grounded, the power factor correction control circuit is connected with the third end of the switch tube S3, the first end of the resonance control driving circuit is connected with the third end of the switch tube S1, and the second end of the resonance control driving circuit is connected with the third end of the switch tube S2;

the power factor correction control circuit controls the conduction time of the switch tube S3, and can limit and stabilize the voltage of the capacitor C1; when the current of the inductor L1 flows in the positive half cycle, the conduction time of the switch tube S3 is controlled, the current which is supplied to the capacitor C1 through the rectifier bridge DB1 and the input power grid Vin can be controlled, the longer the conduction time of the switch tube S3 is, the smaller the current which is charged to the capacitor C1 is, and on the contrary, the shorter the conduction time of the switch tube S3 is, the larger the current which is charged to the capacitor C1 is; when the on-time of the switch tube S3 is at a certain value, the charging and discharging currents of the capacitor C1 are equal, and the voltage of the capacitor C1 is at a steady state;

the power factor correction control circuit controls and modulates the conduction time and the conduction duty ratio of the switching tube S3 according to the input power grid voltage, so that the average value of the current flowing through the rectifier bridge DB1 and the power grid tracks the input power grid voltage in a power frequency period, and the power factor correction function is realized;

the power factor correction control circuit samples a Vir signal, a steamed bread wave voltage Vin _ rec signal obtained by rectifying the power grid Vin, and a bus capacitor voltage Vbus, and realizes the limiting and stable control of the bus voltage C1 and the power factor correction function of the power grid by adopting a double-loop control mode of average current control of an outer loop and an inner loop of a voltage loop.

Further, the capacitor C1 is a polar capacitor.

Further, the capacitor Co is a polar capacitor.

Further, the resonance control driving circuit performs feedback control to obtain a desired output voltage Vo and a desired current Io; the power factor correction control circuit controls the voltage of the stabilizing capacitor C1 in a feedback mode, and the power factor correction function is achieved.

Further, when the current of the inductor L1 flows from right to left in the negative half cycle, the diode D1 is turned on, the rectifier bridge DB1 is turned off, and the current does not pass through the input grid Vin.

Further, when the current of the inductor L1 flows from left to right in a positive half cycle, if the switching tube S3 is turned on, the rectifier bridge DB1 is turned off, and the current does not pass through the input grid Vin.

Further, when the current of the inductor L1 flows from left to right in a positive half cycle, if the switching tube S3 is turned off, the rectifier bridge DB1 is turned on, and the current passes through the input grid Vin.

Further, the resonance control driving circuit supplies energy to the output capacitor and the load through the transformer and the first output rectifying circuit.

Further, the resonant control driving circuit adopts frequency feedback control of output voltage and output current, the control mode of the resonant control driving circuit is similar to that of a common series resonant and series-parallel resonant circuit, the switching tube S1 and the switching tube S2 are symmetrically and complementarily driven, and the set output voltage Vo and the set output current Io are obtained through frequency control.

According to another aspect of the present invention, there is provided a driving power supply composed of the above power factor correction control circuit.

The invention has the beneficial effects that:

the power factor correction control circuit and the driving power supply limit and stabilize the voltage of the bus capacitor C1 by controlling the conduction time of the active switching tube S3, thereby preventing the overstress of circuit devices. Meanwhile, the input power grid current is sampled, a double-loop average current control mode is adopted, and the input current tracks the input power grid voltage by controlling the conduction time of the active switching tube S3, so that the power factor correction function is realized. The power factor correction control circuit and the driving power supply have the advantages of simple circuit and convenience in control. Compared with a two-stage circuit, the circuit has lower cost. Compared with a passive charge pump PFC, the method can well give consideration to bus capacitance voltage and power factors, and can be suitable for a wider input and output load range.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic diagram of a first embodiment;

FIG. 2 is a voltage waveform diagram of the first embodiment

FIG. 3 is a partial schematic view of FIG. 1;

FIG. 4 is a schematic view of the second embodiment;

FIG. 5 is a voltage waveform diagram of the second embodiment;

FIG. 6 is a schematic diagram of the power factor correction control circuit of FIG. 4;

fig. 7 is a voltage waveform diagram of fig. 6.

Detailed Description

For further explanation of the various embodiments, the drawings which form a part of the disclosure and which are incorporated in and constitute a part of this specification, illustrate embodiments and, together with the description, serve to explain the principles of operation of the embodiments, and to enable others of ordinary skill in the art to understand the various embodiments and advantages of the invention, and, by reference to these figures, reference is made to the accompanying drawings, which are not to scale and wherein like reference numerals generally refer to like elements.

According to the embodiment of the invention, the power factor correction control circuit and the driving power supply are provided.

Example one

Referring to the drawings and the detailed description, as shown in fig. 1-3, a power factor correction control circuit according to an embodiment of the present invention includes a grid input Vin, a rectifier bridge DB1, a capacitor C1, a capacitor C2, a switching tube S1, a switching tube S2, a switching tube S3, a diode D1, an inductor L1, a resistor R1, a transformer T1, a first output rectifier circuit, an output capacitor Co, a power factor correction control circuit, and a resonance control driving circuit; the grid input Vin is connected to the first end and the third end of the rectifier bridge DB1, the second end of the rectifier bridge DB1 is sequentially connected to the positive electrode of the capacitor C1 and the first end of the switch tube S1, the second end of the switch tube S1 is sequentially connected to one end of the resistor R1 and the first end of the switch tube S2, the other end of the resistor R1 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to the first input end of the transformer T1, the second input end of the transformer T1 is connected to one end of the capacitor C2, the output end of the transformer T1 is connected to the first output rectifying circuit in parallel, the first output rectifying circuit is connected to the output capacitor Co in parallel, the other end of the capacitor C2 is sequentially connected to the first end of the switch tube S3, the negative electrode of the diode D1 and the fourth end of the rectifier bridge DB1, and the positive electrode of the diode D1 is sequentially connected to the negative electrode of the capacitor C1, The second end of the switch tube S3 and the second end of the switch tube S2 are connected to ground, the power factor correction control circuit is connected to the third end of the switch tube S3, the first end of the resonance control driving circuit is connected to the third end of the switch tube S1, and the second end of the resonance control driving circuit is connected to the third end of the switch tube S2.

In one embodiment, the capacitor C1 is a polar capacitor.

In one embodiment, the capacitor Co is a polar capacitor.

In one embodiment, the resonance control driving circuit performs feedback control to obtain a desired output voltage Vo and current Io; the power factor correction control circuit controls the voltage of the stabilizing capacitor C1 in a feedback mode, and the power factor correction function is achieved.

In one embodiment, when the current of the inductor L1 flows from right to left in a negative half cycle, the diode D1 is turned on, the rectifier bridge DB1 is turned off, and the current does not pass through the input grid Vin.

In one embodiment, when the current of the inductor L1 flows from left to right in a positive half cycle, if the switching tube S3 is turned on, the rectifier bridge DB1 is turned off, and the current does not pass through the input grid Vin.

In one embodiment, when the current of the inductor L1 flows from left to right in a positive half cycle, if the switch tube S3 is turned off, the rectifier bridge DB1 is turned on, and the current passes through the input grid Vin.

In one embodiment, the resonant control drive circuit supplies energy to the output capacitor and the load through the transformer via the first output rectifier circuit.

In one embodiment, the resonant control driving circuit adopts frequency feedback control of the output voltage and the output current, the control mode of the resonant control driving circuit is similar to that of a common series resonant and series-parallel resonant circuit, the switching tube S1 and the switching tube S2 are symmetrically and complementarily driven, and the set output voltage Vo and the set output current Io are obtained through frequency control.

The invention also provides a driving power supply which consists of the power factor correction control circuit.

In one embodiment, when the switching tube S3 is in a continuous conduction state, the input voltage is input to the grid Vin, the rectifier bridge DB1 and the capacitor C1 to form an uncontrolled rectifier circuit, and no power factor correction function is provided, at this time, the working voltage of the capacitor C1 is the lowest, and the grid current harmonic is also large; the positive half-cycle resonant current of the inductor L1 is input into the power grid Vin through the rectifier bridge DB1, and the capacitor C1 is charged. The current flowing through the switching tube S1 is necessarily smaller than the positive half-cycle current of the inductor L1, so that the charging current is always larger than the discharging current, and the voltage of the capacitor C1 rises all the time until the device is damaged; as shown in fig. 2 and fig. 3, the pfc control circuit controls the on-time of the switch transistor S3 to limit and stabilize the voltage of the capacitor C1. When the current of the inductor L1 flows in the positive half cycle, the on-time of the switch tube S3 is controlled, so that the current supplied to the capacitor C1 through the rectifier bridge DB1 and the input grid Vin can be controlled, the longer the on-time of the switch tube S3 is, the smaller the current supplied to the capacitor C1 is, and conversely, the shorter the on-time of the switch tube S3 is, the larger the current supplied to the capacitor C1 is. When the on-time of the switch tube S3 is at a certain value, the charging and discharging currents of the capacitor C1 are equal, and the voltage of the capacitor C1 is in a steady state. Therefore, the on-time of the switch tube S3 is controlled to limit and stabilize the voltage of the capacitor C1, thereby avoiding overstressing the circuit device.

In one embodiment, the power factor correction control circuit controls and modulates the conduction time and the conduction duty ratio of the switching tube S3 according to the input power grid voltage, so that the average value of the current flowing through the rectifier bridge DB1 and the power grid tracks the input power grid voltage in the power frequency period, the power factor correction function is realized, the power factor is improved, and the current harmonic is reduced.

In one embodiment, the power factor correction control circuit samples a Vir signal, a steamed bread wave voltage Vin _ rec signal obtained by rectifying the power grid Vin, and a bus capacitor voltage Vbus, and realizes the limiting and stable control of a bus voltage C1 and the power factor correction function of the power grid by adopting a double-loop control mode of average current control of an outer loop and an inner loop of a voltage loop.

Example two

As shown in fig. 4, the power factor correction control circuit according to the embodiment of the present invention includes a grid input Vin, a rectifier bridge DB1, a capacitor C1, a capacitor C2, a switch tube S1, a switch tube S2, a switch tube S3, a diode D1, an inductor L1, a resistor R1, a transformer T1, a first output rectifying circuit, a second output rectifying circuit, an output capacitor Co, a power factor correction control circuit, and a resonance control driving circuit; the grid input Vin is connected to the first end and the third end of the rectifier bridge DB1, the second end of the rectifier bridge DB1 is sequentially connected to the positive electrode of the capacitor C1 and the first end of the switch tube S1, the second end of the switch tube S1 is sequentially connected to one end of the resistor R1 and the first end of the switch tube S2 and grounded, the other end of the resistor R1 is sequentially connected to the first end of the power factor correction control circuit and one end of the inductor L1, the other end of the inductor L1 is connected to the first input end of the transformer T1, the second input end of the transformer T1 is connected to one end of the capacitor C2, the output end of the transformer T1 is connected in parallel to the first output rectifying circuit, the first output rectifying circuit is connected in parallel to the output capacitor Co, and the other end of the capacitor C2 is sequentially connected to the first end of the switch tube S3, the negative electrode of the diode D1 and the fourth end of the rectifier bridge DB1, the anode of the diode D1 is sequentially connected to the cathode of the capacitor C1, the second end of the switch tube S3 and the second end of the switch tube S2, the Vg _ S3 end of the power factor correction control circuit is connected to the third end of the switch tube S3, the Vin _ rec end of the power factor correction control circuit is connected to the second output rectifying circuit, the Vg _ S1 end of the resonance control driving circuit is connected to the third end of the switch tube S1, and the Vg _ S2 end of the resonance control driving circuit is connected to the third end of the switch tube S2.

In one embodiment, see fig. 6, the voltage across the sampling resistor R1 is used as a signal to characterize the resonant current of the inductor L1. The midpoint of the connection between the switching tube S1 and the switching tube S2 is used as a sampling signal reference ground, and two voltage terminals Vir are IL 1R 1. When the inductor L1 current flows from left to right in the positive direction, the Vir signal is negative. When the inductor L1 current flows in the reverse direction from right to left, the Vir signal is positive. As shown in fig. 4, the S4 driving signal in fig. 6 is the same as the S3 driving in fig. 4. After Vir is controlled by S4 in fig. 6, the resultant signal is proportional to the input current.

In one embodiment, the power factor correction control circuit samples a Vir signal, a steamed bread wave voltage Vin _ rec signal obtained by rectifying the power grid Vin, and a bus capacitor voltage Vbus, and realizes the limiting and stable control of the bus voltage C1 and the power factor correction function of the power grid by adopting a double-loop control mode of average current control of an outer loop and an inner loop of a voltage loop.

In one embodiment, as shown in fig. 6, the voltage-loop feedback operational amplifier output Vcomp is multiplied by Vin _ rec as the reference of the current inner loop, which is superimposed with the input current sampling signal as the non-inverting input of the current inner loop operational amplifier, and the operational amplifier output signal Icomp is compared with the signal generator signal Vt to trigger the control switch S3 to be turned on.

In one embodiment, when the current of the inductor L1 changes from positive to negative half cycles, the switch tube S3 is still in the conducting state, instead of the diode D1 conducting, so as to reduce the conducting loss. The switch tube S3 is turned off when the negative half-cycle current flowing through the switch tube S3 gradually decreases to the set comparison value.

In one embodiment, as shown in fig. 5 and 6, the Vt signal is a sawtooth signal obtained by charging the capacitor C with a fixed constant current source, and the constant current source charges the capacitor when the detected Vir signal is higher than the set comparison threshold Vth. When the Vir signal is detected to be lower than the set comparison threshold Vth, the switch connected in parallel with the capacitor is kept on, and the Vt signal is kept to be zero.

In one embodiment, as shown in fig. 6 and 7, when the Vir signal is detected to be lower than the set comparison threshold Vth and during the conduction period of the switch tube S1, i.e. when the driving signal HG is at a high level, the flip-flop latch is reset, and the switch tube S3 is turned off.

For the convenience of understanding the technical solutions of the present invention, the following detailed description will be made on the working principle or the operation mode of the present invention in the practical process.

In practical application, when the switch tube S1 is turned on and the switch tube S2 is turned off, and the switch tube S3 or the diode D1 is turned on, a current passes through the switch tube S1, the inductor L1, the transformer T1, the resonant capacitor C2, the switch tube S3, the diode D1 or the capacitor C1;

when the switch tube S1 turns off the switch tube S2 and turns on, and the switch tube S3 or the diode D1 turns on, the current passes through the diode S2, the inductor L1, the transformer T1, the resonant capacitor C2, the switch tube S3 or the diode D1;

when the switch tube S1 is connected and the switch tube S2 is turned off, and the switch tube S3 and the diode D1 are turned off, current passes through the switch tube S1, the inductor L1, the transformer T1, the resonant capacitor C2, the rectifier bridge DB1 and is input into a power grid Vin;

when the switch tube S1 turns off the switch tube S2 and turns on, and the switch tube S3 and the diode D1 turn off, current flows through the switch tube S1, the inductor L1, the transformer T1, the resonant capacitor C2, the rectifier bridge DB1, and is input to the grid Vin.

In summary, the power factor correction control circuit and the driving power supply of the present invention limit and stabilize the voltage of the bus capacitor C1 by controlling the on-time of the active switching transistor S3, thereby preventing the circuit device from overstressing. Meanwhile, the input power grid current is sampled, a double-loop average current control mode is adopted, and the input current tracks the input power grid voltage by controlling the conduction time of the active switching tube S3, so that the power factor correction function is realized. The power factor correction control circuit and the driving power supply have the advantages of simple circuit and convenience in control. Compared with a two-stage circuit, the circuit has lower cost. Compared with a passive charge pump PFC, the method can well give consideration to bus capacitance voltage and power factors, and can be suitable for a wider input and output load range.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.