Safe power supply circuit of energy storage system

Abstract

The utility model discloses a safe power supply circuit of an energy storage system, which relates to the technical field of energy storage and power supply, and comprises an undervoltage detection module used for detecting the undervoltage states of a first energy storage module, a second energy storage module and a third energy storage module, and when all energy storage modules are not undervoltage, the undervoltage detection module is used for detecting the undervoltage states of the first energy storage module, the second energy storage module and the third energy storage module. The state control module controls the first energy storage module, the second energy storage module and the third energy storage module to perform series power supply, the electric energy transmission module performs electric energy transmission, and the output processing module performs power adjustment and filtering. And the state control module performs disconnection control on the first energy storage module, the second energy storage module or the third energy storage module in an undervoltage state according to the undervoltage detection module, performs undervoltage quantity detection through the protection control module, and controls the electric energy transmission module to perform power-off protection when the undervoltage quantity exceeds an undervoltage quantity threshold value. The safe power supply circuit of the energy storage system can improve the power supply safety and prolong the service life of the energy storage system.

Description

Technical Field

[0001] This utility model relates to the field of energy storage power supply technology, specifically a safe power supply circuit for an energy storage system. Background Technology

[0002] An energy storage system is a technological device that can store energy in some form and release it when needed. In order to improve the power supply voltage of the energy storage system, the existing technology generally consists of multiple battery packs connected in series and discharged in series during discharge. When the energy storage system experiences low voltage, it stops supplying power. However, due to the different discharge rates between the battery packs, a single battery pack in the series connection may experience undervoltage. Continuing to supply power can easily reduce the endurance of the energy storage system and damage it. Therefore, improvements are needed. Utility Model Content

[0003] This utility model provides a safe power supply circuit for an energy storage system to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] A safe power supply circuit for an energy storage system includes: a first energy storage module, a second energy storage module, a third energy storage module, a status control module, an undervoltage detection module, a protection control module, a power transmission module, and an output processing module.

[0006] The first energy storage module is used for energy storage and discharge.

[0007] The second energy storage module is used for energy storage and discharge.

[0008] The third energy storage module is used for energy storage and discharge.

[0009] The undervoltage detection module is connected to the first energy storage module, the second energy storage module and the third energy storage module. It is used to set the undervoltage threshold, detect the undervoltage of the first energy storage module, the second energy storage module and the third energy storage module, and output a first signal when the first energy storage module is undervoltage, a second signal when the second energy storage module is undervoltage, and a third signal when the third energy storage module is undervoltage.

[0010] The status control module is connected to the undervoltage detection module, the first energy storage module, the second energy storage module, and the third energy storage module. It is used to control the first energy storage module, the second energy storage module, and the third energy storage module to be connected in series for power supply when the undervoltage detection module detects that the first energy storage module, the second energy storage module, and the third energy storage module are not undervoltage; when the first energy storage module is undervoltage, it controls the second energy storage module and the third energy storage module to be connected in series for power supply; when the second energy storage module is undervoltage, it controls the first energy storage module and the third energy storage module to be connected in series for power supply; when the third energy storage module is undervoltage, it controls the first energy storage module and the second energy storage module to be connected in series for power supply.

[0011] The protection control module, connected to the undervoltage detection module, is used to perform addition processing on the first signal, the second signal, or the third signal, and output a protection signal when the processed signal exceeds the set undervoltage quantity threshold.

[0012] The power transmission module is connected to the first energy storage module, the status control module, the output processing module, and the protection control module. It is used to transmit the power provided by the status control module or the first energy storage module to the output processing module and to perform power-off protection when a protection signal is received.

[0013] The output processing module is used to perform power regulation and filtering on the electrical energy transmitted by the power transmission module.

[0014] As a further embodiment of this utility model: the first energy storage module includes a first battery pack; the state control module includes a first thyristor, a second thyristor, a third thyristor, and a fourth thyristor; the second energy storage module includes a second battery pack;

[0015] Preferably, the first end of the first battery pack is connected to the first end of the first thyristor and the power transmission module; the second end of the first battery pack is connected to the first end of the second thyristor and the first end of the fourth thyristor; the second end of the second thyristor is connected to the second end of the first thyristor and the first end of the second battery pack; the second end of the second battery pack is connected to the first end of the third thyristor; the control ends of the first thyristor, the second thyristor, the third thyristor, and the fourth thyristor are all connected to the undervoltage detection module; and the second end of the third thyristor is connected to the second end of the fourth thyristor and the third energy storage module.

[0016] As a further embodiment of this utility model: the third energy storage module includes a third battery pack; the state control module also includes a fifth thyristor, a first switching transistor and a third resistor;

[0017] Preferably, the first end of the third battery is connected to the second end of the third thyristor, the second end of the third battery pack is connected to the emitter of the first switching transistor, the first end of the fifth thyristor and ground, the second end of the fifth thyristor is connected to the second end of the second battery pack, the control end of the fifth thyristor is connected to the base of the first switching transistor through the third resistor, and the collector of the first switching transistor is connected to the control end of the third thyristor.

[0018] As a further embodiment of this utility model: the undervoltage detection module includes a first resistor, a second resistor, a first comparator, a first reference power supply, a first inverter, a first detection device, a second detection device, and a second inverter;

[0019] Preferably, one end of the first resistor is connected to the second terminal of the first battery pack, and the other end of the first resistor is connected to the inverting terminal of the first comparator and connected to the first terminal of the first battery pack through the second resistor. The non-inverting terminal of the first comparator is connected to the first reference power supply. The output terminal of the first comparator is connected to the control terminal of the first thyristor and the input terminal of the first inverter. The output terminal of the first inverter is connected to the control terminal of the second thyristor. The first and second input terminals of the first detection device are respectively connected to the first and second terminals of the second battery pack. The output terminal of the first detection device is connected to the control terminal of the fourth thyristor and the input terminal of the second inverter. The output terminal of the second inverter is connected to the control terminal of the third thyristor. The first and second input terminals of the second detection device are respectively connected to the first and second terminals of the third battery pack. The output terminal of the second detection device is connected to the control terminal of the fifth thyristor.

[0020] As a further embodiment of this utility model: the power transmission module includes a fourth resistor, a first power transistor, and a second switching transistor; the output processing module includes a power adjustment device, a first capacitor, and an output port;

[0021] Preferably, the drain of the first power transistor is connected to the first terminal of the first battery pack and is connected to the gate of the first power transistor and the collector of the second switching transistor through a fourth resistor. The source of the first power transistor is connected to the input terminal of the power regulation device. The output terminal of the power regulation device is connected to the first terminal of the output port and is connected to the second terminal of the output port, the ground terminal of the power regulation device, the emitter of the second switching transistor and the ground terminal through a first capacitor. The base of the second switching transistor is connected to the protection control module.

[0022] As a further improvement of this utility model: the protection control module includes a fifth resistor, a non-inverting adder, and a first diode;

[0023] Preferably, the first, second, and third terminals of the in-phase adder are connected to the output terminals of the first detection device, the first comparator, and the second detection device, respectively. The output terminal of the in-phase adder is connected to the cathode of the first diode through a fifth resistor, and the anode of the first diode is connected to the base of the second switching transistor.

[0024] Compared with the prior art, the beneficial effects of this utility model are as follows: The safe power supply circuit of the energy storage system of this utility model can detect the undervoltage status of the first, second, and third energy storage modules by the undervoltage detection module. When none of them are undervoltage, the status control module controls the first, second, and third energy storage modules to be connected in series for power supply. The power transmission module performs power transmission, the output processing module performs power regulation and filtering, and the status control module performs disconnection control on the first, second, or third energy storage module that is in an undervoltage state according to the undervoltage detection module. At the same time, the protection control module detects the number of undervoltages, and when the number of undervoltages exceeds the undervoltage threshold, it controls the power transmission module to perform power-off protection, thereby improving the power supply safety and service life of the energy storage system. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic block diagram of a safe power supply circuit for an energy storage system, provided as an example of this utility model.

[0027] Figure 2 A circuit diagram of a safe power supply circuit for an energy storage system provided for this utility model embodiment.

[0028] Figure 3 A connection circuit diagram of the protection control module provided for this utility model embodiment. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0030] In one embodiment, see Figure 1 A safe power supply circuit for an energy storage system includes: a first energy storage module 1, a second energy storage module 2, a third energy storage module 3, a status control module 4, an undervoltage detection module 5, a protection control module 6, a power transmission module 7, and an output processing module 8.

[0031] Specifically, the first energy storage module 1 is used for energy storage and discharge;

[0032] The second energy storage module 2 is used for energy storage and discharge;

[0033] The third energy storage module 3 is used for energy storage and discharge;

[0034] The undervoltage detection module 5 is connected to the first energy storage module 1, the second energy storage module 2 and the third energy storage module 3. It is used to set the undervoltage threshold, detect undervoltage of the first energy storage module 1, the second energy storage module 2 and the third energy storage module 3, and output a first signal when the first energy storage module 1 is undervoltage, a second signal when the second energy storage module 2 is undervoltage, and a third signal when the third energy storage module 3 is undervoltage.

[0035] The status control module 4 is connected to the undervoltage detection module 5, the first energy storage module 1, the second energy storage module 2, and the third energy storage module 3. It is used to control the first energy storage module 1, the second energy storage module 2, and the third energy storage module 3 to be connected in series for power supply when the undervoltage detection module 5 detects that the first energy storage module 1, the second energy storage module 2, and the third energy storage module 3 are not undervoltage; when the first energy storage module 1 is undervoltage, it controls the second energy storage module 2 and the third energy storage module 3 to be connected in series for power supply; when the second energy storage module 2 is undervoltage, it controls the first energy storage module 1 and the third energy storage module 3 to be connected in series for power supply; when the third energy storage module 3 is undervoltage, it controls the first energy storage module 1 and the second energy storage module 2 to be connected in series for power supply.

[0036] The protection control module 6 is connected to the undervoltage detection module 5 and is used to perform addition processing on the first signal, the second signal or the third signal and output a protection signal when the processed signal exceeds the set undervoltage quantity threshold.

[0037] The power transmission module 7 is connected to the first energy storage module 1, the status control module 4, the output processing module 8 and the protection control module 6. It is used to transmit the power provided by the status control module 4 or the first energy storage module 1 to the output processing module 8, and to perform power-off protection when a protection signal is received.

[0038] The output processing module 8 is used to perform power regulation and filtering on the electrical energy transmitted by the power transmission module 7.

[0039] In a specific embodiment, the first energy storage module 1 can be a first energy storage circuit composed of a battery pack for energy storage and discharge; the second energy storage module 2 can be a second energy storage circuit composed of a battery pack for energy storage and discharge; the third energy storage module 3 can be a third energy storage circuit composed of a battery pack for energy storage and discharge; the state control module 4 can be a state control circuit composed of a thyristor, a transistor, and a resistor, which can control the series connection and connection state of the first energy storage module 1, the second energy storage module 2, and the third energy storage module 3; the undervoltage detection module 5 can be an undervoltage detection circuit composed of a resistor, a comparator, an inverter, a detection device, etc., which can set an undervoltage threshold and compare the first energy storage module 1, the second energy storage module 2, and the third energy storage module 3. The voltage of energy storage module 2 and the third energy storage module 3 are compared with the undervoltage threshold to perform undervoltage detection, and the output signal is inverted. The protection control module 6 can be a protection control circuit composed of a non-inverting adder, resistors and diodes. It can set an undervoltage threshold and detect the voltage of the signal after addition and the voltage of the undervoltage threshold. The undervoltage threshold is twice the voltage of the first signal. The power transmission module 7 can be a power transmission circuit composed of field-effect transistors, resistors and transistors to control the transmission and cutoff of power. The output processing module 8 can be an output processing circuit composed of a power adjustment device, capacitors and output ports to perform power adjustment and filtering on the input power.

[0040] In one embodiment, see Figure 1 , Figure 2 and Figure 3 The first energy storage module 1 includes a first battery pack; the state control module 4 includes a first thyristor S1, a second thyristor S2, a third thyristor S3, and a fourth thyristor S4; the second energy storage module 2 includes a second battery pack.

[0041] Specifically, the first end of the first battery pack is connected to the first end of the first thyristor S1 and the power transmission module 7; the second end of the first battery pack is connected to the first end of the second thyristor S2 and the first end of the fourth thyristor S4; the second end of the second thyristor S2 is connected to the second end of the first thyristor S1 and the first end of the second battery pack; the second end of the second battery pack is connected to the first end of the third thyristor S3; the control ends of the first thyristor S1, the second thyristor S2, the third thyristor S3, and the fourth thyristor S4 are all connected to the undervoltage detection module 5; and the second end of the third thyristor S3 is connected to the second end of the fourth thyristor S4 and the third energy storage module 3.

[0042] In a specific embodiment, the first thyristor S1, the second thyristor S2, the third thyristor S3, and the fourth thyristor S4 can all be bidirectional thyristors.

[0043] Furthermore, the third energy storage module 3 includes a third battery pack; the state control module 4 also includes a fifth thyristor S5, a first switching transistor V1, and a third resistor R3;

[0044] Specifically, the first end of the third battery is connected to the second end of the third thyristor S3, the second end of the third battery pack is connected to the emitter of the first switch V1, the first end of the fifth thyristor S5 and the ground, the second end of the fifth thyristor S5 is connected to the second end of the second battery pack, the control end of the fifth thyristor S5 is connected to the base of the first switch V1 through the third resistor R3, and the collector of the first switch V1 is connected to the control end of the third thyristor S3.

[0045] In a specific embodiment, the fifth thyristor S5 can be a bidirectional thyristor; the first switching transistor V1 can be an NPN transistor.

[0046] Furthermore, the undervoltage detection module 5 includes a first resistor R1, a second resistor R2, a first comparator A1, a first reference power supply VREF1, a first inverter J1, a first detection device, a second detection device, and a second inverter J2.

[0047] Specifically, one end of the first resistor R1 is connected to the second end of the first battery pack, and the other end of the first resistor R1 is connected to the inverting input of the first comparator A1 and connected to the first end of the first battery pack through the second resistor R2. The non-inverting input of the first comparator A1 is connected to the first reference power supply VREF1. The output of the first comparator A1 is connected to the control terminal of the first thyristor S1 and the input terminal of the first inverter J1. The output of the first inverter J1 is connected to the control terminal of the second thyristor S2. The first and second input terminals of the first detection device are respectively connected to the first and second ends of the second battery pack. The output of the first detection device is connected to the control terminal of the fourth thyristor S4 and the input terminal of the second inverter J2. The output of the second inverter J2 is connected to the control terminal of the third thyristor S3. The first and second input terminals of the second detection device are respectively connected to the first and second ends of the third battery pack. The output of the second detection device is connected to the control terminal of the fifth thyristor S5.

[0048] In a specific embodiment, the first resistor R1 and the second resistor R2 are used for voltage sampling; the first comparator A1 can be an LM358 comparator; the first reference power supply VREF1 can be set with an undervoltage threshold; the first inverter J1 and the second inverter J2 can both be NOT gate chips; the circuit composition structure of the first detection device and the circuit composition structure of the second detection device are the same as the circuit composition structure of the first resistor R1, the second resistor R2, the first comparator A1 and the first reference power supply VREF1.

[0049] Furthermore, the power transmission module 7 includes a fourth resistor R4, a first power transistor Q1, and a second switching transistor V2; the output processing module 8 includes a power adjustment device, a first capacitor C1, and an output port.

[0050] Specifically, the drain of the first power transistor Q1 is connected to the first terminal of the first battery pack and is connected to the gate of the first power transistor Q1 and the collector of the second switch transistor V2 through the fourth resistor R4. The source of the first power transistor Q1 is connected to the input terminal of the power regulation device. The output terminal of the power regulation device is connected to the first terminal of the output port and is connected to the second terminal of the output port, the ground terminal of the power regulation device, the emitter of the second switch transistor V2 and the ground terminal through the first capacitor C1. The base of the second switch transistor V2 is connected to the protection control module 6.

[0051] In a specific embodiment, the first power transistor Q1 can be an N-channel MOSFET; the second switching transistor V2 can be an NPN transistor; and the power regulation device can be composed of a Boost circuit.

[0052] Furthermore, the protection control module 6 includes a fifth resistor R5, a non-inverting adder, and a first diode D1;

[0053] Specifically, the first, second, and third terminals of the in-phase adder are connected to the output terminals of the first detection device, the first comparator A1, and the second detection device, respectively. The output terminal of the in-phase adder is connected to the cathode of the first diode D1 through the fifth resistor R5, and the anode of the first diode D1 is connected to the base of the second switching transistor V2.

[0054] In a specific embodiment, the above-mentioned in-phase adder can be composed of a resistor and an operational amplifier, which can perform addition processing on the first signal, the second signal and the third signal output by the undervoltage detection module 5, and the voltages of the first signal, the second signal and the third signal are equal; the above-mentioned fifth resistor R5 and the first diode D1 set the undervoltage quantity threshold.

[0055] In this embodiment of a safe power supply circuit for an energy storage system, the voltage of the first battery pack is sampled by a first resistor R1 and a second resistor R2. When the sampled signal is greater than the undervoltage threshold provided by the first reference power supply VREF1, the first comparator A1 outputs a low level. At this time, the first inverter J1 performs inversion processing and triggers the second thyristor S2 to conduct. Similarly, when the second battery pack is not undervoltage, the second inverter J2 triggers the third thyristor S3 to conduct, so that the first, second, and third battery packs are connected in series for power supply. When the first battery pack is undervoltage, the first comparator A1 outputs a first signal, triggering the first thyristor S1 to conduct and the second thyristor S2 to disconnect, so that the second and third battery packs are connected in series. Similarly, when the second battery pack is undervoltage, the first detection device outputs a second signal, and the fourth thyristor S2... When the thyristor S4 is turned on and the third thyristor S3 is turned off, the first battery pack and the third battery pack are connected in series. Similarly, when the third battery pack is undervoltage, the second detection device outputs a third signal and triggers the first switch V1 and the fifth thyristor S5 to turn on, so that the first battery pack and the second battery pack are connected in series to supply power. The supplied power is transmitted through the first power transistor Q1, the power adjustment device performs power adjustment, the first capacitor C1 performs filtering, and finally the output port receives and outputs the signal. When the in-phase adder performs addition processing on the first signal, the second signal, or the third signal, if the number of undervoltages in the first detection device, the second detection device, or the first comparator A1 exceeds the undervoltage threshold set by the fifth resistor R5 and the first diode D1, the second switch V2 will be turned on, the first power transistor Q1 will be turned off, and the power supply will stop.

[0056] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0057] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A safe power supply circuit for an energy storage system, characterized in that, The safe power supply circuit of the energy storage system includes: a first energy storage module, a second energy storage module, a third energy storage module, a status control module, an undervoltage detection module, a protection control module, a power transmission module, and an output processing module; The first energy storage module is used for energy storage and discharge; The second energy storage module is used for energy storage and discharge; The third energy storage module is used for energy storage and discharge; The undervoltage detection module is connected to the first energy storage module, the second energy storage module and the third energy storage module. It is used to set an undervoltage threshold, perform undervoltage detection on the first energy storage module, the second energy storage module and the third energy storage module, and output a first signal when the first energy storage module is undervoltage, a second signal when the second energy storage module is undervoltage, and a third signal when the third energy storage module is undervoltage. The state control module is connected to the undervoltage detection module, the first energy storage module, the second energy storage module, and the third energy storage module. It is used to control the first energy storage module, the second energy storage module, and the third energy storage module to be connected in series for power supply when the undervoltage detection module detects that the first energy storage module, the second energy storage module, and the third energy storage module are not undervoltage; to control the second energy storage module and the third energy storage module to be connected in series for power supply when the first energy storage module is undervoltage; and to control the first energy storage module and the second energy storage module to be connected in series for power supply when the third energy storage module is undervoltage. The protection control module is connected to the undervoltage detection module and is used to perform addition processing on the first signal, the second signal or the third signal, and output a protection signal when the processed signal exceeds the set undervoltage quantity threshold. The power transmission module is connected to the first energy storage module, the state control module, the output processing module, and the protection control module. It is used to transmit the power provided by the state control module or the first energy storage module to the output processing module and to perform power-off protection when a protection signal is received. The output processing module is used to perform power regulation and filtering on the electrical energy transmitted by the power transmission module.

2. The safe power supply circuit for an energy storage system according to claim 1, characterized in that, The first energy storage module includes a first battery pack; the state control module includes a first thyristor, a second thyristor, a third thyristor, and a fourth thyristor; the second energy storage module includes a second battery pack. The first end of the first battery pack is connected to the first end of the first thyristor and the power transmission module. The second end of the first battery pack is connected to the first end of the second thyristor and the first end of the fourth thyristor. The second end of the second thyristor is connected to the second end of the first thyristor and the first end of the second battery pack. The second end of the second battery pack is connected to the first end of the third thyristor. The control ends of the first thyristor, the second thyristor, the third thyristor, and the fourth thyristor are all connected to the undervoltage detection module. The second end of the third thyristor is connected to the second end of the fourth thyristor and the third energy storage module.

3. The safe power supply circuit for an energy storage system according to claim 2, characterized in that, The third energy storage module includes a third battery pack; the state control module also includes a fifth thyristor, a first switching transistor, and a third resistor. The first end of the third battery is connected to the second end of the third thyristor. The second end of the third battery pack is connected to the emitter of the first switching transistor, the first end of the fifth thyristor, and ground. The second end of the fifth thyristor is connected to the second end of the second battery pack. The control end of the fifth thyristor is connected to the base of the first switching transistor through a third resistor. The collector of the first switching transistor is connected to the control end of the third thyristor.

4. A safe power supply circuit for an energy storage system according to claim 3, characterized in that, The undervoltage detection module includes a first resistor, a second resistor, a first comparator, a first reference power supply, a first inverter, a first detection device, a second detection device, and a second inverter; One end of the first resistor is connected to the second end of the first battery pack, and the other end of the first resistor is connected to the inverting input of the first comparator and connected to the first end of the first battery pack through the second resistor. The non-inverting input of the first comparator is connected to the first reference power supply. The output of the first comparator is connected to the control terminal of the first thyristor and the input terminal of the first inverter. The output of the first inverter is connected to the control terminal of the second thyristor. The first and second input terminals of the first detection device are respectively connected to the first and second ends of the second battery pack. The output of the first detection device is connected to the control terminal of the fourth thyristor and the input terminal of the second inverter. The output of the second inverter is connected to the control terminal of the third thyristor. The first and second input terminals of the second detection device are respectively connected to the first and second ends of the third battery pack. The output of the second detection device is connected to the control terminal of the fifth thyristor.

5. A safe power supply circuit for an energy storage system according to claim 4, characterized in that, The power transmission module includes a fourth resistor, a first power transistor, and a second switching transistor; the output processing module includes a power regulation device, a first capacitor, and an output port. The drain of the first power transistor is connected to the first terminal of the first battery pack and is connected to the gate of the first power transistor and the collector of the second switching transistor through the fourth resistor. The source of the first power transistor is connected to the input terminal of the power regulation device. The output terminal of the power regulation device is connected to the first terminal of the output port and is connected to the second terminal of the output port, the ground terminal of the power regulation device, the emitter of the second switching transistor and the ground terminal through the first capacitor. The base of the second switching transistor is connected to the protection control module.

6. A safe power supply circuit for an energy storage system according to claim 5, characterized in that, The protection control module includes a fifth resistor, a non-inverting adder, and a first diode; The first, second, and third terminals of the in-phase adder are respectively connected to the output terminals of the first detection device, the first comparator, and the second detection device. The output terminal of the in-phase adder is connected to the cathode of the first diode through the fifth resistor, and the anode of the first diode is connected to the base of the second switching transistor.

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