Bridge arm overcurrent protection circuit of high-frequency off-grid system

Abstract

The utility model discloses a bridge arm overcurrent protection circuit of a high-frequency off-grid system, and the circuit is provided with an inversion main power module, an output module, an AC load, a bridge arm overcurrent protection module, and a chip control module. The bridge arm overcurrent protection module detects a level and sends the level to the chip control module, the chip control module outputs high and low levels and controls on or off of a PWM signal of the inversion main power module to realize an overcurrent protection function, so that an MOS tube of the inversion main power module is effectively protected, and the circuit is simple in structure and low in cost. And the working stability of the high-frequency off-grid system is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of overcurrent protection, and in particular relates to a bridge arm overcurrent protection circuit of a high-frequency off-grid system. Background Art

[0002] The off-grid power generation system converts solar energy into electrical energy when there is sunlight, and supplies power to the load through the solar control inverter, while charging the battery; when there is no sunlight, the battery supplies power to the AC load through the inverter. However, in high-frequency off-grid systems, when the current exceeds the predetermined maximum value, if overcurrent protection is not provided, it will cause circuit failure, and the power devices in the high-frequency off-grid system will be damaged and unable to work, causing very large economic losses to users. Therefore, it is necessary to provide a simple, reliable and precise overcurrent protection circuit to protect the high-frequency off-grid system. Utility Model Content

[0003] In view of the above problems, the utility model provides a bridge arm overcurrent protection circuit of a high-frequency off-grid system, which can realize the overcurrent protection function, thereby protecting the MOS tube of the inverter main power module and protecting the high-frequency off-grid system from damage, so as to solve the problems raised in the above background technology.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] The utility model provides a bridge arm overcurrent protection circuit of a high-frequency off-grid system, comprising an inverter main power module, an output module, an AC load, a bridge arm overcurrent protection module and a chip control module, wherein the inverter main power module and the bridge arm overcurrent protection module are connected to the chip control module, the bridge arm overcurrent protection module and the output module are connected to the inverter main power module, and the output module is connected to the AC load;

[0006] The bridge arm overcurrent protection module is used to detect the operating voltage of the inverter main power module and output a corresponding electrical level to the chip control module according to the operating voltage. The chip control module controls the inverter main power module to send a PWM signal to the output module according to the electrical level, and the output module supplies power to the AC load according to the PWM signal.

[0007] As a further improvement of the above technical solution, the inverter main power module includes a bus, a capacitor C1, a first bridge arm and a second bridge arm, and the first bridge arm, the second bridge arm and the capacitor C1 are connected in parallel through the bus;

[0008] The first bridge arm includes a MOS transistor Q1, a MOS transistor Q2, a resistor R1 and a resistor R2, the MOS transistor Q1 is connected to the MOS transistor Q2, the MOS transistor Q1 is connected to the anode of the capacitor C1, and the resistor R1 and the resistor R2 are connected in parallel to the cathode of the capacitor C1 and the MOS transistor Q2;

[0009] The second bridge arm includes a MOS transistor Q3, a MOS transistor Q4, a resistor R3 and a resistor R4, the MOS transistor Q3 is connected to the MOS transistor Q4, the MOS transistor Q3 is connected to the anode of the capacitor C1, and the resistor R3 and the resistor R4 are connected in parallel to the cathode of the capacitor C1 and the MOS transistor Q4.

[0010] As a further improvement of the above technical solution, the bridge arm overcurrent protection module includes a first overcurrent protection circuit connected to the first bridge arm and a second overcurrent protection circuit connected to the second bridge arm;

[0011] The first overcurrent protection circuit includes a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a capacitor C3, a capacitor C4 and a comparator U1A, the resistor R5 and the capacitor C3 are connected in parallel to the resistor R7, the resistor R7 and the R9 are connected in parallel to the positive input terminal of the comparator U1A, the resistor R6 and the capacitor C4 are connected in parallel to the resistor R8, and the resistor R8 is connected to the negative input terminal of the comparator U1A;

[0012] The second overcurrent protection circuit includes a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a capacitor C5, a capacitor C6 and a comparator U1B, the resistor R10 and the capacitor C5 are connected in parallel to the resistor R12, the resistor R12 is connected to the negative input terminal of the comparator U1B, the resistor R11 and the capacitor C6 are connected in parallel to the resistor R13, the resistor R13 and the resistor R14 are connected in parallel to the positive input terminal of the comparator U1B, and the output terminal of the comparator U1B is connected to the output terminal of the comparator U1A.

[0013] As a further improvement of the above technical solution, the current of the first bridge arm flows through the first current detection resistor and inverts and flows through the MOS tube Q1 and the MOS tube Q2. When the voltage received by the negative input terminal of the comparator U1A is greater than the first preset overcurrent protection value of the negative input terminal of the comparator U1A, the output terminal of the comparator U1A outputs a first low voltage OSP and sends it to the chip control module. The chip control module detects the low level corresponding to the first low voltage OSP and turns off the PWM signal of the first bridge arm.

[0014] The first current detection resistor is composed of the resistor R1 and the resistor R2, and the first preset over-current protection value is a voltage value of 5V obtained by dividing the voltage between the resistor R7 and the resistor R9.

[0015] As a further improvement of the above technical solution, when the voltage received at the positive input terminal of the comparator U1A is less than a first preset overcurrent protection value of the positive input terminal of the comparator U1A, the output terminal of the comparator U1A outputs a first high level and sends it to the chip control module, and the chip control module turns on the PWM signal of the first bridge arm according to the first high level.

[0016] As a further improvement of the above technical solution, the current of the second bridge arm flows through the second current detection resistor and inverts to flow through the MOS tube Q3 and the MOS tube Q4. When the voltage received by the negative input terminal of the comparator U1B is greater than the second preset overcurrent protection value of the negative input terminal of the comparator U1B, the output terminal of the comparator U1B outputs a second low voltage OSP and sends it to the chip control module. The chip control module detects the low level corresponding to the second low voltage OSP and turns off the PWM signal of the second bridge arm.

[0017] The second current detection resistor is composed of the resistor R3 and the resistor R4, and the second preset over-current protection value is a voltage value of 5V obtained by dividing the resistor R13 and the resistor R14.

[0018] As a further improvement of the above technical solution, when the voltage received at the positive input terminal of the comparator U1B is less than the second preset overcurrent protection value of the positive input terminal of the comparator U1B, the output terminal of the comparator U1B outputs a second high level and sends it to the chip control module, and the chip control module turns on the PWM signal of the second bridge arm according to the second high level.

[0019] As a further improvement of the above technical solution, the bridge arm overcurrent protection module aggregates the overcurrent protection signals of the first bridge arm and the second bridge arm through the first overcurrent protection circuit and the second overcurrent protection circuit and sends them to the chip control module.

[0020] As a further improvement of the above technical solution, the chip control module includes a DSP chip and peripheral circuits. The chip control module receives the overcurrent protection signal to control the inverter main power module to send a PWM signal to control the opening or closing of the MOS tube, and controls the relay signal of the output module.

[0021] As a further improvement of the above technical solution, the output module includes an inductor L1, an inductor L2, a capacitor C2 and a relay RY1, the inductor L1 and the inductor L2 are connected in parallel at both ends of the capacitor C2, and the inductor L1 and the capacitor C2 are connected to the relay RY1.

[0022] Compared with the prior art, the beneficial effects of the utility model are:

[0023] By arranging an inverter main power module, an output module, an AC load, a bridge arm overcurrent protection module and a chip control module in the circuit, when it is detected that the MOS tubes of the first bridge arm and the second bridge arm in the inverter main power module have overcurrent, the bridge arm overcurrent protection module detects the level and sends it to the chip control module, and the chip control module outputs high and low levels to control the opening or closing of the PWM signal of the inverter main power module to realize the overcurrent protection function, thereby effectively protecting the MOS tube of the inverter main power module. The circuit structure is simple and the working stability of the high-frequency off-grid system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural block diagram of the bridge arm overcurrent protection circuit of the high-frequency off-grid system proposed by the utility model;

[0025] Figure 2 This is a structural block diagram of the bridge arm overcurrent protection circuit proposed by the utility model;

[0026] Figure 3 This is a circuit schematic diagram of a bridge arm overcurrent protection circuit of a high-frequency off-grid system proposed by the utility model.

[0027] The main component symbols are described as follows:

[0028] 1-inverter main power module; 11-first bridge arm; 12-second bridge arm; 2-output module; 3-AC load; 4-bridge arm overcurrent protection module; 41-first overcurrent protection circuit; 42-second overcurrent protection circuit; 5-chip control module. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0031] See also Figure 1 and Figure 2 The utility model provides a bridge arm overcurrent protection circuit of a high-frequency off-grid system, comprising an inverter main power module 1, an output module 2, an AC load 3, a bridge arm overcurrent protection module 4 and a chip control module 5, wherein the inverter main power module 1 and the bridge arm overcurrent protection module 4 are connected to the chip control module 5, the bridge arm overcurrent protection module 4 and the output module 2 are connected to the inverter main power module 1, and the output module 2 is connected to the AC load 3;

[0032] The bridge arm overcurrent protection module 4 is used to detect the operating voltage of the inverter main power module 1 and output a corresponding electrical level to the chip control module 5 according to the operating voltage. The chip control module 5 controls the inverter main power module 1 to send a PWM signal to the output module 2 according to the electrical level, and the output module 2 supplies power to the AC load 3 according to the PWM signal.

[0033] In this embodiment, the inverter main power module 1 includes a bus, a capacitor C1, a first bridge arm 11 and a second bridge arm 12, the first bridge arm 11, the second bridge arm 12 and the capacitor C1 are connected in parallel through the bus; the first bridge arm 11 includes a MOS tube Q1, a MOS tube Q2, a resistor R1 and a resistor R2, the MOS tube Q1 is connected to the MOS tube Q2, the MOS tube Q1 is connected to the anode of the capacitor C1, the resistor R1 and the resistor R2 are connected in parallel to the cathode of the capacitor C1 and the MOS tube Q2; the second bridge arm 12 includes a MOS tube Q3, a MOS tube Q4, a resistor R3 and a resistor R4, the MOS tube Q3 is connected to the MOS tube Q4, the MOS tube Q3 is connected to the anode of the capacitor C1, the resistor R3 and the resistor R4 are connected in parallel to the cathode of the capacitor C1 and the MOS tube Q4. The chip control module 5 includes a DSP chip and peripheral circuits. The chip control module 5 receives the overcurrent protection signal to control the inverter main power module 1 to send a PWM signal to control the on or off of the MOS tube, and controls the relay signal of the output module 2. The output module 2 includes an inductor L1, an inductor L2, a capacitor C2 and a relay RY1. The inductor L1 and the inductor L2 are connected in parallel at both ends of the capacitor C2, and the inductor L1 and the capacitor C2 are connected to the relay RY1.

[0034] The bridge arm overcurrent protection module 4 includes a first overcurrent protection circuit 41 connected to the first bridge arm 11, and a second overcurrent protection circuit 42 connected to the second bridge arm 12; the first overcurrent protection circuit 41 includes a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a capacitor C3, a capacitor C4 and a comparator U1A, the resistor R5 and the capacitor C3 are connected in parallel to the resistor R7, the resistor R7 and the R9 are connected in parallel to the positive input terminal of the comparator U1A, the resistor R6 and the capacitor C4 are connected in parallel to the resistor R8, and the resistor R8 is connected to the comparator The negative input terminal of U1A; the second overcurrent protection circuit 42 includes a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a capacitor C5, a capacitor C6 and a comparator U1B, the resistor R10 and the capacitor C5 are connected in parallel to the resistor R12, the resistor R12 is connected to the negative input terminal of the comparator U1B, the resistor R11 and the capacitor C6 are connected in parallel to the resistor R13, the resistor R13 and the resistor R14 are connected in parallel to the positive input terminal of the comparator U1B, and the output terminal of the comparator U1B is connected to the output terminal of the comparator U1A. The bridge arm overcurrent protection module 4 aggregates the overcurrent protection signals of the first bridge arm 11 and the second bridge arm 12 through the first overcurrent protection circuit 41 and the second overcurrent protection circuit 42 and sends them to the chip control module 5.

[0035] It should be noted that the DSP (Digital Signal Processing) chip refers to a chip that can implement digital signal processing technology. The bus is recorded as BUS and can connect various MOS tubes and resistors. The first bridge arm 11 and the second bridge arm 12 each include two MOS tubes and two resistors. Inversion refers to converting direct current into alternating current. The inverter main power module 1 is mainly used to realize the inverter output function. The resistor R1 and the resistor R2 constitute the first current detection resistor, which can sample the current of the first bridge arm 11. The resistor R3 and the resistor R4 constitute the second current detection resistor, which can sample the current of the second bridge arm 12. The inductor L1 and the inductor L2 in the output module 2 are filter inductors, and the capacitor C2 is a filter capacitor. The inductor L1 and the inductor L2 respectively form an LC filter structure with the capacitor C2. The inverter main power module 1 outputs a pure sine wave after LC filtering. After the chip control module 5 detects that the voltage is normal, it controls the output module 2 to close the relay and outputs a normal voltage to power the AC load 3. The comparator U1A and the comparator U1B are preferably of the type TS3721. The comparator U1A and the comparator U1B detect the voltage of the first current detection resistor and the second current detection resistor respectively to determine whether the current in the first bridge arm 11 and the second bridge arm 12 is too large and implement overcurrent protection.

[0036] It should be understood that by setting the inverter main power module 1, the output module 2, the AC load 3, the bridge arm overcurrent protection module 4 and the chip control module 5 in the circuit, when it is detected that the MOS tubes of the first bridge arm 11 and the second bridge arm 12 in the inverter main power module 1 have overcurrent, the bridge arm overcurrent protection module 4 detects the level and sends it to the chip control module 5, and the chip control module 5 will output high and low levels to control the opening or closing of the PWM signal of the inverter main power module 1 to realize the overcurrent protection function, thereby effectively protecting the MOS tube of the inverter main power module 1, the circuit structure is simple, and the working stability of the high-frequency off-grid system is improved.

[0037] See also Figure 3 , the current of the first bridge arm 11 flows through the first current detection resistor and inverts to flow through the MOS tube Q1 and the MOS tube Q2. When the voltage received by the negative input terminal of the comparator U1A is greater than the first preset over-current protection value of the negative input terminal of the comparator U1A, the output terminal of the comparator U1A outputs a first low voltage OSP and sends it to the chip control module. The chip control module detects the low level corresponding to the first low voltage OSP and turns off the PWM signal of the first bridge arm 11;

[0038] The first current detection resistor is composed of the resistor R1 and the resistor R2, and the first preset over-current protection value is a voltage value of 5V obtained by dividing the voltage between the resistor R7 and the resistor R9.

[0039] In this embodiment, when the voltage received by the positive input terminal of the comparator U1A is less than the first preset overcurrent protection value of the positive input terminal of the comparator U1A, the output terminal of the comparator U1A outputs a first high level and sends it to the chip control module 5, and the chip control module 5 turns on the PWM signal of the first bridge arm 11 according to the first high level. Overcurrent protection is a protection mode that causes the protection device to operate when the current exceeds a predetermined maximum value. When the current flowing through the protected component exceeds a predetermined value, the protection device starts, and uses a time limit to ensure the selectivity of the action, causing the circuit breaker to trip or give an alarm signal.

[0040] It should be noted that the process of overcurrent protection detection of the first bridge arm 11 is as follows: resistors R1 and R2 are current detection resistors, 5V is divided by resistors R7 and R9 to obtain a voltage value, which is the overcurrent protection value set for the high-frequency off-grid system; when the current of the first bridge arm 11, i.e. the left bridge arm, flows through the current detection resistor, a voltage will be generated. When the current of the inverter flowing through the MOS tube Q1 and the MOS tube Q2 is too large, the voltage input to the reverse end of the comparator U1A is greater than the same-direction end (the set overcurrent protection setting value), thereby outputting a low voltage OSP and sending it to the chip control module. After the chip control module detects the low level, it will be judged as abnormal, and all PWM signals will be turned off to achieve overcurrent protection and protect the high-frequency off-grid system. When the current value flowing through the MOS tube Q1 and the MOS tube Q2 is less than the same-direction end (the set overcurrent protection setting value), a high level is output, and the chip control module 5 detects that the high level is normal and will not start the protection action.

[0041] Optionally, the current of the second bridge arm 12 flows through the second current detection resistor and inverts to flow through the MOS transistor Q3 and the MOS transistor Q4. When the voltage received by the negative input terminal of the comparator U1B is greater than the second preset overcurrent protection value of the negative input terminal of the comparator U1B, the output terminal of the comparator U1B outputs a second low voltage OSP and sends it to the chip control module. The chip control module detects the low level corresponding to the second low voltage OSP and turns off the PWM signal of the second bridge arm 12.

[0042] The second current detection resistor is composed of the resistor R3 and the resistor R4, and the second preset over-current protection value is a voltage value of 5V obtained by dividing the resistor R13 and the resistor R14.

[0043] In this embodiment, when the voltage received at the positive input terminal of the comparator U1B is less than the second preset overcurrent protection value of the positive input terminal of the comparator U1B, the output terminal of the comparator U1B outputs a second high level and sends it to the chip control module, and the chip control module turns on the PWM signal of the second bridge arm 12 according to the second high level.

[0044] It should be noted that the process of overcurrent protection detection of the second bridge arm 12 is as follows: resistors R3 and R4 are current detection resistors, 5V is divided by resistors R13 and R14 to obtain a voltage value, which is the overcurrent protection value set for the high-frequency off-grid system; when the current of the second bridge arm 12, i.e. the right bridge arm, flows through the current detection resistor, a voltage will be generated. When the current of the inverter flowing through the MOS tube Q3 and the MOS tube Q4 is too large, the voltage input to the reverse end of the comparator U1B is greater than the same-direction end (the set overcurrent protection setting value), thereby outputting a low voltage OSP and sending it to the chip control module. After the chip control module detects the low level, it will be judged as abnormal, and all PWM signals will be turned off to achieve overcurrent protection and protect the high-frequency off-grid system. When the current value flowing through the MOS tube Q3 and the MOS tube Q4 is less than the same-direction end (the set overcurrent protection setting value), a high level is output, and the chip control module 5 detects that the high level is normal and will not start the protection action.

[0045] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A bridge arm overcurrent protection circuit for a high-frequency off-grid system, characterized in that: It includes an inverter main power module, an output module, an AC load, a bridge arm overcurrent protection module and a chip control module, wherein the inverter main power module and the bridge arm overcurrent protection module are connected to the chip control module, the bridge arm overcurrent protection module and the output module are connected to the inverter main power module, and the output module is connected to the AC load; The bridge arm overcurrent protection module is used to detect the operating voltage of the inverter main power module and output a corresponding electrical level to the chip control module according to the operating voltage. The chip control module controls the inverter main power module to send a PWM signal to the output module according to the electrical level, and the output module supplies power to the AC load according to the PWM signal.

2. The bridge arm overcurrent protection circuit of the high-frequency off-grid system according to claim 1, characterized in that: The inverter main power module comprises a bus, a capacitor C1, a first bridge arm and a second bridge arm, wherein the first bridge arm, the second bridge arm and the capacitor C1 are connected in parallel via the bus; The first bridge arm includes a MOS transistor Q1, a MOS transistor Q2, a resistor R1 and a resistor R2, the MOS transistor Q1 is connected to the MOS transistor Q2, the MOS transistor Q1 is connected to the anode of the capacitor C1, and the resistor R1 and the resistor R2 are connected in parallel to the cathode of the capacitor C1 and the MOS transistor Q2; The second bridge arm includes a MOS transistor Q3, a MOS transistor Q4, a resistor R3 and a resistor R4, the MOS transistor Q3 is connected to the MOS transistor Q4, the MOS transistor Q3 is connected to the anode of the capacitor C1, and the resistor R3 and the resistor R4 are connected in parallel to the cathode of the capacitor C1 and the MOS transistor Q4.

3. The bridge arm overcurrent protection circuit of the high-frequency off-grid system according to claim 2, characterized in that: The bridge arm overcurrent protection module comprises a first overcurrent protection circuit connected to the first bridge arm and a second overcurrent protection circuit connected to the second bridge arm; The first overcurrent protection circuit includes a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a capacitor C3, a capacitor C4 and a comparator U1A, the resistor R5 and the capacitor C3 are connected in parallel to the resistor R7, the resistor R7 and the R9 are connected in parallel to the positive input terminal of the comparator U1A, the resistor R6 and the capacitor C4 are connected in parallel to the resistor R8, and the resistor R8 is connected to the negative input terminal of the comparator U1A; The second overcurrent protection circuit includes a resistor R10, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a capacitor C5, a capacitor C6 and a comparator U1B, the resistor R10 and the capacitor C5 are connected in parallel to the resistor R12, the resistor R12 is connected to the negative input terminal of the comparator U1B, the resistor R11 and the capacitor C6 are connected in parallel to the resistor R13, the resistor R13 and the resistor R14 are connected in parallel to the positive input terminal of the comparator U1B, and the output terminal of the comparator U1B is connected to the output terminal of the comparator U1A.

4. The bridge arm overcurrent protection circuit of the high-frequency off-grid system according to claim 3, characterized in that: The current of the first bridge arm flows through the first current detection resistor and inverts and flows through the MOS transistor Q1 and the MOS transistor Q2. When the voltage received by the negative input terminal of the comparator U1A is greater than the first preset overcurrent protection value of the negative input terminal of the comparator U1A, the output terminal of the comparator U1A outputs a first low voltage OSP and sends it to the chip control module. The chip control module detects the low level corresponding to the first low voltage OSP and turns off the PWM signal of the first bridge arm. The first current detection resistor is composed of the resistor R1 and the resistor R2, and the first preset over-current protection value is a voltage value of 5V obtained by dividing the voltage between the resistor R7 and the resistor R9.

5. The bridge arm overcurrent protection circuit of the high-frequency off-grid system according to claim 4, characterized in that: When the voltage received at the positive input terminal of the comparator U1A is less than the first preset overcurrent protection value of the positive input terminal of the comparator U1A, the output terminal of the comparator U1A outputs a first high level and sends it to the chip control module, and the chip control module turns on the PWM signal of the first bridge arm according to the first high level.

6. The bridge arm overcurrent protection circuit of the high-frequency off-grid system according to claim 3, characterized in that: The current of the second bridge arm flows through the second current detection resistor and inverts and flows through the MOS transistor Q3 and the MOS transistor Q4. When the voltage received by the negative input terminal of the comparator U1B is greater than the second preset overcurrent protection value of the negative input terminal of the comparator U1B, the output terminal of the comparator U1B outputs the second low voltage OSP and sends it to the chip control module. The chip control module detects the low level corresponding to the second low voltage OSP and turns off the PWM signal of the second bridge arm. The second current detection resistor is composed of the resistor R3 and the resistor R4, and the second preset over-current protection value is a voltage value of 5V obtained by dividing the resistor R13 and the resistor R14.

7. The bridge arm overcurrent protection circuit of the high-frequency off-grid system according to claim 6, characterized in that: When the voltage received at the positive input terminal of the comparator U1B is less than the second preset over-current protection value of the positive input terminal of the comparator U1B, the output terminal of the comparator U1B outputs a second high level and sends it to the chip control module, and the chip control module turns on the PWM signal of the second bridge arm according to the second high level.

8. The bridge arm overcurrent protection circuit of the high-frequency off-grid system according to claim 3, characterized in that: The bridge arm overcurrent protection module aggregates the overcurrent protection signals of the first bridge arm and the second bridge arm through the first overcurrent protection circuit and the second overcurrent protection circuit and sends the aggregated signals to the chip control module.

9. The bridge arm overcurrent protection circuit of the high-frequency off-grid system according to claim 3, characterized in that: The chip control module includes a DSP chip and peripheral circuits. The chip control module receives the overcurrent protection signal to control the inverter main power module to send a PWM signal to control the on or off of the MOS tube, and controls the relay signal of the output module.

10. The bridge arm overcurrent protection circuit of the high-frequency off-grid system according to claim 9, characterized in that: The output module includes an inductor L1, an inductor L2, a capacitor C2 and a relay RY1. The inductor L1 and the inductor L2 are connected in parallel at both ends of the capacitor C2, and the inductor L1 and the capacitor C2 are connected to the relay RY1.

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