Power factor correction circuit and switching power supply

Abstract

The invention provides a power factor correction circuit and a switching power supply, and the power factor correction circuit comprises a first power frequency rectification circuit, a second power frequency rectification circuit, a third power frequency rectification circuit, a first high-frequency rectification circuit, and a bus capacitor. The first end of the boost inductor is connected with the first input end of the power factor correction circuit and the midpoint of the bridge arm of the first power frequency rectification circuit, and the second end of the boost inductor is connected with the midpoint of the bridge arm of the first high-frequency rectification circuit; the lightning protection inductor comprises a power winding and a detection winding, the first end of the power winding is simultaneously connected with the second input end of the power factor correction circuit and the midpoint of the bridge arm of the second power frequency rectification circuit, and the second end of the power winding is connected with the midpoint of the bridge arm of the third power frequency rectification circuit; the detection device is used for generating a surge protection signal when detecting that the voltage at the two ends of the winding is greater than a set value; and the controller is used for controlling the switching tube in the third power frequency rectifying circuit to be switched off for a fixed time after receiving the surge protection signal. The reliability of the third power frequency rectifying circuit can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power factor correction, and in particular to a power factor correction circuit and a switching power supply. Background Art

[0002] The commonly used high-efficiency totem pole bridgeless power factor correction circuit adopts industrial frequency diode rectification technology, such as Figure 1a As shown, the diodes D3 and D4 are power frequency diodes, which usually adopt critical control mode or continuous control mode. The scheme is composed of power frequency diodes D1, D2, D3 and D4 to form a clamping circuit, which can timely clamp the voltage stress under various lightning strikes, and the power frequency diodes have the ability to withstand large currents, and the product reliability is also very high, but its defect is that it cannot be reversed, and the current ultra-high efficiency primary rectifier module technology requires a peak efficiency of about 98%. In order to further improve the efficiency, active switching tubes are usually used to replace power frequency diode rectification, and the bidirectional power supply also needs to use active switching tubes for power frequency rectification. Therefore, the prior art proposes the following Figure 1b The scheme shown.

[0003] Taking the positive half cycle of AC input as an example, Figure 1b The working principle of the scheme is: MOS tube Q1L is the main tube, and MOS tube Q1H is the freewheeling tube; when the boost inductor L1 is excited: MOS tube Q1L is turned on and MOS tube Q1H is turned off, and the current flow direction of the inductor L1 is: inductor L1→MOS tube Q1L→MOS tube QT2→AC source→inductor L1; when the boost inductor L1 is demagnetized: MOS tube Q1H is turned on and MOS tube Q1L is turned off, and the current flow direction of the inductor L1 is: inductor L1→MOS tube Q1H→bus capacitor C1→MOS tube QT2→AC source→inductor L1. Figure 1b Although the solution can improve efficiency and realize the inverter function, the current impact resistance of conventional active switching tubes is much lower than that of diodes, which will lead to a decrease in lightning resistance and an increase in the possibility of circuit failure. Taking the positive half-cycle of AC input as an example: if a lightning strike of a positive half-cycle occurs, the lightning current flows as follows: diode D1→bus capacitor C1→MOS tube QT2→AC source. The lightning current is very large and will damage the MOS tube QT2. If a lightning strike of a negative half-cycle occurs at this time, the lightning current flows as follows: MOS tube QT2→diode D2→AC source. The lightning current is very large and will also damage the MOS tube QT2.

[0004] The more traditional solution is to select multiple active switches with low internal resistance and high current resistance in parallel, but the cost is very high and the reliability is poor. There is also a solution to limit the peak current by adding lightning protection inductors and clamping diodes at the input end, but this will result in the PFC inductor not being well clamped when lightning strikes, causing the PFC inductor to instantly withstand an extremely high voltage and cause the inductor to saturate, which still has certain inherent defects.

[0005] Patent publication number CN109067167A discloses a power factor correction lightning protection circuit, such as Figure 2 As shown (derived from the patent appendix Figure 3 ), from the contents recorded in its drawings and claim 2, "When lightning strikes, the input current is sampled to an abnormal current value, and all semiconductor power tubes of the first rectifier circuit and the second rectifier circuit are turned off", it can be seen that although the semiconductor power tubes of the first and second rectifier circuits are turned off, and the surge voltage is borne by the inductor L2, which can effectively suppress the peak current flowing through the body diode of the first rectifier circuit, it is precisely because of the inductor L2 that the voltage across the inductor L1 cannot be clamped, and there is a risk of saturation and breakdown of the switch tube Q1 power tube. Taking the positive half cycle as an example, before the lightning signal comes, the voltage at the A end of the power supply is +, and the voltage at the B end is -. After the forward lightning surge comes, there will be a huge voltage difference between the A end and the positive end of the bus capacitor C1. This voltage difference is also directly added to the inductor L1 and the body diode of the switch tube Q1, resulting in a huge peak current on the inductor L1. Moreover, when the power supply is powered on, when the output capacitor rises from 0V to the maximum value of the input voltage, there will be a huge current in the inductors L1 and L2, which will also cause the saturation of the inductor L1 and the breakdown of the switch tube Q1 power tube.

[0006] As analyzed above, the lightning protection circuits currently implemented in bridgeless PFC circuits still have certain defects. Summary of the invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide a power factor correction circuit, which can at least to some extent solve the deficiencies of the above-mentioned prior art.

[0008] As a first aspect, the technical solution of the power factor correction circuit embodiment proposed by the present invention is as follows:

[0009] A power factor correction circuit, comprising:

[0010] The first power frequency rectifier circuit, the second power frequency rectifier circuit, the third power frequency rectifier circuit, the first high-frequency rectifier circuit and the bus capacitor are all connected in parallel between the positive output terminal and the negative output terminal of the power factor correction circuit, wherein the first power frequency rectifier circuit, the second power frequency rectifier circuit, the third power frequency rectifier circuit and the first high-frequency rectifier circuit all include a bridge arm formed by two switch tubes;

[0011] A boost inductor, a first end of which is connected to the first input end of the power factor correction circuit and the midpoint of the bridge arm of the first power frequency rectifier circuit, and a second end of which is connected to the midpoint of the bridge arm of the first high-frequency rectifier circuit;

[0012] A lightning protection inductor, comprising: a power winding and a detection winding, wherein a first end of the power winding is simultaneously connected to a second input end of the power factor correction circuit and a bridge arm midpoint of the second power frequency rectification circuit, and a second end is connected to a bridge arm midpoint of the third power frequency rectification circuit;

[0013] A detection device, used for generating a surge protection signal when the voltage across the detection winding is greater than a set value;

[0014] The controller is used to control the switch tube in the third power frequency rectifier circuit to be turned off for a fixed time after receiving the surge protection signal, thereby limiting the current peak flowing through the switch tube in the third power frequency rectifier circuit.

[0015] Preferably, the detection winding is a single winding, and the detection device comprises: a fifth diode, a sixth diode, a seventh diode, an eighth diode, a first resistor, a second resistor and a comparator, the anode of the fifth diode and the cathode of the sixth diode are connected to the first end of the detection winding, the anode of the seventh diode and the cathode of the eighth diode are connected to the second end of the detection winding, the cathode of the fifth diode and the cathode of the seventh diode are connected to the first end of the first resistor, the anode of the sixth diode, the anode of the eighth diode and the second end of the second resistor are simultaneously connected to the ground terminal of the controller, the second end of the first resistor and the first end of the second resistor are connected to an input terminal of the comparator, the other input terminal of the comparator inputs a reference voltage, and the output terminal of the comparator outputs the surge protection signal;

[0016] Or the detection winding is a double winding, and the detection device includes: a ninth diode, a tenth diode, the third resistor, the fourth resistor and a comparator; the first end of the first detection winding is connected to the anode of the ninth diode, the second end of the second detection winding is connected to the anode of the tenth diode, the second end of the first detection winding, the first end of the second detection winding, and the second end of the fourth resistor are simultaneously connected to the ground terminal of the controller, the cathode of the ninth diode, the cathode of the tenth diode and the first end of the third resistor are connected, the second end of the third resistor and the first end of the fourth resistor are connected to an input terminal of the comparator, the other input terminal of the comparator inputs a reference voltage, and the output terminal of the comparator outputs the surge protection signal.

[0017] Preferably, the first high-frequency rectification circuit includes a bridge arm formed by two active semiconductor power tubes.

[0018] Preferably, the first power frequency rectification circuit comprises a bridge arm formed by two passive semiconductor power tubes connected in series in the same direction.

[0019] Preferably, the second power frequency rectification circuit comprises a bridge arm formed by two passive semiconductor power tubes connected in series in the same direction.

[0020] Preferably, the third industrial frequency rectification circuit comprises a bridge arm formed by two active semiconductor power tubes, so that the power factor correction circuit is a bidirectional rectification totem bridgeless power factor correction circuit.

[0021] Furthermore, the power factor correction circuit includes N boost inductors and N first high-frequency rectifier circuits, where N is a natural number greater than or equal to 2, and the first end of each boost inductor is simultaneously connected to the first input end of the power factor correction circuit and the midpoint of the bridge arm of the first industrial frequency rectifier circuit, and the second end is connected to the midpoint of the bridge arm of one of the N first high-frequency rectifier circuits.

[0022] As a second aspect, the technical solution of the switching power supply embodiment proposed by the present invention is as follows:

[0023] A switching power supply, comprising: a power factor correction circuit as described in any one of the first aspects above.

[0024] The present invention uses two diodes in the second power frequency rectifier circuit, two switch tubes in the third power frequency rectifier circuit and the bus capacitor C1 to clamp the voltage across the lightning protection inductor LT1. The working principle is described in detail in conjunction with a specific embodiment, which will not be repeated here. The beneficial effects of the present invention are as follows:

[0025] 1. In the embodiment of the power factor correction circuit of the present invention, a detection winding is added to the lightning protection inductor. When a negative phase lightning strike is generated in the positive half cycle of the input or a positive phase lightning strike is generated in the negative half cycle of the input, the first and second power frequency rectifier circuits are used to store the lightning strike energy on the bus capacitor. At the same time, the maximum value of the voltage across the lightning protection inductor is clamped to the voltage value of the bus capacitor through the second power frequency rectifier circuit. The controller receives a surge protection signal and then controls the switch tube in the third power frequency rectifier circuit to turn off for a fixed time, which can significantly limit the current peak flowing through the switch tube in the third power frequency rectifier circuit, improve product reliability, and significantly reduce the volume and cost of the lightning protection inductor.

[0026] 2. In the embodiment of the power factor correction circuit of the present invention, when a positive phase lightning strike is generated in the positive half cycle of the input or a negative phase lightning strike is generated in the negative half cycle of the input, the first and second power frequency rectification circuits are used to store the lightning strike energy in the bus capacitor, and at the same time, the maximum value of the voltage across the lightning protection inductor is clamped to the voltage drop of the diode (about 0.7V) through the second power frequency rectification circuit, which can significantly limit the current peak flowing through the switch tube in the third power frequency rectification circuit, thereby improving product reliability;

[0027] 3. The power factor correction circuit embodiment of the present invention can be applied to both a rectification-only power factor correction circuit and a reversible power factor correction circuit. It has wide applicability, improves the overall lightning protection level, and improves product reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1a The circuit schematic diagram of the existing bridgeless power factor correction circuit with power frequency diode rectification;

[0029] Figure 1b The circuit schematic diagram of the existing bridgeless power factor correction circuit with power frequency active switch tube rectification;

[0030] Figure 2 It is the circuit schematic diagram of the existing power factor correction lightning protection circuit;

[0031] Figure 3 is a schematic diagram of a power factor correction circuit of the present invention;

[0032] Figure 4 for Figure 3 A first specific embodiment principle diagram of the detection device in FIG.

[0033] Figure 5 for Figure 3 A schematic diagram of a second specific embodiment of the detection device in FIG.

[0034] Figure 6 It is a schematic diagram of a two-phase power factor correction circuit of the present invention;

[0035] Figure 7 It is a schematic diagram of the multi-phase power factor correction circuit of the present invention. DETAILED DESCRIPTION

[0036] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0037] It should be noted that the terms "including" and "having" and any variations thereof described in the specification and claims of the present application are intended to cover non-exclusive inclusions. For example, the inclusion of a series of components, unit circuits or control timings is not necessarily limited to those components, unit circuits or control timings clearly listed, but may include components, unit circuits or control timings that are not clearly listed or inherent to these circuits.

[0038] In addition, the embodiments and features of the embodiments in this application may be combined with each other if there is no conflict.

[0039] It should be understood that, in the specification and the claims, when an element is described as being “connected” to another element, the element may be “directly connected” to the other element, or be “connected” to the other element through a third element; when a step is described as being continued to another step, the step may be directly continued to the other step, or be continued to the other step through a third step.

[0040] Figure 3The schematic diagram of the power factor correction circuit of the present invention includes: a first power frequency rectifier circuit, a second power frequency rectifier circuit, a third power frequency rectifier circuit, a first high frequency rectifier circuit and a bus capacitor C1, all of which are connected in parallel between the positive output terminal and the negative output terminal of the power factor correction circuit, wherein the first power frequency rectifier circuit, the second power frequency rectifier circuit, the third power frequency rectifier circuit and the first high frequency rectifier circuit all include a bridge arm formed by two switch tubes; a boost inductor L1, a first end of which is simultaneously connected to the first input terminal of the power factor correction circuit and the midpoint of the bridge arm of the first power frequency rectifier circuit, The second end is connected to the midpoint of the bridge arm of the first high-frequency rectifier circuit; the lightning protection inductor includes: a power winding and a detection winding; wherein the first end of the power winding is simultaneously connected to the second input end of the power factor correction circuit and the midpoint of the bridge arm of the second power frequency rectifier circuit, and the second end is connected to the midpoint of the bridge arm of the third power frequency rectifier circuit; wherein the first power frequency rectifier circuit, the second power frequency rectifier circuit, the third power frequency rectifier circuit, the lightning protection inductor and the bus capacitor C1 can form a loop when the third power frequency rectifier circuit is in the power frequency switch, which is used to limit the current spike flowing through the switch tube in the third power frequency rectifier circuit. The detection device generates a surge protection signal after detecting the signal on the winding, and the controller controls the switch tube in the third power frequency rectifier circuit to turn off for a fixed time after receiving the surge protection signal, so as to limit the current spike flowing through the switch tube in the third power frequency rectifier circuit.

[0041] Among them, the first high-frequency rectifier circuit includes a bridge arm formed by two active semiconductor power tubes. Specifically, the two active semiconductor power tubes are SiMOS tube Q1H and SiMOS tube Q1L. The switch tube type can also be selected as IGBT, SIC, GAN, etc., and technicians in this field can make a selection as needed, and the present invention is not limited.

[0042] The first power frequency rectification circuit includes a bridge arm formed by two passive semiconductor power tubes connected in series in the same direction. Specifically, the two active semiconductor power tubes are a diode D1 and a diode D2.

[0043] The second power frequency rectification circuit includes a bridge arm formed by two passive semiconductor power tubes connected in series in the same direction. Specifically, the two active semiconductor power tubes are diode D3 and diode D4.

[0044] Among them, the third industrial frequency rectification circuit includes a bridge arm formed by two active semiconductor power tubes, so that the power factor correction circuit is a bidirectional rectification totem bridgeless circuit. Specifically, the two active semiconductor power tubes are SiMOS tube QTH and SiMOS tube QTL, respectively. The switch tube type can also be replaced by IGBT, SIC, GAN, etc., and technicians in this field can make choices as needed, and the present invention is not limited.

[0045] The power factor correction circuit of the present invention can be applied to both a rectification-only power factor correction circuit and a reversible power factor correction circuit. It not only has wide applicability but also can improve the overall lightning protection level, thereby improving product reliability.

[0046] As an implementation mode of the power factor correction circuit of the present invention, the first industrial frequency rectification circuit and the second industrial frequency rectification circuit both include a bridge arm formed by two passive semiconductor power tubes connected in series in the same direction, and the first high-frequency rectification circuit includes a bridge arm formed by two active semiconductor power tubes, so that the power factor correction circuit is a unidirectional rectification totem bridgeless circuit.

[0047] The following combination Figure 3 A detailed analysis is carried out, in which when the positive half cycle is input, the controller outputs a control signal to make the MOS tube QTL always turned on and the MOS tube QTH always turned off; when the negative half cycle is input, the controller outputs a control signal to make the MOS tube QTH always turned on and the MOS tube QTL always turned off; in the positive half cycle and the negative half cycle of the input, the MOS tube Q1H and the MOS tube Q1L both perform high-frequency switching actions, and the control signals of the MOS tube Q1H and the MOS tube Q1L are complementary signals with a dead zone in the middle.

[0048] Taking the positive half cycle of the input as an example, at this time, the voltage at 101 is positive and the voltage at 102 is negative. After the output voltage of the power factor correction circuit is established, the voltage across the bus capacitor C1 is greater than Vac, and the diode D1 is cut off:

[0049] When the MOS tube Q1L is turned on and the MOS tube Q1H is turned off, the inductor L1 is excited, and the current flows as follows: 101 → inductor L1 → MOS tube Q1L → the network of "MOS tube QTL connected in series with inductor LT1 and then connected in parallel with D4" → 102;

[0050] When the MOS tube Q1H is turned on and the MOS tube Q1L is turned off, the inductor L1 is demagnetized, and the current flows as follows: 101 → inductor L1 → MOS tube Q1H → network of “bus capacitor C1 connected in parallel with load Rload” → network of “MOS tube QTL connected in series with inductor LT1 and then connected in parallel with D4” → 102;

[0051] When a positive phase lightning signal is generated, at this time, 101 is a positive voltage and 102 is a negative voltage. Since Vac is greater than the voltage across the bus capacitor C1, the current flows as follows: 101→diode D1→bus capacitor C1→diode D4→102, storing the lightning energy on the bus capacitor C1. At this time, the voltage across the lightning protection inductor LT1 and the MOS tube QTL is clamped to the conduction voltage drop of the diode D4, which is about 0.7V. Most of the surge current flows through the diode D4, thereby limiting the current flowing through the MOS tube QTL and protecting the MOS tube QTL from being broken down by the surge current; the inductor L1 is clamped to the voltage across the bus capacitor C1 through the diode D1 and the MOS tube Q1L, limiting the current flowing through the MOS tube Q1L and protecting the MOS tube Q1L from being broken down by the surge current. This is the conventional PFC inductor and switch tube surge suppression mechanism, which will not be described in detail later.

[0052] Figure 4 for Figure 3 The first specific embodiment principle diagram of the detection device in the embodiment detects the surge protection signal V1 in a single winding manner; Figure 5 for Figure 3 The second specific embodiment of the detection device in the schematic diagram uses a double winding method to detect the surge protection signal V1, which is a common detection method in the industry. Figure 4 Taking a single winding detection device as an example, when a forward lightning strike signal is generated, most of the surge current flows through the diode D4, the current in the power winding P1 is about 0A, the induced voltage in the detection winding S1 is about 0V, and the sampling signal after bridge rectification by diodes D5, D6, D7 and D8 and voltage division by resistors R3 and R4 is also about 0V. The controller receives a surge protection signal V1 of low level, and the MOS tube QTL in the third power frequency rectification circuit remains turned on, and the diode D4 is used to protect the MOS tube QTL from being broken down by the surge current;

[0053] When a negative lightning signal is generated, the voltage at 101 is negative and the voltage at 102 is positive. The current flows in the direction ①: 102 → diode D3 → bus capacitor C1 → diode D2 → 101, and part of the lightning energy is stored in the bus capacitor C1. The current flows in the direction ②: 102 → power winding of lightning protection inductor LT1 → MOS tube QTL → diode D2 → 101. At this time, the lightning protection inductor LT1 is clamped to the bus capacitor C1 by the MOS tube QTL and the diode D3. The current flowing through the lightning protection inductor LT1 and the MOS tube QTL will rise rapidly, and another part of the lightning energy is stored in the lightning protection inductor LT1. Figure 4 Taking a single winding detection device as an example, we analyze how to prevent the MOS tube QTL from being broken down by surge current:

[0054] The induced voltage in the detection winding S1 is ≈ the voltage across the bus capacitor C1 × the number of turns of the winding S1 ÷ the number of turns of the winding P1. The sampling signal after the bridge rectification by the diodes D5, D6, D7 and D8 and the voltage division by the resistors R3 and R4 is configured to be greater than the reference voltage Vref. The controller receives the surge protection signal V1 as a high level. At this time, the MOS tube QTL in the third power frequency rectification circuit can be quickly turned off for a fixed time. The fixed time can be set according to the required surge protection effect. For example, it can be configured to be 1mS, and the shutdown During this period, the current flow direction ② changes to: 102→lightning protection inductor LT1→MOS tube QTH→bus capacitor C1→diode D2→101, and then the energy stored in the lightning protection inductor LT1 is transferred to the bus capacitor C1, and the current flowing through the lightning protection inductor LT1 and the MOS tube QTH decreases rapidly until the diode D3 is turned on, thereby protecting the MOS tubes QTL and QTH from being broken down by the surge current. After the surge ends, the on / off of the MOS tubes QTL and QTH are re-matched according to the positive and negative half cycles of the input voltage.

[0055] When the negative half cycle is input, the switch tubes turned on / off in each bridge arm are exchanged with those when the positive half cycle is input, which can also achieve the lightning protection function. The specific working process can be deduced by technicians in this field by themselves and will not be repeated here.

[0056] Figure 3 The power factor correction circuit is single-phase, and the circuit can also be expanded to two-phase and multi-phase interleaved power factor correction circuits. The purpose of expanding to two-phase and multi-phase interleaved is to further improve the power level of the power factor correction circuit and reduce the current ripple of the bus capacitor C1. At this time, Figure 3 On the basis of further including N boost inductors (for the convenience of the following description, starting from the second said boost inductor, they are renamed as the second boost inductor, the third boost inductor, ..., the Nth boost inductor) and N first high-frequency rectifier circuits (for the convenience of the following description, starting from the second said first high-frequency rectifier circuit, they are renamed as the second high-frequency rectifier circuit, the third high-frequency rectifier circuit, ..., the Nth high-frequency rectifier circuit), N is a natural number greater than or equal to 2, and the first end of each boost inductor is simultaneously connected to the first input end of the power factor correction circuit and the midpoint of the bridge arm of the first industrial frequency rectifier circuit, and the second end is connected to the midpoint of the bridge arm of one of the N first high-frequency rectifier circuits.

[0057] Figure 6 The schematic diagram of the two-phase power factor correction circuit of the present invention is shown in FIG. Figure 3The circuit is similar, except that a second boost inductor L2 and a second high-frequency rectifier circuit are added, wherein the second high-frequency rectifier circuit includes a bridge arm formed by two active semiconductor power tubes, specifically, the two active semiconductor power tubes are SiMOS tube Q2H and SiMOS tube Q2L, and the switch tube type can also be selected as IGBT, SIC, GAN, etc. The control signal phase difference between the MOS tube Q1H and the MOS tube Q2H is 180°, and the control signal phase difference between the MOS tube Q1L and the MOS tube Q2L is 180°.

[0058] Figure 7 The schematic diagram of the multi-phase power factor correction circuit of the present invention is similar to Figure 3 Similar, the difference is that the second to nth boost inductors Ln and the second to nth high-frequency rectifier circuits are added, wherein the second to nth high-frequency rectifier circuits each include a bridge arm formed by two active semiconductor power tubes, specifically, the two active semiconductor power tubes are SiMOS tube QnH and SiMOS tube QnL, and the switch tube type can also be selected as IGBT, SIC, GAN, etc. The phase difference of the control signal of the MOS tube Q1H to the MOS tube QnH is 360° / n respectively, and the phase difference of the control signal of the MOS tube Q1L to the MOS tube QnL is 360° / n respectively.

[0059] The power factor correction circuit of the embodiment of the present invention can use the second power frequency rectifier circuit to clamp the voltage across the lightning protection inductor, thereby limiting the peak current flowing through the third power frequency rectifier circuit, and can also turn off the switch tube in the third power frequency rectifier circuit through the detection device and the controller, thereby improving the reliability of the third power frequency rectifier circuit and ensuring lightning resistance. In addition, the circuit structure and control of the present invention are simple, the cost is low, and the volume of the lightning protection inductor is significantly reduced.

[0060] An embodiment of the present invention also provides a switching power supply, including a power factor correction circuit of any of the above embodiments, thereby fundamentally suppressing the current flowing through the industrial frequency rectifier tube. The dual protection of inductive current limiting and detection and shutting down the rectifier tube makes the power supply more reliable.

[0061] The above are merely implementation modes of the present invention. It should be particularly pointed out that the above implementation modes should not be regarded as limitations of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A power factor correction circuit, characterized in that: include: The first power frequency rectifier circuit, the second power frequency rectifier circuit, the third power frequency rectifier circuit, the first high-frequency rectifier circuit and the bus capacitor are all connected in parallel between the positive output terminal and the negative output terminal of the power factor correction circuit, wherein the first power frequency rectifier circuit, the second power frequency rectifier circuit, the third power frequency rectifier circuit and the first high-frequency rectifier circuit all include a bridge arm formed by two switch tubes; A boost inductor, a first end of which is connected to the first input end of the power factor correction circuit and the midpoint of the bridge arm of the first power frequency rectifier circuit, and a second end of which is connected to the midpoint of the bridge arm of the first high-frequency rectifier circuit; A lightning protection inductor, comprising: a power winding and a detection winding, wherein a first end of the power winding is simultaneously connected to a second input end of the power factor correction circuit and a bridge arm midpoint of the second power frequency rectification circuit, and a second end is connected to a bridge arm midpoint of the third power frequency rectification circuit; A detection device, used for generating a surge protection signal when the voltage across the detection winding is greater than a set value; The controller is used to control the switch tube in the third power frequency rectifier circuit to be turned off for a fixed time after receiving the surge protection signal, thereby limiting the current peak flowing through the switch tube in the third power frequency rectifier circuit.

2. The detection winding and detection device according to claim 1, characterized in that: The detection winding is a single winding, and the detection device includes: a fifth diode, a sixth diode, a seventh diode, an eighth diode, a first resistor, a second resistor and a comparator, wherein the anode of the fifth diode and the cathode of the sixth diode are connected to the first end of the detection winding, the anode of the seventh diode and the cathode of the eighth diode are connected to the second end of the detection winding, the cathode of the fifth diode and the cathode of the seventh diode are connected to the first end of the first resistor, the anode of the sixth diode, the anode of the eighth diode and the second end of the second resistor are simultaneously connected to the ground end of the controller, the second end of the first resistor and the first end of the second resistor are connected to an input end of the comparator, the other input end of the comparator inputs a reference voltage, and the output end of the comparator outputs the surge protection signal; Or the detection winding is a double winding, and the detection device includes: a ninth diode, a tenth diode, the third resistor, the fourth resistor and a comparator; the first end of the first detection winding is connected to the anode of the ninth diode, the second end of the second detection winding is connected to the anode of the tenth diode, the second end of the first detection winding, the first end of the second detection winding, and the second end of the fourth resistor are simultaneously connected to the ground terminal of the controller, the cathode of the ninth diode, the cathode of the tenth diode and the first end of the third resistor are connected, the second end of the third resistor and the first end of the fourth resistor are connected to an input terminal of the comparator, the other input terminal of the comparator inputs a reference voltage, and the output terminal of the comparator outputs the surge protection signal.

3. The power factor correction circuit according to claim 1, characterized in that: The first high-frequency rectifying circuit includes a bridge arm formed by two active semiconductor power tubes.

4. The power factor correction circuit according to claim 1, characterized in that: The first power frequency rectification circuit comprises a bridge arm formed by two passive semiconductor power tubes connected in series in the same direction.

5. The power factor correction circuit according to claim 1, characterized in that: The second power frequency rectification circuit comprises a bridge arm formed by two passive semiconductor power tubes connected in series in the same direction.

6. The power factor correction circuit according to claim 1, characterized in that: The third industrial frequency rectification circuit includes a bridge arm formed by two active semiconductor power tubes, so that the power factor correction circuit is a bidirectional rectification totem bridgeless power factor correction circuit.

7. The power factor correction circuit according to any one of claims 1 to 6, characterized in that: The power factor correction circuit includes N boost inductors and N first high-frequency rectifier circuits, where N is a natural number greater than or equal to 2, and the first end of each boost inductor is simultaneously connected to the first input end of the power factor correction circuit and the midpoint of the bridge arm of the first industrial frequency rectifier circuit, and the second end is connected to the midpoint of the bridge arm of one of the N first high-frequency rectifier circuits.

8. A switching power supply, characterized in that: The invention comprises a power factor correction circuit as described in any one of claims 1 to 7.

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