Channel selection switch circuit and controller for PFC chip circuit

Abstract

The utility model relates to the technical field of switch circuits, and provides a channel selection switch circuit and a controller for a PFC chip circuit, the PFC chip circuit is provided with multiple output channels and comprises at least one normally open channel and at least one switch channel, and the switch circuit comprises an acquisition module, a control module and a switching module, the current acquisition module is used for proportionally acquiring current signals of a power supply and converting into direct-current voltage; the comparison module is used for comparing the threshold voltage with the direct-current voltage and outputting a level signal; the switch control module is used for controlling the switch-on or switch-off of the switch channel according to the level signal; and the normally-open control module is used for controlling the normally-open channel to be conducted. According to the utility model, hardware is used for detection and comparison to control the on and off of the switch channel, and a normally open channel is configured, so that the PFC chip circuit can ensure higher power utilization rate under low power or high input voltage and low output power, an I / O port of a single chip microcomputer is not needed, and the software workload and development cost are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of switch circuits, in particular to a channel selection switch circuit and a controller for a PFC chip circuit. Background Art

[0002] In order to improve the utilization rate of the input power of electrical appliances, a PFC circuit is usually added to the electronic circuit.

[0003] For high-power electrical appliances, an interleaved multi-channel PFC topology is often used. However, this topology sometimes results in the PFC chip working in multiple channels at the same time in an interleaved manner once it is turned on. In this case, if the appliance is in a low-power or high-input voltage and low-output power operating state, the PFC chip will enter the Burst control mode, so that the output channel cannot be fully turned on, resulting in low power utilization.

[0004] If a single-chip microcomputer is used to detect input current or output power, and then the PFC chip is controlled to switch the output channel, this can solve the above problems. However, on the one hand, the I / O port detection of the single-chip microcomputer is required, which increases the software workload and the cost of using the single-chip microcomputer. On the other hand, after the corresponding software is modified, the reliability of the software and the reliability of the input and output capabilities of the single-chip microcomputer pins require a long time to evaluate.

[0005] Therefore, providing a method for solving the above-mentioned technical problems is a problem that technical personnel in the field currently need to solve. Utility Model Content

[0006] The technical problem to be solved by the utility model is that a PFC chip circuit using an interleaved multi-channel form will enter a Burst control mode under the condition of low power or high input voltage and low output power, resulting in reduced power utilization, and using software to detect and control the output channel will increase the cost of a single-chip computer and the workload of the software. A channel selection switch circuit and a controller for a PFC chip circuit are provided, so that a PFC chip circuit using an interleaved multi-channel form can also ensure a high power utilization under the condition of low power or high input voltage and low output power, without using a single-chip computer I / O port, thereby reducing the workload of the software and the development cost.

[0007] In a first aspect, in order to solve the above technical problems, an embodiment of the utility model provides a channel selection switch circuit for a PFC chip circuit, wherein the PFC chip circuit has multiple output channels, wherein the output channels include at least one normally open channel and at least one switch channel, and the channel selection switch circuit includes:

[0008] A collection module, the collection module is connected to the power supply, and is used to collect the current signal of the power supply in proportion and convert it into a DC voltage output;

[0009] A comparison module, which is connected to the acquisition module and is used to compare the threshold voltage with the DC voltage and output a level signal;

[0010] A switch control module, the switch control module is connected to the comparison module and is used to control the on or off of the switch channel according to the level signal;

[0011] A normally open control module, wherein the normally open control module is used to control the conduction of the normally open channel.

[0012] In one embodiment of the present utility model, the acquisition module includes a current transformer, a rectifier, a filter unit and a current limiting resistor; wherein,

[0013] The current transformer is connected to the power supply;

[0014] The rectifier is connected to the current transformer;

[0015] The filtering unit includes an electrolytic capacitor and a load resistor connected in parallel;

[0016] The current limiting resistor is connected to the comparison module.

[0017] In one embodiment of the utility model, the comparison module includes a comparator and an adjustment unit; wherein the negative input terminal of the comparator is connected to the acquisition module, and the output terminal of the comparator is connected to the switch control module; the comparator and the adjustment unit constitute a hysteresis comparison circuit.

[0018] In one embodiment of the present utility model, the adjustment unit includes a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor and a fourth voltage-dividing resistor; wherein,

[0019] The first end of the first voltage-dividing resistor is connected to the first control voltage, the second end of the first voltage-dividing resistor is connected to the first end of the second voltage-dividing resistor, and the second end of the first voltage-dividing resistor is also connected to the positive input terminal of the comparator; the second end of the second voltage-dividing resistor is grounded; the first end of the third voltage-dividing resistor is connected to the first control voltage, and the second end of the third voltage-dividing resistor is connected to the output terminal of the comparator; the fourth voltage-dividing resistor is connected between the second end of the first voltage-dividing resistor and the second end of the third voltage-dividing resistor.

[0020] In one embodiment of the present invention,

[0021] When the output terminal of the comparator is at a high level, the equivalent circuit of the hysteresis comparator circuit is that the third voltage-dividing resistor and the fourth voltage-dividing resistor are connected in series and then connected in parallel with the first voltage-dividing resistor to obtain a first parallel circuit, and one end of the first parallel circuit is connected to the first control voltage, and the other end is connected in series with the second voltage-dividing resistor and then grounded; at this time, the voltage at the positive input terminal of the comparator is the turn-on threshold voltage;

[0022] When the output of the comparator is at a low level, the equivalent circuit of the hysteresis comparator circuit is that the second voltage-dividing resistor and the fourth voltage-dividing resistor are connected in parallel to obtain a second parallel circuit, and one end of the second parallel circuit is grounded, and the other end is connected in series with the first voltage-dividing resistor and then connected to the first control voltage; at this time, the voltage at the positive input terminal of the comparator is the shutdown threshold voltage.

[0023] In an embodiment of the present invention, the on-threshold voltage is 1V, and the off-threshold voltage is 0.7V.

[0024] In one embodiment of the present invention,

[0025] When the voltage at the negative input terminal of the comparator is greater than or equal to the conduction threshold voltage, the output terminal of the comparator is at a low level;

[0026] When the voltage at the negative input terminal of the comparator is greater than or equal to the turn-off threshold voltage and less than the turn-on threshold voltage, the output terminal of the comparator remains unchanged;

[0027] When the voltage at the negative input terminal of the comparator is less than the turn-off threshold voltage, the output terminal of the comparator is at a high level.

[0028] In one embodiment of the present utility model, the switch control module includes a switch control port, a pull-up resistor and a triode; wherein,

[0029] The switch control port is arranged on the PFC control chip;

[0030] The first end of the pull-up resistor is connected to the second control voltage, the second end of the pull-up resistor is connected to the switch control port, and the second end of the pull-up resistor is also connected to the emitter of the transistor;

[0031] The collector of the transistor is grounded, and a resistor is connected in series between the base of the transistor and the comparison module.

[0032] In one embodiment of the utility model, the normally open control module includes a normally open control port and a grounding resistor; wherein the normally open control port is arranged on the PFC control chip; and the normally open control port is connected in series with a grounding resistor and then grounded.

[0033] In a second aspect, in order to solve the above technical problems, an embodiment of the utility model further provides a channel selection switch controller for a PFC chip circuit, comprising a control circuit board, and the channel selection switch circuit for the PFC chip circuit, wherein the channel selection switch circuit for the PFC chip circuit is arranged on the control circuit board.

[0034] The above technical solution of the utility model has at least the following advantages compared with the prior art:

[0035] The utility model provides a channel selection switch circuit and a controller for a PFC chip circuit, uses hardware to detect and compare to control the on and off of the switch channel of the PFC chip circuit, and configures a normally open channel, so that the PFC chip circuit in an interleaved multi-channel form can ensure a high power utilization rate under low power or high input voltage and low output power conditions, without using a single-chip microcomputer I / O port, thereby reducing software workload and development costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to make the content of the utility model easier to understand, the utility model is further described in detail according to the specific embodiments of the utility model in combination with the accompanying drawings, wherein:

[0037] Figure 1 It is a schematic diagram of a channel selection switch circuit for a PFC chip circuit provided by a preferred embodiment of the utility model;

[0038] Figure 2 yes Figure 1 In the schematic diagram shown, the equivalent circuit diagram of the hysteresis comparison circuit when the output terminal of the comparator IC1A outputs a high-level signal;

[0039] Figure 3 yes Figure 1 In the schematic diagram shown, the equivalent circuit diagram of the hysteresis comparison circuit when the output terminal of the comparator IC1A outputs a low-level signal;

[0040] Figure 4 It is a circuit schematic diagram of a channel selection switch circuit for a PFC chip circuit provided by an embodiment of the utility model in a specific application scenario.

[0041] Description of the Figures in the Specification:

[0042] AC-L~AC-N power supply; CT1 current transformer; DB1 rectifier bridge; IC1A comparator;

[0043] CM1 normally open control port; CM2 switch control port;

[0044] OPFC1 is a normally open channel; OPFC2 is a switch channel;

[0045] D1, D2, D3, D4, D5, D6 diodes;

[0046] L1, L2 inductors; C1, C2 electrolytic capacitors;

[0047] IGBT1, IGBT2 insulated gate bipolar transistor;

[0048] R1 load resistor; R2 current limiting resistor; R3 first voltage dividing resistor; R4 second voltage dividing resistor; R5 third voltage dividing resistor; R6 fourth voltage dividing resistor; R7 resistor; R8 pull-up resistor; R9 grounding resistor. DETAILED DESCRIPTION

[0049] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention. Embodiment 1

[0050] This embodiment provides a channel selection switch circuit for a PFC chip circuit. The PFC chip circuit has multiple output channels. The output channels include at least one normally open channel and at least one switch channel. The channel selection switch circuit includes:

[0051] A collection module, the collection module is connected to the power supply, and is used to collect the current signal of the power supply in proportion and convert it into a DC voltage output;

[0052] A comparison module, which is connected to the acquisition module and is used to compare the threshold voltage with the DC voltage and output a level signal;

[0053] A switch control module, the switch control module is connected to the comparison module and is used to control the on or off of the switch channel according to the level signal;

[0054] A normally open control module, wherein the normally open control module is used to control the conduction of the normally open channel.

[0055] This embodiment provides a channel selection switch circuit for a PFC chip circuit, uses hardware detection and comparison to control the on and off of the switch channel of the PFC chip circuit, and configures a normally open channel, so that the PFC chip circuit in an interleaved multi-channel form can ensure a high power utilization rate under low power or high input voltage and low output power conditions, without using a single-chip microcomputer I / O port, reducing software workload and development costs.

[0056] The channel selection switch circuit for the PFC chip circuit described in this embodiment is described in detail below:

[0057] Reference Figure 1 As shown, the working condition of the staggered dual-path PFC chip circuit is described, and the PFC chip circuit has two output channels, OPFC1 and OPFC2; wherein, the output channel OPFC1 is required to be a normally open channel and remain turned on; the output channel OPFC2 is a switch channel and can be switched between on and off; when the detection voltage of the pin CM1 is set to be lower than 4V, the normally open channel OPFC1 is turned on, and when the detection voltage of the pin CM2 is lower than 4V, the switch channel OPFC2 is turned on; the channel selection switch circuit for the PFC chip circuit includes:

[0058] 1. Collection Module

[0059] Optionally, the acquisition module includes a current transformer CT1, a rectifier, a filter unit and a current limiting resistor R2;

[0060] The current transformer CT1 is connected to a power supply;

[0061] The rectifier is composed of diodes D1, D2, D3 and D4, and the rectifier is connected to the current transformer CT1;

[0062] The filter unit includes an electrolytic capacitor C1 and a load resistor R1 connected in parallel; one end of the filter unit is grounded, and the other end is connected to the rectifier and the current limiting resistor R2 respectively; the load resistor R1 is used to avoid inaccurate detection due to the continuous rise of the voltage on the electrolytic capacitor C1;

[0063] By setting each component in the acquisition module, the detection ratio is set to 10:1, and a DC voltage is output.

[0064] 2. Comparison Module

[0065] Optionally, the comparison module includes a comparator IC1A and an adjustment unit;

[0066] The negative input terminal of the comparator IC1A is connected to the current limiting resistor R2; the comparator IC1A and the adjustment unit constitute a hysteresis comparison circuit;

[0067] The adjustment unit includes a first voltage-dividing resistor R3, a second voltage-dividing resistor R4, a third voltage-dividing resistor R5 and a fourth voltage-dividing resistor R6;

[0068] Specifically, the first end of the first voltage-dividing resistor R3 is connected to the first control voltage, the second end of the first voltage-dividing resistor R3 is connected to the first end of the second voltage-dividing resistor R4, and the second end of the first voltage-dividing resistor R3 is also connected to the positive input end of the comparator IC1A; the second end of the second voltage-dividing resistor R4 is grounded; the first end of the third voltage-dividing resistor R5 is connected to the first control voltage, and the second end of the third voltage-dividing resistor R5 is connected to the output end of the comparator IC1A; the fourth voltage-dividing resistor R6 is connected between the second end of the first voltage-dividing resistor R3 and the second end of the third voltage-dividing resistor R5; the first control voltage is 5V;

[0069] like Figure 2 As shown, when the output terminal of the comparator IC1A is at a high level, the equivalent circuit of the hysteresis comparison circuit is that the third voltage-dividing resistor R5 and the fourth voltage-dividing resistor R6 are connected in series and then connected in parallel with the first voltage-dividing resistor R3 to obtain a first parallel circuit, and one end of the first parallel circuit is connected to the first control voltage, and the other end is connected in series with the second voltage-dividing resistor R4 and then grounded; at this time, the positive input terminal voltage of the comparator IC1A is the turn-on threshold voltage 1V;

[0070] like Figure 3 As shown, when the output terminal of the comparator IC1A is at a low level, the equivalent circuit of the hysteresis comparison circuit is that the second voltage-dividing resistor R4 is connected in parallel with the fourth voltage-dividing resistor R6 to obtain a second parallel circuit, and one end of the second parallel circuit is grounded, and the other end is connected in series with the first voltage-dividing resistor R3 and then connected to the first control voltage; at this time, the positive input terminal voltage of the comparator IC1A is the turn-off threshold voltage of 0.7V;

[0071] By adjusting the resistance values ​​of the first voltage-dividing resistor R3 , the second voltage-dividing resistor R4 , the third voltage-dividing resistor R5 and the fourth voltage-dividing resistor R6 , the magnitudes of the on-threshold voltage and the off-threshold voltage can be freely set.

[0072] When the voltage at the negative input terminal of the comparator IC1A is greater than or equal to the conduction threshold voltage 1V, the output terminal of the comparator IC1A is at a low level;

[0073] When the voltage at the negative input terminal of the comparator IC1A is greater than or equal to the turn-off threshold voltage 0.7V and less than the turn-on threshold voltage 1V, the output terminal of the comparator IC1A remains unchanged;

[0074] When the voltage at the negative input terminal of the comparator IC1A is less than the turn-off threshold voltage 0.7V, the output terminal of the comparator IC1A is at a high level;

[0075] The comparison module compares the threshold voltage with the DC voltage output by the acquisition module and outputs a level signal.

[0076] 3. Switch Control Module

[0077] Optionally, the switch control module includes a switch control port CM2, a pull-up resistor R8 and a transistor Q1;

[0078] The switch control port CM2 is arranged on the PFC control chip;

[0079] The first end of the pull-up resistor R8 is connected to the second control voltage, the second end of the pull-up resistor R8 is connected to the switch control port CM2, and the second end of the pull-up resistor R8 is also connected to the emitter of the transistor Q1; the second control voltage is 5V;

[0080] The collector of the transistor Q1 is grounded, and a resistor R7 is connected in series between the base of the transistor Q1 and the output end of the comparator IC1A;

[0081] The switch control module is used to control the on or off of the switch channel OPFC2 according to the level signal output by the comparison module.

[0082] 4. Normally open control module

[0083] Optionally, the normally open control module includes a normally open control port CM1 and a grounding resistor R9;

[0084] The normally open control port CM1 is provided in the PFC control chip; the normally open control port CM1 is connected in series with a grounding resistor R9 and then grounded;

[0085] The normally open control module is used to control the normally open channel OPFC1 to be turned on.

[0086] Please refer to Figure 4 As shown, the following takes a specific application scenario as an example to illustrate:

[0087] The maximum input power of power supply AC-L~AC-N is 6600W, and the maximum input current is 30A;

[0088] The power sources AC-L~AC-N are connected to the load via a rectifier bridge DB1; an electrolytic capacitor C2 is connected in parallel between the rectifier bridge DB1 and the load; a first end of an inductor L1 is connected to the rectifier bridge DB1 and the first end of an inductor L2 respectively, a second end of the inductor L1 is connected to the anode of a diode D5, a cathode of the diode D5 is connected to the positive electrode of the electrolytic capacitor C2 and the cathode of a diode D6 respectively; a second end of the inductor L2 is connected to the anode of the diode D6;

[0089] The normally open channel OPFC1 is connected to the gate of the insulated gate bipolar transistor IGBT1, the collector of the insulated gate bipolar transistor IGBT1 is connected to the second end of the inductor L1, and the emitter of the insulated gate bipolar transistor IGBT1 is grounded;

[0090] The switch channel OPFC2 is connected to the gate of the insulated gate bipolar transistor IGBT2, the collector of the insulated gate bipolar transistor IGBT2 is connected to the second end of the inductor L2, and the emitter of the insulated gate bipolar transistor IGBT2 is grounded.

[0091] Figure 4 In the circuit schematic diagram shown, the dotted line part of the circuit is Figure 1 The schematic diagram is consistent with that shown and will not be repeated here.

[0092] In the initial state, when the input power is 2200W and the input current is less than 10A, for example, the current flowing through the current transformer CT1 is 6A, after rectification and filtering, a DC voltage of 0.6V is sent to the negative input terminal of the comparator IC1A after passing through the current limiting resistor R1. At this time, the voltage of 0.6V at the negative input terminal is less than the conduction threshold voltage of 1V at the positive input terminal of the comparator IC1A, and the output terminal of the comparator IC1A outputs a high-level signal, the transistor Q1 is cut off, and the switch control port CM2 detects a 5V voltage similar to the first control voltage, which is greater than the set 4V detection voltage, and the switch channel OPFC2 is turned off. At this time, only the normally open channel OPFC1 is turned on, and single-channel operation is performed;

[0093] As the input power increases, when the input current is ≥10A, for example, the current flowing through the current transformer CT1 is 10A, after rectification and filtering, a DC voltage of 1V is sent to the negative input terminal of the comparator IC1A after passing through the current limiting resistor R1. At this time, the voltage 1V of the negative input terminal is equal to the conduction threshold voltage 1V of the positive input terminal of the comparator IC1A, and the output terminal of the comparator IC1A outputs a low-level signal, the transistor Q1 is turned on, the detection voltage of the switch control port CM2 is less than 4V, and the switch channel OPFC2 is turned on. At this time, the normally open channel OPFC1 and the switch channel OPFC2 are both turned on and work in an interleaved manner; at the same time, the reference voltage of the positive input terminal of the comparator IC1A is converted from the conduction threshold voltage 1V to the turn-off threshold voltage 0.7V;

[0094] As the input power decreases, when 7A≤input current<10A, the DC voltage is greater than or equal to the shutdown threshold voltage 0.7V, the output end of the comparator IC1A remains unchanged and still outputs a low-level signal, and the normally open channel OPFC1 and the switch channel OPFC2 remain turned on and perform staggered operation;

[0095] As the input power decreases, when the input power drops to 1500W and the input current is <7A, the DC voltage is less than the shutdown threshold voltage of 0.7V, the output end of the comparator IC1A outputs a high-level signal, the transistor Q1 is cut off, the detection voltage of the switch control port CM2 is greater than 4V, the switch channel OPFC2 is turned off, and only the normally open channel OPFC1 is turned on, performing single-channel operation; at the same time, the reference voltage of the positive input end of the comparator IC1A is converted from the shutdown threshold voltage of 0.7V to the conduction threshold voltage of 1V again.

[0096] In summary, this embodiment provides a channel selection switch circuit for a PFC chip circuit, which uses hardware detection and comparison to control the on and off of the switch channel of the PFC chip circuit, and is configured with a normally open channel, so that the PFC chip circuit using an interleaved multi-channel form can also ensure a high power utilization rate under low power or high input voltage and low output power conditions, without using a single-chip microcomputer I / O port, reducing software workload and development costs, while having the advantages of simple circuit structure, small number of components and easy adjustment. Embodiment 2

[0097] This embodiment provides a channel selection switch controller for a PFC chip circuit, including a control circuit board, and the channel selection switch circuit for the PFC chip circuit as described above, wherein the channel selection switch circuit for the PFC chip circuit is arranged on the control circuit board.

[0098] For the introduction of a channel selection switch controller for a PFC chip circuit provided in this embodiment, please refer to the above embodiment, and this embodiment will not be described in detail here.

[0099] The channel selection switch controller for a PFC chip circuit provided in this embodiment has the same beneficial effects as the channel selection switch circuit for a PFC chip circuit described above.

[0100] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention of the utility model.

Claims

1. A channel selection switch circuit for a PFC chip circuit, the PFC chip circuit having multiple output channels, characterized in that: The output channel includes at least one normally open channel and at least one switch channel, and the channel selection switch circuit includes: A collection module, the collection module is connected to the power supply, and is used to collect the current signal of the power supply in proportion and convert it into a DC voltage output; A comparison module, which is connected to the acquisition module and is used to compare the threshold voltage with the DC voltage and output a level signal; A switch control module, the switch control module is connected to the comparison module and is used to control the on or off of the switch channel according to the level signal; A normally open control module, wherein the normally open control module is used to control the conduction of the normally open channel.

2. The channel selection switch circuit for a PFC chip circuit according to claim 1, characterized in that: The acquisition module includes a current transformer, a rectifier, a filter unit and a current limiting resistor; wherein, The current transformer is connected to the power supply; The rectifier is connected to the current transformer; The filtering unit includes an electrolytic capacitor and a load resistor connected in parallel; The current limiting resistor is connected to the comparison module.

3. The channel selection switch circuit for a PFC chip circuit according to claim 1, characterized in that: The comparison module includes a comparator and an adjustment unit; wherein the negative input terminal of the comparator is connected to the acquisition module, and the output terminal of the comparator is connected to the switch control module; the comparator and the adjustment unit constitute a hysteresis comparison circuit.

4. The channel selection switch circuit for a PFC chip circuit according to claim 3, characterized in that: The adjustment unit includes a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor and a fourth voltage-dividing resistor; wherein, The first end of the first voltage-dividing resistor is connected to the first control voltage, the second end of the first voltage-dividing resistor is connected to the first end of the second voltage-dividing resistor, and the second end of the first voltage-dividing resistor is also connected to the positive input terminal of the comparator; the second end of the second voltage-dividing resistor is grounded; the first end of the third voltage-dividing resistor is connected to the first control voltage, and the second end of the third voltage-dividing resistor is connected to the output terminal of the comparator; the fourth voltage-dividing resistor is connected between the second end of the first voltage-dividing resistor and the second end of the third voltage-dividing resistor.

5. The channel selection switch circuit for a PFC chip circuit according to claim 4, characterized in that: When the output terminal of the comparator is at a high level, the equivalent circuit of the hysteresis comparator circuit is that the third voltage-dividing resistor and the fourth voltage-dividing resistor are connected in series and then connected in parallel with the first voltage-dividing resistor to obtain a first parallel circuit, and one end of the first parallel circuit is connected to the first control voltage, and the other end is connected in series with the second voltage-dividing resistor and then grounded; at this time, the voltage at the positive input terminal of the comparator is the turn-on threshold voltage; When the output of the comparator is at a low level, the equivalent circuit of the hysteresis comparator circuit is that the second voltage-dividing resistor and the fourth voltage-dividing resistor are connected in parallel to obtain a second parallel circuit, and one end of the second parallel circuit is grounded, and the other end is connected in series with the first voltage-dividing resistor and then connected to the first control voltage; at this time, the voltage at the positive input terminal of the comparator is the shutdown threshold voltage.

6. The channel selection switch circuit for a PFC chip circuit according to claim 5, characterized in that: The on-threshold voltage is 1V, and the off-threshold voltage is 0.7V.

7. The channel selection switch circuit for a PFC chip circuit according to claim 5, characterized in that: When the voltage at the negative input terminal of the comparator is greater than or equal to the conduction threshold voltage, the output terminal of the comparator is at a low level; When the voltage at the negative input terminal of the comparator is greater than or equal to the turn-off threshold voltage and less than the turn-on threshold voltage, the output terminal of the comparator remains unchanged; When the voltage at the negative input terminal of the comparator is less than the turn-off threshold voltage, the output terminal of the comparator is at a high level.

8. The channel selection switch circuit for a PFC chip circuit according to claim 1, characterized in that: The switch control module includes a switch control port, a pull-up resistor and a transistor; wherein, The switch control port is arranged on the PFC control chip; The first end of the pull-up resistor is connected to the second control voltage, the second end of the pull-up resistor is connected to the switch control port, and the second end of the pull-up resistor is also connected to the emitter of the transistor; The collector of the transistor is grounded, and a resistor is connected in series between the base of the transistor and the comparison module.

9. The channel selection switch circuit for a PFC chip circuit according to claim 8, characterized in that: The normally open control module includes a normally open control port and a grounding resistor; wherein the normally open control port is arranged on the PFC control chip; and the normally open control port is connected in series with a grounding resistor and then grounded.

10. A channel selection switch controller for a PFC chip circuit, characterized in that: It comprises a control circuit board, and a channel selection switch circuit for a PFC chip circuit according to any one of claims 1 to 9, wherein the channel selection switch circuit for the PFC chip circuit is arranged on the control circuit board.

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