Overcurrent protection circuit of inverter

Abstract

The utility model relates to the technical field of over-current protection, in particular to an over-current protection circuit of an inverter, which comprises a first positive half-cycle driving module, a second positive half-cycle driving module, a first negative half-cycle driving module, a second negative half-cycle driving module and an over-current judgment module. The overcurrent judgment module is used for controlling the first positive half-cycle driving module and the second positive half-cycle driving module to turn off the first bridge arm and the fourth bridge arm only when it is detected that the positive half-cycle current signals of the first bridge arm and the fourth bridge arm or the negative half-cycle current signals of the second bridge arm and the third bridge arm exceed a preset signal range; or the first negative half-cycle driving module and the second negative half-cycle driving module are controlled to turn off the second bridge arm and the third bridge arm; the structure is simpler, the cost is lower, and the normal operation of the inverter can be quickly recovered after the overcurrent fault is removed.

Description

Technical Field

[0001] The utility model relates to the technical field of overcurrent protection, in particular to an overcurrent protection circuit of an inverter. Background Art

[0002] The core capability of the inverter is to convert direct current into alternating current. It is widely used in various fields, especially in the fields of home appliances, photovoltaics and energy storage. It is a key device. The stable operation of the inverter in the system is crucial to the efficiency and safety of the entire system. Therefore, in order to prevent the working current of the inverter from exceeding its design tolerance range and to avoid overcurrent causing oscillation or unstable operation of the system, the inverter is usually equipped with overcurrent protection measures.

[0003] At present, the overcurrent protection method of the inverter uses current transformers and Hall sensors to collect the current on the primary side of the transformer in the inverter and transmit it to the controller to determine whether there is an overcurrent phenomenon in the inverter. The controller then outputs a protection signal to shut down the inverter for overcurrent protection.

[0004] The current overcurrent protection method uses high-current power devices for current collection, but the overcurrent of the inverter is relatively small compared to its current collection range, resulting in excess sampling performance and high cost of high-current power devices. More importantly, the sampling device does not have the ability to control the inverter. After the overcurrent fault is removed, the controller must determine and restore the normal operation of the inverter, resulting in untimely recovery and affecting the normal operation of the load. For example, in application scenarios such as air conditioners, refrigerators, and motors with large instantaneous current at startup, it is necessary to suppress the current in time at the moment of startup, and then immediately resume normal operation to ensure the normal operation of the load. Utility Model Content

[0005] In view of the above-mentioned defects, the purpose of the utility model is to provide an overcurrent protection circuit for an inverter, which has a simpler structure, lower cost, and can quickly restore the normal operation of the inverter after the overcurrent fault is removed.

[0006] To achieve this purpose, the utility model adopts the following technical solutions:

[0007] An overcurrent protection circuit for an inverter comprises a first positive half-cycle drive module, a second positive half-cycle drive module, a first negative half-cycle drive module, a second negative half-cycle drive module and an overcurrent judgment module; the output ends of the first positive half-cycle drive module, the second positive half-cycle drive module, the first negative half-cycle drive module and the second negative half-cycle drive module are respectively electrically connected to the control ends of the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm of the inverter; the GND ends of the first positive half-cycle drive module, the second positive half-cycle drive module, the first negative half-cycle drive module and the second negative half-cycle drive module are respectively electrically connected to the negative ends of the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm; the first collection end and the second collection end of the overcurrent judgment module are respectively electrically connected to the negative ends of the third bridge arm and the fourth bridge arm; the first output end, the fourth output end, the second output end and the third output end of the overcurrent judgment module are respectively electrically connected to the input ends of the first positive half-cycle drive module, the second positive half-cycle drive module, the first negative half-cycle drive module and the second negative half-cycle drive module;

[0008] The overcurrent judgment module is used to control the first positive half-cycle driving module and the second positive half-cycle driving module to turn off the first bridge arm and the fourth bridge arm, or control the first negative half-cycle driving module and the second negative half-cycle driving module to turn off the second bridge arm and the third bridge arm only when it is detected that the positive half-cycle current signal of the first bridge arm and the fourth bridge arm or the negative half-cycle current signal of the second bridge arm and the third bridge arm exceeds a preset signal range.

[0009] Further, the overcurrent judgment module includes an amplifier circuit, a comparison circuit, a first isolation circuit, a second isolation circuit, a third isolation circuit and a fourth isolation circuit; the output ends of the first isolation circuit, the second isolation circuit, the third isolation circuit and the fourth isolation circuit are respectively used as the first output end, the second output end, the third output end and the fourth output end of the overcurrent judgment module, and the first input end and the second input end of the amplifier circuit are respectively used as the second collection end and the first collection end of the overcurrent judgment module;

[0010] The first input terminal and the second input terminal of the comparison circuit are both electrically connected to the output terminal of the amplifier circuit, the input terminals of the first isolation circuit and the second isolation circuit are both electrically connected to the first output terminal of the comparison circuit, and the input terminals of the third isolation circuit and the fourth isolation circuit are both electrically connected to the second output terminal of the comparison circuit;

[0011] The amplifier circuit is used to amplify the positive half-cycle current signal or the negative half-cycle current signal;

[0012] The comparison circuit is used for outputting a shutdown signal when the received positive half-cycle current signal or the received negative half-cycle current signal exceeds the preset signal range;

[0013] The first isolation circuit, the second isolation circuit, the third isolation circuit and the fourth isolation circuit are all used to isolate output side signal interference.

[0014] Further, the comparison circuit includes a resistor R6, a resistor R9, a resistor R10, a resistor R13, a resistor R14, a resistor R15, a comparator U5A and a comparator U5B; the positive input terminal of the comparator U5A is used as the first input terminal of the comparison circuit, the output terminal of the comparator U5A is used as the first output terminal of the comparison circuit, and the output terminal of the comparator U5B is used as the second output terminal of the comparison circuit;

[0015] One end of the resistor R10 is connected to a reference voltage Vef, the other end of the resistor R10 and one end of the resistor R9 are both electrically connected to the negative input end of the comparator U5A, one end of the resistor R9 is grounded, one end of the resistor R6 is electrically connected to the positive input end of the comparator U5A, the other end of the resistor R6 and one end of the resistor R5 are both electrically connected to the output end of the comparator U5A, the other end of the resistor R5 is connected to a +5V power supply, the output end of the comparator U5A is electrically connected to the output end of the comparator U5B, one end of the resistor R14 is connected to a reference voltage Vef, the other end of the resistor R14 and one end of the resistor R13 are both electrically connected to the positive input end of the comparator U5B, the other end of the resistor R13 is grounded, one end of the resistor R15 is electrically connected to the positive input end of the comparator U5B, and the other end of the resistor R15 is electrically connected to the output end of the comparator U5B.

[0016] Furthermore, the preset signal range includes a positive half-cycle threshold UI1 and a negative half-cycle threshold UI2; only when the positive half-cycle current signal is greater than the positive half-cycle threshold UI1 or less than the negative half-cycle threshold UI2, the comparison circuit 52 outputs the shutdown signal.

[0017] Further, the positive half cycle threshold UI1 is: UI1 = [Vef / (R14+R13)]*R13, where R13 and R14 are the resistance values ​​of resistor R13 and resistor R14;

[0018] The negative half-cycle threshold UI2 is: UI2=[Vef / (R10+R9)]*R9, wherein R9 and R10 are the resistance values ​​of the resistor R9 and the resistor R10.

[0019] Furthermore, the circuit structures of the first positive half-cycle driving module, the second positive half-cycle driving module, the first negative half-cycle driving module and the second negative half-cycle driving module are the same;

[0020] The first positive half-cycle driving module includes a resistor R1 and a photocoupler U1; the output end of the photocoupler U1 is used as the output end of the first positive half-cycle driving module, the GND end of the photocoupler U1 is used as the GND end of the first positive half-cycle driving module, and the cathode of the photocoupler U1 is used as the input end of the first positive half-cycle driving module;

[0021] The anode of the photocoupler U1 and one end of the resistor R1 are both connected to a +5V power supply, the cathode of the photocoupler U1 is electrically connected to the other end of the resistor R1, and the VCC end of the photocoupler U1 is connected to a VCC power supply.

[0022] Further, the amplifier circuit includes a resistor R7, a resistor R8, a resistor R11, a resistor R12, a capacitor C2, a capacitor C3 and a comparator U6A; the output end of the comparator U6A is used as the output end of the amplifier circuit, one end of the resistor R7 is used as the first input end of the amplifier circuit, and one end of the resistor R11 is used as the second input end of the amplifier circuit;

[0023] The other end of the resistor R7, one end of the resistor R8, and one end of the capacitor C2 are electrically connected to the negative input terminal of the comparator U6A, the other end of the capacitor C2 and the other end of the resistor R8 are electrically connected to the output terminal of the comparator U6A, the other end of the resistor R11, one end of the resistor R12, and one end of the capacitor C3 are electrically connected to the positive input terminal of the comparator U6A, and the other end of the resistor R12 and the other end of the capacitor C3 are connected to the +1.65VDA power supply.

[0024] Furthermore, the circuit structures of the first isolation circuit, the second isolation circuit, the third isolation circuit and the fourth isolation circuit are the same;

[0025] The first isolation circuit is a diode D2; the anode of the diode D2 is used as the output end of the first isolation circuit, and the cathode of the diode D2 is used as the input end of the first isolation circuit.

[0026] The technical solution provided by the utility model may include the following beneficial effects: four driving modules are electrically connected to the four bridge arms of the H-bridge inverter circuit respectively, and then the overcurrent judgment module detects a sinusoidal current signal from the ground terminal of the bridge arm, that is, when the first bridge arm and the fourth bridge arm are turned on, a positive half-cycle current signal of the B+ power supply is detected through the first bridge arm, the transformer TX1, the fourth bridge arm to the ground terminal; when the second bridge arm and the third bridge arm are turned on, a negative half-cycle current signal of the B+ power supply is detected through the second bridge arm, the transformer TX1, the third bridge arm to the ground terminal; thus, the overcurrent judgment module can judge whether the sinusoidal current signal exceeds the preset signal range through the positive half-cycle current signal and the negative half-cycle current signal at this time, and only shut down the corresponding bridge arm when it exceeds, so that all the bridge arms are in the off state, so as to realize overcurrent protection; when it does not exceed the preset signal range, the overcurrent judgment module does not control the bridge arm, so as to realize rapid recovery of the normal operation of the inverter after the overcurrent fault is removed.

[0027] In summary, the overcurrent protection circuit eliminates the high-cost acquisition devices and controllers, has a simpler structure, lower cost, and can quickly restore the normal operation of the inverter after the overcurrent fault is removed. It is particularly suitable for overcurrent protection of instantaneous overcurrent. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a circuit diagram of an overcurrent protection circuit for an inverter according to one embodiment of the present invention.

[0029] Wherein: a first positive half-cycle driving module 1, a second positive half-cycle driving module 4, a first negative half-cycle driving module 2, a second negative half-cycle driving module 3, an overcurrent judgment module 5, a first bridge arm Q1, a second bridge arm Q2, a third bridge arm Q3, a fourth bridge arm Q4, a transformer TX1, an amplifier circuit 51, a comparison circuit 52, a first isolation circuit 53, a second isolation circuit 54, a third isolation circuit 55, a fourth isolation circuit 56, a resistor R6, a resistor R9, a resistor R10, a resistor R13, a resistor R14, a resistor R15, a comparator U5A, a comparator U5B, a resistor R1, a photocoupler U1, a resistor R7, a resistor R8, a resistor R11, a resistor R12, a capacitor C2, a capacitor C3, a comparator U6A, and a diode D2. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0031] In the description of the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0032] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0033] Combine the following Figure 1 , describing an overcurrent protection circuit of an inverter according to an embodiment of the utility model.

[0034] An overcurrent protection circuit for an inverter comprises a first positive half-cycle driving module 1, a second positive half-cycle driving module 4, a first negative half-cycle driving module 2, a second negative half-cycle driving module 3 and an overcurrent judgment module 5; the output ends of the first positive half-cycle driving module 1, the second positive half-cycle driving module 4, the first negative half-cycle driving module 2 and the second negative half-cycle driving module 3 are respectively electrically connected to the control ends of the first bridge arm Q1, the second bridge arm Q4, the third bridge arm Q2 and the fourth bridge arm Q3 of the inverter; the first positive half-cycle driving module 1, the second positive half-cycle driving module 4, the first negative half-cycle driving module 2 and the second negative half-cycle driving module 3 are respectively electrically connected to the control ends of the first bridge arm Q1, the second bridge arm Q4, the third bridge arm Q2 and the fourth bridge arm Q3 of the inverter; The GND terminals of the driving module 2 and the second negative half-cycle driving module 3 are electrically connected to the negative terminals of the first bridge arm Q1, the second bridge arm Q4, the third bridge arm Q2 and the fourth bridge arm Q3, respectively; the first collecting terminal and the second collecting terminal of the overcurrent judging module 5 are electrically connected to the negative terminals of the third bridge arm Q3 and the fourth bridge arm Q4, respectively; the first output terminal, the fourth output terminal, the second output terminal and the third output terminal of the overcurrent judging module 5 are electrically connected to the input terminals of the first positive half-cycle driving module 1, the second positive half-cycle driving module 4, the first negative half-cycle driving module 2 and the second negative half-cycle driving module 3, respectively;

[0035] The overcurrent judgment module 5 is used to control the first positive half-cycle driving module 1 and the second positive half-cycle driving module 4 to turn off the first bridge arm Q1 and the fourth bridge arm Q4, or control the first negative half-cycle driving module 2 and the second negative half-cycle driving module 3 to turn off the second bridge arm Q2 and the third bridge arm Q3, only when it is detected that the positive half-cycle current signal of the first bridge arm Q1 and the fourth bridge arm Q4 or the negative half-cycle current signal of the second bridge arm Q2 and the third bridge arm Q3 exceeds the preset signal range.

[0036] The inverter includes a first bridge arm Q1, a second bridge arm Q2, a third bridge arm Q3, a fourth bridge arm Q4 and a transformer TX1. Taking the bridge arm as an example, the gate of the MOS tube is the control end of the bridge arm, the drain of the MOS tube is the positive end of the bridge arm, the source of the MOS tube is the negative end of the bridge arm, the positive ends of the first bridge arm Q1 and the second bridge arm Q2 are both connected to the B+ power supply, the negative end of the first bridge arm Q1 and the positive end of the third bridge arm Q3 are both electrically connected to one end of the primary side of the transformer TX1, the negative end of the second bridge arm Q2 and the positive end of the fourth bridge arm Q4 are both electrically connected to the other end of the primary side of the transformer TX1, and the negative ends of the third bridge arm Q3 and the fourth bridge arm Q4 are both grounded, thereby forming an H-bridge inverter circuit of the inverter. The utility model proposes a preferred embodiment of an overcurrent protection circuit of an inverter, such as Figure 1 As shown, four driving modules are electrically connected to the four bridge arms of the H-bridge inverter circuit respectively, and then the overcurrent judgment module 5 detects the sinusoidal current signal from the ground terminal of the bridge arm, that is, when the first bridge arm Q1 and the fourth bridge arm Q4 are turned on, the positive half-cycle current signal of the B+ power supply is detected through the first bridge arm Q1, the transformer TX1, and the fourth bridge arm Q4 to the ground terminal; when the second bridge arm Q2 and the third bridge arm Q3 are turned on, the negative half-cycle current signal of the B+ power supply is detected through the second bridge arm Q2, the transformer TX1, and the third bridge arm Q3 to the ground terminal; thus, the overcurrent judgment module 5 can judge whether the sinusoidal current signal exceeds the preset signal range at this time through the positive half-cycle current signal and the negative half-cycle current signal, and only shut down the corresponding bridge arm when it exceeds, so that all the bridge arms are in the off state, so as to realize overcurrent protection; when it does not exceed the preset signal range, the overcurrent judgment module 5 does not control the bridge arm, so as to realize that the normal operation of the inverter is quickly restored after the overcurrent fault is removed.

[0037] In summary, the overcurrent protection circuit eliminates the high-cost acquisition devices and controllers, has a simpler structure, lower cost, and can quickly restore the normal operation of the inverter after the overcurrent fault is removed. It is particularly suitable for overcurrent protection of instantaneous overcurrent.

[0038] Furthermore, the overcurrent judgment module 5 includes an amplifier circuit 51, a comparison circuit 52, a first isolation circuit 53, a second isolation circuit 54, a third isolation circuit 55 and a fourth isolation circuit 56; the output ends of the first isolation circuit 53, the second isolation circuit 54, the third isolation circuit 55 and the fourth isolation circuit 56 are respectively used as the first output end, the second output end, the third output end and the fourth output end of the overcurrent judgment module 5, and the first input end and the second input end of the amplifier circuit 51 are respectively used as the second collection end and the first collection end of the overcurrent judgment module 5;

[0039] The first input terminal and the second input terminal of the comparison circuit 52 are both electrically connected to the output terminal of the amplifier circuit 51, the input terminals of the first isolation circuit 53 and the second isolation circuit 54 are both electrically connected to the first output terminal of the comparison circuit 52, and the input terminals of the third isolation circuit 55 and the fourth isolation circuit 56 are both electrically connected to the second output terminal of the comparison circuit 52;

[0040] The amplifier circuit 51 is used to amplify the positive half-cycle current signal or the negative half-cycle current signal;

[0041] The comparison circuit 52 is used to output a shutdown signal when the received positive half-cycle current signal or negative half-cycle current signal exceeds a preset signal range;

[0042] The first isolation circuit 53 , the second isolation circuit 54 , the third isolation circuit 55 and the fourth isolation circuit 56 are all used to isolate output side signal interference.

[0043] In this embodiment, the overcurrent judgment module 5 first amplifies the collected positive half-cycle current signal or negative half-cycle current signal by the amplifier circuit 51 so that the comparison circuit 52 can identify it; then the comparison circuit 52 determines whether the positive half-cycle current signal or the negative half-cycle current signal exceeds the preset signal range, and outputs a shutdown signal only when it exceeds, otherwise it does not take action, thereby realizing the overcurrent protection logic; finally, the first isolation circuit 53, the second isolation circuit 54, the third isolation circuit 55 and the fourth isolation circuit 56 isolate the output side signal interference, that is, prevent the reverse output signal of the driving module from being transmitted to the comparison circuit 52 to cause interference.

[0044] Furthermore, the comparison circuit 52 includes a resistor R6, a resistor R9, a resistor R10, a resistor R13, a resistor R14, a resistor R15, a comparator U5A and a comparator U5B; the positive input terminal of the comparator U5A is used as a first input terminal of the comparison circuit 52, the output terminal of the comparator U5A is used as a first output terminal of the comparison circuit 52, and the output terminal of the comparator U5B is used as a second output terminal of the comparison circuit 52;

[0045] One end of resistor R10 is connected to a reference voltage Vef, the other end of resistor R10 and one end of resistor R9 are electrically connected to the negative input terminal of comparator U5A, one end of resistor R9 is grounded, one end of resistor R6 is electrically connected to the positive input terminal of comparator U5A, the other end of resistor R6 and one end of resistor R5 are electrically connected to the output terminal of comparator U5A, the other end of resistor R5 is connected to a +5V power supply, the output terminal of comparator U5A is electrically connected to the output terminal of comparator U5B, one end of resistor R14 is connected to the reference voltage Vef, the other end of resistor R14 and one end of resistor R13 are electrically connected to the positive input terminal of comparator U5B, the other end of resistor R13 is grounded, one end of resistor R15 is electrically connected to the positive input terminal of comparator U5B, and the other end of resistor R15 is electrically connected to the output terminal of comparator U5B.

[0046] In this embodiment, the comparison circuit 52 is composed of comparator U5A and comparator U5B and their peripheral circuits to form positive and negative half-cycle comparator circuits respectively, which can judge the positive and negative half-cycle peak values ​​of the sinusoidal current signal respectively. When the positive and negative half-cycle peak values ​​are too large, it means that they exceed the preset signal range.

[0047] Furthermore, the preset signal range includes a positive half-cycle threshold UI1 and a negative half-cycle threshold UI2; only when the positive half-cycle current signal is greater than the positive half-cycle threshold UI1 or less than the negative half-cycle threshold UI2, the comparison circuit 52 outputs a shutdown signal.

[0048] In this embodiment, since the comparison circuit 52 is composed of positive and negative half-cycle comparator circuits, the preset signal range is also composed of positive half-cycle threshold UI1 and negative half-cycle threshold UI2 respectively. It should be noted that the shutdown signal is a low-level signal, which can cause the driving module to shut down the bridge arm.

[0049] Further, the positive half cycle threshold UI1 is: UI1 = [Vef / (R14+R13)]*R13, where R13 and R14 are the resistance values ​​of the resistor R13 and the resistor R14;

[0050] The negative half cycle threshold UI2 is: UI2=[Vef / (R10+R9)]*R9, where R9 and R10 are the resistance values ​​of resistors R9 and R10.

[0051] In this embodiment, the positive half-cycle threshold UI1 is set by the positive half-cycle comparison circuit. From the circuit analysis, it can be known that UI1 = [Vef / (R14+R13)]*R13. The positive half-cycle threshold UI1 can be freely set by adjusting the reference voltage Vef; the negative half-cycle threshold UI2 is the same.

[0052] Furthermore, the circuit structures of the first positive half-cycle driving module 1, the second positive half-cycle driving module 4, the first negative half-cycle driving module 2 and the second negative half-cycle driving module 3 are the same;

[0053] The first positive half-cycle driving module 1 includes a resistor R1 and a photocoupler U1; the output end of the photocoupler U1 is used as the output end of the first positive half-cycle driving module 1, the GND end of the photocoupler U1 is used as the GND end of the first positive half-cycle driving module 1, and the cathode of the photocoupler U1 is used as the input end of the first positive half-cycle driving module 1;

[0054] The anode of the photocoupler U1 and one end of the resistor R1 are both connected to a +5V power supply, the cathode of the photocoupler U1 is electrically connected to the other end of the resistor R1, and the VCC end of the photocoupler U1 is connected to the VCC power supply.

[0055] In this embodiment, because the driving module needs to be able to drive the control bridge arm to shut down when overcurrent occurs and has the functions of isolating the inverter and overcurrent protection circuit, the driving module is preferably composed of a photocoupler U1, which has the ability to drive power devices such as MOS tubes and IGBTs. In addition, because the first positive half-cycle driving module 1, the second positive half-cycle driving module 4, the first negative half-cycle driving module 2, and the second negative half-cycle driving module 3 are all used to control the bridge arm and have the same function, the circuit structure can be the same.

[0056] Further, the amplifier circuit 51 includes a resistor R7, a resistor R8, a resistor R11, a resistor R12, a capacitor C2, a capacitor C3 and a comparator U6A; the output end of the comparator U6A is used as the output end of the amplifier circuit 51, one end of the resistor R7 is used as the first input end of the amplifier circuit 51, and one end of the resistor R11 is used as the second input end of the amplifier circuit 51;

[0057] The other end of resistor R7, one end of resistor R8, and one end of capacitor C2 are electrically connected to the negative input terminal of comparator U6A, the other end of capacitor C2 and the other end of resistor R8 are electrically connected to the output terminal of comparator U6A, the other end of resistor R11, one end of resistor R12, and one end of capacitor C3 are electrically connected to the positive input terminal of comparator U6A, and the other end of resistor R12 and the other end of capacitor C3 are connected to the +1.65VDA power supply.

[0058] In this embodiment, the amplifier circuit 51 is composed of a comparator U6A and its peripheral circuits to form an operational amplifier circuit to achieve the amplification function. It should be noted that the +1.65VDA power supply is used to provide a DC bias for the input signal of the comparator U6A.

[0059] Furthermore, the circuit structures of the first isolation circuit 53, the second isolation circuit 54, the third isolation circuit 55 and the fourth isolation circuit 56 are the same;

[0060] The first isolation circuit 53 is a diode D2 ; the anode of the diode D2 is used as the output end of the first isolation circuit 53 , and the cathode of the diode D2 is used as the input end of the first isolation circuit 53 .

[0061] In this embodiment, due to the unidirectional conductivity of the diode, the reverse protection function of the isolation circuit can be realized, making the circuit the simplest, so the first isolation circuit 53, the second isolation circuit 54, the third isolation circuit 55 and the fourth isolation circuit 56 are all diodes, that is, Figure 1 The output ends of the diode D2, the diode D4, the diode D3, the diode D1, the first isolation circuit 53, the second isolation circuit 54, the third isolation circuit 55 and the fourth isolation circuit 56 are all anodes of their respective diodes, and the input ends of the first isolation circuit 53, the second isolation circuit 54, the third isolation circuit 55 and the fourth isolation circuit 56 are all cathodes of their respective diodes.

[0062] Other structures and operations of the overcurrent protection circuit of an inverter according to the embodiment of the utility model are known to ordinary technicians in the field and will not be described in detail here.

[0063] In the description of this specification, the description with reference to the terms "embodiment", "example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0064] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An overcurrent protection circuit for an inverter, characterized in that: It includes a first positive half-cycle drive module, a second positive half-cycle drive module, a first negative half-cycle drive module, a second negative half-cycle drive module and an overcurrent judgment module; the output ends of the first positive half-cycle drive module, the second positive half-cycle drive module, the first negative half-cycle drive module and the second negative half-cycle drive module are respectively electrically connected to the control ends of the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm of the inverter, the GND ends of the first positive half-cycle drive module, the second positive half-cycle drive module, the first negative half-cycle drive module and the second negative half-cycle drive module are respectively electrically connected to the negative ends of the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm, the first collection end and the second collection end of the overcurrent judgment module are respectively electrically connected to the negative ends of the third bridge arm and the fourth bridge arm, and the first output end, the fourth output end, the second output end and the third output end of the overcurrent judgment module are respectively electrically connected to the input ends of the first positive half-cycle drive module, the second positive half-cycle drive module, the first negative half-cycle drive module and the second negative half-cycle drive module; The overcurrent judgment module is used to control the first positive half-cycle driving module and the second positive half-cycle driving module to turn off the first bridge arm and the fourth bridge arm, or control the first negative half-cycle driving module and the second negative half-cycle driving module to turn off the second bridge arm and the third bridge arm only when it is detected that the positive half-cycle current signal of the first bridge arm and the fourth bridge arm or the negative half-cycle current signal of the second bridge arm and the third bridge arm exceeds a preset signal range.

2. The overcurrent protection circuit of an inverter according to claim 1, characterized in that: The overcurrent judgment module comprises an amplifier circuit, a comparison circuit, a first isolation circuit, a second isolation circuit, a third isolation circuit and a fourth isolation circuit; the output ends of the first isolation circuit, the second isolation circuit, the third isolation circuit and the fourth isolation circuit are respectively used as the first output end, the second output end, the third output end and the fourth output end of the overcurrent judgment module, and the first input end and the second input end of the amplifier circuit are respectively used as the second collection end and the first collection end of the overcurrent judgment module; The first input terminal and the second input terminal of the comparison circuit are both electrically connected to the output terminal of the amplifier circuit, the input terminals of the first isolation circuit and the second isolation circuit are both electrically connected to the first output terminal of the comparison circuit, and the input terminals of the third isolation circuit and the fourth isolation circuit are both electrically connected to the second output terminal of the comparison circuit; The amplifier circuit is used to amplify the positive half-cycle current signal or the negative half-cycle current signal; The comparison circuit is used for outputting a shutdown signal when the received positive half-cycle current signal or the received negative half-cycle current signal exceeds the preset signal range; The first isolation circuit, the second isolation circuit, the third isolation circuit and the fourth isolation circuit are all used to isolate output side signal interference.

3. The overcurrent protection circuit of an inverter according to claim 2, characterized in that: The comparison circuit includes a resistor R6, a resistor R9, a resistor R10, a resistor R13, a resistor R14, a resistor R15, a comparator U5A and a comparator U5B; the positive input terminal of the comparator U5A is used as the first input terminal of the comparison circuit, the output terminal of the comparator U5A is used as the first output terminal of the comparison circuit, and the output terminal of the comparator U5B is used as the second output terminal of the comparison circuit; One end of the resistor R10 is connected to a reference voltage Vef, the other end of the resistor R10 and one end of the resistor R9 are both electrically connected to the negative input end of the comparator U5A, one end of the resistor R9 is grounded, one end of the resistor R6 is electrically connected to the positive input end of the comparator U5A, the other end of the resistor R6 and one end of the resistor R5 are both electrically connected to the output end of the comparator U5A, the other end of the resistor R5 is connected to a +5V power supply, the output end of the comparator U5A is electrically connected to the output end of the comparator U5B, one end of the resistor R14 is connected to a reference voltage Vef, the other end of the resistor R14 and one end of the resistor R13 are both electrically connected to the positive input end of the comparator U5B, the other end of the resistor R13 is grounded, one end of the resistor R15 is electrically connected to the positive input end of the comparator U5B, and the other end of the resistor R15 is electrically connected to the output end of the comparator U5B.

4. The overcurrent protection circuit of an inverter according to claim 3, characterized in that: The preset signal range includes a positive half-cycle threshold UI1 and a negative half-cycle threshold UI2; only when the positive half-cycle current signal is greater than the positive half-cycle threshold UI1 or less than the negative half-cycle threshold UI2, the comparison circuit (52) outputs the shutdown signal.

5. The overcurrent protection circuit of an inverter according to claim 4, characterized in that: The positive half cycle threshold UI1 is: UI1 = [Vef / (R14+R13)]*R13, where R13 and R14 are the resistance values ​​of resistor R13 and resistor R14; The negative half-cycle threshold UI2 is: UI2=[Vef / (R10+R9)]*R9, wherein R9 and R10 are the resistance values ​​of the resistor R9 and the resistor R10.

6. The overcurrent protection circuit of an inverter according to claim 1, characterized in that: The circuit structures of the first positive half-cycle driving module, the second positive half-cycle driving module, the first negative half-cycle driving module and the second negative half-cycle driving module are the same; The first positive half-cycle driving module includes a resistor R1 and a photocoupler U1; the output end of the photocoupler U1 is used as the output end of the first positive half-cycle driving module, the GND end of the photocoupler U1 is used as the GND end of the first positive half-cycle driving module, and the cathode of the photocoupler U1 is used as the input end of the first positive half-cycle driving module; The anode of the photocoupler U1 and one end of the resistor R1 are both connected to a +5V power supply, the cathode of the photocoupler U1 is electrically connected to the other end of the resistor R1, and the VCC end of the photocoupler U1 is connected to a VCC power supply.

7. The overcurrent protection circuit of an inverter according to claim 2, characterized in that: The amplifier circuit includes a resistor R7, a resistor R8, a resistor R11, a resistor R12, a capacitor C2, a capacitor C3 and a comparator U6A; the output end of the comparator U6A is used as the output end of the amplifier circuit, one end of the resistor R7 is used as the first input end of the amplifier circuit, and one end of the resistor R11 is used as the second input end of the amplifier circuit; The other end of the resistor R7, one end of the resistor R8, and one end of the capacitor C2 are electrically connected to the negative input terminal of the comparator U6A, the other end of the capacitor C2 and the other end of the resistor R8 are electrically connected to the output terminal of the comparator U6A, the other end of the resistor R11, one end of the resistor R12, and one end of the capacitor C3 are electrically connected to the positive input terminal of the comparator U6A, and the other end of the resistor R12 and the other end of the capacitor C3 are connected to the +1.65VDA power supply.

8. The overcurrent protection circuit of an inverter according to claim 2, characterized in that: The first isolation circuit, the second isolation circuit, the third isolation circuit and the fourth isolation circuit have the same circuit structure; The first isolation circuit is a diode D2; the anode of the diode D2 is used as the output end of the first isolation circuit, and the cathode of the diode D2 is used as the input end of the first isolation circuit.

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