Alternating current quantity bilateral protection circuit and method based on single power supply and battery pack

Abstract

The invention discloses an alternating-current quantity bilateral protection circuit and method based on a single power supply and a battery pack. According to the circuit, two comparison circuits are arranged, a positive half-cycle voltage is compared with a positive half-cycle reference voltage through a first comparison circuit, a negative half-cycle voltage is compared with a negative half-cycle reference voltage through a second comparison circuit, and meanwhile, an external protection signal is connected, so that overcurrent protection of the inverter is realized. According to the method, alternating-current quantity voltage is raised by half of preset reference voltage, negative voltage is converted into positive voltage, and comparison of negative half-cycle voltage is achieved in combination with an inverter circuit. By combining the circuit and the method, the bilateral protection of the alternating current quantity of the inverter can be realized only by a single power supply.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management systems, and in particular to an alternating current bilateral protection circuit, method and battery pack based on a single power supply. Background Art

[0002] With the widespread popularity of energy storage equipment, various technologies in battery packs have developed rapidly. Inverters, as a device that can convert direct current into alternating current, are indispensable in energy storage equipment. However, the components in the inverter are often easily damaged due to overcurrent problems, so overcurrent protection of the inverter is very important. At this stage, the conventional practices for inverter overcurrent protection are divided into software methods and hardware methods. The software method requires cumbersome steps to implement inverter overcurrent protection, and the response speed is low; while the hardware method is used to implement the inverter AC quantity comparison protection, usually using positive and negative power supplies for independent protection, or using absolute value circuits for protection. Both methods require the use of positive and negative power supplies, of which the negative power supply needs to be added additionally. Therefore, a new AC quantity comparison protection circuit and method are needed to improve the above problems. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a bilateral protection circuit, method and battery pack for AC quantity based on a single power supply. The circuit is provided with two comparison circuits, and the positive half-cycle voltage is compared with the positive half-cycle reference voltage through the first comparison circuit, and the negative half-cycle voltage is compared with the negative half-cycle reference voltage through the second comparison circuit, and an external protection signal is connected at the same time to realize overcurrent protection of the inverter. The method converts the negative voltage into a positive voltage by raising the AC quantity voltage by half of the preset reference voltage, and combines the inverter circuit to realize the comparison of the negative half-cycle voltage. Combined with the above circuit and method, bilateral protection of the inverter AC quantity can be realized with only a single power supply.

[0004] The technical solution adopted by the present invention is specifically: an AC bilateral protection circuit based on a single power supply according to an embodiment of the present invention includes a first comparison circuit, a second comparison circuit and an inverter circuit, wherein the first comparison circuit includes a first comparator, the inverting input terminal of the first comparator is connected to the positive half-cycle voltage of the AC quantity, and the output terminal is connected to an external protection signal; the second comparison circuit includes a second comparator, and the inverter circuit includes a third comparator, the inverting input terminal of the second comparator is connected to the negative half-cycle voltage of the AC quantity, the output terminal is connected to the inverting input terminal of the third comparator, and the output terminal of the third comparator is connected to an external protection signal. Among them, the positive power supply terminals of the first comparator, the second comparator and the third comparator are connected to the onboard voltage, and the negative power supply terminals are grounded.

[0005] As an optional scheme of the technical scheme of the present invention, the in-phase input terminal of the first comparator is connected to the first resistor and then to the positive half-cycle reference voltage, connected to the second resistor and the first capacitor in parallel and then to ground, and simultaneously connected to the first diode and the third resistor in series and then to the output terminal of the first comparator, wherein the anode of the first diode is connected to the in-phase input terminal of the first comparator; the inverting input terminal of the first comparator is connected to the fourth resistor and then to the positive half-cycle voltage of the alternating current, and simultaneously connected to the second capacitor and the second diode in parallel and then to ground, wherein the cathode of the second diode is connected to the inverting input terminal of the first comparator; the output terminal of the first comparator is connected to the fifth resistor, the fifth resistor is connected in series with the sixth resistor and then to the onboard voltage, connected in series with the third capacitor and then to ground, and simultaneously connected in series with the third diode and then to the external protection signal, wherein the cathode of the third diode is connected to the fifth resistor.

[0006] As an optional scheme of the technical scheme of the present invention, the in-phase input terminal of the second comparator is connected to the seventh resistor and then to the negative half-cycle reference voltage, connected to the eighth resistor and the fourth capacitor in parallel and then to ground, and connected to the fourth diode and the ninth resistor in series and then to the output terminal of the second comparator, wherein the positive electrode of the fourth diode is connected to the in-phase input terminal of the second comparator; the inverting input terminal of the second comparator is connected to the tenth resistor and then to the negative half-cycle voltage of the alternating current, and connected to the fifth capacitor and the fifth diode in parallel and then to ground, wherein the cathode of the fifth diode is connected to the inverting input terminal of the second comparator; the output terminal of the second comparator is connected to the eleventh resistor, and the eleventh resistor is connected in series with the twelfth resistor and then to the board voltage, and is connected in series with the sixth capacitor and then to ground; the positive power supply terminal of the second comparator is connected to the board voltage, and is connected in series with the seventh capacitor and then to ground, and the negative power supply terminal is grounded.

[0007] As an optional scheme of the technical scheme of the present invention, the non-inverting input terminal of the third comparator is connected to the thirteenth resistor and then to the inverting reference voltage, connected to the fourteenth resistor and the eighth capacitor in parallel and then to ground, and at the same time connected to the fifteenth resistor and then to the output terminal of the third comparator; the inverting input terminal of the third comparator is connected in series with the eleventh resistor and then to the output terminal of the second comparator; the output terminal of the third comparator is connected in series with the sixteenth resistor and then to the board voltage, connected in series with the ninth capacitor and then to ground, and at the same time connected in series with the sixth diode and then to the external protection signal, wherein the cathode of the sixth diode is connected to the output terminal of the third comparator.

[0008] As an optional solution of the technical solution of the present invention, the first comparator non-inverting input terminal is further provided with a first voltage detection terminal.

[0009] As an optional solution of the technical solution of the present invention, the second comparator non-inverting input terminal is further provided with a second voltage detection terminal.

[0010] As an optional solution of the technical solution of the present invention, according to another embodiment of the present invention, a bilateral protection method for AC quantity based on a single power supply is provided, using the above-mentioned bilateral protection circuit for AC quantity based on a single power supply, and the method comprises the steps of: S1: Raise the input AC voltage by 0.5V cc , the peak-to-peak value of the AC voltage is ±V0, the V cc is the preset reference voltage, and V cc > ±V0, set the first comparator reference voltage V1 and the second comparator reference voltage V2, where (V0+0.5V cc )<V1<V cc ,0<V2<(-V0+0.5V cc ); S2: The positive half cycle of the AC quantity is input into the first comparison circuit. If the voltage value is greater than V1, the output of the first comparison circuit is low level, then the external protection signal is turned on and the AC quantity input stops; S3: The negative half cycle of the AC quantity is input into the second comparison circuit. If the voltage value is less than V2, the output of the second comparison circuit is high level, and after passing through the inverter circuit, the output is low level, then the external protection signal is turned on, and the AC quantity input stops; S4: After the external protection signal is turned on, the AC input stops, the output of the first comparison circuit returns to a high level, the output of the second comparison circuit returns to a low level, and the external protection signal is cut off.

[0011] As an optional solution of the technical solution of the present invention, a battery pack according to another embodiment of the present invention includes a battery cell, an inverter and a control circuit, and also includes the above-mentioned AC bilateral protection circuit based on a single power supply, and through the above-mentioned AC bilateral protection method based on a single power supply, overcurrent protection of the inverter is achieved.

[0012] The beneficial effects achieved by the present invention are as follows: the AC bilateral protection circuit based on a single power supply sets two comparison circuits, compares the positive half-cycle voltage with the positive half-cycle reference voltage through the first comparison circuit, and compares the negative half-cycle voltage with the negative half-cycle reference voltage through the second comparison circuit, and simultaneously connects an external protection signal to achieve overcurrent protection for the inverter. The AC bilateral protection method based on a single power supply converts the negative voltage into a positive voltage by raising the AC voltage by half of the preset reference voltage, and combines an inverter circuit to achieve comparison of the negative half-cycle voltage. Combined with the above circuit and method, only a single power supply is required to achieve bilateral protection of the inverter AC quantity, which is more accurate than software protection methods and less expensive than existing hardware protection methods.

[0013] The effects of the present invention are not limited to the above effects, and those skilled in the art can derive effects not described above from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The positive half-cycle voltage comparison circuit diagram of the AC quantity bilateral protection circuit based on a single power supply according to an embodiment of the present invention.

[0015] Figure 2 The present invention is a negative half-cycle voltage comparison circuit diagram and an inverter circuit diagram of an AC quantity bilateral protection circuit based on a single power supply according to an embodiment of the present invention.

[0016] Figure 3 It is the waveform of the AC voltage.

[0017] Figure 4 It is the waveform after the AC voltage is increased. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the following specific embodiments are only used to explain the present invention, but not to limit the present invention. Based on the following embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0019] It should be noted that in the description of the present invention, the terms "include" and "comprise" indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections, and are only for the convenience of describing the simplified description of the present invention, and therefore cannot be understood as limiting the present invention. In the description of the embodiments, unless otherwise clearly specified and limited, the terms "set", "connect" and the like should be understood in a broad sense. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. First embodiment

[0020] like Figure 1The diagram shows a positive half-cycle voltage comparison circuit diagram of an AC bilateral protection circuit based on a single power supply according to an embodiment of the present invention. The first comparison circuit comprises a first comparator CMP1, wherein the first comparator non-inverting input terminal is connected to the first resistor R1 and then to the positive half-cycle reference voltage, and then to the ground by connecting the second resistor R2 in series. The reference voltage value of the first comparator is set by adjusting the resistance values ​​of the first resistor R1 and the second resistor R2, and a first voltage detection terminal TP1 is provided at the non-inverting input terminal of the first comparator for detecting the reference voltage value. The first comparator non-inverting input terminal is connected to the ground after connecting the first capacitor C1 in series, and is connected to the output terminal of the first comparator after connecting the first diode D1 and the third resistor R3 in series. The positive electrode of the first diode D1 is connected to the non-inverting input terminal of the first comparator, and is used to limit the range of the output voltage, prevent the output voltage from being too high or too low, and thus protect the subsequent circuit from being damaged by overvoltage or undervoltage. The first comparator inverting input terminal is connected to the fourth resistor R4 and then to the AC positive half-cycle voltage, and is connected to the second capacitor C2 and the second diode D2 in parallel and then to the ground, wherein the cathode of the second diode D2 is connected to the inverting input terminal of the first comparator. The output end of the first comparator is connected to the fifth resistor R5, which is connected in series with the sixth resistor R6 and then connected to the board voltage, connected in series with the third capacitor C3 and then grounded, and connected in series with the third diode D3 and then connected to the external protection signal TZ1, wherein the cathode of the third diode D3 is connected to the fifth resistor R5, and the external protection signal TZ1 is connected to the board voltage. In addition, the positive power supply end of the first comparator is connected to the board voltage, and the negative power supply end is grounded.

[0021] In the above first comparison circuit, when the positive half-cycle voltage is less than the reference voltage value, the output terminal of the first comparator outputs a high level (onboard voltage), the third diode D3 is turned off, and the external protection signal TZ1 is turned off. When the positive half-cycle voltage is greater than the reference voltage value, the output terminal of the first comparator outputs a low level (grounded), the third diode D3 is turned on, the external protection signal TZ1 is turned on, and the protection is turned on.

[0022] like Figure 2The negative half-cycle voltage comparison circuit diagram and the inverter circuit diagram of the AC quantity bilateral protection circuit based on a single power supply according to an embodiment of the present invention are shown. The second comparison circuit comprises a second comparator CMP2, the in-phase input terminal of the second comparator is connected to the seventh resistor R7 and then to the negative half-cycle reference voltage, and is connected in series with the eighth resistor R8 and then to ground. The reference voltage value of the second comparator is set by adjusting the resistance values ​​of the seventh resistor R7 and the eighth resistor R8, and a second voltage detection terminal TP2 is provided at the in-phase input terminal of the second comparator for detecting the reference voltage value. The in-phase input terminal of the second comparator is connected in series with the fourth capacitor C4 and then to ground, and is connected in series with the fourth diode D4 and the ninth resistor R9 and then to the output terminal of the second comparator. The positive electrode of the fourth diode D4 is connected to the in-phase input terminal of the second comparator, and is used to limit the range of the output voltage to prevent the output voltage from being too high or too low, thereby protecting the subsequent circuit from damage by overvoltage or undervoltage. The inverting input terminal of the second comparator is connected to the tenth resistor R10 and then to the negative half-cycle voltage of the AC quantity, and is also connected to the fifth capacitor C5 and the fifth diode D5 in parallel and then to ground, wherein the cathode of the fifth diode D5 is connected to the inverting input terminal of the second comparator. The output terminal of the second comparator is connected to the eleventh resistor R11, which is connected in series with the twelfth resistor R12 and then to the board voltage, and is connected in series with the sixth capacitor C6 and then to ground. The negative power supply terminal of the second comparator is connected to the board voltage, and is also connected in series with the seventh capacitor C7 and then to ground, and the positive power supply terminal is grounded. Figure 2 As shown in the right half, the inverter circuit includes a third comparator CMP3, the third comparator non-inverting input terminal is connected to the thirteenth resistor R13 and then to the inverting reference voltage, connected to the fourteenth resistor R14 and the eighth capacitor C8 in parallel and then to ground, and connected to the fifteenth resistor R15 and then to the output terminal of the third comparator, and the reference voltage value of the second comparator is set by adjusting the resistance values ​​of the thirteenth resistor R13 and the fourteenth resistor R14. As an inverter, the reference voltage is usually set to half of the inverting input terminal voltage. The inverting input terminal of the third comparator is connected to the eleventh resistor R11 and connected to the output terminal of the second comparator, the output terminal of the third comparator is connected in series with the sixteenth resistor R16 and then to the board voltage, connected in series with the ninth capacitor C9 and then to ground, and at the same time connected in series with the sixth diode D6 and then to the external protection signal TZ1, wherein the cathode of the sixth diode D6 is connected to the output terminal of the third comparator. In addition, the positive power supply terminal of the third comparator is connected to the board voltage, and the negative power supply terminal is grounded.

[0023] In the above-mentioned second comparison circuit, the input AC voltage needs to be raised by 0.5V0, where V0 is the peak-to-peak value of the AC voltage. When the negative half-cycle voltage is less than the reference voltage value, the output terminal of the second comparator outputs a high level (on-board voltage), that is, the inverting input terminal of the third comparator inputs a high level, then the output terminal of the third comparator outputs a low level (grounded), the sixth diode D6 is turned on, the external protection signal TZ1 is turned on, and the protection is turned on. When the negative half-cycle voltage is greater than the reference voltage value, the output terminal of the second comparator outputs a low level (grounded), that is, the inverting input terminal of the third comparator inputs a low level, then the output terminal of the third comparator outputs a high level (on-board voltage), the sixth diode D6 is turned off, and the external protection signal TZ1 is turned on. Second embodiment

[0024] The AC bilateral protection circuit based on a single power supply described in the first embodiment is used to implement the AC bilateral protection method based on a single power supply. Next, the above method is further described in combination with actual cases. It should be noted that the actual cases are only used to explain the above method in detail and clearly, and are not used as data to limit the scope of use of the above method. The specific method includes the following steps: Step S1: Raise the input AC voltage by 0.5V cc , the peak-to-peak value of the AC voltage is ±V0, The V cc is the preset reference voltage, and V cc >±V0,V cc The smaller the difference with ±V0, the more sensitive the comparison protection is. Set the first comparator reference voltage V1 and the second comparator reference voltage V2, where (V0+0.5V cc )<V1<V cc ,0<V2<(-V0+0.5V cc ).like Figure 3 The figure shows the AC voltage waveform collected before the voltage is raised. If a direct comparison is made, a negative power supply needs to be set for the second comparator reference voltage V2. Figure 4 The voltage is shown to be raised by 0.5V cc After the AC voltage waveform, the voltage valley value is greater than 0, then the second comparator reference voltage V2 can be set to be positive, thereby reducing the use of negative power. Preferably, the first comparator reference voltage V1 can be set close to V by adjusting the resistance values ​​of the first resistor R1 and the second resistor R2 as needed. cc ; The second comparator reference voltage V2 is set close to 0 by adjusting the resistance values ​​of the seventh resistor R7 and the eighth resistor R8.

[0025] Step S2: The positive half-cycle voltage of the AC quantity is input into the inverting input terminal of the first comparator in the first comparison circuit. If the voltage value is less than the first comparator reference voltage V1, the output terminal of the first comparator outputs a high level (onboard voltage), the third diode D3 is turned off, and the external protection signal TZ1 is turned off. If the voltage value is greater than the first comparator reference voltage V1, the output terminal of the first comparator outputs a low level (grounded), the third diode D3 is turned on, the external protection signal TZ1 is turned on, and the protection is turned on.

[0026] Step S3: The negative half-cycle voltage of the AC quantity is input to the inverting input terminal of the second comparator in the second comparison circuit. If the voltage value is less than the second comparator reference voltage V2, the output terminal of the second comparator outputs a high level (on-board voltage), that is, the inverting input terminal of the third comparator inputs a high level, then the output terminal of the third comparator outputs a low level (grounded), the sixth diode D6 is turned on, the external protection signal TZ1 is turned on, and the protection is turned on. If the voltage value is greater than the second comparator reference voltage V2, the output terminal of the second comparator outputs a low level (grounded), that is, the inverting input terminal of the third comparator inputs a low level, then the output terminal of the third comparator outputs a high level (on-board voltage), the sixth diode D6 is turned off, and the external protection signal TZ1 is turned on.

[0027] Step S4: After the external protection signal TZ1 is turned on, the input of the alternating current stops, the output of the first comparison circuit returns to a high level, the output of the second comparison circuit returns to a low level, and the external protection signal TZ1 is turned off. Third embodiment

[0028] This embodiment discloses a battery pack, which includes battery cells, an inverter and a control circuit, and also includes an AC bilateral protection circuit based on a single power supply as described in the first embodiment, and implements overcurrent protection for the inverter through the AC bilateral protection method based on a single power supply as described in the second embodiment.

[0029] In summary, the AC bilateral protection circuit based on a single power supply sets two comparison circuits, compares the positive half-cycle voltage with the positive half-cycle reference voltage through the first comparison circuit, and compares the negative half-cycle voltage with the negative half-cycle reference voltage through the second comparison circuit, and connects the external protection signal at the same time to achieve overcurrent protection for the inverter. The AC bilateral protection method based on a single power supply converts the negative voltage into a positive voltage by raising the AC voltage by half of the preset reference voltage, and combines the inverter circuit to achieve the comparison of the negative half-cycle voltage. Combined with the above circuit and method, only a single power supply is required to achieve bilateral protection of the inverter AC quantity, which is more accurate than the software protection method and lower cost than the existing hardware protection method.

[0030] The effects of the present invention are not limited to the effects listed above, and those skilled in the art can derive effects not described above from the description.

[0031] The above-described embodiments of the AC bilateral protection circuit, method and battery pack based on a single power supply are merely illustrative preferred embodiments and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. In addition, various technical solutions can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them; when the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

Claims

1. A bilateral protection circuit for AC quantity based on a single power supply, characterized in that: include: A first comparison circuit, the first comparison circuit comprises a first comparator, an inverting input terminal of the first comparator is connected to a positive half-cycle voltage of an alternating current quantity, and an output terminal of the first comparator is connected to an external protection signal; A second comparison circuit and an inverter circuit, wherein the second comparison circuit comprises a second comparator, the inverter circuit comprises a third comparator, the inverting input terminal of the second comparator is connected to the negative half-cycle voltage of the alternating current quantity, the output terminal is connected to the inverting input terminal of the third comparator, and the output terminal of the third comparator is connected to an external protection signal; Wherein, the positive power supply terminals of the first comparator, the second comparator and the third comparator are connected to the onboard voltage, and the negative power supply terminals are grounded.

2. The AC bilateral protection circuit based on a single power supply according to claim 1, characterized in that: The non-inverting input terminal of the first comparator is connected to the first resistor and then to the positive half-cycle reference voltage, and then to the second resistor and the first capacitor in parallel, and then to ground, and at the same time connected to the first diode and the third resistor in series, and then to the output terminal of the first comparator, wherein the anode of the first diode is connected to the non-inverting input terminal of the first comparator; the inverting input terminal of the first comparator is connected to the fourth resistor and then to the positive half-cycle voltage of the alternating current, and at the same time connected to the second capacitor and the second diode in parallel, and then to ground, wherein the cathode of the second diode is connected to the inverting input terminal of the first comparator; the output terminal of the first comparator is connected to the fifth resistor, and the fifth resistor is connected in series with the sixth resistor and then to the onboard voltage, and then to the third capacitor in series, and then to ground, and at the same time connected in series with the third diode and then to the external protection signal, wherein the cathode of the third diode is connected to the fifth resistor.

3. The AC bilateral protection circuit based on a single power supply according to claim 1, characterized in that: The non-inverting input terminal of the second comparator is connected to the seventh resistor and then to the negative half-cycle reference voltage, and then to the eighth resistor and the fourth capacitor in parallel, and then to ground, and then to the fourth diode and the ninth resistor in series, and then to the output terminal of the second comparator, wherein the anode of the fourth diode is connected to the non-inverting input terminal of the second comparator; the inverting input terminal of the second comparator is connected to the tenth resistor and then to the negative half-cycle voltage of the alternating current, and then to the fifth capacitor and the fifth diode in parallel, and then to ground, wherein the cathode of the fifth diode is connected to the inverting input terminal of the second comparator; the output terminal of the second comparator is connected to the eleventh resistor, and the eleventh resistor is connected in series with the twelfth resistor and then to the board voltage, and then to the sixth capacitor in series, and then to ground; the positive power supply terminal of the second comparator is connected to the board voltage, and then to the seventh capacitor in series, and then to ground, and the negative power supply terminal is grounded.

4. The AC bilateral protection circuit based on a single power supply as claimed in claim 3, characterized in that: The non-inverting input terminal of the third comparator is connected to the thirteenth resistor and then to the inverting reference voltage, connected to the fourteenth resistor and the eighth capacitor in parallel and then to ground, and at the same time connected to the fifteenth resistor and then to the output terminal of the third comparator; the inverting input terminal of the third comparator is connected in series with the eleventh resistor and then to the output terminal of the second comparator; the output terminal of the third comparator is connected in series with the sixteenth resistor and then to the board voltage, connected in series with the ninth capacitor and then to ground, and at the same time connected in series with the sixth diode and then to the external protection signal, wherein the cathode of the sixth diode is connected to the output terminal of the third comparator.

5. The AC bilateral protection circuit based on a single power supply as claimed in claim 2, characterized in that: The non-inverting input terminal of the first comparator is also provided with a first voltage detection terminal.

6. The AC bilateral protection circuit based on a single power supply as claimed in claim 3, characterized in that: The non-inverting input terminal of the second comparator is also provided with a second voltage detection terminal.

7. A method for bilateral protection of an alternating current quantity based on a single power supply, using the bilateral protection circuit of an alternating current quantity based on a single power supply as claimed in any one of claims 1 to 6, characterized in that: The method comprises the following steps: S1: Raise the input AC voltage by 0.5V cc , the peak-to-peak value of the AC voltage is ±V0, the V cc is the preset reference voltage, and V cc > ±V0, set the first comparator reference voltage V1 and the second comparator reference voltage V2, where (V0+0.5V cc )<V1<V cc ,0<V2<(-V0+0.5V cc ); S2: The positive half cycle of the AC quantity is input into the first comparison circuit. If the voltage value is greater than V1, the output of the first comparison circuit is low level, then the external protection signal is turned on and the AC quantity input stops; S3: The negative half cycle of the AC quantity is input into the second comparison circuit. If the voltage value is less than V2, the output of the second comparison circuit is high level, and after passing through the inverter circuit, the output is low level, then the external protection signal is turned on, and the AC quantity input stops; S4: After the external protection signal is turned on, the AC input stops, the output of the first comparison circuit returns to a high level, the output of the second comparison circuit returns to a low level, and the external protection signal is cut off.

8. A battery pack, comprising a battery cell, an inverter and a control circuit, characterized in that: The battery pack also includes an AC bilateral protection circuit based on a single power supply as described in any one of claims 1 to 6, and implements overcurrent protection for the inverter through an AC bilateral protection method based on a single power supply as described in claim 7.

Images