A medium frequency power supply linkage protection control system

Abstract

The invention discloses a medium frequency power supply linkage protection control system, comprising at least two linkage protection control modules with the same circuit structure, each linkage protection control module is coupled to its corresponding medium frequency power supply mainboard, and is coupled to other linkage protection control modules through a linkage signal line; the linkage protection control module comprises a conversion unit and a control unit; the conversion unit comprises a signal conversion circuit, inputs a fault signal of the linkage signal line to the control unit, or receives a fault signal of the control unit and converts it to the linkage signal line; the control unit comprises a control circuit and a plurality of levels of switch circuits with the same circuit structure coupled to the control circuit, each level of the switch circuit is respectively coupled to a rectifier or inverter unit control end of the medium frequency power supply, and the control circuit is used to control the switch circuit to turn off the power supply of the rectifier or inverter unit control end after receiving a mainboard fault signal output by the signal conversion circuit, or sends a fault signal output by any level of the switch circuit to the conversion circuit after receiving it.

Description

Technical Field

[0001] The present invention relates to the application field of medium frequency power supply, and is mainly aimed at the protection and control of medium frequency power supply. Background Art

[0002] Nowadays, most medium-frequency induction heating equipment is high-power equipment, so most of them adopt a power supply system including multiple medium-frequency power supplies. Each medium-frequency power supply includes multiple rectifier control units. However, in actual applications, one medium-frequency power supply often fails and trips while the other medium-frequency power supply works normally. The medium-frequency power supply that fails and stops is subjected to high voltage and burns out a large number of electrical components, resulting in increased losses. Summary of the invention

[0003] In order to overcome the deficiencies of the above technologies, the present invention provides a medium frequency power supply linkage protection control system with simple circuit, strong operability and reliable control.

[0004] The present invention is implemented by the following technical solutions:

[0005] A medium frequency power supply linkage protection control system includes at least two linkage protection control modules with the same circuit structure, each linkage protection control module is coupled to its corresponding medium frequency power supply mainboard, and is coupled to other linkage protection control modules through a linkage signal line. Each linkage protection control module includes a conversion unit and a control unit. The conversion unit includes a signal conversion circuit, the power supply access end of the signal conversion circuit is coupled to the power supply, the first signal transmission end coupling module itself corresponds to the medium frequency power supply main control board fault signal output end and the linkage signal line, the second signal input end and the signal output end are coupled to the control unit, and the signal conversion circuit is used to convert the fault signal input from the first signal transmission end to the signal output end and input to the control unit, or receive the fault signal output from the control unit through the second signal input end and convert it to the first signal transmission end. The control unit includes a control circuit and several levels of switch circuits with the same circuit structure coupled to the control circuit. Each level of the switch circuit is respectively coupled to the rectifier or inverter unit control end of the module corresponding to the medium frequency power supply. The control circuit is used to control the switch circuit to cut off the power supply of the rectifier or inverter unit control end after receiving the mainboard fault signal output by the signal conversion circuit, or to send a fault signal to the conversion circuit after receiving the fault signal output by any level of the switch circuit.

[0006] In a power supply system including multiple intermediate frequency power supplies, if one intermediate frequency power supply fails, the main control board sends a fault signal to the first signal transmission end, and controls the faulty intermediate frequency power supply to shut down the power supply of the rectifier or inverter unit control end through the signal conversion circuit in the conversion unit and the control circuit and switch circuit in the control unit. At the same time, the fault signal is input to the first signal transmission end of other intermediate frequency power supplies in the power supply system through the linkage signal line, and controls the normally working intermediate frequency power supply to shut down the power supply of the rectifier or inverter unit control end through the signal conversion circuit in the conversion unit and the control circuit and switch circuit in the control unit. When the power supply of the rectifier or inverter unit control end of any intermediate frequency power supply in the power supply system is short-circuited or open-circuited, the fault signal is fed back to the control circuit in the control unit through the switch circuit in the intermediate frequency power control unit, and the power supply of the rectifier or inverter unit control end of the intermediate frequency power supply is shut down. At the same time, the fault signal is input to other intermediate frequency power supplies in the power supply system through the linkage signal line through the second signal input end of the conversion circuit of the intermediate frequency power conversion unit, and the power supply of the rectifier or inverter unit control end of the intermediate frequency power supply is shut down through the linkage protection control module of the other intermediate frequency power supplies.

[0007] Furthermore, the signal conversion circuit includes optocouplers UF1-UF2 and a resistor R1. One end of the resistor R1 is coupled to the power supply VCC1 as a first power access terminal, and the other end is coupled to the first input terminal of the optocoupler UF1. The second input terminal of the optocoupler UF1 and the first output terminal of the optocoupler UF2 are coupled as a first signal transmission terminal, the first output terminal of the optocoupler UF1 is coupled to the control circuit as a signal output terminal, and the second output terminal is coupled to the signal ground. The first input terminal of the optocoupler UF2 is coupled to the control circuit as a second signal input terminal, the second input terminal is coupled to the signal ground, and the second output terminal is coupled to the power ground as a second power access terminal.

[0008] The first input end of the optocoupler UF1 is connected to the power supply VCC1 through the resistor R1, and the second input end inputs the low-level fault signal transmitted by the linkage signal line, the optocoupler UF1 is turned on, and the first output end of the optocoupler UF1 outputs the low-level fault signal to the control circuit. The first input end of the optocoupler UF2 inputs the low-level control signal output by the control circuit, the optocoupler UF2 is turned on, and the first output end of UF2 outputs the low-level fault signal to the linkage signal line.

[0009] Furthermore, the control circuit includes a single-chip microcomputer IC5, resistors R2-R3, capacitors C1-C3, capacitors C6-C7, capacitor EC1, a voltage regulator module IC1 and a crystal oscillator CY1; the VCC pin of the single-chip microcomputer IC5 is coupled to the pin Vout of the voltage regulator module IC1, the P3.4 pin is coupled to the signal output end of the signal conversion circuit, the P3.0 pin is coupled to the second signal input end of the signal conversion circuit through the resistor R3, the P1.5 pin, the P1.1 pin and the P3.7 pin are respectively coupled to the signal input end of the switch circuit, and the P1.6 pin and the P1.2 pin are respectively coupled to the signal input end of the switch circuit. The pin and P1.0 pin are respectively coupled to the fault signal output end of the switch circuit, the RST pin is coupled to the signal ground through the resistor R2, the XTAL1 pin is coupled to the signal ground through the capacitor C2, the XTAL2 pin is coupled to the signal ground through the capacitor C1, and the GND pin is coupled to the signal ground; the crystal oscillator CY1 is coupled between the XTAL1 pin and the XTAL2 pin of the microcontroller IC5; the pin VIN of the voltage regulator module IC1 is coupled to the +22V power supply, and the GND pin is used as the signal ground reference terminal; the capacitor C3 and the capacitor EC1 are coupled in parallel between the pins VIN and GND of the voltage regulator module IC1.

[0010] The Vout output of the voltage regulator module IC1 provides a stable working power supply for the microcontroller IC5, the crystal oscillator CY1 provides a basic clock signal for the microcontroller, the P3.4 pin is used to detect the fault signal input by the signal conversion circuit, the P1.5, P1.1 and P3.7 pins control the output voltage of the switching circuit according to the detected fault signal, the P1.6, P1.2 and P1.0 pins are used to detect whether the output voltage of the switching circuit has an open circuit or short circuit fault, and the P3.0 pin outputs the fault signal fed back by the switching circuit to the signal conversion circuit.

[0011] Furthermore, each level of the switching circuit includes a power switch module ICAn, the in pin of the power switch module ICAn is coupled to the microcontroller of the control circuit as a signal input terminal, the st pin is coupled to the microcontroller of the control circuit as a fault signal output terminal, the Vbb pin is coupled to the +22V power supply, the out pin is coupled to the rectifier or inverter unit control terminal of the medium frequency power supply as a power output terminal, and the gnd pin is coupled to the signal ground.

[0012] If the medium frequency power rectifier or inverter unit control end power supply coupled to the out pin of the power switch module LCan has a short circuit or open circuit fault, st outputs a fault signal to the microcontroller.

[0013] Furthermore, the linkage protection control module also includes a first indicator light unit for indicating the working status of the medium frequency power supply. The first indicator light unit includes resistors R4, R7-R8, optocoupler UF3, capacitors C4-C5, bidirectional thyristor T1 and signal lamp L2. The first input end of the optocoupler UF3 is coupled to the P3.3 pin of the single-chip microcomputer IC5 through the resistor R7, the second input end is coupled to the signal ground, the first output end is coupled to one end of the resistor R4, and the second output end is coupled to one end of the resistor R8, one end of the capacitor C5 and the control end of the bidirectional thyristor T1. The other end of the resistor R4, the first terminal of the bidirectional thyristor T1 and one end of the capacitor C4 are coupled to one end of the signal lamp L2, the other end of the resistor R8, the other end of the capacitor C5, the second terminal of the bidirectional thyristor T1 and the other end of the capacitor C4 are coupled to the first power supply end of the signal lamp L2, and the other end of the signal lamp L2 is coupled to the second power supply end.

[0014] The P3.3 pin of the microcontroller IC5 is used to control the conduction of the optocoupler UF3, and then control the conduction of the bidirectional thyristor T1 to control the lighting state of the signal lamp L2.

[0015] Furthermore, the linkage protection control module also includes a second indicator light unit for indicating its own working state. The second indicator light unit includes a resistor R5 and a light emitting diode L1, one end of the resistor R5 is coupled to the P1.7 pin of the single chip microcomputer IC5, and the other end is coupled to the anode of the light emitting diode L1, and the cathode of the light emitting diode L1 is coupled to the signal ground.

[0016] Furthermore, the linkage protection control module further includes a third indicator light unit, which includes a resistor Ran and a light emitting diode LAn, wherein the resistor Ran and the light emitting diode LAn are coupled in series between the out pin and the gnd pin of the power switch module LCAn. The third indicator light unit is used to indicate whether the switch unit has power output.

[0017] The present invention has the following technical advantages or beneficial effects:

[0018] The connection relationship of the medium frequency power supply linkage protection control system is simple. In a power supply system using multiple medium frequency power supplies, the mainboard of each medium frequency power supply is connected to the linkage protection control module. The linkage protection control modules are coupled through linkage signal lines. If any one of the medium frequency power supplies in the power supply system fails, the other medium frequency power supplies in the medium frequency power supply system can be shut down through the medium frequency power supply linkage protection control system. At the same time, the linkage protection control module can also detect whether the control end power supply of the controlled rectifier unit or inverter unit has an open circuit or short circuit fault, and feed back the fault to the medium frequency power supply linkage protection control system to shut down other non-fault medium frequency power supplies in the power supply system. The above scheme can effectively solve the problem that after a medium frequency power supply in the medium frequency power supply system fails, it will be subjected to the high voltage input from another normally working medium frequency power supply, which will burn out a large number of electrical components and increase the loss.

[0019] In the linkage protection control system of the present invention, each linkage protection control module requires a small number of components and parts, has low cost, strong operability, reliable control, and good economy and practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a circuit schematic diagram of an embodiment of the linkage protection control module in the present invention.

[0021] Figure 2 It is a schematic diagram of the connection relationship of an application embodiment of the medium frequency power supply linkage protection control system of the present invention. DETAILED DESCRIPTION

[0022] In order to facilitate those skilled in the art to better understand the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The following is only exemplary and does not limit the protection scope of the present invention.

[0023] like Figure 1 The figure shows a specific embodiment of the linkage protection control module in the present invention, which includes a conversion unit, a control unit and first to third indicator light units.

[0024] Wherein, the conversion unit includes a signal conversion circuit, and the signal conversion circuit includes optocouplers UF1~UF2 and a resistor R1. One end of the resistor R1 is coupled to the power supply VCC1, and the other end is coupled to the first input end of the optocoupler UF1. The second input end of the optocoupler UF1 and the first output end of the optocoupler UF2 are coupled as the first signal transmission end, the first output end of the optocoupler UF1 is coupled to the control circuit, and the second output end is coupled to the signal ground. The first input end of the optocoupler UF2 is coupled to the control circuit, the second input end is coupled to the signal ground, and the second output end is coupled to the power ground as the power input end. The signal conversion circuit is used to convert the fault signal input by the linkage signal line to the input end of the control unit or to convert the fault signal at the output end of the control unit to the linkage signal line. Wherein, the optocoupler UF1 is used to convert the fault signal of the main control board input through the linkage signal line or the fault signal of other linkage protection control modules to the input end of the control unit, and the optocoupler UF2 is used to output the fault signal output by the control unit to the linkage signal line.

[0025] The control unit includes a control circuit and a switch circuit with the same three-level circuit structure. The control circuit includes a single-chip microcomputer IC5, resistors R2-R3, capacitors C1-C3, capacitors C6-C7, capacitor EC1, voltage regulator module IC1 and crystal oscillator CY1. The voltage regulator module IC1 inputs +22V voltage and outputs +5V voltage to provide a stable working power supply for the single-chip microcomputer. Each level of the switch circuit includes a power switch module ICAn, a resistor RAn and a light-emitting diode LAn. The crystal oscillator CY1 provides a basic clock signal for the single-chip microcomputer. Pin P3.4 of the microcontroller is used as an input pin to detect the fault signal output by the optocoupler UF1. Pins P1.5, P1.1, and P1.3 are used as output pins to control whether the power switch module ICAn outputs +22Vn normally. Pins P1.6, P1.2, and P1.0 are used as input pins to detect whether the +22Vn controlled by the power switch module has a short circuit or open circuit fault. When pins P1.6, P1.2, and P1.0 detect that a fault has occurred, pin P3.0 is used as an output pin to input the fault signal to the conversion unit.

[0026] The linkage protection control module also includes a first indicator light unit indicating the working state of the medium frequency power supply, a second indicator light unit indicating its own working state, and a third indicator light unit indicating the working state of the switch unit.

[0027] The first indicator light unit includes an optical coupler UF3, a resistor R4, resistors R7-R8, a bidirectional thyristor T1, capacitors C4-C5 and a signal light L2. The single chip pin machine P3.3 controls the optical coupler UF3 to conduct, thereby conducting the bidirectional thyristor T1, so that the signal light L2 indicates the working state of the intermediate frequency power supply corresponding to the linkage control module itself.

[0028] The second indicator light unit includes a resistor R5 and a light emitting diode L1. The single chip pin machine P1.7 controls the light emitting diode L1, and L1 is used to indicate the state of the linkage protection control module.

[0029] The third indicator light unit includes a resistor RAn and a light emitting diode LAn. When the OUT terminal of the switch module ICAn outputs normally, the light emitting diode LAn emits light. When there is no output at the OUT terminal, the light emitting diode LAn turns off.

[0030] In this embodiment, the medium frequency power supply linkage protection control system is used for a power supply system including at least two medium frequency power supplies, and the two medium frequency power supplies are respectively coupled to the 1# linkage protection control module and the 2# linkage protection control module, and the connection relationship is as follows: Figure 2 As shown below, combined Figure 1 and Figure 2 The protection control system is described in detail.

[0031] As an implementation method of the embodiment, the signal transmission end of the 1# linkage protection control module is coupled to the signal transmission end of the 2# linkage protection control module, the signal transmission end of the 1# linkage protection control module is coupled to the 1# intermediate frequency power supply main control board, and the signal transmission end of the 2# linkage protection control module is coupled to the 2# intermediate frequency power supply main control board. The +22V1~+22V3 of the 1# linkage protection control module are respectively coupled to the 1# rectifier unit of the 1# intermediate frequency power supply, the 2# rectifier unit of the 1# intermediate frequency power supply, and the inverter unit of the 1# intermediate frequency power supply, and the terminals +22V1~+22V3 of the 2# linkage protection control module are respectively coupled to the 1# rectifier unit of the 2# intermediate frequency power supply, the 2# rectifier unit of the 2# intermediate frequency power supply, and the inverter unit.

[0032] When the intermediate frequency power supply works normally, the signal transmission end, namely the first signal transmission end, is always at a high level, and the optical couplers UF1 and UF2 are cut off. The power switch modules ICA1 to ICA3 normally output +22V1 to +22V3 power supplies.

[0033] When the 1# intermediate frequency power supply has an overcurrent, overvoltage or power phase failure, the 1# intermediate frequency power supply main control board sends a low-level fault signal to the signal transmission end of the 1# linkage protection control module, and transmits the fault signal to the signal transmission end of the 2# linkage protection control module through the linkage control line. The fault signal at the signal transmission end of the 1# linkage protection control module turns on the optocoupler UF1 of the 1# linkage protection control module. After the pin P3.4 of the single-chip computer detects the low-level fault signal output by the optocoupler UF1, the pins P1.5, P1.1, and P3.7 control the power switch modules ICA1~ICA3 to stop outputting +22V1~+22V3 power, so that the 1#~2# rectifier units and inverter units of the 1# intermediate frequency power supply stop running, and the 1# intermediate frequency power supply is shut down. The indicator lights LA1~LA3 are off. Pins P1.7 and P1.3 control the light-emitting states of L1 and L2 respectively.

[0034] The fault signal output to the signal transmission end of the 2# linkage protection control module controls the 2# linkage protection control module optocoupler UF1 to turn on, thereby controlling the single chip of the 2# linkage protection control module to disconnect the switch circuit, so that the 1#~2# rectifier units and inverter units of the 2# intermediate frequency power supply stop running, and the 2# intermediate frequency power supply is shut down.

[0035] As a second implementation method of the embodiment, when the +22V1 power supply output by the switch circuit of the 1# linkage protection control module has a short circuit or open circuit fault, the corresponding power switch module ICA1 is fed back to the single-chip microcomputer pin P1.6 through the pin st, and the single-chip microcomputer controls the power switches ICA1~ICA3 to stop outputting +22V1~+22V3 power supplies through pins P1.5, P1.1 and P3.7, so that the 1#~2# rectifier units and inverter units of the 1# intermediate frequency power supply stop running, and the 1# intermediate frequency power supply is shut down. The P3.0 pin of the single-chip microcomputer outputs a high level at the same time, turning on the optical coupler UF2, that is, the 1# intermediate frequency power supply signal transmission end outputs a low-level fault signal to the linkage signal line.

[0036] The signal transmission end of the 2# linkage protection control module receives the fault signal and controls the optocoupler UF1 of the 2# linkage protection control module to be turned on, thereby controlling the single chip of the 2# linkage protection control module to shut down the 1#~2# rectifier units and inverter units of the 2# intermediate frequency power supply to stop running, and the 2# intermediate frequency power supply is shut down.

[0037] This medium frequency power supply linkage protection control system avoids the situation in which, during the actual use of the medium frequency power supply system, one medium frequency power supply experiences overcurrent, overvoltage, power phase loss, or a short circuit or open circuit in the power supply at the control end of the rectifier or inverter unit, while the other medium frequency power supply operates normally, causing the medium frequency power supply that has failed to shut down to be subjected to high voltage, causing a large number of electrical components to burn out.

[0038] The medium frequency power supply linkage protection control system in this embodiment has simple circuits and connection relationships, a small number of components required for each linkage protection control module, low cost, strong operability, reliable control, and good economy and practicality.

[0039] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A medium frequency power supply linkage protection control system, characterized by: It includes at least two linkage protection control modules with the same circuit structure, each linkage protection control module is coupled to its corresponding intermediate frequency power supply mainboard, and is coupled to other linkage protection control modules through a linkage signal line; Wherein, each linkage protection control module includes a conversion unit and a control unit; The conversion unit includes a signal conversion circuit, a power supply access end of the signal conversion circuit is coupled to the power supply, a first signal transmission end coupling module itself corresponds to the fault signal output end of the intermediate frequency power supply main control board and the linkage signal line, and a second signal input end and a signal output end are coupled to the control unit, and is used to convert the fault signal input from the first signal transmission end to the signal output end and input to the control unit, or receive the fault signal output from the control unit through the second signal input end and convert it to the first signal transmission end; The control unit includes a control circuit and several levels of switching circuits with the same circuit structure coupled to the control circuit. Each level of the switching circuit is respectively coupled to the rectifier or inverter unit control end of the module corresponding to the medium frequency power supply. The control circuit is used to control the switching circuit to cut off the power supply of the rectifier or inverter unit control end after receiving the fault signal output by the signal conversion circuit, or to send a fault signal to the conversion circuit after receiving the fault signal output by any level of the switching circuit.

2. The medium frequency power supply linkage protection control system according to claim 1 is characterized in that: The signal conversion circuit includes optical couplers UF1~UF2 and a resistor R1; one end of the resistor R1 is coupled to the power supply VCC1 as a first power access end, and the other end is coupled to the first input end of the optical coupler UF1; the second input end of the optical coupler UF1 and the first output end of the optical coupler UF2 are coupled as a first signal transmission end, the first output end of the optical coupler UF1 is coupled to the control circuit as a signal output end, and the second output end is coupled to the signal ground; The first input terminal of the optical coupler UF2 is coupled to the control circuit as the second signal input terminal, the second input terminal is coupled to the signal ground, and the second output terminal is coupled to the power ground as the second power supply access terminal.

3. The medium frequency power supply linkage protection control system according to claim 1 or 2, characterized in that: The control circuit includes a single-chip microcomputer IC5, resistors R2-R3, capacitors C1-C3, capacitor EC1, a voltage regulator module IC1 and a crystal oscillator CY1; the VCC pin of the single-chip microcomputer IC5 is coupled to the pin Vout of the voltage regulator module IC1, and the P3.4 pin is coupled to the signal output end of the signal conversion circuit as an input pin. The P3.0 pin is coupled to the second signal input end of the signal conversion circuit through a resistor R3 as an output pin, the P1.5 pin, the P1.1 pin and the P3.7 pin are coupled to the signal input end of the switch circuit as output pins, respectively, the P1.6 pin, the P1.2 pin and the P1.0 pin are coupled to the fault signal output end of the switch circuit as input pins, respectively, the RST pin is coupled to the signal ground through a resistor R2, the XTAL1 pin is coupled to the signal ground through a capacitor C2, the XTAL2 pin is coupled to the signal ground through a capacitor C1, and the GND pin is coupled to the signal ground; the crystal oscillator CY1 is coupled between the XTAL1 pin and the XTAL2 pin of the single-chip computer IC5; the pin VIN of the voltage regulator module IC1 is coupled to the +22V power supply, and the GND pin is used as the signal ground reference end; the capacitor C3 and the capacitor EC1 are coupled in parallel between the pins VIN and GND of the voltage regulator module IC1.

4. The medium frequency power supply linkage protection control system according to claim 3 is characterized in that: Each level of the switching circuit includes a power switch module ICAn, the in pin of the power switch module ICAn is coupled to the microcontroller of the control circuit as a signal input terminal, the st pin is coupled to the microcontroller of the control circuit as a fault signal output terminal, the Vbb pin is coupled to the +22V power supply, the out pin is coupled to the power supply of the rectifier or inverter unit control end of the medium frequency power supply as a power output terminal, and the gnd pin is coupled to the signal ground.

5. The medium frequency power supply linkage protection control system according to claim 3 is characterized in that: The linkage protection control module also includes a first indicator light unit for indicating the working status of the medium frequency power supply, and the first indicator light unit includes resistors R4, R7~R8, optocoupler UF3, capacitors C4~C5, bidirectional thyristor T1 and signal light L2; the first input end of the optocoupler UF3 is coupled to the P3.3 pin of the microcontroller IC5 through the resistor R7, the second input end is coupled to the signal ground, the first output end is coupled to one end of the resistor R4, and the second output end is coupled to one end of the resistor R8, one end of the capacitor C5 and the control end of the bidirectional thyristor T1; the other end of the resistor R4, the first terminal of the bidirectional thyristor T1 and one end of the capacitor C4 are coupled to one end of the signal light L2, the other end of the resistor R8, the other end of the capacitor C5, the second terminal of the bidirectional thyristor T1 and the other end of the capacitor C4 are coupled to the first power supply end of the signal light L2, and the other end of the signal light L2 is coupled to the second power supply end, wherein the P3.3 pin is used as an output pin to control the conduction of the optocoupler UF3.

6. The medium frequency power supply linkage protection control system according to claim 3 is characterized in that: The linkage protection control module also includes a second indicator light unit for indicating its own working status. The second indicator light unit includes a resistor R5 and a light-emitting diode L1. One end of the resistor R5 is coupled to the P1.7 pin of the microcontroller IC5, and the other end is coupled to the anode of the light-emitting diode L1. The cathode of the light-emitting diode L1 is coupled to the signal ground, wherein the microcontroller pin P1.7 serves as an output pin to control the light-emitting diode L1.

7. The medium frequency power supply linkage protection control system according to claim 4 is characterized in that: The linkage protection control module also includes a third indicator light unit for indicating the working state of the switch unit. The third indicator light unit includes a resistor Ran and a light emitting diode LAn. The resistor Ran and the light emitting diode LAn are coupled in series between the out pin and the gnd pin of the power switch module LCAn.

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