Power factor correction circuit and switching converter

Abstract

The application is suitable for the field of power electronics, and provides a power factor correction circuit and a switching converter. The circuit comprises an energy storage module, a switching module, an isolation module, a first current sampling module, a second current sampling module and a control module. The first current sampling module is used to convert the first current flowing through the switching module based on the principle of electromagnetic induction to obtain a converted current, and obtain a first voltage based on the converted current and output to the control module. The second current sampling module is used to obtain a second voltage based on the second current flowing directly through the second current sampling module and output to the control module, wherein the second current comprises the current flowing through the load. The control module is used to output corresponding conducting signals and turn-off signals according to the first voltage, the second voltage, the input power supply voltage and the load voltage, so that the input current and the output voltage of the power factor correction circuit meet the preset condition. The application can reduce power consumption and simplify the circuit structure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power electronics, and particularly relates to a power factor correction circuit and a switching inverter. BACKGROUND

[0002] Active Power Factor Correction (APFC) technology is widely used in many industries because it can improve the power factor of power electronic devices on the grid side, reduce line loss, save energy, reduce harmonic pollution of the power grid, and improve the power supply quality of the power grid.

[0003] The implementation of the APFC technology is as follows: taking the input voltage of the APFC circuit as a reference signal, the input current is adjusted so that the input current tracks the input voltage, and the low-frequency component of the input current is approximately the same frequency and phase as the low-frequency component of the input voltage, thereby improving the power factor and suppressing harmonics. Therefore, accurate detection of the input current of the APFC circuit is particularly important.

[0004] In the prior art, there are mainly two ways to detect the input current of the APFC circuit. One way is to directly connect a current sampling device (such as a sampling resistor) in the loop to sample the current, but this way will result in high power consumption. The other way is to convert the large current on the primary side of the loop into a small current on the secondary side (such as a current transformer) according to the principle of electromagnetic induction to sample the current of the loop, but the circuit structure of the current sampling circuit designed by this way is relatively complex, which results in low circuit reliability, large physical space occupied by the circuit structure, and high design cost. SUMMARY

[0005] Therefore, the embodiments of the present application provide a power factor correction circuit and a switching converter to solve the technical problem that the input current sampling circuit of the existing APFC circuit cannot reduce power consumption while meeting the design requirements of simple circuit structure.

[0006] In a first aspect, a power factor correction circuit is provided, comprising:

[0007] An energy storage module is connected to a switching module through a first current sampling module, and is used to connect an input power supply, store electrical energy when the switching module is turned on, and release the electrical energy when the switching module is turned off;

[0008] A switching module is connected to a control module, and is connected to an isolation module and the energy storage module through the first current sampling module, and is used to turn on according to a turn-on signal output by the control module, or is used to turn off according to a turn-off signal output by the control module;

[0009] an isolation module, connected with the energy storage module, and connected with the switch module through the first current sampling module and used for connecting a load, used for turning off when the switch module is turned on, and used for turning on when the switch module is turned off;

[0010] a first current sampling module, connected with the switch module and the control module respectively, used for converting a first current to obtain a converted current based on an electromagnetic induction principle, and used for obtaining a first voltage based on the converted current and outputting the first voltage to the control module, the first current including a current flowing through the switch module;

[0011] a second current sampling module, used for being connected between an electric circuit between a second end of the load and a second end of the switch module, and connected with the control module, used for obtaining a second voltage based on a second current directly flowing through the second current sampling module and outputting the second voltage to the control module, the second current including a current flowing through the load;

[0012] a control module, connected with the switch module, the input power supply and the load, the first current sampling module and the second current sampling module respectively, used for outputting corresponding turn-on signals and turn-off signals according to the first voltage and the second voltage, and an output voltage of the input power supply and an input voltage of the load, so that an input current of the energy storage module and an output voltage of the energy storage module satisfy a preset condition.

[0013] In a possible implementation manner of the first aspect, the first current sampling module includes:

[0014] a current mutual inductance unit, connected with a voltage acquisition unit and the switch module respectively, used for converting the first current to the converted current;

[0015] the voltage acquisition unit, connected with the control module, used for obtaining the first voltage based on the converted current and outputting the first voltage to the control module.

[0016] In a possible implementation manner of the first aspect, the second current sampling module includes a first resistor;

[0017] a first end of the first resistor is connected with a second end of the switch module and a second end used for connecting the input power supply, and a second end of the first resistor is used for connecting a second end of the load.

[0018] In a possible implementation manner of the first aspect, the energy storage module includes a first inductor, the switch module includes a first switch tube, and the isolation module includes a first diode.

[0019] The first end of the first inductor is configured to be connected to a first end of the input power supply, the second end of the first inductor is configured to be connected to the first end of the first current sampling module and the anode of the first diode respectively, the cathode of the first diode is configured to be connected to a first end of the load, the second end of the first current sampling module is configured to be connected to the first end of the first switch tube, the second end of the first switch tube is configured to be connected to the first end of the second current sampling module and the second end of the input power supply, the control end of the first switch tube is configured to be connected to the control module, and the second end of the second current sampling module is configured to be connected to a second end of the load.

[0020] In a possible implementation manner of the first aspect, the current mutual inductance unit comprises a current transformer and a second diode, the current transformer comprises a primary coil and a secondary coil.

[0021] The first end of the primary coil is configured to be connected to the second end of the first inductor and the anode of the first diode respectively, the second end of the primary coil is configured to be connected to the first end of the first switch tube, the first end of the secondary coil is configured to be connected to the cathode of the second diode, the second end of the secondary coil is configured to be connected to the first end of the voltage acquisition unit, the second end of the first switch tube and the first end of the second current sampling module respectively, the anode of the second diode is configured to be connected to the second end of the voltage acquisition unit and the first end of the control module respectively, and the second end of the control module is configured to be grounded.

[0022] In a possible implementation manner of the first aspect, the voltage acquisition unit comprises a second resistor.

[0023] The first end of the second resistor is configured to be connected to the second end of the secondary coil, the second end of the first switch tube and the first end of the second current sampling module respectively, and the second end of the second resistor is configured to be connected to the anode of the second diode and the first end of the control module respectively.

[0024] In a possible implementation manner of the first aspect, the switch module further comprises a third resistor and a fourth resistor.

[0025] The first end of the third resistor is configured to be connected to the control end of the first switch tube and the first end of the fourth resistor respectively, the second end of the third resistor is configured to be connected to the control end of the control module, and the second end of the fourth resistor is configured to be connected to the second end of the first switch tube and the first end of the second current sampling module respectively.

[0026] In a possible implementation manner of the first aspect, the current mutual inductance unit further comprises a fifth resistor.

[0027] The first end of the fifth resistor is connected to the first end of the secondary coil and the cathode of the second diode respectively, and the second end of the fifth resistor is connected to the second end of the secondary coil and the first end of the first resistor respectively.

[0028] In a possible implementation of the first aspect, the power factor correction circuit further includes a first capacitor and a second capacitor.

[0029] The first end of the first capacitor is connected to the first end of the energy storage module and a first end for connecting the input power supply, the second end of the first capacitor is connected to the second end of the switch module and the first end of the second current sampling module respectively, and a second end for connecting the input power supply.

[0030] The first end of the second capacitor is connected to the second end of the isolation module and a first end for connecting the load, and the second end of the second capacitor is connected to the second end of the second current sampling module and a second end for connecting the load.

[0031] In a second aspect, the embodiments of the present application further provide a switching converter, which includes the power factor correction circuit provided by any of the above embodiments.

[0032] The power factor correction circuit and the switching converter provided by the embodiments of the present application have the following beneficial effects:

[0033] The power factor correction circuit provided by the embodiments of the present application includes an energy storage module, a switch module, an isolation module, a first current sampling module, a second current sampling module and a control module, wherein the first current sampling module is configured to convert a first current flowing through the switch module based on the principle of electromagnetic induction to obtain a converted current, and obtain a first voltage based on the converted current; the second current sampling module is connected in series between an electrical circuit between a second end of a load and a second end of the switch module, and is configured to obtain a second voltage based on a second current flowing through a loop of the isolation module.

[0034] The power factor correction circuit in the present application detects the first current flowing through the switch module by the first current sampling module to obtain the first voltage and transmit the first voltage to the control module when the switch module is turned on, and obtains the second voltage based on the second current flowing through the loop of the isolation module by the second current sampling module to transmit the second voltage to the control module when the switch module is turned off. The control module outputs corresponding turn-on signals and turn-off signals to control the working state of the switch module according to the first detection voltage and the second detection voltage, so that the input current of the energy storage module (i.e. the input current of the power factor correction circuit) meets the preset condition, thereby improving the power factor.

[0035] Since the second current sampling module is not put into work when the switch module is turned on, and current sampling is only performed through the first current sampling module, no additional loss of output power caused by the second current sampling module directly connected in the circuit loop will be caused; when the switch module is turned off, the second current sampling module is used to replace the first current sampling module to perform current sampling, compared with the mode of using electromagnetic induction principle to convert the large current on the primary side of the loop into small current on the secondary side to complete current sampling in all working modes (i.e. on state and off state) of the switch module, the complexity of the overall circuit structure is reduced. Through the above mode, on the basis of reducing power consumption, the overall circuit structure of the power factor correction circuit is also simplified, which has higher reliability, smaller size and lower design cost. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0037] Figure 1 A structural schematic diagram of a power factor correction circuit provided by an embodiment of the present application is shown in the figure.

[0038] Figure 2 A structural schematic diagram of a power factor correction circuit provided by another embodiment of the present application is shown in the figure.

[0039] Figure 3 A circuit structural schematic diagram of a power factor correction circuit provided by an embodiment of the present application is shown in the figure.

[0040] Figure 4 A circuit structural schematic diagram of a power factor correction circuit provided by another embodiment of the present application is shown in the figure.

[0041] Figure 5 A circuit structural schematic diagram of a power factor correction circuit provided by another embodiment of the present application is shown in the figure.

[0042] Figure 6 A circuit structural schematic diagram of a power factor correction circuit provided by another embodiment of the present application is shown in the figure.

[0043] Figure 7 A waveform schematic diagram of each voltage in a power factor correction circuit provided by an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0044] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not intended to limit the present application.

[0045] It should be noted that the terms used in the implementation part of the embodiments of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application. In the description of the embodiments of the present application, unless otherwise specified, " / " represents the meaning of or, for example, A / B can represent A or B; "and / or" herein only describes the association relationship of the association, which means that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist simultaneously, and B exists alone.

[0046] In addition, the terms "first", "second" are only for description purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. The terms "include", "contain", "have" and their variants mean "include but not limited to".

[0047] Because of the advantages of improving the power factor of the grid-side power electronic device, reducing line loss, saving energy, reducing power grid harmonic pollution, and improving power supply quality, active power factor correction (APFC) technology is widely used in many industries.

[0048] The implementation of APFC technology is as follows: taking the input voltage of the APFC circuit as a reference signal, the input current is adjusted so that the input current tracks the input voltage, and the low-frequency component of the input current and the low-frequency component of the input voltage are as same as possible in frequency and phase, so as to improve the power factor and suppress harmonics. As can be seen, accurate detection of the input current of the APFC circuit is a prerequisite for accurate adjustment of the input current.

[0049] In existing technologies, there are two main methods for detecting the input current of APFC circuits. One method is to sample the current by directly connecting a current sampling device (such as a sampling resistor) in series in the loop. However, this method results in significant power consumption. For example, directly connecting a sampling resistor in series in the main loop of the APFC circuit to sample the input current of the APFC circuit results in power consumption. Since the sampling resistor is a purely power-dissipating element, it will inevitably consume power when current flows through it. Moreover, the power consumed is proportional to the square of the current flowing through it. That is, the larger the current flowing through the sampling resistor (the larger the output power of the APFC circuit), the greater the power consumed by the sampling resistor. The higher the efficiency, the greater the power dissipation, thus reducing the efficiency of the APFC circuit. Another approach is to use the principle of electromagnetic induction to convert the large primary current of the circuit into a small secondary current for sampling. However, this approach requires the addition of a current conversion module (such as a current transformer) to the circuit. Therefore, the circuit implementation scheme and wiring arrangement of the aforementioned functional module must also be considered, resulting in a relatively complex circuit structure for the current sampling circuit designed in this way. Consequently, the circuit reliability is low, the physical space occupied by the circuit structure is large, and the design cost is also high.

[0050] To address the aforementioned issues, embodiments of this application provide a power factor correction circuit and a switching converter, which, while reducing power consumption, also simplify the overall circuit structure of the current sampling circuit when detecting the input current of the power factor correction circuit. This results in a power factor correction circuit with lower power consumption, higher reliability, smaller size, and lower design cost.

[0051] This application first provides a power factor correction circuit, please refer to... Figure 1 , Figure 1 This is a schematic diagram of a power factor correction circuit provided in an embodiment of this application. Figure 1 As shown, the power factor correction circuit 10 includes an energy storage module 101, a switching module 102, an isolation module 103, a first current sampling module 104, a second current sampling module 105, and a control module 106.

[0052] The energy storage module 101 is connected to the isolation module 103 and to the switch module 102 via the first current sampling module 104. It is also used to connect to the input power supply 20, to store electrical energy when the switch module 102 is turned on, and to release electrical energy when the switch module 102 is turned off.

[0053] The energy storage module 101 includes, but is not limited to, an inductor, a boost circuit structure composed of the inductor, etc. When the switch module 102 is turned on, a first electric circuit is formed by the energy storage module 101, the switch module 102, the first current sampling module 104, and the input power supply 20, the energy storage module 101 stores energy, and when the switch module 102 is turned off, the first electric circuit is disconnected, a second electric circuit is formed by the energy storage module 101, the isolation module 103, the load 30, and the input power supply 20, and the energy stored in the energy storage module 101 is released. If there is another energy storage unit (such as a capacitor) at the back end ， When the sum of the amount of electricity provided by the input power supply 20 in a single switch cycle and the amount of electricity of the energy storage module 101 is greater than the amount of electricity consumed by the load in a single switch cycle, the released electricity and the electricity of the above-mentioned energy storage unit (such as a capacitor) are superimposed, thereby realizing the function of voltage boosting.

[0054] The switch module 102 is connected to the control module 106 and is connected to the energy storage module 101 and the isolation module 103 through the first current sampling module 104, respectively, for being turned on according to the turn-on signal output by the control module 106 or for being turned off according to the turn-off signal output by the control module 106.

[0055] The switch module 102 adjusts the working state through the control signal (i.e., the turn-on signal or the turn-off signal) output by the control module 106, so that the input current of the energy storage module 101 (i.e., the input current of the power factor correction circuit 10) and the input voltage of the load 30 (i.e., the output voltage of the power factor correction circuit 10) satisfy the preset condition, thereby improving the power factor. It should be noted that the above-mentioned preset condition means that the input current of the power factor correction circuit 10 follows the input voltage (i.e., the output voltage of the input power supply 20) as much as possible, that is, the low-frequency component of the input current is as much as possible as the low-frequency component of the input voltage in frequency and phase (such as the frequency and phase of the input current and the input voltage reaching 90% similarity), thereby improving the input power factor of the circuit, wherein the specific implementation requirements of the similarity of the frequency and phase of the input current and the input voltage can be set by the specific working condition, which is not limited here. In addition, it should be noted that the closer the frequency of the input current and the input voltage and the phase of the input current and the input voltage, the higher the input power factor, and when the frequency and phase of the input current and the input voltage are completely the same, the input power factor is 1, that is, the input power factor reaches the highest level.

[0056] The isolation module 103 is connected with the energy storage module 101, and is connected through the first current sampling module 104 and the switch module 102, and is used for connecting the load 30, for being turned off when the switch module 102 is turned on, and for being turned on when the switch module 102 is turned off. The isolation module 103 can include but is not limited to a diode, an electrical isolation structure composed of a diode, and the like. The isolation module 103 is turned off when the switch module 102 is turned on, so that when other energy storage units (such as capacitors) are provided at the back end, the energy storage units are prevented from discharging energy to the ground, causing waste of electrical energy, and the isolation module 103 is turned on when the switch module 102 is turned off, to form a complete power supply loop, thereby meeting the power supply requirements of the back-end load device, or meeting the charging requirements of the back-end energy storage device.

[0057] The first current sampling module 104 is connected with the switch module 102 and the control module 106, respectively, for converting the first current based on the principle of electromagnetic induction to obtain a converted current, and obtaining a first voltage based on the converted current, and outputting the first voltage to the control module 106, wherein the first current includes a current flowing through the switch module 102.

[0058] The first current sampling module 104 is used for sampling the current of a first electrical circuit composed of the energy storage module 101, the switch module 102, the first current sampling module 104, and the input power supply 20 (i.e., the current flowing through the switch module 102) when the switch module 102 is turned on. By using the principle of electromagnetic induction, the primary side large current (i.e., the current of the circuit in which the switch module 102 is located) can be converted into a secondary side small current for sampling, thereby achieving the purpose of indirect measurement. Compared with the way of directly sampling the current by connecting a sampling resistor in series on the primary side, not only the conduction loss of the sampling resistor is avoided, the conversion efficiency is improved, but also the risk of overheating failure of the sampling resistor or abnormal operation of the switch module 102 (such as short circuit failure caused by failure) is avoided, which causes the voltage across the sampling resistor to be too high and damages the control module 106 (for example, the voltage across the sampling resistor is higher than the maximum specification voltage that the control module 106 can withstand).

[0059] The second current sampling module 105 is used for being connected in series between the electrical circuit between the second end of the load 30 and the second end of the switch module 102, and the control module 106, for obtaining a second voltage based on the second current flowing through the second current sampling module 105, and outputting the second voltage to the control module 106, wherein the second current includes a current flowing through the isolation module 103 and the load 30.

[0060] The second current sampling module 105 is configured to sample the current of a second electric circuit formed by the energy storage module 101, the isolation module 103, the load 30 and the input power supply 20 (i.e. the current flowing through the isolation module 103 and the load 30) when the switch module 102 is turned off. Compared with the indirect sampling mode based on the electromagnetic induction principle, the current sampling element or circuit structure directly connected in the electric circuit is more convenient and fast, and the design of the circuit structure is relatively simple, thereby improving the reliability of the overall circuit, and reducing the circuit volume and design cost.

[0061] The control module 106 is connected with the switch module 102, the first current sampling module 104 and the second current sampling module 105, and the input power supply 20 and the load 30, respectively, and is configured to output corresponding conducting signals and turn-off signals according to the first voltage, the second voltage, the output voltage of the input power supply 20 and the input voltage of the load 30, so as to control the working state of the switch module 102, so that the input current of the energy storage module 101 and the input voltage of the load 30 meet the preset condition.

[0062] The control module 106 can include but is not limited to MCU (Microcontroller Unit), DSP (Digital Signal Processing) and special control chip, etc. The control module 106 obtains the input current of the power factor correction circuit 10 based on the first voltage obtained by the first current sampling module 104 and the second voltage obtained by the second current sampling module 105, and outputs corresponding conducting signals or turn-off signals to the switch module 102 according to the input current of the energy storage module 101, the output voltage of the input power supply 20 and the input voltage of the load 30, and based on the peak current method, the average current method, the hysteresis current method and other control modes, so as to adjust the working state of the switch module 102, so that the input current of the energy storage module 101 and the input voltage of the load 30 meet the preset condition, thereby improving the input power factor. It should be noted that the peak current method, the average current method, the hysteresis current method and other control modes are the conventional input current control mode of the power factor correction circuit, and the specific working principle can refer to the description of related technologies, which will not be repeated here.

[0063] Figure 1 The working principle of the power factor correction circuit 10 is as follows:

[0064] The power factor correction circuit 10 can be divided into two working modes, i.e. a first working mode when the switch module 102 is turned on, and a second working mode when the switch module 102 is turned off. In the first working mode, a first loop is formed by the input power supply 20, the energy storage module 101, the switch module 102 and the first current sampling module 104, the first current sampling module 104 samples the current of the first loop based on the electromagnetic induction principle, obtains a first voltage and transmits it to the control module 106; in the second working mode, a second loop is formed by the input power supply 20, the energy storage module 101, the isolation module 103, the load 30 and the second current sampling module 105, at this time, the second current sampling module 105 directly samples the current flowing through the loop, obtains a second voltage and outputs it to the control module 106; the control module 106 obtains the input current of the power factor correction circuit 10 according to the first voltage for representing the first loop current (i.e. the first current mentioned above) and the second voltage for representing the second loop current (i.e. the second current mentioned above), the input current is the superposition of the first current and the second current, the control module 106 outputs corresponding turn-on signals and turn-off signals based on the input current of the power factor correction circuit 10 (i.e. the input current of the energy storage module 101), the input voltage of the power factor correction circuit 10 (i.e. the output voltage of the input power supply 20), the output voltage of the power factor correction circuit 10 (i.e. the input voltage of the load 30) and the preset control mode, adjusts the working state of the switch module 102, so that the input current and the output voltage of the power factor correction circuit 10 meet the preset conditions, and finally the output power factor is improved.

[0065] It should be noted that the input voltage of the power factor correction circuit 10 (i.e. the output voltage of the input power supply 20) and the output voltage of the power factor correction circuit 10 (i.e. the input voltage of the load 30) can be detected and obtained by an external input voltage detection device and transmitted to the control module 106, or obtained by a voltage detection module built in the control module 106, etc. which is not limited here. In addition, it should be noted that the preset control mode can include but is not limited to the conventional peak current method, average current method, hysteresis current method, etc.

[0066] As can be seen from the above, the power factor correction circuit 10 provided by the embodiments of the present application can, when the switching module 102 is turned on, detect the first current flowing through the switching module 102 based on the electromagnetic induction principle through the first current sampling module 104 to obtain the first voltage and transmit the first voltage to the control module 106, and when the switching module 102 is turned off, obtain the second voltage based on the second current flowing through the isolation module 103 and the load 30 through the second current sampling module 105 and transmit the second voltage to the control module 106, and output the corresponding turn-on signal and turn-off signal to control the working state of the switching module 102 according to the first voltage, the second voltage, the output voltage of the input power supply 20 and the input voltage of the load 30 through the control module 106, so that the input current of the power factor correction circuit 10 (i.e., the input current of the energy storage module 101) and the output voltage of the power factor correction circuit 10 (i.e., the input voltage of the load 30) meet the preset conditions, thereby improving the output power factor.

[0067] Since the second current sampling module 105 does not work when the switching module 102 is turned on, and only the first current sampling module 104 is used for current sampling, the second current sampling module 105 directly connected in the circuit loop does not cause additional loss of output power. When the switching module 102 is turned off, the second current sampling module 105 is used instead of the first current sampling module 104 for current sampling, which reduces the complexity of the overall circuit structure compared to the way of converting the large current on the primary side of the loop into the small current on the secondary side through electromagnetic induction principle to complete the current sampling in all working modes (i.e., the turn-on state and the turn-off state) of the switching module 102. Through the above method, the power consumption is reduced, and the overall circuit structure of the power factor correction circuit is simplified, which has higher reliability, smaller size and lower design cost.

[0068] In some embodiments, referring to Figure 2 , the first current sampling module 104 includes a current mutual inductance unit 1041 and a voltage acquisition unit 1042.

[0069] The current mutual inductance unit 1041 is connected with the voltage acquisition unit 1042 and the switching module 102 respectively, and is used to convert the first current flowing through the switching module 102 into a converted current based on the electromagnetic induction principle; the voltage acquisition unit 1042 is connected with the control module 106, and is used to obtain the first voltage based on the converted current and output the first voltage to the control module 106. The current mutual inductance unit 1041 can include but is not limited to a current transformer, other circuit structures composed of a primary coil, a secondary coil and a magnetic core, etc., and the voltage acquisition unit 1042 can include but is not limited to a single resistor, a resistor network, a voltage acquisition circuit structure composed of a resistor and other circuit elements, etc.

[0070] In some embodiments, referring to Figure 3 , Figure 3 a circuit structure of a power factor correction circuit is shown, in Figure 3 In the embodiment shown, the second current sampling module 105 includes a first resistor R1.

[0071] The first end of the first resistor R1 is connected to the second end of the switch module 102 and the second end for connecting the input power supply 20, and the second end of the first resistor R1 is used for connecting the second end of the load 30. The first resistor R1 obtains the voltage difference across its two ends by directly sampling the current in the loop where it is located, thereby obtaining the first voltage and transmitting it to the control module 106.

[0072] In some embodiments, referring again to Figure 3 , in Figure 3 In the embodiment shown, the energy storage module 101 includes a first inductor L1, the switch module 102 includes a first switch tube Q1, and the isolation module 103 includes a first diode D1.

[0073] The first end of the first inductor L1 is used for connecting the first end of the input power supply 20, the second end of the first inductor L1 is respectively connected to the first end of the first current sampling module 104 and the anode of the first diode D1, the cathode of the first diode D1 is used for connecting the first end of the load 30, the second end of the first current sampling module 104 is connected to the first end of the first switch tube Q1, the second end of the first switch tube Q1 is connected to the first end of the second current sampling module 105 and the second end for connecting the input power supply 20, the control end of the first switch tube Q1 is connected to the control module 106, and the second end of the second current sampling module 105 is used for connecting the second end of the load 30.

[0074] Exemplarily, Figure 3 In the embodiment shown, the first switch tube Q1 is an NMOS tube, wherein the drain of the NMOS tube corresponds to the first end of the switch tube, the source of the NMOS tube corresponds to the second end of the switch tube, and the gate of the NMOS tube corresponds to the control end of the switch tube, that is, when the control end of the first switch tube Q1 is high, the first switch tube Q1 is turned on, and when the control end of the first switch tube Q1 is low, the first switch tube Q1 is turned off. When the first switch tube Q1 is turned on, the first inductor L1 stores electrical energy, and the first diode D1 is reverse-biased and cut off, and when the first switch tube Q1 is turned off, the first inductor L1 releases electrical energy, and the first diode D1 is forward-biased and conducts. In some embodiments, a energy storage unit (such as a capacitor) is provided at the back end of the first diode D1. By the above-mentioned manner, the electrical energy stored by the first inductor L1 and the electrical energy stored by the energy storage unit can be superimposed, thereby achieving the effect of voltage boosting.

[0075] In some embodiments, referring to Figure 4 ,Figure 4 The circuit structure of another power factor correction circuit is shown in Figure 4 In the embodiment shown, the current mutual inductance unit 1041 includes a current transformer TR1 and a second diode D2, and the current transformer TR1 includes a primary coil and a secondary coil.

[0076] The first end of the primary coil of the current transformer TR1 is connected to the second end of the first inductor L1 and the anode of the first diode D1, respectively, the second end of the primary coil of the current transformer TR1 is connected to the first end of the first switch tube Q1, the first end of the secondary coil of the current transformer TR1 is connected to the cathode of the second diode D2, the second end of the secondary coil of the current transformer TR1 is connected to the first end of the voltage acquisition unit 1042, the second end of the first switch tube Q1 and the first end of the second current sampling module 105, respectively, the anode of the second diode D2 is connected to the second end of the voltage acquisition unit 1042 and the first end of the control module 106, respectively, and the second end of the control module 106 is connected to the ground.

[0077] When there is a current (i.e. the first current described above) flowing through the primary coil of the current transformer TR1, the secondary coil of the current transformer TR1 will generate a corresponding conversion current. By setting the turns ratio of the primary coil and the secondary coil of the current transformer TR1, the conversion of the first current and the conversion current in a preset ratio can be achieved. For example, when the turns ratio of the primary coil and the secondary coil is 1:100, the first current of 1A can be converted into a conversion current of 0.01A; the voltage acquisition unit 1042 obtains the first voltage based on the conversion current described above and transmits it to the control module 106, and the first voltage can be used to represent the first current described above, that is, the sampling of the first current is achieved.

[0078] In some embodiments, please refer to Figure 4 The voltage acquisition unit 1042 includes a second resistor R2.

[0079] The first end of the second resistor R2 is connected to the second end of the secondary coil of the current transformer TR1, the second end of the first switch tube Q1 and the first end of the second current sampling module 105, respectively, and the second end of the second resistor R2 is connected to the anode of the second diode D2 and the first end of the control module 106, respectively. That is, by the second resistor R2, the conversion current described above is converted into the form of the first voltage, and the first voltage is transmitted to the control module 106, thereby achieving the sampling of the first current described above.

[0080] In some embodiments, please refer to Figure 5 , Figure 5 The circuit structure of another power factor correction circuit is shown in Figure 5 In the embodiment shown, the switch module 102 further includes a third resistor R3 and a fourth resistor R4.

[0081] The first end of the third resistor R3 is connected to the control end of the first switch tube Q1 and the first end of the fourth resistor R4, respectively, the second end of the third resistor R3 is connected to the control end of the control module 106, and the second end of the fourth resistor R4 is connected to the second end of the first switch tube Q1 and the first end of the second current sampling module 105, respectively. The third resistor R3 is a current limiting resistor, which is used to prevent the gate of the first switch tube Q1 from being damaged by overcurrent, and the fourth resistor R4 is a bias resistor, which is used to ensure that the gate of the first switch tube Q1 is reliably cut off.

[0082] In some embodiments, referring again to Figure 5 , the current mutual inductance unit 1041 further includes a fifth resistor R5.

[0083] The first end of the fifth resistor R5 is connected to the first end of the secondary coil of the current transformer TR1 and the cathode of the second diode D2, respectively, and the second end of the fifth resistor R5 is connected to the second end of the secondary coil of the current transformer TR1 and the first end of the first resistor R1, respectively. The fifth resistor R5 can be used for the magnetic core reset current path of the current transformer TR1, so that the reset voltage of the secondary coil of the current transformer TR1 is lower than the set value.

[0084] In some embodiments, referring to Figure 6 , Figure 6 Another circuit structure of the power factor correction circuit is shown, and in the embodiment shown in Figure 6 , the power factor correction circuit 10 further includes a first capacitor C1 and a second capacitor C2.

[0085] The first end of the first capacitor C1 is connected to the first end of the energy storage module 101 and the first end for connecting the input power supply 20, the second end of the first capacitor C1 is connected to the second end of the switch module 102 and the first end of the second current sampling module 105, respectively, and the second end for connecting the input power supply 20; the first end of the second capacitor C2 is connected to the second end of the isolation module 103 and the first end for connecting the load 30, and the second end of the second capacitor C2 is connected to the second end of the second current sampling module 105 and the second end for connecting the load 30. The first capacitor C1 and the second capacitor C2 are both filter capacitors, the first capacitor C1 is used to reduce the ripple of the input voltage of the power factor correction circuit 10, and the second capacitor C2 is used to reduce the ripple of the output voltage of the power factor correction circuit 10.

[0086] Hereinafter, taking the circuit structure of the power factor correction circuit shown in Figure 4 as an example, the sampling principle of the input current of the power factor correction circuit 10 is described as follows:

[0087] Among them, the current sampling signal can be represented by the following formula, that is:

[0088] U(IS, GND) = U(IS, VI-) + U(VI-, GND) (1)

[0089] Wherein, U(IS, GND) is the voltage difference between the current sampling signal input node IS and the reference ground GND, U(IS, VI-) is the voltage difference between the current sampling signal input node IS and the second end VI- of the input power supply 20, U(VI-, GND) is the voltage difference between the second end VI- of the input power supply 20 and the reference ground GND.

[0090] From the circuit structure analysis of the power factor correction circuit shown in Figure 3 It can be seen that the voltage difference between the current sampling signal input node IS and the second end VI- of the input power supply 20 in formula (1) is equal to the voltage across the second resistor R2, that is:

[0091] U(IS, VI-) = U(R2) = I(Q1) * R2 / N (2)

[0092] Wherein, U(IS, VI-) is the voltage difference between the current sampling signal input node IS and the second end VI- of the input power supply 20, U(R2) is the voltage across the second resistor R2, I(Q1) is the current flowing through the first switch tube Q1, that is, the first current mentioned above, and N is the ratio of the number of turns of the secondary coil to the number of turns of the primary coil of the current transformer TR1.

[0093] In addition, the voltage difference between the second end VI- of the input power supply 20 and the reference ground GND in the above formula (1) is equal to the voltage across the first resistor R1, that is:

[0094] U(VI-, GND) = U(R1) = I(D1) * R1 (3)

[0095] Wherein, U(VI-, GND) is the voltage difference between the second end VI- of the input power supply 20 and the reference ground GND, U(R1) is the voltage across the first resistor R1, and I(D1) is the current flowing through the first diode D1, that is, the second current mentioned above.

[0096] When the power factor correction circuit 10 is in the first working mode (i.e. the first switch Q1 is on), the potential difference between the first end of the first switch Q1 and the second end of the first switch Q1 is close to 0V, at this time, the current flows out from the first end VI+ of the input power supply 20, and flows back to the second end VI- of the input power supply 20 through the first inductor L1, the primary coil of the current transformer TR1, the first end of the first switch Q1 and the second end of the first switch Q1. The current I(Q1) (i.e. the first current) in the loop formed by the input power supply 20, the first inductor L1, the primary coil of the current transformer TR1, the first end of the first switch Q1 and the second end of the first switch Q1 increases at a certain slope.

[0097] At this time, as shown in Fig. 2, since the primary coil of the current transformer TR1 is in the same loop with the first end of the first switch Q1 and the second end of the first switch Q1, and the voltage drop on the primary coil of the current transformer TR1 is negligible, i.e. it is equivalent to short circuit, therefore, the potential difference between the anode of the first diode D1 and the second end of the first switch Q1 is close to 0V, at this time, the voltage across the first diode D1 is reverse biased, and no current flows through the first diode D1, and the first resistor R1 is also in the same loop with the first diode D1, therefore, the current flowing through the first resistor R1 is also 0A, i.e. at this time, the voltage across the first resistor R1 is 0V. Figure 3 Therefore, in the first working mode of the power factor correction circuit 10, the above formula (1) can be simplified as follows:

[0098] U(IS,GND)_1 = I(Q1) * R2 / N (5)

[0099] When the power factor correction circuit 10 is in the second working mode (i.e. the first switch Q1 is off), the first current I(Q1) reaches a peak value I(Q1_M) at the moment before the first switch Q1 is off, since the current of the first inductor L1 cannot change abruptly, at this time, the first diode D1 is on under the electromotive force of the first inductor L1, and the peak value I(D1_M) of the current of the first diode D1 at the moment when the first diode D1 is on is equal to the peak value I(Q1_M) of the first current I(Q1); at this time, the current flows out from the first end VI+ of the input power supply 20, and flows back to the second end VI- of the input power supply 20 through the first inductor L1, the first diode D1, the load 30 and the first resistor R1. Since the primary coil of the current transformer TR1 is in the same loop with the first switch Q1, at this time, the current of the primary coil of the current transformer TR1, i.e. the first current I(Q1) is 0A, i.e. at this time, the voltage across the second resistor R2 is 0V.

[0100]

[0101] ​Therefore, in the second working mode of the power factor correction circuit 10, the above formula (1) can be simplified as the following formula:

[0102] U(IS, GND)_2 = U(VI-, GND) = I(D1) * R1 (6)

[0103] For example, in the power factor correction circuit 10 shown in the figure, the ratio of the number of turns of the secondary coil to the number of turns of the primary coil of the current transformer TR1 is 100, the resistance value of the first resistor R1 is 0.01Ω, the resistance value of the second resistor R2 is 1Ω, and the peak value of the current flowing through the first switch tube Q1 and the peak value of the current flowing through the first diode D1 are both 10A. Figure 3

[0104] At this time, the peak value of the sampling signal output voltage U(IS, GND)_1 of the power factor correction circuit 10 in the first working mode is equal to the peak value of the sampling signal output voltage U(IS, GND)_2 of the power factor correction circuit 10 in the second working mode, both of which are 0.1V.

[0105] As can be seen from the above, through reasonable parameter configuration, the ratio of the sampling signal output voltage value U(IS, GND)_1 of the power factor correction circuit 10 in the first working mode to the first current I(Q1) and the ratio of the sampling signal output voltage value U(IS, GND)_2 of the power factor correction circuit 10 in the second working mode to the second current I(D1) are the same. That is, the current sampling output voltage signal U(IS, GND) has the same current signal to voltage signal conversion ratio in the first working mode and the second working mode, that is, the value of the current sampling output voltage signal U(IS, GND) is proportional to the value of the current it samples.

[0106] It should be noted that in the power factor correction circuit 10 shown in the figure, Figure 4 ​In the embodiment shown, by connecting the sampling resistor (i.e. the first resistor R1) in series between the cathode of the first diode D1, the load 30 and the electrical circuit of the first switch tube Q1, the above-mentioned second current is sampled in a manner that not only reduces the overall power consumption, but also reduces the probability that the voltage drop generated across the sampling resistor when the first switch tube Q1 fails in an abnormal state and causes a short-circuit fault, exceeds the maximum pressure threshold of the control module 106, thereby damaging the control module 106, thereby improving the reliability of the circuit. In addition, by using the first current sampling module 104 composed of the current sensor TR1, the second diode D2 and the second resistor R2 to sample the current of the first loop (i.e. the loop composed of the input power supply 20, the first inductor L1 and the first switch tube Q1) when the first switch tube Q1 is turned on, and using the second current sampling module 105 composed of the first resistor R1 to sample the current of the second loop (i.e. the loop composed of the input power supply 20, the first inductor L1, the first diode D1, the load 30 and the first resistor R1) when the first switch tube Q1 is turned off, compared to the manner of sampling the current of the above-mentioned first loop and the above-mentioned second loop by setting a circuit structure based on the principle of electromagnetic induction in each loop, the complexity of the overall circuit structure can be reduced, thereby making it have higher reliability, smaller size and lower design cost.

[0107] In some embodiments, please refer to Figure 3 and Figure 7 , Figure 7 illustrates a Figure 3 The waveforms of the voltages of the power factor correction circuit 10 shown are shown, wherein U(G, GND) is the voltage at the control terminal of the first switch tube Q1, U(IS, VI-) is the voltage between the current sampling signal input node IS and the second end VI- of the input power supply 20, U(VI-, GND) is the voltage between the second end VI- of the input power supply 20 and the reference ground GND, U(IS, GND) is the voltage between the current sampling signal input node IS and the reference ground GND, V is the voltage, t is the time, Ton is the on time of the first switch tube Q1, and Toff is the off time of the first switch tube Q1.

[0108] By Figure 7It can be seen that the current sampling output voltage signal, i.e. U(IS, GND), is a segmented combination of the rectified output voltage of the secondary coil of the current transformer TR1 in the first working mode of the power factor correction circuit 10, i.e. U(IS, VI-), and the voltage across the first resistor R1 in the second working mode of the power factor correction circuit 10, i.e. U(VI-, GND).

[0109] The embodiment of the present application further provides a switching converter, which comprises the power factor correction circuit 10 provided by any of the above embodiments and is used for converting the voltage input by the input power supply 20 to obtain a converted voltage and output, so as to improve the power factor of the input power supply 20.

[0110] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A power factor correction circuit, characterized by, The application relates to a power supply device, which comprises the following components: a storage module, a second end of the storage module being connected with a first end of a switch module through a first current sampling module, and a first end of the storage module being used for connecting a first end of an input power supply, for storing electric energy when the switch module is turned on, and for releasing the electric energy when the switch module is turned off; a switch module, a control end of the switch module being connected with a control module, and a first end of the switch module being connected with a first end of an isolation module and a second end of the storage module through the first current sampling module, for being turned on according to a turn-on signal output by the control module, or for being turned off according to a turn-off signal output by the control module; an isolation module, the first end of the isolation module being connected with the second end of the storage module, and the first end of the isolation module being connected with the first end of the switch module through the first current sampling module, and a second end of the isolation module being used for connecting a first end of a load, for being turned off when the switch module is turned on, and for being turned on when the switch module is turned off; a first current sampling module, the first current sampling module being connected with the first end, the second end of the switch module and the control module, for converting a first current into a converted current based on the principle of electromagnetic induction, obtaining a first voltage based on the converted current, and outputting the first voltage to the control module, the first current comprising a current flowing through the switch module; a second current sampling module, the second current sampling module being connected between an electric circuit between a second end of the load and a second end of the switch module, and the control module, for obtaining a second voltage based on a second current directly flowing through the second current sampling module, and outputting the second voltage to the control module, the second current comprising a current flowing through the load; a control module, the control module being connected with the control end of the switch module, the first current sampling module and the second current sampling module, and the first end of the input power supply and the first end of the load, for outputting corresponding turn-on signals and turn-off signals according to the first voltage, the second voltage, and output voltages of the input power supply and input voltages of the load, so that input currents of the storage module and input voltages of the load meet preset conditions.

2. The power factor correction circuit of claim 1, wherein, The first current sampling module comprises: a current mutual inductance unit, the current mutual inductance unit being connected with a voltage acquisition unit and the first end of the switch module, for converting the first current into the converted current; the voltage acquisition unit, the voltage acquisition unit being connected with the control module, for obtaining the first voltage based on the converted current and outputting the first voltage to the control module.

3. The power factor correction circuit of claim 2, wherein, The second current sampling module comprises a first resistor; a first end of the first resistor being connected with the second end of the switch module and being used for connecting a second end of the input power supply, and a second end of the first resistor being used for connecting a second end of the load.

4. The power factor correction circuit of claim 3, wherein, The storage module comprises a first inductor, the switch module comprises a first switch tube, and the isolation module comprises a first diode. The first end of the first inductor is connected to the first end of the input power supply, the second end of the first inductor is connected to the first end of the first current sampling module and the anode of the first diode respectively, the cathode of the first diode is connected to the first end of the load, the second end of the first current sampling module is connected to the first end of the first switch tube, the second end of the first switch tube is connected to the first end of the second current sampling module and the second end of the input power supply, the control end of the first switch tube is connected to the control module, and the second end of the second current sampling module is connected to the second end of the load.

5. The power factor correction circuit of claim 4, wherein, The current mutual inductance unit comprises a current transformer and a second diode, and the current transformer comprises a primary coil and a secondary coil. The first end of the primary coil is connected to the second end of the first inductor and the anode of the first diode respectively, the second end of the primary coil is connected to the first end of the first switch tube, the first end of the secondary coil is connected to the cathode of the second diode, the second end of the secondary coil is connected to the first end of the voltage acquisition unit, the second end of the first switch tube and the first end of the second current sampling module respectively, the anode of the second diode is connected to the second end of the voltage acquisition unit and the first end of the control module respectively, and the second end of the control module is grounded.

6. The power factor correction circuit of claim 5, wherein, The voltage acquisition unit comprises a second resistor. The first end of the second resistor is connected to the second end of the secondary coil, the second end of the first switch tube and the first end of the second current sampling module respectively, and the second end of the second resistor is connected to the anode of the second diode and the first end of the control module.

7. The power factor correction circuit of claim 4, wherein, The switch module further comprises a third resistor and a fourth resistor. The first end of the third resistor is connected to the control end of the first switch tube and the first end of the fourth resistor respectively, the second end of the third resistor is connected to the control end of the control module, the second end of the fourth resistor is connected to the second end of the first switch tube and the first end of the second current sampling module respectively.

8. The power factor correction circuit of claim 5, wherein, The current mutual inductance unit further comprises a fifth resistor. The first end of the fifth resistor is connected to the first end of the secondary coil and the cathode of the second diode respectively, and the second end of the fifth resistor is connected to the second end of the secondary coil and the first end of the first resistor.

9. The power factor correction circuit of any one of claims 1 to 8, wherein, Further comprising a first capacitor and a second capacitor. The first end of the first capacitor is connected to the first end of the energy storage module and the first end for connecting the input power supply, the second end of the first capacitor is connected to the second end of the switch module and the first end of the second current sampling module respectively, and the second end for connecting the input power supply; The first end of the second capacitor is connected to the second end of the isolation module and the first end for connecting the load, and the second end of the second capacitor is connected to the second end of the second current sampling module and the second end for connecting the load.

10. A switching converter, characterized by The power factor correction circuit comprises any one of claims 1 to 9.

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