PFC circuit, circuit board and household appliance

Abstract

The utility model discloses a PFC circuit, a circuit board and a household electrical appliance. The PFC circuit comprises a power supply access end, a control end, an inductor, a silicon carbide Schottky diode, a power switch tube, a driving resistor module and a switching speed adjusting module. One end of the inductor is connected to the power supply access end; the positive electrode of the silicon carbide Schottky diode is connected to the other end of the inductor; one switch pin of the power switch tube is connected to the positive electrode of the silicon carbide Schottky diode, and the other switch pin of the power switch tube is grounded; one end of the driving resistor module is connected to the control end, and the other end of the driving resistor module is connected to a control pin of the power switch tube; the switch speed adjusting module is connected to a control pin of the power switch tube so as to adjust the turn-on speed and / or turn-off speed of the power switch tube. According to the PFC circuit, the switching speed of the power switch tube can be improved, and balance can be achieved between reduction of the loss of the power switch tube and mitigation of the EMI problem of the circuit.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, and in particular to a PFC circuit, a circuit board and a household appliance. Background Art

[0002] In the field of power electronics, PFC (Power Factor Correction) circuits are widely used in electrical equipment such as air conditioners due to their high power factor correction capabilities. PFC circuit topologies are diverse, and the working modes are also different. The typical boost structure is commonly used in variable-frequency household appliances. The PFC circuit includes devices such as energy storage inductors, power switch tubes, diodes, and large electrolytic capacitors. The energy storage inductor stores energy when the power switch tube is turned on, and when the power switch tube is turned off, the energy storage inductor induces a negative voltage on the left and a positive voltage on the right, thereby charging the large electrolytic capacitor with the energy stored when it is turned on through the diode, and outputting energy to power the load.

[0003] At present, with the application of silicon carbide power devices, the switching speed of power switch tubes is constantly increasing, which also leads to heat loss problems in power switch tubes. At this time, the loss of the power switch tube can be reduced by adjusting the driving resistance of the control pin of the power switch tube, but this will also cause EMI problems in the circuit. Therefore, how to balance the adjustment of the switching speed of the power switch tube, reduce the loss of the power switch tube and solve the circuit EMI problem has become one of the major problems facing PFC. Utility Model Content

[0004] The purpose of the utility model is to solve at least one of the technical problems existing in the prior art, and to provide a PFC circuit, a circuit board and a household appliance, which can improve the switching speed of the power switch tube and achieve a balance between reducing the loss of the power switch tube and alleviating the circuit EMI problem.

[0005] In a first aspect, an embodiment of the utility model provides a PFC circuit, including a power supply access terminal, a control terminal, an inductor, a silicon carbide Schottky diode, a power switch tube, a driving resistance module and a switch speed adjustment module, wherein:

[0006] The power supply access terminal is used to access a DC power supply;

[0007] The control terminal is used to access the PWM drive signal;

[0008] One end of the inductor is connected to the power supply access end;

[0009] The anode of the silicon carbide Schottky diode is connected to the other end of the inductor;

[0010] One switch pin of the power switch tube is connected to the positive electrode of the silicon carbide Schottky diode, and the other switch pin is grounded;

[0011] One end of the driving resistor module is connected to the control end, and the other end is connected to the control pin of the power switch tube;

[0012] The switching speed adjustment module is connected to the control pin of the power switch tube to adjust the turn-on speed and / or turn-off speed of the power switch tube.

[0013] The PFC circuit provided by the embodiment of the utility model has at least the following beneficial effects: the DC power supply connected to the power supply access end charges the inductor when the power switch tube is turned on, and the electric energy stored in the inductor is supplied to the load at the rear end through the silicon carbide Schottky diode when the power switch tube is turned off; the control end is connected to the PWM drive signal, so as to control the power switch tube to be alternately turned on and off through the driving resistor module; the diode in the PFC circuit can increase the switching speed of the power switch tube by adopting the silicon carbide Schottky diode, so that the inductance selection of the inductor can be reduced; and by providing a switching speed adjustment module connected to the control pin of the power switch tube, To adjust the turn-on speed and / or turn-off speed of the power switch tube, wherein adjusting the turn-on speed of the power switch tube can adjust the oscillation of the circuit current and reduce EMI problems; adjusting the turn-off speed of the power switch tube can adjust the discharge speed of the power switch tube when it is turned off, thereby reducing heat loss problems; therefore, after the PFC circuit uses a silicon carbide Schottky diode to increase the switching speed of the power switch tube, the turn-on speed and / or turn-off speed of the power switch tube can be adjusted by adjusting the resistance value of the driving resistor module and by using the switching speed adjustment module, thereby achieving a balance between reducing the loss of the power switch tube and reducing the circuit EMI problem.

[0014] According to the PFC circuit provided by some embodiments of the present invention, the switching speed adjustment module includes a first resistor and a first diode; the positive electrode of the first diode is connected to the control pin of the power switch tube, and the negative electrode is connected to one end of the first resistor; the other end of the first resistor is connected to the control end.

[0015] According to the PFC circuit provided by some embodiments of the present invention, the resistance value of the first resistor is smaller than the equivalent resistance value of the driving resistor module.

[0016] According to the PFC circuit provided by some embodiments of the present invention, the switching speed adjustment module includes a first capacitor, one end of which is connected to the control pin of the power switch tube, and the other end is grounded.

[0017] According to the PFC circuit provided by some embodiments of the present invention, the switching speed adjustment module includes a first resistor, a first diode and a first capacitor; the positive electrode of the first diode and one end of the first capacitor are both connected to the control pin of the power switch tube, and the negative electrode of the first diode is connected to one end of the first resistor; the other end of the first resistor is connected to the control end; the other end of the first capacitor is grounded.

[0018] According to the PFC circuit provided by some embodiments of the present invention, the switching speed adjustment module includes a thermistor for measuring the temperature of the power switch tube, and the thermistor is connected in parallel with the driving resistance module.

[0019] According to the PFC circuit provided by some embodiments of the present invention, the thermistor is located directly below the power switch tube when arranged on a board.

[0020] According to some embodiments of the present invention, the PFC circuit further includes an absorption buffer module connected in parallel with the silicon carbide Schottky diode, and the absorption buffer module includes a second capacitor and a second resistor connected in series.

[0021] According to the PFC circuit provided by some embodiments of the present invention, the driving resistor module includes a third resistor and a fourth resistor connected in parallel with each other.

[0022] According to some embodiments of the present invention, the PFC circuit further includes a Zener diode and a fifth resistor, wherein the positive electrode of the Zener diode and one end of the fifth resistor are connected to the control pin of the power switch tube, and the negative electrode of the Zener diode and the other end of the fifth resistor are grounded.

[0023] In a second aspect, an embodiment of the utility model provides a circuit board, comprising the PFC circuit as described in the embodiment of the first aspect above.

[0024] The circuit board provided by the embodiment of the utility model has at least the following beneficial effects: the DC power supply connected to the power access end of the PFC circuit charges the inductor when the power switch tube is turned on, and the electric energy stored in the inductor is supplied to the rear-end load through the silicon carbide Schottky diode when the power switch tube is turned off; the control end is connected to the PWM drive signal, so as to control the power switch tube to be alternately turned on and off through the driving resistor module; the diode in the PFC circuit can increase the switching speed of the power switch tube by adopting the silicon carbide Schottky diode, so that the inductance selection of the inductor can be reduced; and by setting a switching speed adjustment module connected to the control pin of the power switch tube The PFC circuit adopts a silicon carbide Schottky diode to increase the switching speed of the power switch tube. The PFC circuit can adjust the turn-on speed and / or turn-off speed of the power switch tube by adjusting the resistance value of the driving resistor module and the turn-on speed and / or turn-off speed of the power switch tube by the switch speed adjustment module, thereby achieving a balance between reducing the loss of the power switch tube and reducing the EMI problem of the circuit.

[0025] In a third aspect, an embodiment of the utility model provides a household appliance, comprising the PFC circuit as described in the embodiment of the first aspect above or comprising the circuit board as described in the embodiment of the second aspect above.

[0026] The household appliance provided by the embodiment of the utility model has at least the following beneficial effects: the DC power supply connected to the power access end of the PFC circuit charges the inductor when the power switch tube is turned on, and the electric energy stored in the inductor is supplied to the rear-end load through the silicon carbide Schottky diode when the power switch tube is turned off; the control end is connected to the PWM drive signal, so as to control the power switch tube to be alternately turned on and off through the driving resistor module; the diode in the PFC circuit can increase the switching speed of the power switch tube by adopting the silicon carbide Schottky diode, so that the inductance selection of the inductor can be reduced; and the switching speed adjustment device connected to the control pin of the power switch tube is also provided. A module is used to adjust the turn-on speed and / or turn-off speed of the power switch tube, wherein adjusting the turn-on speed of the power switch tube can adjust the oscillation of the circuit current and reduce the EMI problem; adjusting the turn-off speed of the power switch tube can adjust the discharge speed of the power switch tube when it is turned off, thereby reducing the heat loss problem; therefore, after the PFC circuit selects the silicon carbide Schottky diode to increase the switching speed of the power switch tube, the turn-on speed and / or turn-off speed of the power switch tube can be adjusted by adjusting the resistance value of the driving resistor module and by the switching speed adjustment module, thereby achieving a balance between reducing the loss of the power switch tube and reducing the circuit EMI problem.

[0027] Other features and advantages of the utility model will be described in the following description, and partly become apparent from the description, or understood by practicing the utility model. The purpose and other advantages of the utility model can be realized and obtained by the structures specifically pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the technical solution of the utility model and constitute a part of the specification. Together with the embodiments of the utility model, they are used to explain the technical solution of the utility model and do not constitute a limitation on the technical solution of the utility model.

[0029] The utility model is further described below in conjunction with the accompanying drawings and embodiments;

[0030] Figure 1 This is a circuit schematic diagram of a PFC circuit provided in Embodiment 1 of the present utility model;

[0031] Figure 2 This is a circuit schematic diagram of a PFC circuit provided in Embodiment 2 of the present utility model;

[0032] Figure 3 This is a circuit schematic diagram of a PFC circuit provided in Embodiment 3 of the present utility model;

[0033] Figure 4 This is a circuit schematic diagram of a PFC circuit provided in Embodiment 41 of the present utility model. DETAILED DESCRIPTION

[0034] This section will describe in detail the specific embodiments of the utility model. The preferred embodiments of the utility model are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the utility model, but it cannot be understood as a limitation on the protection scope of the utility model.

[0035] In the description of the embodiments of the present utility model, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, "above", "below", "within", etc. are understood to include the number itself, "at least one" means one or more, "at least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. If there is a description of "first", "second", etc., it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0036] It should be noted that the words such as setting, installing, and connecting in the embodiments of the present invention should be understood in a broad sense, and the technical personnel in the relevant technical field can reasonably determine the specific meanings of the above words in the embodiments of the present invention in combination with the specific content of the technical solution. For example, the term "connection" can be a mechanical connection, an electrical connection, or mutual communication; it can be directly connected or indirectly connected through an intermediate medium.

[0037] It should be noted that the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] In the field of power electronics, PFC (Power Factor Correction) circuits are widely used in electrical equipment such as air conditioners due to their high power factor correction capabilities. PFC circuit topologies are diverse, and the working modes are also different. The typical boost structure is commonly used in variable-frequency household appliances. The PFC circuit includes devices such as energy storage inductors, power switch tubes, diodes, and large electrolytic capacitors. The energy storage inductor stores energy when the power switch tube is turned on, and when the power switch tube is turned off, the energy storage inductor induces a negative voltage on the left and a positive voltage on the right, thereby charging the large electrolytic capacitor with the energy stored when it is turned on through the diode, and outputting energy to power the load.

[0039] At present, with the application of silicon carbide power devices, the switching speed of power switch tubes is constantly increasing, which also leads to heat loss problems in power switch tubes. At this time, the loss of the power switch tube can be reduced by adjusting the driving resistance of the control pin of the power switch tube, but this will also cause EMI problems in the circuit. Therefore, how to balance the adjustment of the switching speed of the power switch tube, reduce the loss of the power switch tube and solve the circuit EMI problem has become one of the major problems facing PFC.

[0040] Based on this, the embodiments of the utility model provide a PFC circuit, a circuit board and a household appliance, which can improve the switching speed of the power switch tube and achieve a balance between reducing the loss of the power switch tube and alleviating the circuit EMI problem.

[0041] The following is a further description of the embodiments of the present invention in conjunction with the accompanying drawings.

[0042] Reference Figures 1 to 4 The first embodiment of the utility model provides a PFC circuit, including a power supply access terminal DC+, a control terminal PFC-C, an inductor L1, a silicon carbide Schottky diode SBD, a power switch tube Q1, a driving resistor module 100 and a switch speed adjustment module 200, wherein:

[0043] The power supply access terminal DC+ is used to access a DC power supply. Generally, a rectifier module, such as a rectifier bridge stack, is also provided at the front end of the PFC circuit. The input end of the rectifier module is connected to an AC power supply. After the rectifier module rectifies the AC power supply into a DC power supply, the DC power supply is provided from the output end of the rectifier module to the power supply access terminal DC+.

[0044] The control terminal PFC-C is used to access the PWM drive signal; one end of the inductor L1 is connected to the power access terminal DC+; the positive electrode of the silicon carbide Schottky diode SBD is connected to the other end of the inductor L1; a switch pin of the power switch tube Q1 is connected to the positive electrode of the silicon carbide Schottky diode SBD, that is, connected to the connection point of the silicon carbide Schottky diode SBD and the inductor L1, and the other switch pin of the power switch tube Q1 is grounded; one end of the driving resistor module 100 is connected to the control terminal PFC-C to obtain the PWM drive signal connected to the control terminal PFC-C, and the other end of the driving resistor module 100 is connected to the control pin of the power switch tube Q1; the switching speed adjustment module 200 is connected to the control pin of the power switch tube Q1 to adjust the turn-on speed and / or turn-off speed of the power switch tube Q1.

[0045] It can be understood that the PFC circuit also includes a large electrolytic capacitor E1 for supplying power to the load at the back end, the positive electrode of the silicon carbide Schottky diode SBD is connected to the positive electrode of the large electrolytic capacitor E1, and the negative electrode of the large electrolytic capacitor E1 is grounded.

[0046] According to the PFC circuit provided by the embodiment of the utility model, the DC power supply connected to the power supply access terminal DC+ charges the inductor L1 when the power switch tube Q1 is turned on, and the electric energy stored in the inductor L1 is charged to the large electrolytic capacitor E1 through the silicon carbide Schottky diode SBD when the power switch tube Q1 is turned off, and then the load at the rear end is supplied with power; the control terminal PFC-C is connected to the PWM drive signal, so as to control the power switch tube Q1 to be alternately turned on and off through the driving resistor module 100; the diode in the PFC circuit can increase the switching speed of the power switch tube Q1 by adopting the silicon carbide Schottky diode SBD, so that the inductance selection of the inductor L1 can be reduced; and the switching speed connected to the control pin of the power switch tube Q1 is set The regulating module 200 is used to regulate the turn-on speed and / or turn-off speed of the power switch tube Q1, wherein regulating the turn-on speed of the power switch tube Q1 can adjust the oscillation of the circuit current and reduce the EMI problem; regulating the turn-off speed of the power switch tube Q1 can adjust the discharge speed of the power switch tube Q1 when it is turned off, thereby reducing the heat loss problem; therefore, after the PFC circuit selects the silicon carbide Schottky diode SBD to increase the switching speed of the power switch tube Q1, the turn-on speed and / or turn-off speed of the power switch tube Q1 can be adjusted by adjusting the resistance value of the driving resistor module 100 and by adjusting the switch speed regulating module 200, thereby achieving a balance between reducing the loss of the power switch tube and reducing the circuit EMI problem.

[0047] Reference Figure 1 In a PFC circuit provided in an embodiment of the present utility model, a switching speed adjustment module 200 includes a first resistor R1 and a first diode D1; the anode of the first diode D1 is connected to the control pin of the power switch tube Q1, and the cathode is connected to one end of the first resistor R1; the other end of the first resistor R1 is connected to the control end PFC-C.

[0048] In this embodiment, the first resistor R1 and the first diode D1 in the switching speed regulating module 200 are connected in series and then connected in parallel with the driving resistor module 100. Due to the unidirectional conduction effect of the first diode D1, the switching speed regulating module 200 does not work when the power switch tube Q1 is turned on, and does not affect the turn-on speed of the power switch tube Q1. The discharge speed of the power switch tube Q1 when it is turned off can be improved, and rapid discharge can be achieved. The turn-off speed of the power switch tube Q1 is improved, thereby reducing the heat loss problem caused by the increase in the switching speed of the power switch tube Q1.

[0049] Reference Figure 1 In the PFC circuit provided in some embodiments of the present invention, the resistance of the first resistor R1 is smaller than the equivalent resistance of the driving resistor module 100 .

[0050] It is understandable that when the power switch tube Q1 is turned off, since the resistance of the first resistor R1 is small, the current flowing through the first resistor R1 via the first diode D1 is large, thereby enabling the power switch tube Q1 to be turned off quickly.

[0051] Reference Figure 2 In a PFC circuit provided in another embodiment of the utility model, the switching speed adjustment module 200 includes a first capacitor C1, one end of the first capacitor C1 is connected to the control pin of the power switch tube Q1, and the other end of the first capacitor C1 is grounded, that is, the first capacitor C1 is connected in parallel between the control pin and the ground pin of the power switch tube Q1.

[0052] It can be understood that in this embodiment, the first capacitor C1 is set to play the role of energy storage, so that when the power switch tube Q1 is turned on, the first capacitor C1 needs to be charged first, and the voltage across the first capacitor C1 can be increased before the power switch tube Q1 can be turned on. For the case where the switching speed of the power switch tube Q1 is fast, the current change when the power switch tube Q1 is turned on can be slowed down, and the oscillation of the circuit current can be reduced, thereby reducing the EMI problem of the circuit. In addition, it should be noted that when the power switch tube Q1 is turned off, the first capacitor C1 also needs to be discharged first, and the voltage across the first capacitor C1 can be reduced before the power switch tube Q1 can be turned off. Therefore, adding the setting of the first capacitor C1 can adjust both the turning-on speed of the power switch tube Q1 and the turning-off speed of the power switch tube Q1.

[0053] Reference Figure 3 In a PFC circuit provided in another embodiment of the utility model, the switching speed adjustment module 200 includes a first resistor R1, a first diode D1 and a first capacitor C1; the anode of the first diode D1 and one end of the first capacitor C1 are both connected to the control pin of the power switch tube Q1, and the cathode of the first diode D1 is connected to one end of the first resistor R1; the other end of the first resistor R1 is connected to the control end PFC-C; the other end of the first capacitor C1 is grounded.

[0054] It can be understood that, in this embodiment, the switching speed adjustment module 200 includes both Figure 1 The first resistor R1 and the first diode D1 shown in the figure also include Figure 2 The first capacitor C1 shown in FIG. 1 , the first resistor R1 and the first diode D1 play roles that can be referred to in Figure 1 The introduction of the embodiment can improve the turn-off speed of the power switch tube Q1, thereby reducing the heat loss problem caused by the increase in the switching speed of the power switch tube Q1; the role of the first capacitor C1 can be referred to Figure 2The introduction of the embodiment can adjust both the turn-on speed and the turn-off speed of the power switch tube Q1. Therefore, in this embodiment, the combination of the first resistor R1, the first diode D1 and the first capacitor C1 greatly improves the adjustment range of the turn-on speed and the turn-off speed of the power switch tube Q1 in the PFC circuit, can be applied to a variety of different control requirements, and greatly reduces the difficulty of balancing the circuit heat loss and EMI problems.

[0055] Reference Figure 4 In a PFC circuit provided in another embodiment of the present utility model, the switch speed adjustment module 200 includes a thermistor NTC for measuring the temperature of the power switch tube Q1, and the thermistor NTC is connected in parallel with the driving resistance module 100.

[0056] In this embodiment, the temperature of the power switch tube Q1 is measured by using a thermistor NTC, and connected in parallel with the driving resistor module 100, so that when the temperature of the power switch tube Q1 rises due to the large heat loss of the power switch tube Q1, the temperature of the thermistor NTC also rises. Due to the characteristics of the thermistor NTC, the resistance of the thermistor NTC decreases, thereby reducing the driving resistance of the power switch tube Q1, thereby reducing the heat loss of the power switch tube Q1. It can be understood that under the regulation of the thermistor NTC, the heat loss of the power switch tube Q1 will eventually reach a stable set value.

[0057] exist Figure 4 In the PFC circuit shown, the thermistor NTC is located directly below the power switch tube Q1 when the board is laid out. It can be understood that the thermistor NTC is located directly below the power switch tube Q1 when the board is laid out, which can more quickly and accurately measure the temperature of the power switch tube Q1, thereby quickly adjusting the heat loss of the power switch tube Q1.

[0058] Reference Figure 1 exist Figure 4 In the PFC circuit provided in some embodiments of the present invention, it also includes an absorption buffer module 300 connected in parallel with the silicon carbide Schottky diode SBD, and the absorption buffer module 300 includes a second capacitor C2 and a second resistor R2 connected in series.

[0059] It can be understood that a second capacitor C2 and a second resistor R2 connected in series are set as an absorption buffer module 300, and the absorption buffer module 300 is connected in parallel with a silicon carbide Schottky diode SBD that generates high-frequency noise, which can effectively suppress the high-frequency noise generated by the silicon carbide Schottky diode SBD at the moment of turning on and off the power switch tube Q1.

[0060] Reference Figure 1 exist Figure 4In the PFC circuit provided in some embodiments of the present invention, the driving resistor module 100 includes a third resistor R3 and a fourth resistor R4 connected in parallel with each other.

[0061] Reference Figure 1 exist Figure 4 In the PFC circuit provided in some embodiments of the present invention, it also includes a voltage regulator tube DZ1 and a fifth resistor R5, the positive electrode of the voltage regulator tube DZ1 and one end of the fifth resistor R5 are connected to the control pin of the power switch tube Q1, and the negative electrode of the voltage regulator tube DZ1 and the other end of the fifth resistor R5 are grounded.

[0062] It can be understood that the provision of the voltage regulator DZ1 can play a role in overvoltage protection for the power switch tube Q1. When the voltage applied to the control pin of the power switch tube Q1 is too high, the voltage regulator DZ1 can be broken down, thereby quickly discharging the voltage to the ground, thereby preventing the power switch tube Q1 from being damaged by the impact of the high voltage. The provision of the fifth resistor R5 can play a role in potential clamping, so that the potential of the control pin of the power switch tube Q1 remains greater than the potential of the grounded pin of the power switch tube Q1.

[0063] In a second aspect, an embodiment of the utility model provides a circuit board, comprising the PFC circuit as described in the embodiment of the first aspect above.

[0064] According to the circuit board provided by the embodiment of the utility model, the DC power supply connected to the power supply access terminal DC+ in the PFC circuit charges the inductor L1 when the power switch tube Q1 is turned on, and the electric energy stored in the inductor L1 is charged to the large electrolytic capacitor E1 through the silicon carbide Schottky diode SBD when the power switch tube Q1 is turned off, and then supplies power to the load at the rear end; the control terminal PFC-C is connected to the PWM drive signal, so as to control the power switch tube Q1 to be alternately turned on and off through the driving resistor module 100; the diode in the PFC circuit can increase the switching speed of the power switch tube Q1 by adopting the silicon carbide Schottky diode SBD, so that the inductance selection of the inductor L1 can be reduced; and by setting a switch connected to the control pin of the power switch tube Q1 The switching speed regulating module 200 is used to regulate the turn-on speed and / or turn-off speed of the power switch tube Q1, wherein regulating the turn-on speed of the power switch tube Q1 can adjust the oscillation of the circuit current and reduce the EMI problem; regulating the turn-off speed of the power switch tube Q1 can adjust the discharge speed of the power switch tube Q1 when it is turned off, thereby reducing the heat loss problem; therefore, after the PFC circuit selects the silicon carbide Schottky diode SBD to increase the switching speed of the power switch tube Q1, the turn-on speed and / or turn-off speed of the power switch tube Q1 can be adjusted by adjusting the resistance value of the driving resistor module 100 and by adjusting the switch speed regulating module 200, thereby achieving a balance between reducing the loss of the power switch tube and reducing the circuit EMI problem.

[0065] In a third aspect, an embodiment of the utility model provides a household appliance, comprising the PFC circuit as described in the embodiment of the first aspect above or comprising the circuit board as described in the embodiment of the second aspect above.

[0066] According to the household appliance provided by the embodiment of the utility model, the DC power supply connected to the power supply access terminal DC+ in the PFC circuit charges the inductor L1 when the power switch tube Q1 is turned on, and the electric energy stored in the inductor L1 is charged to the large electrolytic capacitor E1 through the silicon carbide Schottky diode SBD when the power switch tube Q1 is turned off, and then supplies power to the load at the rear end; the control terminal PFC-C is connected to the PWM drive signal, so as to control the power switch tube Q1 to be alternately turned on and off through the driving resistor module 100; the diode in the PFC circuit can increase the switching speed of the power switch tube Q1 by adopting the silicon carbide Schottky diode SBD, so that the inductance selection of the inductor L1 can be reduced; and by setting a switch connected to the control pin of the power switch tube Q1 The switching speed regulating module 200 is used to regulate the turn-on speed and / or turn-off speed of the power switch tube Q1, wherein regulating the turn-on speed of the power switch tube Q1 can adjust the oscillation of the circuit current and reduce the EMI problem; regulating the turn-off speed of the power switch tube Q1 can adjust the discharge speed of the power switch tube Q1 when it is turned off, thereby reducing the heat loss problem; therefore, after the PFC circuit selects the silicon carbide Schottky diode SBD to increase the switching speed of the power switch tube Q1, the turn-on speed and / or turn-off speed of the power switch tube Q1 can be adjusted by adjusting the resistance value of the driving resistor module 100 and by adjusting the switch speed regulating module 200, thereby achieving a balance between reducing the loss of the power switch tube and reducing the circuit EMI problem.

[0067] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A PFC circuit, characterized in that: include: Power supply access terminal, used to access DC power supply; Control terminal, used to access PWM drive signal; an inductor, one end of which is connected to the power supply access end; A silicon carbide Schottky diode, wherein the anode of the silicon carbide Schottky diode is connected to the other end of the inductor; A power switch tube, wherein one switch pin of the power switch tube is connected to the anode of the silicon carbide Schottky diode, and the other switch pin is grounded; A driving resistor module, one end of which is connected to the control end, and the other end of which is connected to the control pin of the power switch tube; A switching speed regulating module, wherein the switching speed regulating module is connected to the control pin of the power switch tube to regulate the turn-on speed and / or turn-off speed of the power switch tube.

2. The PFC circuit according to claim 1, characterized in that: The switching speed adjustment module includes a first resistor and a first diode; the anode of the first diode is connected to the control pin of the power switch tube, and the cathode is connected to one end of the first resistor; the other end of the first resistor is connected to the control end.

3. The PFC circuit according to claim 2, characterized in that: The resistance of the first resistor is smaller than the equivalent resistance of the driving resistor module.

4. The PFC circuit according to claim 1, characterized in that: The switch speed regulating module comprises a first capacitor, one end of which is connected to the control pin of the power switch tube, and the other end of which is grounded.

5. The PFC circuit according to claim 1, characterized in that: The switching speed adjustment module includes a first resistor, a first diode and a first capacitor; the positive electrode of the first diode and one end of the first capacitor are both connected to the control pin of the power switch tube, and the negative electrode of the first diode is connected to one end of the first resistor; the other end of the first resistor is connected to the control end; the other end of the first capacitor is grounded.

6. The PFC circuit according to claim 1, characterized in that: The switching speed adjustment module includes a thermistor for measuring the temperature of the power switch tube, and the thermistor is connected in parallel with the driving resistance module.

7. The PFC circuit according to claim 6, characterized in that: The thermistor is located directly below the power switch tube when arranged on the board.

8. The PFC circuit according to claim 1, characterized in that: It also includes an absorption buffer module connected in parallel with the silicon carbide Schottky diode, and the absorption buffer module includes a second capacitor and a second resistor connected in series.

9. The PFC circuit according to claim 1, characterized in that: The driving resistor module includes a third resistor and a fourth resistor connected in parallel with each other.

10. The PFC circuit according to claim 1, characterized in that: It also includes a voltage regulator tube and a fifth resistor, wherein the positive electrode of the voltage regulator tube and one end of the fifth resistor are connected to the control pin of the power switch tube, and the negative electrode of the voltage regulator tube and the other end of the fifth resistor are grounded.

11. A circuit board, characterized in that: The PFC circuit comprises the PFC circuit according to any one of claims 1 to 10.

12. A household appliance, characterized in that: A PFC circuit comprising any one of claims 1 to 10 or a circuit board comprising claim 11.

Images