Efficient power factor correction circuit and power converter

Abstract

The invention discloses a high-efficiency power factor correction circuit and a power converter, which are applied to the field of power factor correction circuits, and comprise a bridge rectifier, an inductor arranged at the output end of the bridge rectifier, a first switch tube, a second switch tube, a current transformer, a first diode, a turn-off circuit and a first clamping circuit. When the first switching tube is switched off, the current transformer transmits an electric signal of a relatively low current to the control end of the second switching tube as a control signal through the first diode and the first clamping circuit in a follow current state, and the current far greater than the signal is connected with the first end of the second switching tube through a wire; when the control end of the second switching tube receives an electric signal, the switching tubes are switched on, and current can be output through lower loss, so that the influence of the loss of a diode in a traditional power factor correction circuit on the overall efficiency is reduced, and the power factor of the power factor correction circuit is effectively improved.

Description

Technical Field

[0001] The invention relates to the field of power factor correction circuits, and in particular to a high-efficiency power factor correction circuit and a power converter. Background Art

[0002] For a long time, the power factor correction circuit inside the high-power switching power supply has used the traditional BOOST circuit, that is, the external 220V AC power is rectified by the bridge stack and then sent to the harmonic processing circuit composed of BOOST.

[0003] Usually the practice is Figure 1 and Figure 2 As shown in the figure, during the operation of the circuit, when the power switch tube works at high frequency, high voltage and large current, the switch tube is turned on for t1-t2, and the current of the inductor is in a climbing state, that is, the current rising stage between t1-t2. When the power switch tube is turned off, since the inductor is in a freewheeling state, the current of the inductor charges the capacitor through the diode. As the energy of the inductor is transferred to the capacitor, the current gradually decreases until the charging is finally stopped, that is, the current falling state between t2-t3. During the t2-t3 process, the current passing through the diode is relatively large, and due to the inherent voltage difference characteristics of the diode, the loss on the diode is relatively large.

[0004] Therefore, there is an urgent need to adopt a method to reduce or eliminate the influence of excessive diode power consumption on the power factor of the power factor correction circuit. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a high-efficiency power factor correction circuit and a power converter, which effectively solves the problem of diode loss in the power factor correction circuit. The specific scheme is as follows:

[0006] In a first aspect, the present application provides a high-efficiency power factor correction circuit, comprising: a bridge rectifier, an inductor and a first switch tube, a second switch tube, a current transformer, a first diode, a shutdown circuit and a first clamping circuit arranged at an output end of the bridge rectifier;

[0007] The second end of the inductor and the first end of the first switch tube are connected to the inflow end of the primary side current of the current transformer;

[0008] The inflow end of the secondary side current of the current transformer is connected to the outflow end of the primary side current of the current transformer;

[0009] The outflow end of the secondary current of the current transformer is connected to the anode of the first diode;

[0010] An input terminal of the first clamping circuit is connected to a cathode of the first diode;

[0011] The output end of the first clamp circuit is connected to the control end of the second switch tube, and is used to clamp the electrical signal input to the control end of the second switch tube;

[0012] The shut-off circuit is connected to the second switch tube and is used to control the second switch tube to shut down when the current value output by the current transformer is less than a preset value;

[0013] The outflow end of the primary side current of the current transformer is connected to the load through the second switch tube.

[0014] Optionally, it also includes: a second clamping circuit;

[0015] The second clamping circuit includes: a first resistor and a first voltage regulator tube;

[0016] A first end of the first resistor is connected to an inflow end of the secondary side current of the current transformer;

[0017] The anode of the first voltage regulator tube is connected to the second end of the first resistor;

[0018] The cathode of the first voltage regulator tube, the outflow end of the secondary side current of the current transformer and the anode of the first diode are connected.

[0019] Optionally, it also includes: a second resistor;

[0020] The first end of the second resistor is connected to the first end of the second switch tube, the first end of the first resistor, and the outflow end of the primary side current of the current transformer;

[0021] The second end of the second resistor is connected to the control end of the second switch tube.

[0022] Optionally, the shutdown circuit includes: a third resistor, a fourth resistor and a third switch tube;

[0023] The first end of the third resistor is connected to the anode of the first diode and the cathode of the first voltage regulator tube;

[0024] The second end of the third resistor is connected to the first end of the fourth resistor, and a common end of the two is connected to the control end of the third switch tube;

[0025] The second end of the third switch tube is connected to the second end of the fourth resistor, and a common end of the two is connected to the first end of the second switch tube as an output end of the shutdown circuit.

[0026] Optionally, the shutdown circuit further includes: a second diode and a fifth resistor;

[0027] The anode of the second diode, the second end of the fifth resistor, the second end of the second resistor are connected to the control end of the second switch tube;

[0028] The cathode of the second diode, the first end of the fifth resistor and the first end of the third switch tube are connected.

[0029] Optionally, the first clamping circuit includes: a sixth resistor, a fourth switch tube and a second voltage regulator tube;

[0030] The first end of the sixth resistor and the first end of the fourth switch tube are connected to the cathode of the first diode;

[0031] The second end of the sixth resistor, the cathode of the second voltage-stabilizing tube and the control end of the fourth switch tube are connected;

[0032] The second end of the fourth switch tube serves as the output end of the first clamping circuit;

[0033] The anode of the second voltage regulator tube is connected to the first end of the second switch tube as the second input end of the first clamping circuit.

[0034] Optionally, the third switch tube is a PNP transistor;

[0035] The base of the PNP transistor is the control end of the third switch tube, the emitter of the PNP transistor is the first end of the third switch tube, and the collector of the PNP transistor is the second end of the third switch tube.

[0036] Optionally, the fourth switch tube is an NPN transistor;

[0037] The base of the NPN transistor is the control end of the fourth switch tube, the collector of the NPN transistor is the first end of the second switch tube, and the emitter of the NPN transistor is the second end of the second switch tube.

[0038] Optionally, the bridge rectifier is a full-bridge rectifier.

[0039] In a second aspect, the present application provides a power converter, comprising a high-efficiency power factor correction circuit.

[0040] It can be seen that in the present application, when the first switch tube is turned off, the current transformer transmits an electrical signal of a smaller current through the first diode and the first clamping circuit to the control end of the second switch tube as a control signal in the freewheeling state, and the current much larger than the signal is connected to the first end of the second switch tube through a wire. When the control end of the second switch tube receives the electrical signal, the switch tube is turned on, and the current can be output with lower loss, so as to reduce the influence of the loss of the diode in the traditional power factor correction circuit on the overall efficiency, and effectively improve the power factor of the power factor correction circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0042] Figure 1 A power factor correction circuit diagram provided in an embodiment of the present application;

[0043] Figure 2 An inductor current timing diagram provided in an embodiment of the present application;

[0044] Figure 3 A high-efficiency power factor correction circuit diagram provided in an embodiment of the present application;

[0045] Figure 4 A high-efficiency power factor correction circuit diagram provided in an embodiment of the present application; DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The core of this application is to provide a high-efficiency power factor correction circuit.

[0048] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0049] For a long time, the power factor correction circuit inside the high-power switching power supply has used the traditional BOOST circuit, that is, the external 220V AC power is rectified by the bridge stack and then sent to the harmonic processing circuit composed of BOOST.

[0050] Usually the practice is Figure 1 and as shown, Figure 2This is the timing diagram of the current in the inductor. During the operation of the circuit, when the power switch tube operates at high frequency, high voltage and large current, the switch tube is turned on for t1-t2, and the current of the inductor L1 is in a climbing state, that is, the current rising stage during t1-t2. When the power switch tube is turned off, since the inductor is in a freewheeling state, the current of the inductor charges the capacitor through the diode. As the energy of the inductor is transferred to the capacitor, the current gradually decreases until the charging is finally stopped, that is, the current falling state during t2-t3. During t2-t3, the current passing through the diode is large, and due to the inherent voltage difference characteristics of the diode, the loss on the diode is large.

[0051] Therefore, there is an urgent need to adopt a method to reduce or eliminate the influence of excessive diode power consumption on the power factor of the power factor correction circuit.

[0052] Figure 3 A high-efficiency power factor correction circuit diagram is provided in the embodiment of the present application. Figure 3 As shown, in order to solve the above problems, this embodiment provides a composite synchronous rectification driving circuit including: a bridge rectifier, an inductor L1 and a first switch tube Q1, a second switch tube Q2, a current transformer T1, a first diode D1, a shutdown circuit and a first clamping circuit arranged at the output end of the bridge rectifier;

[0053] The second end of the inductor L1 and the first end of the first switch tube Q1 are connected to the inflow end of the primary side current of the current transformer T1;

[0054] The inflow end of the secondary side current of the current transformer T1 is connected to the outflow end of the primary side current of the current transformer T1;

[0055] The outflow end of the secondary current of the current transformer T1 is connected to the anode of the first diode D1;

[0056] An input end of the first clamping circuit is connected to a cathode of the first diode D1;

[0057] The output end of the first clamp circuit is connected to the control end of the second switch tube Q2, and is used to clamp the electrical signal input to the control end of the second switch tube Q2;

[0058] The shut-off circuit is connected to the second switch tube Q2, and is used to control the second switch tube Q2 to shut down when the current value output by the current transformer T1 is less than a preset value;

[0059] The outflow end of the primary current of the current transformer T1 is connected to the load through the second switch tube Q2.

[0060] like Figure 3As shown, BD1 is a bridge rectifier composed of 4 diodes, and the 2nd and 4th ends of the bridge rectifier serve as the input ends of the alternating current. The 1st end of the bridge rectifier is connected to the first end of the inductor L1, and the second end of the inductor L1 is connected to the first end of the first switch tube Q1. In the figure, a MOS tube is used as an example as the first switch tube Q1, and the first end of the first switch tube is the drain, and the second end of the first switch tube is the source, which is directly grounded.

[0061] When the power factor correction pulse width modulation signal (PFC-PWM, i.e. Power Factor Correction PulseWidth Modulation) controls the first power switch tube Q1 to turn on, the bridge rectifier, inductor L1 and the first switch tube Q1 form a path, and the signal is grounded. When the PFC-PWM controls the first switch tube Q1 to turn off, the inductor L1 is in a freewheeling state, releasing the energy stored when the first switch tube Q1 is turned on. Figure 2 As shown, the inductor is in the period t1-t2, and the current continues to decrease. At this time, the current passes through the current transformer T1, and most of the current flows through the outflow end of the primary current of the current transformer T1 to the first end of the second switch tube Q2, and then flows to the load and capacitor through the body diode of the second switch tube Q2. At the same time, the outflow end of the secondary current of the current transformer T1 will generate an electrical signal with a smaller current value. The electrical signal flows to the first clamping circuit through the first diode D1, and flows to the control end of the second switch tube Q2 after being clamped by the first clamping circuit. Figure 3 Specifically, it is composed of an NPN transistor, a resistor and a voltage regulator. It can be understood that any clamping circuit can achieve the above functions. Figure 3 This is just one specific circuit diagram.

[0062] At this time, the second switch tube Q2 is turned on, and the current originally passing through the body diode of the second switch tube Q2 is changed to pass through the path of the second switch tube Q2. Since the internal resistance of the second switch tube Q2 is small after it is turned on, it is in the milliohm level. The average power consumption can be expressed as: ; Where Q refers to heat, I refers to current, and R refers to resistance. The average heat loss can be calculated by the formula. Under the existing technology, the diode conduction voltage drop is at the volt level, and the average power consumption can be expressed as:

[0063] ; Where Q refers to heat, U refers to voltage, and R refers to resistance. The average heat loss can be calculated by the formula. Substituting the formula into the calculation and comparison, it can be found that the power consumption generated by the current passing through the diode in the circuit of this embodiment has been greatly reduced compared with the prior art.

[0064] It can be seen that in the present application, a smaller current electrical signal is transmitted through the current transformer T1 through the first diode D1 and the first clamping circuit to the control end of the second switch tube Q2 as a control signal, and a current much larger than the signal is connected to the first end of the second switch tube Q2 through a wire. When the control end of the second switch tube Q2 receives the electrical signal, the switch tube is turned on, and the current can be output with lower loss, so as to reduce the influence of the loss of the diode in the traditional power factor correction circuit on the overall efficiency, thereby effectively improving the power factor of the power factor correction circuit.

[0065] Figure 4 An efficient power factor correction circuit is provided in an embodiment of the present application, such as Figure 4 As shown, according to the above embodiment, this embodiment provides a specific solution, further comprising: a second clamping circuit;

[0066] The second clamping circuit includes: a first resistor R1 and a first voltage regulator tube ZD1;

[0067] A first end of the first resistor R1 is connected to an inflow end of the secondary side current of the current transformer T1;

[0068] The anode of the first voltage regulator tube ZD1 is connected to the second end of the first resistor R1;

[0069] The cathode of the first voltage-stabilizing tube ZD1 and the outflow end of the secondary current of the current transformer T1 are connected to the anode of the first diode D1.

[0070] like Figure 3 As shown, when the first switch tube Q1 is turned off, a common-phase current waveform is generated on the secondary side of the current transformer T1, and the first resistor R1 plays a current limiting role here. The current of the current waveform signal is limited to the working range of the first voltage regulator tube ZD1, and then the first voltage regulator tube ZD1 processes the voltage of the current waveform signal to provide a signal value within the working current voltage range for the subsequent operation of the first diode D1.

[0071] It can be seen that the second clamping circuit performs preliminary clamping processing on the signal generated by the current transformer T1, ensuring that the signal will not damage other devices when flowing through the subsequent circuit, thereby providing a guarantee for the normal operation of the subsequent devices in the circuit.

[0072] According to the above embodiment, this embodiment provides a specific solution, further comprising: a second resistor R2;

[0073] The first end of the second resistor R2 is connected to the first end of the second switch tube Q2, the first end of the first resistor R1, and the outflow end of the primary side current of the current transformer T1;

[0074] The second end of the second resistor R2 is connected to the control end of the second switch tube Q2.

[0075] The second resistor R2 is connected to the control end and the first end of the second switch tube Q2, which provides a discharge channel for electrostatic charge. When static electricity accumulates at the control end, the electrostatic charge can be slowly discharged to the first end of the second switch tube Q2 through the second resistor R2, avoiding the instantaneous accumulation of electrostatic voltage. At the same time, the second resistor R2 will also share part of the electrostatic voltage, further reducing the actual voltage on the control end of the second switch tube Q2 and reducing the risk of breakdown of the second switch tube Q2.

[0076] According to the above embodiment, this embodiment provides a specific solution, the shutdown circuit includes: a third resistor R3, a fourth resistor R4 and a third switch tube Q3;

[0077] A first end of the third resistor R3 is connected to the anode of the first diode D1 and the cathode of the first voltage regulator ZD1;

[0078] The second end of the third resistor R3 is connected to the first end of the fourth resistor R4, and a common end of the two is connected to the control end of the third switch tube Q3;

[0079] The second end of the third switch tube Q3 is connected to the second end of the fourth resistor R4, and a common end of the two is connected to the first end of the second switch tube Q2 as an output end of the shutdown circuit.

[0080] like Figure 2 As shown, when the inductor L1 is in a current decreasing state during the period t2-t3, after the current drops to a certain threshold, the third switch tube Q3 is turned on, and at this time, a path is generated from the control end of the second switch tube Q2 to the first end, and the lumped capacitance of the control end of the second switch tube Q2 can be discharged through the third switch tube Q3, thereby turning off the second switch tube Q2.

[0081] This embodiment provides a specific solution, the shutdown circuit further includes: a second diode D2 and a fifth resistor R5;

[0082] The anode of the second diode D2, the second end of the fifth resistor R5, the second end of the second resistor R2 are connected to the control end of the second switch tube Q2;

[0083] The cathode of the second diode D2, the first end of the fifth resistor R5 and the first end of the third switch tube Q3 are connected.

[0084] Due to the unidirectional conduction property of the second diode D2, when the third switch tube Q3 is not turned on, the current is output from the first clamping circuit and then transmitted to the control end of the second switch tube Q2 through the further current limiting of the fifth resistor R5, which further improves the normal operation of the second diode D2 and provides a guarantee. At the same time, when the third switch tube Q3 is turned on, the lumped capacitance at the control end of the second switch tube Q2 can be quickly discharged through the second diode D2, that is, at this time, the shutdown circuit forces the control end of the second switch tube Q2 to be pulled down, and the second switch tube Q2 can be quickly turned off.

[0085] According to the above embodiment, this embodiment provides a specific solution, the first clamping circuit includes: a sixth resistor R6, a fourth switch tube Q4 and a second voltage regulator tube ZD2;

[0086] The first end of the sixth resistor R6 and the first end of the fourth switch tube Q4 are connected to the cathode of the first diode D1;

[0087] The second end of the sixth resistor R6, the cathode of the second voltage-stabilizing tube ZD2 and the control end of the fourth switch tube Q4 are connected;

[0088] The second end of the fourth switch tube Q4 serves as the output end of the first clamping circuit;

[0089] The anode of the second voltage regulator tube ZD2 is connected to the first end of the second switch tube Q2 as the second input end of the first clamping circuit.

[0090] When the electric signal with a smaller current value generated by the current transformer T1 flows from the second clamping circuit and the first diode D1 to the first clamping circuit, the anode of the second voltage regulator tube ZD2 is connected to the current on the primary side of the current transformer T1. At this time, the fourth switch tube Q4 is turned on, that is, as long as the current transformer T1 generates a current signal, the fourth switch tube Q4 is turned on.

[0091] like Figure 4 As shown, according to the above embodiment, this embodiment provides a specific solution, the fourth switch tube Q4 is an NPN transistor;

[0092] The base of the NPN transistor is the control end of the fourth switch tube Q4, the collector of the NPN transistor is the first end of the second switch tube Q2, and the emitter of the NPN transistor is the second end of the second switch tube Q2.

[0093] Since the signal on the secondary side of the current transformer T1 passes through the first switch tube Q1 of the second clamping circuit, a certain voltage drop is generated, and at this time, the voltage flowing through the base and emitter of the fourth switch tube Q4 must be greater than the conduction voltage of the NPN, and the fourth switch tube Q4 is turned on. Then, the fourth switch tube Q4 plays a role of linear voltage stabilization for the signal.

[0094] like Figure 3As shown, according to the above embodiment, this embodiment provides a specific solution, the third switch tube Q3 is a PNP transistor;

[0095] The base of the PNP transistor is the control end of the third switch tube Q3 , the emitter of the PNP transistor is the first end of the third switch tube Q3 , and the collector of the PNP transistor is the second end of the third switch tube Q3 .

[0096] As shown in the figure, the third resistor R3 and the fourth resistor R4 are bias resistors of the third switch tube Q3. When the current passing through the secondary side of the current transformer T1 is less than the threshold, the voltage between the base and the emitter of the third switch tube Q3 is less than the turn-on voltage, and the third switch tube Q3 is turned on to realize the connection from the control end of the second switch tube Q2 to the first end.

[0097] like Figure 3 As shown in or 4, according to the above embodiment, this embodiment provides a specific solution, and the bridge rectifier is a full-bridge rectifier.

[0098] The full-bridge rectifier used in the circuit of this embodiment is composed of four rectifier diodes connected and packaged in the form of a bridge full-wave rectifier circuit, which can efficiently convert alternating current into direct current. This structure makes it easy to achieve standardization and large-scale production during the production process, reducing production costs. At the same time, the simple structure also has a low failure rate and high reliability, and can maintain stable performance during long-term use.

[0099] In order to make it clearer to those skilled in the art Figure 4 The circuit structure and working principle shown will be described in detail below. Figure 4This is a specific implementation of the present application. As shown in the figure, high-frequency high-voltage alternating current flows to the inductor L1 and the first switch tube Q1 through the full-bridge rectifier. When the first switch tube Q1 is closed, the inductor L1 is used to supply power to the current transformer T1. The secondary side of the current transformer will generate a signal with a smaller current value as a control signal for controlling the second switch tube Q2. The first resistor R1 will further limit the magnitude of the control signal current. The first voltage regulator controls the voltage. It can be seen from the figure that the second switch tube Q2 is a field effect MOS tube. The gate of the field effect MOS tube has certain requirements for voltage. In order to prevent the breakdown of the second switch tube Q2, the first resistor R1 and the first voltage regulator ZD1 are set in the first half of the circuit in the box to perform preliminary clamping processing on the control signal. At this time, the control signal is rectified by the first diode D1 and then passes through the fourth switch tube Q4. It can be seen from the figure that the fourth switch tube Q4 is an NPN triode, which is used as a linear regulator here to further process the control signal. The control end of the fourth switch tube Q4 is connected to the primary side of the current transformer T1 through the second voltage regulator tube ZD2, that is, as long as there is current, the fourth switch tube Q4 must be turned on, and the fourth switch tube Q4 does not have a switch function here. The third resistor R3 and the fourth resistor R4 in the circuit serve as bias resistors for the third switch tube Q3 and have a large resistance value. Due to the proportional distribution, the third switch tube Q3 will only be turned on when the current value of the inductor L1 is less than the threshold. Here, the second resistor R2 is connected in parallel to the gate and source of the second switch tube Q2 as an electrostatic protection device. When the current of the inductor L1 is in Figure 2 In the first half of the t2-t3 phase, the current value of the control signal is greater than the threshold value, and the control signal reaches the control end of the second switch tube Q2 via the first resistor R1, the first voltage regulator tube ZD1, the first diode D1, the fourth switch tube Q4, and the fifth resistor R5, so that the second switch tube Q2 is turned on. Figure 2 In the second half of the t2-t3 stage, the control signal current value is less than the threshold value, the third switch tube Q3 meets the conditions to be turned on, the capacitance of the gate of the second switch tube Q2 is discharged through the second diode D2 and the third switch tube Q3, and the second switch tube Q2 is instantly turned off. At this time, the current flows to the load through the body diode.

[0100] exist Figure 1 In traditional power factor correction circuits, the diode uses a high-frequency, high-voltage, fast-recovery diode with a voltage drop of about 1.5V. The circuit is usually connected to a 1KW power supply. The maximum current passing through the diode can reach 20A. The diode conduction duty cycle is calculated as 0.4, and the average power consumption is: 20*1.5*0.4=12W. The heat loss accounts for about 1.5% of the total power of the machine.

[0101] And in Figure 4In a high-efficiency power factor correction circuit provided in this embodiment, under the same working conditions, the current is 20A, the on-resistance of Q4 is 28 milliohms, and the duty cycle is calculated as 0.4. At this time, the circuit power consumption is: 20*20*0.028*0.4=4.48W, which is significantly reduced compared to the power consumption of 12W in the traditional power factor correction circuit.

[0102] Finally, this embodiment provides a power converter, including the above-mentioned high-efficiency power factor correction circuit.

[0103] The above is a detailed introduction to a high-efficiency power factor correction circuit and a power converter provided by the present application. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0104] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. A high efficiency power factor correction circuit, characterized in that: include: A bridge rectifier, an inductor and a first switch tube, a second switch tube, a current transformer, a first diode, a shutoff circuit and a first clamping circuit arranged at an output end of the bridge rectifier; The second end of the inductor and the first end of the first switch tube are connected to the inflow end of the primary side current of the current transformer; The inflow end of the secondary side current of the current transformer is connected to the outflow end of the primary side current of the current transformer; The outflow end of the secondary current of the current transformer is connected to the anode of the first diode; An input end of the first clamping circuit is connected to a cathode of the first diode; The output end of the first clamp circuit is connected to the control end of the second switch tube, and is used to clamp the electrical signal input to the control end of the second switch tube; The shutdown circuit is connected to the second switch tube, and is used to control the second switch tube to shut down when the current value output by the current transformer is less than a preset value; The outflow end of the primary side current of the current transformer is connected to the load through the second switch tube.

2. The high efficiency power factor correction circuit according to claim 1, characterized in that: Also includes: A second clamping circuit; The second clamping circuit includes: a first resistor and a first voltage regulator tube; The first end of the first resistor is connected to the inflow end of the secondary side current of the current transformer; The anode of the first voltage regulator tube is connected to the second end of the first resistor; The cathode of the first voltage regulator tube, the outflow end of the secondary side current of the current transformer and the anode of the first diode are connected.

3. The high efficiency power factor correction circuit according to claim 2, characterized in that: Also includes: A second resistor; The first end of the second resistor is connected to the first end of the second switch tube, the first end of the first resistor, and the outflow end of the primary side current of the current transformer; The second end of the second resistor is connected to the control end of the second switch tube.

4. The high efficiency power factor correction circuit according to claim 3, characterized in that: The shutdown circuit comprises: a third resistor, a fourth resistor and a third switch tube; The first end of the third resistor is connected to the anode of the first diode and the cathode of the first voltage regulator tube; The second end of the third resistor is connected to the first end of the fourth resistor, and a common end of the two is connected to the control end of the third switch tube; The second end of the third switch tube is connected to the second end of the fourth resistor, and a common end of the two is connected to the first end of the second switch tube as the output end of the shutdown circuit.

5. The high efficiency power factor correction circuit according to claim 4, characterized in that: The shutdown circuit further includes: a second diode and a fifth resistor; The anode of the second diode, the second end of the fifth resistor, the second end of the second resistor are connected to the control end of the second switch tube; The cathode of the second diode, the first end of the fifth resistor and the first end of the third switch tube are connected.

6. The high-efficiency power factor correction circuit according to any one of claims 1 to 5, characterized in that: The first clamping circuit includes: a sixth resistor, a fourth switch tube and a second voltage regulator tube; The first end of the sixth resistor and the first end of the fourth switch tube are connected to the cathode of the first diode; The second end of the sixth resistor, the cathode of the second voltage-stabilizing tube and the control end of the fourth switch tube are connected; The second end of the fourth switch tube serves as the output end of the first clamping circuit; The anode of the second voltage regulator tube is connected to the first end of the second switch tube as the second input end of the first clamping circuit.

7. The high efficiency power factor correction circuit according to claim 4, characterized in that: The third switch tube is a PNP transistor; The base of the PNP transistor is the control end of the third switch tube, the emitter of the PNP transistor is the first end of the third switch tube, and the collector of the PNP transistor is the second end of the third switch tube.

8. The high efficiency power factor correction circuit according to claim 6, characterized in that: The fourth switch tube is an NPN transistor; The base of the NPN transistor is the control end of the fourth switch tube, the collector of the NPN transistor is the first end of the second switch tube, and the emitter of the NPN transistor is the second end of the second switch tube.

9. The high efficiency power factor correction circuit according to claim 1, characterized in that: The bridge rectifier is a full-bridge rectifier.

10. A power converter, characterized in that: A high-efficiency power factor correction circuit comprising any one of claims 1 to 9.

Images