Charge and discharge control circuit and battery management system

Abstract

The present invention discloses a charge and discharge control circuit and a battery management system, comprising a power supply, a charge and discharge switch circuit, an analog front-end circuit and a drive circuit; the analog front-end circuit is connected to the drive circuit and is used to output a first drive signal to the drive circuit; the drive circuit is connected to the power supply and the charge and discharge switch circuit and is used to turn on or off the power supply and the charge and discharge switch circuit according to the first drive signal. The charge and discharge switch circuit is used to connect the battery and the charge and discharge connection terminal, and turns on the battery and the charge and discharge connection terminal when receiving the first power supply signal provided by the power supply. This technical solution drives the charge and discharge switch circuit to turn on through a more stable and reliable first power supply signal, thereby preventing the charge and discharge switch circuit from oscillating back and forth and closing and opening, thereby ensuring the stability and safety of battery charging and discharging.

Description

Technical Field

[0001] The present invention relates to the technical field of battery management, and in particular to a charge and discharge control circuit and a battery management system. Background Art

[0002] With the widespread adoption of energy storage technologies and electric vehicles, the market demand for battery protection boards continues to increase. Battery protection boards play a crucial role in battery management systems, primarily responsible for monitoring battery voltage, temperature, and charge and discharge status, and protecting the battery by controlling switches. Currently, most battery protection boards use MOSFETs as switching elements, managing battery charge and discharge by controlling the on and off states of the MOSFETs.

[0003] Figure 1 The circuit structure of a battery protection board currently on the market consists of batteries B1…Bn, a power sampling resistor Rs, an NTC temperature sensor, discharge MOSFETs Qd1…Qdn, charge MOSFETs Qc1…Qcn, pre-discharge MOSFETs Qy, and a pre-discharge resistor Ry. U1 is the analog front-end chip responsible for collecting battery voltage and temperature data and executing protection actions. U2 is a microcontroller that communicates with analog front-end U1, and S1 is a switch. U4 is the load or charger. The positive terminal of battery Bn is connected to the positive terminal of U4, the load or charger. The negative terminal of U4 is connected to one end of the charge MOSFETs Qc1…Qcn. The other ends of the charge MOSFETs Qc1…Qcn are connected to one end of the discharge MOSFETs Qd1…Qdn. The other ends of the discharge MOSFETs Qd1…Qdn are connected to one end of the power sampling resistor Rs. The other end of the power sampling resistor Rs is connected to the negative terminal of battery B1. One end of the Qy pre-discharge MOS transistor is connected to one end of the Qd1...Qdn discharge MOS transistors, the other end of the Qy pre-discharge MOS transistor is connected to one end of the Ry pre-discharge resistor, and the other end of the Ry pre-discharge resistor is connected to the other ends of the Qd1...Qdn discharge MOS transistors. That is, the Qy pre-discharge MOS transistor and the Ry pre-discharge resistor are connected in series, and then connected in parallel with the Qd1...Qdn discharge MOS transistors.

[0004] When a charger is connected or a switch is pressed, the analog front end U1 is activated to close the charging MOSFETs Qc1…Qcn and the discharging MOSFETs Qd1…Qdn, completing the charge and discharge circuits and enabling charging and discharging. However, the existing analog front end U1 outputs a weak MOSFET drive signal, which can easily cause switching oscillation when closing the MOSFETs. This causes them to cycle frequently, increasing power consumption and potentially damaging the MOSFETs. The problem is exacerbated by the presence of a load current. Therefore, improving the stability and safety of battery charging and discharging has become a pressing technical challenge. Summary of the Invention

[0005] The embodiments of the present invention provide a charge and discharge control circuit and a battery management system to solve the problem of poor stability and safety in charging and discharging of existing batteries.

[0006] A charge and discharge control circuit, comprising a power supply, a charge and discharge switch circuit, an analog front-end circuit and a drive circuit;

[0007] The analog front-end circuit is connected to the driving circuit and is used to output a first driving signal to the driving circuit;

[0008] The driving circuit is connected to the power supply and the charge-discharge switch circuit, and is used to turn on or off the power supply and the charge-discharge switch circuit according to the first driving signal.

[0009] The charge and discharge switch circuit is used to connect the battery and the charge and discharge connection end, and conducts between the battery and the charge and discharge connection end when receiving the first power supply signal provided by the power supply.

[0010] Furthermore, the charge and discharge control circuit further includes a main control circuit;

[0011] The analog front-end circuit is connected to the charge and discharge switch circuit and the main control circuit, and is used to collect charge and discharge signals and transmit them to the main control circuit;

[0012] The main control circuit is used to output a first control signal to the analog front-end circuit according to the charge and discharge signal, so that the analog front-end circuit outputs a first drive signal according to the first control signal.

[0013] Furthermore, the main control circuit is also connected to the driving circuit, and is used to output a second driving signal to the driving circuit according to the charge and discharge signal;

[0014] The driving circuit is used to turn on or off the power supply and the charge-discharge switch circuit according to the first driving signal and the second driving signal.

[0015] Furthermore, the charge and discharge switch circuit includes a sampling circuit and a switch tube circuit;

[0016] The first end of the sampling circuit is connected to the battery and the ground end, the second end of the sampling circuit is connected to the first end of the switching tube circuit, the second end of the switching tube circuit is connected to the charge and discharge connection end, and the third end of the switching tube circuit is connected to the driving circuit;

[0017] The analog front-end circuit is connected to a first terminal and a second terminal of the sampling circuit.

[0018] Furthermore, the driving circuit includes a first voltage-dividing resistor circuit, a second voltage-dividing resistor circuit, a first transistor, a second transistor and a third transistor;

[0019] A first end of the first voltage-dividing resistor circuit is connected to the third end of the first transistor, a second end of the first voltage-dividing resistor circuit is grounded, and a third end of the first voltage-dividing resistor circuit is connected to the analog front-end circuit;

[0020] The first end of the first transistor is connected to the first end of the second voltage-dividing resistor circuit, and the second end of the first transistor is grounded;

[0021] The second end of the second voltage-dividing resistor circuit is connected to the power supply and the first end of the second transistor, the third end of the second voltage-dividing resistor circuit is connected to the third end of the second transistor, and the second end of the second transistor is connected to the charge-discharge switch circuit;

[0022] The first end of the third transistor is connected to the power supply, the second end of the third transistor is connected to the charge and discharge switch circuit, and the third end of the third transistor is connected to the second end of the second transistor.

[0023] Furthermore, the charge and discharge control circuit also includes a discharge circuit; the discharge circuit is connected to the drive circuit and the switch tube circuit, and is used to discharge the electrical energy stored in the parasitic capacitance of the switch tube circuit when the switch tube circuit is turned off.

[0024] Further, the discharge circuit includes a fourth transistor, a fifth transistor and a first discharge resistance circuit;

[0025] The first end of the fourth transistor is connected to the third end of the fifth transistor and the third end of the fourth transistor, the second end of the fourth transistor is connected to the charge and discharge switch circuit, and the third end of the fourth transistor is connected to the drive circuit;

[0026] A first end of the fifth transistor is connected to the charge and discharge switch circuit, a second end of the fifth transistor is connected to a first end of the first discharge resistor circuit, and a second end of the first discharge resistor circuit is grounded.

[0027] Furthermore, the discharge circuit further includes a sixth transistor and a first diode;

[0028] An anode of the first diode is connected to the drive circuit, the third terminal of the fourth transistor, and the third terminal of the sixth transistor, and a cathode of the first diode is connected to the first terminal of the fourth transistor, the drive circuit, and the third terminal of the fifth transistor;

[0029] A first end of the sixth transistor is connected to the driving circuit, and a second end of the sixth transistor is connected to a first end of the first discharge resistance circuit.

[0030] Furthermore, the discharge circuit further includes a second diode and a second discharge resistance circuit;

[0031] A first end of the second bleeder resistor circuit is connected to the switch tube circuit, a second end of the second bleeder resistor circuit is connected to the anode of the second diode, and a cathode of the second diode is connected to the first end of the fifth transistor.

[0032] Furthermore, the switching tube circuit includes at least two gallium nitride transistors; and the at least two gallium nitride transistors are arranged in parallel.

[0033] Furthermore, the discharge circuit includes a third discharge resistor circuit; and a third discharge resistor circuit is connected in series between the first terminal and the third terminal of each gallium nitride transistor.

[0034] A battery management system comprises a battery and the above-mentioned charge and discharge control circuit; the battery is connected to the charge and discharge control circuit.

[0035] An embodiment of the present invention provides a charge and discharge control circuit and a battery management system. The charge and discharge control circuit includes a power supply, an analog front-end circuit, a drive circuit, and a charge and discharge switch circuit. The analog front-end circuit is connected to the drive circuit to output a first drive signal to the drive circuit. The drive circuit is connected to the power supply and the charge and discharge switch circuit, and the power supply and the charge and discharge switch circuit are turned on or off according to the first drive signal. The charge and discharge switch circuit is used to connect a battery and a charge and discharge connection terminal. When receiving a first power supply signal provided by the power supply, the battery and the charge and discharge connection terminal are turned on, thereby using the first drive signal to drive the drive circuit to turn on the power supply and the charge and discharge switch circuit, and then using a more stable and reliable first power supply signal to drive the charge and discharge switch circuit to turn on, thereby preventing the charge and discharge switch circuit from oscillating back and forth and closing and opening, preventing the charge and discharge switch circuit from burning, and ensuring the stability and safety of battery charging and discharging. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0037] Figure 1 It is a schematic diagram of a battery protection board in the background technology.

[0038] Figure 2 FIG. 1 is a schematic diagram of a charge and discharge control circuit according to an embodiment of the present invention.

[0039] In the figure: 1. Main control circuit; 2. Analog front-end circuit; 3. Drive circuit; 31. First voltage-divider resistor circuit; 32. Second voltage-divider resistor circuit; 4. Charge-discharge switch circuit; 41. Sampling circuit; 42. Switch tube circuit; 5. Discharge circuit; 51. First discharge resistor circuit; 52. Second discharge resistor circuit; 53. Third discharge resistor circuit. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0041] It should be understood that the present invention can be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to make the disclosure thorough and complete and to fully convey the scope of the invention to those skilled in the art. In the drawings, the dimensions and relative dimensions of layers and regions may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0042] It should be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" another element or layer, it may be directly on, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there may be no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Thus, a first element, component, region, layer, or part discussed below may be represented as a second element, component, region, layer, or part without departing from the teachings of the present invention.

[0043] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," etc., may be used herein for convenience of description to describe the relationship of one element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the drawings is flipped, then the elements or features described as "under" or "beneath" or "beneath" the other elements will be oriented as "over" the other elements or features. Thus, the exemplary terms "under" and "under" may include both the upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or in other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0044] The purpose of the terms used herein is only to describe specific embodiments and is not intended to limit the present invention. When used herein, the singular forms "a", "an" and " / the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprising" and / or "comprising", when used in this specification, identify the presence of features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0045] In order to fully understand the present invention, detailed structures and steps will be provided in the following description to illustrate the technical solutions proposed by the present invention. Preferred embodiments of the present invention are described in detail below. However, in addition to these detailed descriptions, the present invention may also have other implementations.

[0046] This embodiment provides a charge and discharge control circuit, such as Figure 2 As shown, it includes a power supply, an analog front-end circuit 2, a drive circuit 3 and a charge-discharge switch circuit 4; the analog front-end circuit 2 is connected to the drive circuit 3 and is used to output a first drive signal to the drive circuit 3; the drive circuit 3 is connected to the power supply and the charge-discharge switch circuit 4 and is used to turn on or off the power supply and the charge-discharge switch circuit 4 according to the first drive signal; the charge-discharge switch circuit 4 is used to connect the battery and the charge-discharge connection terminal, and when receiving the first power supply signal provided by the power supply, it turns on the battery and the charge-discharge connection terminal.

[0047] The power supply may be a switching power supply. The input terminal of the power supply may be connected to a battery to draw power from the battery, and the first power supply signal may be output through the output terminal of the power supply. The battery includes a plurality of cells, which are arranged in series, for example, B1 to Bn.

[0048] The analog front-end circuit 2 includes an analog front-end chip. For example, the analog front-end chip is an important component of the battery management system. It is responsible for collecting analog signals of battery parameters such as voltage, current, and temperature, and converting the collected analog signals into digital signals for processing and analysis by the battery management system.

[0049] As an example, the charge and discharge control circuit is used in a battery management system that includes a battery. The charge and discharge switch circuit 4 is configured to connect the battery to a charge and discharge connection terminal. Optionally, the charge and discharge connection terminal is configured to connect to a load or a charger. As an example, when the charge and discharge switch circuit 4 is turned on, the battery charges and discharges normally. When the charge and discharge switch circuit 4 is turned off, the battery stops charging and discharging.

[0050] As an example, the analog front-end circuit 2 is connected to the drive circuit 3 and is used to output a first drive signal to the drive circuit 3. For example, the analog front-end circuit 2 can receive an external first control signal and output a first drive signal according to the first control signal. The first control signal can be a control signal output by the main control circuit in the charge and discharge control circuit. As an example, the analog front-end circuit 2 collects the charge and discharge signals of the charge and discharge control circuit and outputs the charge and discharge signals to the main control circuit. The main control circuit determines whether there is a charge and discharge abnormality based on the charge and discharge signals and outputs the corresponding first control signal to the analog front-end circuit 2, so that the analog front-end circuit 2 outputs the first drive signal to the drive circuit 3. The drive circuit 3 can then turn on or off the power supply and the charge and discharge switch circuit 4 according to the first drive signal.

[0051] Optionally, the charge and discharge signal includes a battery voltage, a battery temperature, a charge and discharge voltage, and a charge and discharge current. For example, the analog front-end circuit 2 is connected to the battery to collect the battery voltage. The analog front-end circuit 2 is connected to a thermistor in the setting environment to collect the battery temperature. The analog front-end circuit 2 is connected to the charge and discharge switch circuit 4 to collect the charge and discharge voltage and the charge and discharge current. For example, a sampling circuit 41 is set in the charge and discharge switch circuit 4, and the analog front-end circuit 2 is connected to the sampling circuit 41. When the charge and discharge switch circuit 4 is turned on, the analog front-end circuit 2 can collect the charge and discharge voltage and the charge and discharge current from the charge and discharge switch circuit 4.

[0052] As an example, the drive circuit 3 is connected to the charge and discharge switch circuit 4, and is used to turn on or off the power supply and the charge and discharge switch circuit 4 according to the first drive signal. The charge and discharge switch circuit 4 is used to connect the battery and the charge and discharge connection terminal, and when receiving the first power supply signal provided by the power supply, it turns on the battery and the charge and discharge connection terminal. In this embodiment, because the switching transistors in the charge and discharge switch circuit 4 have input parasitic capacitance, the more switching transistors are connected in parallel in the charge and discharge switch circuit 4, the greater the parasitic capacitance. However, the first drive signal output by the analog front-end circuit 2 is relatively weak and cannot be used directly to drive the charge and discharge switch circuit 4 with parasitic capacitance. Therefore, the power supply and the charge and discharge switch circuit 4 are turned on or off by the driving circuit 3 according to the first driving signal, so that the charge and discharge switch circuit 4 is turned on between the battery and the charge and discharge connection end when receiving the first power supply signal provided by the power supply. Since the power supply and the charge and discharge switch circuit 4 are turned on by the driving circuit 3, the charge and discharge switch circuit 4 can be driven to turn on by the first power supply signal of the power supply, thereby improving the driving capability of the charge and discharge switch circuit 4, thereby preventing the charge and discharge switch circuit 4 from oscillating back and forth, reducing power consumption, preventing the charge and discharge switch circuit 4 from burning, and ensuring the stability and safety of battery charging and discharging.

[0053] In this embodiment, the charge and discharge control circuit includes a power supply, an analog front-end circuit 2, a drive circuit 3 and a charge and discharge switch circuit 4; by connecting the analog front-end circuit 2 to the drive circuit 3, a first drive signal is output to the drive circuit 3; the drive circuit 3 is connected to the power supply and the charge and discharge switch circuit 4, and the power supply and the charge and discharge switch circuit 4 are turned on or off according to the first drive signal; the charge and discharge switch circuit 4 is used to connect the battery and the charge and discharge connection terminal, and when receiving the first power supply signal provided by the power supply, the battery and the charge and discharge connection terminal are turned on, thereby using the first drive signal to drive the drive circuit 3 to turn on the power supply and the charge and discharge switch circuit 4, and then the charge and discharge switch circuit 4 is driven to turn on by a more stable and reliable first power supply signal, thereby preventing the charge and discharge switch circuit 4 from oscillating back and forth and closing and opening, preventing the charge and discharge switch circuit 4 from burning, and ensuring the stability and safety of battery charging and discharging.

[0054] In one embodiment, the charge and discharge control circuit also includes a main control circuit 1; an analog front-end circuit 2, connected to the charge and discharge switch circuit 4 and the main control circuit 1, for collecting charge and discharge signals to the main control circuit 1; the main control circuit 1 is used to output a first control signal to the analog front-end circuit 2 according to the charge and discharge signal, so that the analog front-end circuit 2 outputs a first drive signal according to the first control signal.

[0055] As an example, the main control circuit 1 includes a microcontroller. Exemplarily, the microcontroller includes a single-chip microcomputer. The main control circuit 1 is connected to the analog front-end circuit 2 and is configured to obtain the charge and discharge signals sent by the analog front-end circuit 2 and output a first control signal to the analog front-end circuit 2.

[0056] Exemplarily, when the main control circuit 1 determines that the battery voltage, battery temperature, charge and discharge voltage, and charge and discharge current are normal based on the charge and discharge signal, it outputs a first control signal to control the analog front-end circuit 2 to output a high-level signal, and controls the drive circuit 3 to turn on the power supply and the charge and discharge switch circuit 4. When the charge and discharge switch circuit 4 is based on the first power supply signal provided by the power supply, it turns on the battery and the charge and discharge connection terminal to achieve normal charging and discharging of the battery.

[0057] It can be understood that when the main control circuit 1 determines that any one of the battery voltage, battery temperature, charge and discharge voltage, and charge and discharge current is abnormal based on the charge and discharge signal, it outputs a first control signal to control the analog front-end circuit 2 to output a low-level signal, and controls the drive circuit 3 to disconnect the power supply and the charge and discharge switch circuit 4, so that the charge and discharge switch circuit 4 disconnects the battery and the charge and discharge connection terminal to protect the battery.

[0058] Furthermore, the charge and discharge control circuit also includes a pre-discharge circuit. This pre-discharge circuit is connected to the battery, the charge and discharge connection terminal, the charge and discharge switch circuit 4, and the main control circuit 1, and is used to control the pre-discharge of the battery. Exemplarily, the pre-discharge circuit includes a pre-discharge resistor Ry and a pre-discharge transistor VGaNy. Preferably, the pre-discharge transistor VGaNy is a gallium nitride transistor that can conduct and block in both directions. The first end of the pre-discharge transistor VGaNy is a first drain, the second end of the pre-discharge transistor VGaNy is a second drain, and the third end of the pre-discharge transistor VGaNy is a gate, thereby achieving a bidirectional gallium nitride device replacing two back-to-back MOSFETs. The first end of the pre-discharge resistor is connected to the sampling circuit 41 in the charge and discharge circuit, the second end of the pre-discharge resistor is connected to the first end of the pre-discharge transistor VGaNy, the second end of the pre-discharge transistor VGaNy is connected to the charge and discharge connection terminal, and the third end of the pre-discharge transistor VGaNy is connected to the main control circuit 1. In this example, after the charge and discharge control circuit is connected to the battery and activated, the analog front-end chip in the analog front-end circuit 2 reads parameters such as the battery voltage, temperature, and current, and transmits them to the main control circuit 1. When the main control circuit 1 determines that the battery voltage, temperature, and current are normal, it outputs a high-level signal to the pre-discharge transistor VGaNy, controlling the pre-discharge transistor VGaNy to turn on, thereby limiting the current through the pre-discharge resistor Ry to avoid excessive current when the battery charges the load or the capacitor of the charger, thereby generating short-circuit protection. When the main control circuit 1 detects that the current limiting voltage of the pre-discharge resistor Ry is greater than 90% of the total battery voltage, it determines that the pre-discharge is successful. After the pre-discharge is successful, when the main control circuit 1 determines that the battery voltage, battery temperature, charge and discharge voltage, and charge and discharge current are normal based on the charge and discharge signal, it outputs a first control signal to control the analog front-end circuit 2 to output a high-level signal, controlling the drive circuit 3 to turn on the power supply and the charge and discharge switch circuit 4. When the charge and discharge switch circuit 4 is based on the first power supply signal provided by the power supply, it turns on the battery and the charge and discharge connection terminal to achieve normal charging and discharging of the battery.

[0059] Optionally, a voltage regulator diode Z4 is provided between the first and third terminals of the pre-discharge transistor VGaNy, and a voltage regulator diode Z5 is provided between the second and third terminals of the pre-discharge transistor VGaNy. To stabilize the voltage between the gate and the first and second drains of the pre-discharge transistor VGaNy and prevent the driving voltage from exceeding the withstand voltage of the gate and the first and second drains, thereby damaging the pre-discharge transistor VGaNy, the third terminal of the pre-discharge transistor VGaNy is connected to the main control circuit 1 via a resistor R10.

[0060] Optionally, the voltage regulator Z4 is further connected in series with the isolation diode D4, and the voltage regulator Z5 is further connected in series with the isolation diode D5. A resistor R13 is further provided between the first and third terminals of the pre-discharge transistor VGaNy to discharge the energy stored in the parasitic capacitance of the pre-discharge transistor VGaNy.

[0061] In one embodiment, the main control circuit 1 is also connected to the drive circuit 3, and is used to output a second drive signal to the drive circuit 3 according to the charge and discharge signal; the drive circuit 3 is used to turn on or off the power supply and the charge and discharge switch circuit 4 according to the first drive signal and the second drive signal.

[0062] As an example, after the pre-discharge is successful, when the main control circuit 1 determines that the battery voltage, battery temperature, charge and discharge voltage and charge and discharge current are normal based on the charge and discharge signal, it outputs a first control signal to control the analog front-end circuit 2 to output a high-level signal, that is, the first drive signal, and at the same time outputs the second drive signal to the drive circuit 3. Since the first drive signal output by the analog front-end circuit 2 is relatively weak, the first drive signal and the second drive signal are input to the drive circuit 3 at the same time, which can improve the response speed of the drive circuit 3, that is, the drive circuit 3 can turn on the power supply and the charge and discharge switch circuit 4 faster, thereby providing the conduction speed of the drive circuit 3.

[0063] In one embodiment, the charge and discharge switch circuit 4 includes a sampling circuit 41 and a switch tube circuit 42; a first end of the sampling circuit 41 is connected to the battery and the ground end, a second end of the sampling circuit 41 is connected to a first end of the switch tube circuit 42, a second end of the switch tube circuit 42 is connected to the charge and discharge connection end, and a third end of the switch tube circuit 42 is connected to the drive circuit 3; the analog front-end circuit 2 is connected to the first end and the second end of the sampling circuit 41.

[0064] As an example, the sampling circuit 41 includes a sampling resistor Rs, a first end of which is connected to the negative terminal of the battery and the ground terminal, and a second end of the sampling circuit 41 is connected to the first end of the switching tube circuit 42. It is understood that the number and connection method of the sampling resistor Rs can be selected according to actual needs and are not limited here.

[0065] In this embodiment, the first end of the sampling circuit 41 is connected to the battery and the ground end, the second end of the sampling circuit 41 is connected to the first end of the switching tube circuit 42, the second end of the switching tube circuit 42 is connected to the charge and discharge connection end, and the third end of the switching tube circuit 42 is connected to the drive circuit 3; the analog front-end circuit 2 is connected to the first and second ends of the sampling circuit 41. When the switching tube circuit 42 is turned on, the electrical signal passes through the sampling circuit 41, and the charge and discharge signal can be collected through the sampling circuit 41.

[0066] In one embodiment, the driving circuit 3 includes a first voltage-dividing resistor circuit 31, a second voltage-dividing resistor circuit 32, a first transistor Q1, a second transistor P1 and a third transistor N1; the first end of the first voltage-dividing resistor circuit 31 is connected to the third end of the first transistor Q1, the second end of the first voltage-dividing resistor circuit 31 is grounded, and the third end of the first voltage-dividing resistor circuit 31 is connected to the main control circuit 1 and the analog front-end circuit 2; the first end of the first transistor Q1 is connected to the first end of the second voltage-dividing resistor circuit 32, and the second end of the first transistor Q1 is grounded; the second end of the second voltage-dividing resistor circuit 32 is connected to the power supply V0 and the first end of the second transistor P1, the third end of the second voltage-dividing resistor circuit 32 is connected to the third end of the second transistor P1, and the second end of the second transistor P1 is grounded; the first end of the third transistor N1 is connected to the power supply V0, the second end of the third transistor N1 is connected to the charge and discharge switch circuit 4, and the third end of the third transistor N1 is connected to the second end of the second transistor P1.

[0067] As an example, the first voltage-divider resistor circuit 31 includes a first resistor R1 and a second resistor R2, which are arranged in series between the third terminal of the first transistor Q1 and the ground terminal. The connection node between the first resistor R1 and the second resistor R2 is connected to the main control circuit 1 and the analog front-end circuit 2. In this example, the second end of the first voltage-divider resistor circuit 31 is grounded via the sampling resistor Rs in the charge-discharge switch circuit 4.

[0068] Preferably, the third end of the first voltage-dividing resistor circuit 31 is connected to the analog front-end circuit 2 through an isolation diode D6 and is connected to the main control circuit 1 through an isolation diode D7.

[0069] As an example, the second voltage-dividing resistor circuit 32 includes a third resistor R3 and a fourth resistor R4. The first end of the third resistor R3 is connected to the power supply V0 and the first end of the second transistor P1. The second end of the third resistor R3 is connected to the first end of the fourth resistor R4. The second end of the fourth resistor R4 is connected to the first end of the first transistor Q1. The connection node between the third resistor R3 and the fourth resistor R4 is connected to the third end of the second transistor P1. The second end of the second transistor P1 is connected to the charge-discharge switch circuit 4. In this example, the second end of the second transistor P1 is connected to the charge-discharge switch circuit 4 via the resistor R5. Exemplarily, the second end of the second transistor P1 is grounded via the resistor R5 and the sampling resistor Rs. The power supply is connected to the main control circuit 1 via the voltage stabilizing circuit for supplying power to the main control circuit 1.

[0070] As an example, a first terminal of the third transistor N1 is connected to the power supply V0, a ​​second terminal of the third transistor N1 is connected to the charge-discharge switch circuit 4, and a third terminal of the third transistor N1 is connected to the second terminal of the second transistor P1. Exemplarily, the third terminal of the third transistor N1 is connected to the second terminal of the second transistor P1 via a first diode D1. Exemplarily, the anode of the first diode D1 is connected to the second terminal of the second transistor P1, and the cathode of the first diode D1 is connected to the third terminal of the third transistor N1.

[0071] As an example, the first transistor Q1 is an NMOS transistor, and the second transistor P1 is a PNP transistor. The third transistor N1 is an NPN transistor. For example, the first end of the first transistor Q1 is a drain, the second end of the first transistor Q1 is a source, and the third end of the first transistor Q1 is a gate. The first end of the second transistor P1 is an emitter, the second end of the second transistor P1 is a collector, and the third end of the second transistor P1 is a base. The first end of the third transistor N1 is a collector, the second end of the third transistor N1 is an emitter, and the third end of the third transistor N1 is a base. In this example, the first transistor Q1 acts as a switch tube to control the current in the drive circuit 3 to improve the response speed. The second transistor P1 and the third transistor N1 act as amplifier tubes to amplify the drive signal to improve the driving capability.

[0072] Furthermore, the drive circuit 3 includes a first capacitor C1 and a voltage regulator diode Z1. The first terminal of the first capacitor C1 is connected to the third terminal of the first transistor Q1, and the second terminal of the first capacitor C1 is connected to ground via a sampling resistor Rs in the charge-discharge switch circuit 4. The cathode of the voltage regulator diode Z1 is connected to the third terminal of the first transistor Q1, and the anode of the voltage regulator diode Z1 is connected to ground via a sampling resistor Rs in the charge-discharge switch circuit 4. The second resistor R2 and the first capacitor C1 form a filter circuit that eliminates oscillating drive signals from the isolation diodes D6 and D7. The voltage regulator diode Z1 stabilizes the voltage range of the drive level to prevent damage to the first transistor Q1.

[0073] In one application scenario, the main control circuit 1 outputs a first drive signal to the connection node between the third resistor R3 and the fourth resistor R4 via the isolation diode D7, and simultaneously sends a command to the analog front-end circuit 2 to close the charge-discharge switch circuit 4, i.e., sends a first control signal to the analog front-end circuit 2. After receiving the first control signal, the analog front-end circuit 2 outputs a second drive signal to the connection node between the third resistor R3 and the fourth resistor R4 via the isolation diode D6. In this way, the high-level signals simultaneously output by the main control circuit 1 and the analog front-end circuit 2 drive the first transistor Q1. When the voltage of the first capacitor C1 exceeds the turn-on voltage of the first transistor Q1, the first transistor Q1 is turned on, the second transistor P1 is turned on, and the output voltage VO of the power supply V0 is supplied to the third terminal of the third transistor N1 through the second transistor P1 and the first diode D1. The third transistor N1 is turned on, and the output voltage VO of the power supply V0 is supplied to the switch circuit 42 in the charge-discharge switch circuit 4 through the third transistor N1 to control the switch circuit 42 to turn on. At this time, the second drive signal output by the analog front-end circuit 2 remains stable and no longer oscillates. When main control circuit 1 outputs a low-level signal, the anode voltage of isolation diode D7 is lower than the cathode voltage, and isolation diode D7 is in the off state. At this point, only the second drive signal output by analog front-end circuit 2 is transmitted via isolation diode D6 to the connection node between third resistor R3 and fourth resistor R4, thereby reducing losses.

[0074] In this embodiment, by connecting the first end of the first voltage-dividing resistor circuit 31 to the third end of the first transistor Q1, the second end of the first voltage-dividing resistor circuit 31 is grounded, and the third end of the first voltage-dividing resistor circuit 31 is connected to the main control circuit 1 and the analog front-end circuit 2; connecting the first end of the first transistor Q1 to the first end of the second voltage-dividing resistor circuit 32, and the second end of the first transistor Q1 is grounded; connecting the second end of the second voltage-dividing resistor circuit 32 to the power supply V0 and the first end of the second transistor P1, the third end of the second voltage-dividing resistor circuit 32 is connected to the third end of the second transistor P1, and the second end of the second transistor P1 is grounded; connecting the first end of the third transistor N1 to the power supply V0, the second end of the third transistor N1 is connected to the charge-discharge switch circuit 4, and the third end of the third transistor N1 is connected to the second end of the second transistor P1, so that the structure of the driving circuit 3 is simple, and the switching stability of the charge-discharge switch circuit 4 can be ensured while reducing losses.

[0075] In one embodiment, the charge and discharge control circuit further includes a discharge circuit 5 ; the discharge circuit 5 is connected to the drive circuit 3 and the switch tube circuit 42 , and is used to discharge the electrical energy stored in the parasitic capacitance of the switch tube circuit 42 when the switch tube circuit 42 is turned off.

[0076] In this embodiment, the discharge circuit 5 is connected to the drive circuit 3 and the switch tube circuit 42 to discharge the electric energy stored in the parasitic capacitance of the switch tube circuit 42 when the switch tube circuit 42 is turned off. In this way, when charging and discharging are abnormal, the electric energy stored in the parasitic capacitance of the switch tube circuit 42 can be discharged in time, thereby improving safety.

[0077] In one embodiment, the bleeder circuit 5 includes a fourth transistor P4, a fifth transistor P2, and a first bleeder resistor circuit 51; a first end of the fourth transistor P4 is connected to the third end of the fifth transistor P2 and the third end of the fourth transistor P4, a second end of the fourth transistor P4 is grounded, and a third end of the fourth transistor P4 is connected to the drive circuit 3; a first end of the fifth transistor P2 is connected to the charge and discharge switch circuit 4, a second end of the fifth transistor P2 is connected to the first end of the first bleeder resistor circuit 51, and a second end of the first bleeder resistor circuit 51 is grounded.

[0078] As an example, the fourth transistor P4 is of a different type than the first transistor Q1 and the third transistor N1, but is of the same type as the second transistor P1. The fifth transistor P2 is of the same type as the fourth transistor P4. For example, the fourth transistor P4 and the fifth transistor P2 are both PNP transistors. The first end of the fourth transistor P4 is an emitter, the second end of the fourth transistor P4 is a collector, and the third end of the fourth transistor P4 is a base. The first end of the fifth transistor P2 is an emitter, the second end of the fifth transistor P2 is a collector, and the third end of the fifth transistor P2 is a base.

[0079] In one application scenario, when the voltage of the first capacitor C1 exceeds the turn-on voltage of the first transistor Q1, the first transistor Q1 is closed, the second transistor P1 is turned on, and the output voltage VO of the power supply V0 is supplied to the base of the fourth transistor P4, the base of the fifth transistor P2, and the anode of the first diode D1 through the second transistor P1. Because the EBs of the fourth transistor P4 and the fifth transistor P2 are turned off, the fourth transistor P4 and the fifth transistor P2 are both turned off. The output voltage VO of the power supply V0 is supplied to the third terminal of the third transistor N1 through the second transistor P1 and the first diode D1. The third transistor N1 is turned on, and the output voltage VO of the power supply V0 is supplied to the switch tube circuit 42 in the charge and discharge switch circuit 4 through the third transistor N1 to control the switch tube circuit 42 to turn on.

[0080] When the analog front-end circuit 2 detects that the voltage across the current-sense resistor Rs is too high, it determines that a charge overcurrent, a discharge overcurrent, or a short circuit has occurred. The analog front-end circuit 2 stops outputting the second drive signal, the isolation diode D6 turns off, and the electrical energy stored in the first capacitor C1 is discharged through the first resistor R1 and the second resistor R2. When the voltage across the first capacitor C1 is lower than the turn-on voltage of the first transistor Q1, the first transistor Q1 turns off, and the second transistor P1 also turns off. The base of the fourth transistor P4 is pulled to a low level by the resistor R5, and the fourth transistor P4 turns on, thereby causing the base of the fifth transistor P2 to be pulled to a low level by the fourth transistor P4. The fifth transistor P2 turns on, the first diode D1 turns off, and the base of the third transistor N1 is pulled to a low level by the fourth transistor P4. The third transistor N1 turns off, and the parasitic capacitance of the switch circuit 42 in the charge-discharge switch circuit 4 begins to discharge through the first discharge resistor circuit 51, thereby ensuring the safety of the charge-discharge control circuit.

[0081] In one embodiment, the bleeder circuit 5 further includes a sixth transistor P3 and a first diode D1; an anode of the first diode D1 is connected to the drive circuit 3, the third terminal of the fourth transistor P4, and the third terminal of the sixth transistor P3, and a cathode of the first diode D1 is connected to the first terminal of the fourth transistor P4, the drive circuit 3, and the third terminal of the fifth transistor P2; a first terminal of the sixth transistor P3 is connected to the drive circuit 3, and a second terminal of the sixth transistor P3 is connected to the first terminal of the first bleeder resistor circuit 51.

[0082] Optionally, the first diode D1 is a Schottky diode.

[0083] As an example, the sixth transistor P3 is an NPN transistor, wherein a first terminal of the sixth transistor P3 is an emitter, a second terminal of the sixth transistor P3 is a collector, and a third terminal of the sixth transistor P3 is a base.

[0084] In this embodiment, the anode of the first diode D1 is connected to the drive circuit 3, the third end of the fourth transistor P4, and the third end of the sixth transistor P3, and the cathode of the first diode D1 is connected to the first end of the fourth transistor P4, the drive circuit 3, and the third end of the fifth transistor P2; the first end of the sixth transistor P3 is connected to the drive circuit 3, and the second end of the sixth transistor P3 is connected to the first end of the first bleeder resistor circuit 51, so that when the fifth transistor P2 and the sixth transistor P3 are both turned on, two bleeder circuits are formed, thereby improving the bleeder speed.

[0085] In one embodiment, the switch circuit 42 includes at least two GaN transistors; and the at least two GaN transistors are connected in parallel.

[0086] In this example, each GaN transistor is bidirectionally conductive and blocking. The first terminal of the GaN transistor serves as a first drain, the second terminal of the GaN transistor serves as a second drain, and the third terminal of the GaN transistor serves as a gate. This allows a single bidirectional GaN device to replace two back-to-back MOSFETs. In this embodiment, at least two GaN transistors are connected in parallel to reduce the on-resistance of the switch circuit 42. It is understood that the switch circuit 42 may also include at least two MOSFET circuits. Each MOSFET circuit includes two MOSFET transistors connected in series.

[0087] For example, a voltage regulator diode Z2 and a diode D2 are connected in series between the first and third terminals of the switch circuit 42, and a voltage regulator diode Z3 and a diode D3 are connected in series between the second and third terminals of the switch circuit 42. The voltage regulator diodes Z2 and Z3 are used to stabilize the driving voltage of the switch circuit 42, and the diodes D2 and D3 are used for backflow protection.

[0088] In one embodiment, the bleeder circuit 5 further includes a second diode SD1 and a second bleeder resistor circuit 52; a first end of the second bleeder resistor circuit 52 is connected to the switch tube circuit 42, a second end of the second bleeder resistor circuit 52 is connected to the anode of the second diode SD1, and a cathode of the second diode SD1 is connected to the first end of the fifth transistor P2.

[0089] As an example, the second bleeder resistor circuit 52 includes multiple bleeder resistors, and the gate of each gallium nitride transistor is connected to the drive circuit 3 via a bleeder resistor. Optionally, the second bleeder resistor circuit 52 is further connected to the drive circuit 3 via a resistor R9. Exemplarily, the second bleeder resistor circuit 52 includes resistors R8 and R7, with resistor R8 connected to the gate of gallium nitride transistor VGaN1 and resistor R7 connected to the gate of gallium nitride transistor VGaNn. It is understood that for ease of description, resistors R8 and R7 are merely examples, and the gates of gallium nitride transistors VGaN2 to VGaNn-1 may also be provided with a bleeder resistor connected to the drive circuit 3 via resistor R9.

[0090] In one application scenario, when the analog front-end circuit 2 stops outputting the second drive signal, the first transistor Q1 is turned off, and the second transistor P1 is also turned off. The bases of the fourth transistor P4 and the fifth transistor P2 are both pulled to a low level by the resistor R5, the fourth transistor P4 and the sixth transistor P3 are turned on, the base of the fifth transistor P2 is pulled to a low level by the fourth transistor P4, the fifth transistor P2 is turned on, the first diode D1 is turned off, and the base of the third transistor N1 is pulled to a low level by the fourth transistor P4. The third transistor N1 is turned off, and the parasitic capacitance of the switch circuit 42 in the charge-discharge switch circuit 4 begins to discharge through the first bleeder resistor circuit 51, thereby ensuring the safety of the charge-discharge control circuit. This forms two bleeder circuits 5: bleeder circuit 1: parasitic capacitance of switching circuit 42 → resistors R7 and R8 → second diode SD1 → fifth transistor P2 → resistor R6 → parasitic capacitance of switching circuit 42; bleeder circuit 2: parasitic capacitance of switching circuit 42 → resistors R7 and R8 → second diode SD1 → sixth transistor P3 → resistor R6 → parasitic capacitance of switching circuit 42. Because the base current of fifth transistor P2 is amplified by fourth transistor P4, the current discharged through bleeder circuit 1 is much greater than that discharged through bleeder circuit 2. When the voltage across the parasitic capacitance of switching circuit 42 is less than approximately 1.5V, bleeder circuit 1 is cut off. Because the conduction voltage across the PN junctions of the fifth transistor P2 and the fourth transistor P4 is approximately 1.2V, and the conduction voltage across the second diode SD1 is approximately 0.3V, the sum of the voltages across the three PN junctions of the fifth transistor P2, the fourth transistor P4, and the second diode SD1 is approximately 1.5V. At this point, the fifth transistor P2 and the fourth transistor P4 are turned off, and discharge loop 1 is open. Only discharge loop 2 is discharging. When the voltage across the parasitic capacitance of the switch circuit 42 is less than approximately 0.9V, the sum of the voltages across the PN junctions of the sixth transistor P3 and the second diode SD1 is approximately 0.9V, and discharge loop 2 is also turned off.

[0091] In one embodiment, the bleeder circuit 5 includes a third bleeder resistor circuit 53 ; a third bleeder resistor circuit 53 is connected in series between the first terminal and the third terminal of each gallium nitride transistor.

[0092] Exemplarily, the third bleeder resistor circuit 53 includes a resistor R11 and a resistor R12. Resistor R11 is connected to the first and third terminals of the gallium nitride transistor VGaN1, while resistor R12 is connected to the first and third terminals of the gallium nitride transistor VGaNn. It will be appreciated that for ease of description, resistors R11 and R12 are merely examples; a bleeder resistor may also be provided between the first and third terminals of the gallium nitride transistors VGaN2 through VGaNn-1.

[0093] In this example, when the voltage on the parasitic capacitance of the switching tube circuit 42 is less than approximately 0.9V, the sum of the voltages across the two PN junctions of the sixth transistor P3 and the second diode SD1 is approximately 0.9V, and the discharge loop 2 is also cut off. Discharge occurs through the discharge loop 3: the parasitic capacitance of the switching tube circuit 42 → resistors R7 and R8 → resistor R9 → sixth transistor P3P3 → resistor R6 → parasitic capacitance of the switching tube circuit 42. When the voltage on the parasitic capacitance of the switching tube circuit 42 is less than approximately 0.6V, the discharge loop 3 is also cut off. At this point, the voltage on the parasitic capacitance of the switching tube circuit 42 can only be discharged through resistors R11 and R12, discharging the remaining 0.6V of energy.

[0094] In this embodiment, a multi-channel discharge circuit is formed by the discharge circuit 5 in this application, thereby increasing the discharge speed of the parasitic capacitance and improving the safety of the charge and discharge control circuit.

[0095] In this embodiment, a battery management system includes a battery and the above-mentioned charge and discharge control circuit; the battery is connected to the charge and discharge control circuit.

[0096] As an example, the battery management system may also include multiple functional modules. These multiple functional modules are connected to the main control circuit 1 in the charge and discharge control circuit. For example, the multiple functional modules include LCD display, 485 communication, 232 communication, 4G + GPS communication, reverse connection detection, reset, switch detection, dial detection, heating control, and buzzer.

[0097] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A charge and discharge control circuit, characterized in that: Including power supply, charge and discharge switch circuit, analog front-end circuit and drive circuit; The analog front-end circuit is connected to the driving circuit and is used to output a first driving signal to the driving circuit; The driving circuit is connected to the power supply and the charge-discharge switch circuit, and is used to turn on or off the power supply and the charge-discharge switch circuit according to the first driving signal; The charge-discharge switch circuit is used to connect the battery and the charge-discharge connection terminal, and conducts between the battery and the charge-discharge connection terminal when receiving the first power supply signal provided by the power supply; The driving circuit includes a first voltage-dividing resistor circuit, a second voltage-dividing resistor circuit, a first transistor, a second transistor and a third transistor; A first end of the first voltage-dividing resistor circuit is connected to the third end of the first transistor, a second end of the first voltage-dividing resistor circuit is grounded, and a third end of the first voltage-dividing resistor circuit is connected to the analog front-end circuit; The first end of the first transistor is connected to the first end of the second voltage-dividing resistor circuit, and the second end of the first transistor is grounded; The second end of the second voltage-dividing resistor circuit is connected to the power supply and the first end of the second transistor, the third end of the second voltage-dividing resistor circuit is connected to the third end of the second transistor, and the second end of the second transistor is grounded; The first end of the third transistor is connected to the power supply, the second end of the third transistor is connected to the charge and discharge switch circuit, and the third end of the third transistor is connected to the second end of the second transistor.

2. The charge and discharge control circuit according to claim 1, wherein: The charge and discharge control circuit also includes a main control circuit; The analog front-end circuit is connected to the charge and discharge switch circuit and the main control circuit, and is used to collect charge and discharge signals and transmit them to the main control circuit; The main control circuit is used to output a first control signal to the analog front-end circuit according to the charge and discharge signal, so that the analog front-end circuit outputs a first drive signal according to the first control signal.

3. The charge and discharge control circuit according to claim 2, wherein: The main control circuit is also connected to the driving circuit, and is used to output a second driving signal to the driving circuit according to the charge and discharge signal; The driving circuit is used to turn on or off the power supply and the charge-discharge switch circuit according to the first driving signal and the second driving signal.

4. The charge and discharge control circuit according to claim 2, wherein: The charge and discharge switch circuit includes a sampling circuit and a switch tube circuit; The first end of the sampling circuit is connected to the battery and the ground end, the second end of the sampling circuit is connected to the first end of the switching tube circuit, the second end of the switching tube circuit is connected to the charge and discharge connection end, and the third end of the switching tube circuit is connected to the driving circuit; The analog front-end circuit is connected to a first terminal and a second terminal of the sampling circuit.

5. The charge and discharge control circuit according to claim 4, wherein: The charge and discharge control circuit also includes a discharge circuit; the discharge circuit is connected to the drive circuit and the switch tube circuit, and is used to discharge the electrical energy stored in the parasitic capacitance of the switch tube circuit when the switch tube circuit is turned off.

6. The charge and discharge control circuit according to claim 5, wherein: The discharge circuit includes a fourth transistor, a fifth transistor and a first discharge resistance circuit; The first terminal of the fourth transistor is connected to the third terminal of the fifth transistor and the third terminal of the fourth transistor, the second terminal of the fourth transistor is grounded, and the third terminal of the fourth transistor is connected to the second terminal of the second transistor; A first end of the fifth transistor is connected to the switch tube circuit, a second end of the fifth transistor is connected to a first end of the first bleeder resistor circuit, and a second end of the first bleeder resistor circuit is grounded.

7. The charge and discharge control circuit according to claim 6, wherein: The discharge circuit further includes a sixth transistor and a first diode; an anode of the first diode is connected to the second end of the second transistor, the third end of the fourth transistor, and the third end of the sixth transistor, and a cathode of the first diode is connected to the first end of the fourth transistor, the third end of the third transistor, and the third end of the fifth transistor; The first end of the sixth transistor is connected to the second end of the third transistor, and the second end of the sixth transistor is connected to the first end of the first discharge resistance circuit.

8. The charge and discharge control circuit according to claim 6, wherein: The discharge circuit further includes a second diode and a second discharge resistance circuit; A first end of the second bleeder resistor circuit is connected to the switch tube circuit, a second end of the second bleeder resistor circuit is connected to the anode of the second diode, and a cathode of the second diode is connected to the first end of the fifth transistor.

9. The charge and discharge control circuit according to claim 5, wherein: The switching tube circuit includes at least two gallium nitride transistors; and the at least two gallium nitride transistors are arranged in parallel.

10. The charge and discharge control circuit according to claim 9, wherein: The discharge circuit includes a third discharge resistor circuit; a third discharge resistor circuit is connected in series between the first terminal and the third terminal of each gallium nitride transistor.

11. A battery management system, characterized in that: The invention comprises a battery and the charge and discharge control circuit according to any one of claims 1 to 10; the battery is connected to the charge and discharge control circuit.

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