A battery management circuit and a battery management system

Abstract

The present application provides a battery management circuit and a battery management system, and relates to the field of battery technology. In the battery management circuit, the first end of the discharge switch unit is connected to the positive power supply end of the battery module, the second end of the discharge switch unit is connected to the positive power supply end of the load through the charging switch unit, and the negative power supply end of the load is connected to the negative power supply end of the battery module; the first end and the second end of the first switch unit in the slow-start circuit are respectively connected to the first end and the second end of the discharge switch unit; the preset sampling point is connected to the negative input end of the negative feedback circuit, the control end of the first switch unit is connected to the output end of the negative feedback circuit, and the positive input end of the negative feedback circuit is connected to the two voltage ends of the preset reference voltage source; the input end of the control unit is connected to the preset sampling point, and the control ends of the discharge switch unit, the charging switch unit and the negative feedback circuit are respectively connected to the first output end, the second output end and the third output end of the control unit. The present application can reduce the startup time and improve the safety of the battery module.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a battery management circuit and a battery management system. Background Art

[0002] BMS (Battery Management System) is the link between the battery and the user. In actual applications, if the power load has a large capacitance, if the discharge switch unit and the charging switch unit are directly powered on and turned on, the battery module will quickly charge the power load and generate a large surge current. This large surge current can easily burn the power load and other devices in the BMS circuit, causing the BMS circuit to fail to work properly.

[0003] In order to avoid the above problems, the general practice is to connect a slow-start circuit consisting of a current-limiting resistor and a switch tube in series in parallel at both ends of the discharge switch unit. When the slow-start circuit is powered on, the switch tube of the slow-start circuit is turned on first, and the battery module charges the power load through the slow-start circuit and the charging switch unit. When the charging time of the power load is extended for a period of time, the voltage of the power load increases. When it is close to the voltage of the battery module being fully charged, the discharge switch unit is turned on and the switch tube of the slow-start circuit is turned off.

[0004] However, when using this method to charge the power load, since the full charging time of the power load depends on the resistance of the current limiting resistor and the capacitance of the power load, the charging time of the power load is relatively long, thereby affecting the user experience of the product in which the BMS circuit is located. Utility Model Content

[0005] The purpose of this application is to provide a battery management circuit and a battery management system, which can realize constant current slow start of the battery management circuit, reduce the startup time, and improve the safety of the battery module when charging and discharging are started, thereby improving the user experience of the product in which the battery management circuit is located.

[0006] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0007] In a first aspect, an embodiment of the present application provides a battery management circuit, the battery management circuit comprising: a discharge switch unit, a charge switch unit, a slow-start circuit and a control unit;

[0008] The first end of the discharge switch unit is used to connect the positive power supply end of the battery module, the second end of the discharge switch unit is connected to the positive power supply end of the power load through the charging switch unit, and the negative power supply end of the power load is used to connect the negative power supply end of the battery module;

[0009] Wherein, the slow-start circuit comprises: a first switch unit and a negative feedback circuit;

[0010] Wherein, the first end and the second end of the first switch unit are connected to the first end and the second end of the discharge switch unit respectively;

[0011] A preset sampling point between the second end of the discharge switch unit and the charge switch unit is connected to a negative input end of the negative feedback circuit, a control end of the first switch unit is connected to an output end of the negative feedback circuit, and a positive input end of the negative feedback circuit is connected to two voltage ends of a preset reference voltage source;

[0012] The input end of the control unit is connected to the preset sampling point, and the control end of the discharge switch unit, the control end of the charge switch unit and the control end of the negative feedback circuit are respectively connected to the first output end, the second output end and the third output end of the control unit.

[0013] Optionally, the negative feedback circuit includes: an operational amplifier, a second switch unit and a current sampling unit;

[0014] The second end of the first switch unit is connected to one end of the current sampling unit;

[0015] The other end of the current sampling unit is the negative input end of the negative feedback circuit, the other end of the current sampling unit is connected to the preset sampling point, and the other end of the current sampling unit is also connected to the negative input end of the operational amplifier;

[0016] The positive input terminal of the operational amplifier is the positive input terminal of the negative feedback circuit, the positive input terminal of the operational amplifier is connected to the first terminal of the second switch unit, and the second terminal and the third terminal of the second switch unit are respectively connected to the two voltage terminals of the preset reference voltage source;

[0017] The output end of the operational amplifier is the output end of the negative feedback circuit, and the output end of the operational amplifier is connected to the control end of the first switch unit; the control end of the second switch unit is connected to the third output end of the control unit.

[0018] Optionally, the slow-start circuit further includes: a filtering unit;

[0019] The output end of the operational amplifier is connected to the control end of the first switch unit through the filter unit.

[0020] Optionally, the filtering unit includes: a filtering resistor and a filtering capacitor;

[0021] The output end of the operational amplifier is connected to the control end of the first switch unit through the filter resistor, and the control end of the first switch unit is also connected to the other end of the current sampling unit through the filter capacitor.

[0022] Optionally, the current sampling unit includes: a sampling resistor or a Hall voltage sensor.

[0023] Optionally, the first switch unit is an NMOS switch tube, the first end of the first switch unit is a drain, the second end of the first switch unit is a source, and the control end of the first switch unit is a gate.

[0024] Optionally, the first switch unit is an N-type transistor, the first end of the first switch unit is the collector of the N-type transistor, the second end of the first switch unit is the emitter of the N-type transistor, and the control end of the first switch unit is the base of the N-type transistor.

[0025] Optionally, the discharge switch unit is an NMOS switch tube, the first end of the discharge switch unit is a drain, the second end of the discharge switch unit is a source, and the control end of the discharge switch unit is a gate.

[0026] Optionally, the charging switch unit is an NMOS switch tube, the first end of the charging switch unit is a source, the second end of the charging switch unit is a drain, and the control end of the charging switch unit is a gate.

[0027] In a second aspect, an embodiment of the present application provides a battery management system, the battery management system comprising: a battery module, and a battery management circuit as described in any one of the first aspects above;

[0028] The positive power supply terminal and the negative power supply terminal of the battery module are respectively connected to the positive power supply terminal and the negative power supply terminal of the battery management circuit.

[0029] The beneficial effects of a battery management circuit and a battery management system provided by the present application are:

[0030] The present application provides a battery management circuit and a battery management system, the battery management circuit comprising: a discharge switch unit, a charging switch unit, a slow-start circuit and a control unit; the first end of the discharge switch unit is used to connect to the positive power supply end of the battery module, the second end of the discharge switch unit is connected to the positive power supply end of the power load through the charging switch unit, and the negative power supply end of the power load is used to connect to the negative power supply end of the battery module; wherein the slow-start circuit comprises: a first switch unit and a negative feedback circuit; wherein the first end and the second end of the first switch unit are respectively connected to the first end and the second end of the discharge switch unit; a preset sampling point between the second end of the discharge switch unit and the charging switch unit is connected to the negative input end of the negative feedback circuit, the control end of the first switch unit is connected to the output end of the negative feedback circuit, and the positive input end of the negative feedback circuit is connected to two voltage ends of a preset reference voltage source; the input end of the control unit is connected to the output end of the negative feedback circuit, and the control end of the discharge switch unit, the control end of the charging switch unit and the control end of the negative feedback circuit are respectively connected to the first output end, the second output end and the third output end of the control unit. Therefore, the current collected by the current sampling unit in the present application is fed back to the negative input terminal of the operational amplifier to form negative feedback of the slow-start circuit, and then the operational amplifier automatically adjusts the voltage of the control terminal of the first switch unit according to the feedback of the current sampling unit, and then controls the charging current of the power load to be in a constant current state, so as to realize charging the power load in a constant current slow-start mode, avoiding the very large current surge generated when the discharge switch unit is used alone when it is just turned on, and ensuring the safety of the battery module when charging and discharging are turned on. At the same time, due to the comparison between the slow-start circuit method in the embodiment of the present application and the slow-start circuit method in the prior art, it can be obtained that by adopting the constant current slow-start mode, the entire slow-start process can charge the power load with a larger limiting current, which greatly reduces the startup time. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic diagram of the structure of a battery management system provided in an embodiment of the present application;

[0033] Figure 2 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 1 ;

[0034] Figure 3 A schematic diagram of a battery management circuit in the prior art provided in an embodiment of the present application;

[0035] Figure 4 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 2 ;

[0036] Figure 5 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 3 ;

[0037] Figure 6 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 4 ;

[0038] Figure 7 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 5 ;

[0039] Figure 8 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 6 ;

[0040] Fig. 9 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 7 ;

[0041] Fig.10 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 8 ;

[0042] Fig.11 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 9 . DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0045] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0046] In the description of the present application, it should be understood that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the utility model product is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0047] Furthermore, the terms “first”, “second”, “third”, etc. are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0048] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0049] In order to better understand the various solutions provided in the embodiments of the present application, a battery management circuit and a battery management system provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0050] The battery management system provided in the embodiments of the present application is first described with reference to the accompanying drawings as follows. Figure 1 This is a schematic diagram of the structure of a battery management system provided in an embodiment of the present application. Figure 1 As shown, the battery management system 400 may include: a battery module 300 and a battery management circuit 200 .

[0051] Among them, the positive power supply terminal and the negative power supply terminal of the battery module 300 are respectively connected to the positive power supply terminal and the negative power supply terminal in the battery management circuit 200, so that the battery management circuit 200 is connected to the positive and negative power supplies of the battery module 300. The charging and discharging of the battery module 300 can be managed by the battery management circuit 200, thereby improving the safety and user experience of the product in which the battery module 300 is located, and avoiding the risk of over-discharge and over-charging of the battery module 300.

[0052] The battery module 300 may be selected according to actual conditions. For example, the battery module 300 may be selected as a battery pack.

[0053] The present application provides a battery management system including: a battery module and a battery management circuit; the positive power supply terminal and the negative power supply terminal of the battery module are respectively connected to the positive power supply terminal and the negative power supply terminal of the battery management circuit. Therefore, the present application can manage the charging and discharging of the battery module through the battery management circuit, improve the safety and user experience of the product in which the battery module is located, and avoid the risk of over-discharging and over-charging of the battery module.

[0054] To facilitate understanding of the above-mentioned battery management system 400, the embodiment of the present application further provides a battery management circuit 200. Figure 2 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 1 .like Figure 2 As shown, the battery management circuit 200 may include: a discharge switch unit 210 , a charge switch unit 220 , a slow-start circuit 100 and a control unit 230 .

[0055] Among them, the first end of the discharge switch unit 210 is used to connect to the positive power supply end of the battery module, so as to provide an operating current to the first end of the discharge switch unit 210 through the positive power supply end of the battery module; the second end of the discharge switch unit 210 is connected to the positive power supply end of the electrical load through the charging switch unit 220, and the negative power supply end of the electrical load is used to connect to the negative power supply end of the battery module, so as to charge the electrical load through the charging switch unit 220, and also discharge the electrical load through the discharge switch unit 210; wherein, the electrical load can be selected according to actual conditions, and is not limited here. For example, the electrical load may include: load capacitance, etc.

[0056] Since the slow-start circuit 100 may include: a first switch unit 110 and a negative feedback circuit 120, the first end and the second end of the first switch unit 110 in the slow-start circuit 100 are respectively connected to the first end and the second end of the discharge switch unit 210. Since the first end of the discharge switch unit 210 is used to connect to the positive power supply end of the battery module, the first end of the first switch unit 110 is also connected to the positive power supply end of the battery module, so as to provide the first switch unit 110 with an operating current through the positive power supply end of the battery module; the second end of the first switch unit 110 is connected to the second end of the discharge switch unit 210 to control one of the first switch unit 110 and the discharge switch unit 210 to be turned on or off.

[0057] The preset sampling point A between the second end of the discharge switch unit 210 and the charge switch unit 220 is connected to the negative input end of the negative feedback circuit 120 to feed back the electrical signal collected at the preset sampling point A to the negative input end of the negative feedback circuit 120; the control end of the first switch unit 110 is connected to the output end of the negative feedback circuit 120 to control the conduction and disconnection of the first switch unit 110 according to the output electrical signal of the negative feedback circuit 120; the positive input end of the negative feedback circuit 120 is connected to the two voltage ends of the preset reference voltage source to control the operation of the negative feedback circuit according to the two voltage ends of the preset reference voltage source. Among them, the two voltage ends of the preset reference voltage source can be selected according to actual conditions, for example, the two voltage ends of the preset reference voltage source can be selected as a 5V voltage source and a 0V voltage source. Optionally, in a possible implementation method, the two voltage ends of the preset reference voltage source can be a power supply end and a ground end. That is, according to the opening of the preset reference voltage source and the setting of the constant current size, the closing of the slow-start circuit 100 can be realized through the ground end of the preset reference voltage source. That is, the power supply terminal and the ground terminal of any preset reference voltage source can be selected as the input signal of the positive input terminal of the negative feedback circuit 120 .

[0058] It should be noted that the voltage magnitudes of the two voltage terminals of the preset reference power supply can be set according to the actual set value and corresponding relationship of the output current in the slow-start circuit (i.e., the current at the preset sampling point A), which should not be considered as a limitation of the present application.

[0059] The input end of the control unit 230 is connected to the preset sampling point A to collect the magnitude of the output current of the slow-start circuit 100, and then determine the start time of the slow-start circuit 100 according to the magnitude of the output current and the capacitance value of the power load; the control end of the discharge switch unit 210, the control end of the charging switch unit 220 and the control end of the negative feedback circuit 120 are respectively connected to the first output end, the second output end and the third output end of the control unit 230, so as to control the control end of the discharge switch unit 210, the control end of the charging switch unit 220 and the control end of the negative feedback circuit 120 according to the first output end, the second output end and the third output end of the control unit 230.

[0060] It should be noted that, in actual applications, an isolation driver can be added between the control unit 230 and the control end of the discharge switch unit 210, the control end of the charge switch unit 220, and the control end of the negative feedback circuit 120, that is, the control end of the discharge switch unit 210, the control end of the charge switch unit 220, and the control end of the negative feedback circuit 120 are all connected to the control unit 230 through an isolation driver, so as to isolate the power signal from the control signal and improve the safety and stability of the battery management circuit. In addition, it should be noted that before the isolation driver connected to the discharge switch unit 210, the charge switch unit 220, and the control end of the negative feedback circuit 120, an isolation DCDC (direct current-direct current) needs to be connected to provide a preset DC power supply Vd+ to the isolation driver. Similarly, the working power supply of the control unit 230 is also a DC power supply, and the battery module 300 can be powered by the power taking module to power the control unit 230.

[0061] In a possible implementation, when the battery management circuit 200 is powered on, the slow-start circuit 100 is first turned on, and at the same time, the discharge switch unit 210 is kept closed. Then, by connecting the positive input terminal of the negative feedback circuit 120 to a preset reference voltage source (such as 5V, such as a voltage terminal), since the negative input terminal signal of the negative feedback circuit 120 in the initial state is an isolated ground, the output terminal of the negative feedback circuit 120 outputs a high voltage, driving the first switch unit 110 to turn on. After the first switch unit 110 is turned on, the output current of the positive power supply terminal of the battery module can reach the preset sampling point A through the first switch unit 110, and form a voltage at the preset sampling point A, which is fed back to the negative input terminal of the negative feedback circuit 120, thereby forming a A closed loop is formed, that is, in the negative feedback circuit 120, the voltages at the positive input terminal and the negative input terminal of the negative feedback circuit 120 are equal, thereby ensuring that the current flowing through the preset sampling point A is constant, and then charging the electrical load according to the constant current until the control unit 230 detects that the current at the preset sampling point A has changed, and then it can be determined that the charging voltage of the electrical load is close to the power supply voltage of the battery module. The control unit 230 can control the control end of the negative feedback circuit 120 to connect the positive input terminal of the negative feedback circuit 120 to a preset reference voltage source (such as 0V, i.e., the ground terminal), or pull down and close the control end of the first switch unit 110 in the slow-start circuit 100 to end the power-on process of the slow-start circuit 100, and then turn on the discharge switch unit 210.

[0062] In another possible implementation, the slow-start time of the battery management circuit using constant current provided in the embodiment of the present application and the slow-start method using resistor current limiting in the prior art can be compared. Figure 3 The structure diagram of a battery management circuit of the prior art provided in the embodiment of the present application is shown in FIG. Figure 3As shown, the battery management circuit 500 in the prior art may include: a discharge switch unit 510 , a charge switch unit 520 and a slow-start circuit 530 .

[0063] The slow-start circuit 530 may include: a current-limiting resistor 531 and a first switch unit 532 .

[0064] Among them, the first end of the discharge switch unit 510 is connected to one end of the current limiting resistor 531 in the slow start circuit 530, and the other end of the current limiting resistor 531 is connected to the first switch unit 532, that is, the current limiting resistor 531 and the first switch unit 532 are connected in series, and the second end of the first switch unit 532 is connected to the second end of the discharge switch unit 510, and the second end of the discharge switch unit 510 is connected to the power load through the charging switch unit 520. When the battery management circuit 500 of the prior art is powered on and started, the first switch unit 532 of the slow start circuit 530 is first turned on. At this time, due to the current limiting of the current limiting resistor 531, the first switch unit 532 is in a short circuit state, so that the battery module charges the power load through the slow start circuit 530 and the charging switch unit 520. After a delay period, the charging voltage of the power load increases. After it is close to the power supply voltage of the battery module, the discharge switch unit 510 is turned on and the first switch unit 532 in the slow start circuit 530 is turned off.

[0065] For example, assuming that the power supply voltage U of the battery module is 48V, the capacitor C in the power load is 100*1000UF, the current value I limited by the current limiting resistor 531 in the prior art is 10A, and the current value I of the slow start mode of the constant current battery management circuit in the embodiment of the present application is also 10A, and assuming that the voltage of the capacitor C of the power load reaches 95% of the power supply voltage U of the battery module to be in a full state. Then the slow start time T can be calculated using the following formulas (1) and (2).

[0066] Among them, the slow start time of the current limiting resistor in the prior art is:

[0067] R=48V / 10A=4.8 ohms

[0068] T = 3RC = 1.44 seconds Formula (1)

[0069] Wherein, R is the resistance value of the current limiting resistor 531 .

[0070] The slow start time T of the constant current battery management circuit slow start mode in the embodiment of the present application is:

[0071] Q=C*U=∫Idt to obtain

[0072] 0.1*48*0.95=10*T

[0073] T = 0.456 seconds Formula (2)

[0074] Among them, Q is the capacitance of the electrical load.

[0075] It can be seen that under the same conditions, there is a difference in calculating the slow-start time T according to formula (1) and formula (2). Using the constant current battery management circuit slow-start method in the embodiment of the present application to charge the power load capacitor can greatly reduce the charging time and speed up the charging speed. However, the current limiting resistor method in the prior art is used to charge the power load capacitor. During the charging process, the charging speed is fast at the beginning, but gradually decreases later, resulting in a long charging time. Therefore, the constant current battery management circuit slow-start method provided in the embodiment of the present application reduces the charging time of the power load capacitor relative to the prior art solution.

[0076] The present application provides a battery management circuit, which includes: a discharge switch unit, a charging switch unit, a slow-start circuit and a control unit; the first end of the discharge switch unit is used to connect to the positive power supply end of the battery module, the second end of the discharge switch unit is connected to the positive power supply end of the power load through the charging switch unit, and the negative power supply end of the power load is used to connect to the negative power supply end of the battery module; wherein the slow-start circuit includes: a first switch unit and a negative feedback circuit; wherein the first end and the second end of the first switch unit are respectively connected to the first end and the second end of the discharge switch unit; a preset sampling point between the second end of the discharge switch unit and the charging switch unit is connected to the negative input end of the negative feedback circuit, the control end of the first switch unit is connected to the output end of the negative feedback circuit, and the positive input end of the negative feedback circuit is connected to two voltage ends of a preset reference voltage source; the input end of the control unit is connected to the output end of the negative feedback circuit, and the control end of the discharge switch unit, the control end of the charging switch unit and the control end of the negative feedback circuit are respectively connected to the first output end, the second output end and the third output end of the control unit. Therefore, the current collected by the current sampling unit in the present application is fed back to the negative input terminal of the operational amplifier to form negative feedback of the slow-start circuit, and then the operational amplifier automatically adjusts the voltage of the control terminal of the first switch unit according to the feedback of the current sampling unit, and then controls the charging current of the power load to be in a constant current state, so as to realize charging the power load in a constant current slow-start mode, avoiding the very large current surge generated when the discharge switch unit is used alone when it is just turned on, and ensuring the safety of the battery module when charging and discharging are turned on. At the same time, due to the comparison between the slow-start circuit method in the embodiment of the present application and the slow-start circuit method in the prior art, it can be obtained that by adopting the constant current slow-start mode, the entire slow-start process can charge the power load with a larger limiting current, which greatly reduces the startup time.

[0077] exist Figure 2 Based on the above, the battery management circuit 200 is further described with reference to examples as follows. Figure 4A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 2 .like Figure 4 As shown, the negative feedback circuit 120 in the slow-start circuit 100 may include: an operational amplifier 121 , a second switch unit 122 and a current sampling unit 123 .

[0078] The second end of the first switch unit 110 is connected to one end of the current sampling unit 123, so that the current flowing out of the first switch unit 110 is collected through the current sampling unit 123; the other end of the current sampling unit 123 is the negative input end of the negative feedback circuit 120, the other end of the current sampling unit 123 is connected to the preset sampling point A, and the other end of the current sampling unit 123 is also connected to the negative input end of the operational amplifier 121, so that the electrical signal collected by the current sampling unit 123 is fed back to the negative input end of the operational amplifier 121 through the connection between the current sampling unit 123 and the negative input end of the operational amplifier 121; the positive input end of the operational amplifier 121 is the positive input end of the negative feedback circuit 120, and the positive input end of the operational amplifier 121 The first end of the second switch unit 122 is connected to the first end of the second switch unit 122, the second end and the third end of the second switch unit 122 are respectively connected to the two voltage ends of the preset reference voltage source, and the control end of the second switch unit 122 is connected to the third output end of the control unit 230, so that the two ports of the second switch unit 122 are switched according to the control unit 230, so that any one of the two voltage ends of the preset reference voltage source can provide an input electrical signal for the positive input end of the operational amplifier 121; the output end of the operational amplifier 121 is the output end of the negative feedback circuit 120, and the output end of the operational amplifier 121 is connected to the control end of the first switch unit 110, so as to control the on and off of the first switch unit 110 according to the output signal of the operational amplifier 121.

[0079] In one possible implementation, when the battery management circuit 200 is powered on, the slow-start circuit 100 is first turned on, and at the same time, the discharge switch unit 210 is kept closed. Then, the positive input terminal of the operational amplifier 121 is connected to a preset reference voltage source (such as 5V, i.e., the power supply terminal). Since the negative input terminal signal of the operational amplifier 121 in the initial state is isolated ground, the output terminal of the operational amplifier 121 outputs a high voltage, driving the first switch unit 110 to turn on. After the first switch unit 110 is turned on, the output current of the positive power supply terminal of the battery module can pass through the current sampling unit 123 to form a voltage on the current sampling unit 123, and the voltage is fed back to the operational amplifier. The negative input terminal of 121 forms a closed loop, i.e., a feedback circuit of the operational amplifier 121, so that the voltages at the positive input terminal and the negative input terminal of the operational amplifier 121 are equal, thereby ensuring that the current flowing through the current sampling unit 123 is constant, and then charging the electrical load according to the constant current, until the control unit 230 collects that the charging voltage of the electrical load is close to the power supply voltage of the battery module, the positive input terminal of the operational amplifier 121 is connected to a preset reference voltage source (e.g., 0V, i.e., the ground terminal), or the control terminal of the first switch unit 110 in the slow-start circuit 100 is pulled down and closed, so as to end the power-on process of the slow-start circuit 100, and then turn on the discharge switch unit 210.

[0080] The battery management circuit provided by the present application, wherein the negative feedback circuit may include an operational amplifier, a second switch unit and a current sampling unit; the second end of the first switch unit is connected to one end of the current sampling unit; the other end of the current sampling unit is the negative input end of the negative feedback circuit, the other end of the current sampling unit is connected to a preset sampling point, and the other end of the current sampling unit is also connected to the negative input end of the operational amplifier; the positive input end of the operational amplifier is the positive input end of the negative feedback circuit, the positive input end of the operational amplifier is connected to the first end of the second switch unit, and the second end and the third end of the second switch unit are respectively connected to two voltage ends of a preset reference voltage source; the output end of the operational amplifier is the output end of the negative feedback circuit, the output end of the operational amplifier is connected to the control end of the first switch unit, and the control end of the second switch unit is connected to the third output end of the control unit. Therefore, the present application can feed back the voltage collected by the current sampling unit to the negative input terminal of the operational amplifier to form feedback of the slow-start circuit, and then according to the feedback of the slow-start circuit, control the charging current of the capacitor of the power load to be in a constant state to achieve a constant-current battery management circuit slow-start, and then because the charging current of the capacitor of the power load is in a constant state, the charging and discharging of the battery module is safer, avoiding the surge current generated by the discharge switch unit when the power is turned on. At the same time, since the embodiments of the present application and the prior art compare the slow-start time of the slow-start circuit, it can be obtained that the slow-start method of the battery management circuit using a constant current can greatly reduce the slow-start time in the battery management circuit compared to the slow-start method using resistor current limiting in the prior art.

[0081] exist Figure 4 Based on the above, the battery management circuit 200 is further described with reference to examples as follows. Figure 5 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 3 .like Figure 5 As shown, the slow-start circuit 100 may further include: a filtering unit 130 .

[0082] The output end of the operational amplifier 121 is connected to the control end of the first switch unit 110 through the filter unit 130 to filter the output signal of the operational amplifier 121 so that the signal flowing into the control end of the first switch unit 110 can be stably input.

[0083] The slow-start circuit in the battery management circuit provided in the present application may further include a filter unit, and the output end of the operational amplifier is connected to the control end of the first switch unit through the filter unit. Thus, the present application can filter the output signal of the operational amplifier through the filter unit, so that the signal flowing into the control end of the first switch unit can be stably input.

[0084] exist Figure 5 Based on the above, the battery management circuit 200 is further described with reference to examples as follows. Figure 6 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 4 .like Figure 6 As shown, the filtering unit 130 may include: a filtering resistor R1 and a filtering capacitor C1.

[0085] Among them, the output end of the operational amplifier 121 is connected to the control end of the first switch unit 110 through the filter resistor R1, so that the output signal of the operational amplifier 121 can be stably output; the control end of the first switch unit 110 is also connected to the other end of the current sampling unit 123 through the filter capacitor C1, so that the output signal of the operational amplifier 121 is filtered according to the filter capacitor C1, so that the signal flowing into the control end of the first switch unit 110 can be stably input.

[0086] The filter unit of the slow-start circuit in the battery management circuit provided by the present application may include: a filter resistor and a filter capacitor, the output end of the operational amplifier is connected to the control end of the first switch unit through the filter resistor, and the control end of the first switch unit is also connected to the other end of the current sampling unit through the filter capacitor. Therefore, the present application can filter the output signal of the operational amplifier through the filter resistor and the filter capacitor, so that the signal flowing into the control end of the first switch unit can be stably input.

[0087] Optionally, in a possible implementation example, the current sampling unit 123 may be selected to be a sampling resistor.

[0088] For example. Figure 4 On the basis of Figure 7 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 5 .like Figure 7 As shown, the current sampling unit 123 is a sampling resistor. The resistance of the sampling resistor can be selected according to actual conditions. However, it should be noted that the resistance of the sampling resistor needs to be smaller than the resistance of the current limiting resistor in the battery management circuit 200.

[0089] For example, assuming that the voltage input to the positive input terminal of the operational amplifier 121 is V, the resistance of the current sampling unit 123 is R, and the current flowing through the current sampling unit 123 is I, when the voltages of the positive input terminal and the negative input terminal of the operational amplifier 121 are balanced, that is, the voltages of the positive input terminal and the negative input terminal of the operational amplifier 121 are equal, the current I=V / R. The constant current I is used to charge the capacitor of the electrical load.

[0090] Optionally, in a possible implementation, the current sampling unit 123 may also be a Hall voltage sensor, which can be used to collect the current flowing through itself and feed it back to the negative input terminal of the operational amplifier 121 to form a closed loop.

[0091] Optionally, in a possible embodiment, the first switch unit 110 is an NMOS switch tube, the first end of the first switch unit 110 is a drain, the second end of the first switch unit 110 is a source, and the control end of the first switch unit 110 is a gate.

[0092] exist Figure 6 , Figure 7 On the basis of Figure 8 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 6 ,like Figure 8 As shown, the first switch unit 110 is an NMOS switch tube, the first end of the first switch unit 110 is a drain, and the drain is connected to the first end of the discharge switch unit 210; the second end of the first switch unit 110 is a source, and the source is connected to the current sampling unit 123 (such as a sampling resistor); the control end of the first switch unit 110 is a gate, and the gate is connected to the output end of the operational amplifier 121 through the filtering unit 130.

[0093] Optionally, in a possible embodiment, the first switch unit 110 is an N-type transistor, the first end of the first switch unit 110 is the collector of the N-type transistor, the second end of the first switch unit 110 is the emitter of the N-type transistor, and the control end of the first switch unit 110 is the base of the N-type transistor.

[0094] exist Figure 6 , Figure 7 On the basis of Fig. 9 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 7 ,like Figure 7 As shown, an N-type transistor, the first end of the first switch unit 110 is the collector of the N-type transistor, and the collector is connected to the first end of the discharge switch unit 210; the second end of the first switch unit 110 is the emitter of the N-type transistor, and the emitter is connected to the current sampling unit 123 (such as a sampling resistor); the control end of the first switch unit 110 is the base of the N-type transistor, and the base is connected to the output end of the operational amplifier 121 through the filtering unit 130.

[0095] Optionally, in a possible implementation example, the discharge switch unit 210 may be selected as an NMOS switch tube.

[0096] For example, in Figure 8 On the basis of Fig.10 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 8 ,like Fig.10 As shown, the discharge switch unit 210 is an NMOS switch tube, and the first end of the discharge switch unit 210 is the drain of the NMOS switch tube, which is connected to the first end of the first switch unit 110; the second end of the discharge switch unit 210 is the source of the NMOS switch tube, which is connected to the current sampling unit 144 (such as a sampling resistor); the third end of the discharge switch unit 210 is the gate of the NMOS switch tube, which is the control end of the discharge switch unit 210 and is connected to the control unit 230.

[0097] Optionally, in a possible implementation example, the charging switch unit 220 may be selected as an NMOS switch tube.

[0098] For example, in Fig.10 On the basis of Fig.11 A schematic diagram of a battery management circuit provided in an embodiment of the present application Figure 9 ,like Fig.11 As shown, the charging switch unit 220 is an NMOS switch tube, and the first end of the charging switch unit 220 is the source of the NMOS switch tube, and the source is connected to the second end of the discharge switch unit 210; the second end of the charging switch unit 220 is the drain of the NMOS switch tube, and the drain is connected to the power load; the third end of the charging switch unit 220 is the gate of the NMOS switch tube, and the gate is the control end of the charging switch unit 220, and is connected to the control unit 230.

[0099] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery management circuit, characterized in that: The battery management circuit comprises: a discharge switch unit, a charge switch unit, a slow-start circuit and a control unit; The first end of the discharge switch unit is used to connect the positive power supply end of the battery module, the second end of the discharge switch unit is connected to the positive power supply end of the power load through the charging switch unit, and the negative power supply end of the power load is used to connect the negative power supply end of the battery module; Wherein, the slow-start circuit comprises: a first switch unit and a negative feedback circuit; Wherein, the first end and the second end of the first switch unit are connected to the first end and the second end of the discharge switch unit respectively; A preset sampling point between the second end of the discharge switch unit and the charge switch unit is connected to a negative input end of the negative feedback circuit, a control end of the first switch unit is connected to an output end of the negative feedback circuit, and a positive input end of the negative feedback circuit is connected to two voltage ends of a preset reference voltage source; The input end of the control unit is connected to the preset sampling point, and the control end of the discharge switch unit, the control end of the charge switch unit and the control end of the negative feedback circuit are respectively connected to the first output end, the second output end and the third output end of the control unit.

2. The battery management circuit according to claim 1, characterized in that: The negative feedback circuit comprises: an operational amplifier, a second switch unit and a current sampling unit; The second end of the first switch unit is connected to one end of the current sampling unit; The other end of the current sampling unit is the negative input end of the negative feedback circuit, the other end of the current sampling unit is connected to the preset sampling point, and the other end of the current sampling unit is also connected to the negative input end of the operational amplifier; The positive input terminal of the operational amplifier is the positive input terminal of the negative feedback circuit, the positive input terminal of the operational amplifier is connected to the first terminal of the second switch unit, and the second terminal and the third terminal of the second switch unit are respectively connected to the two voltage terminals of the preset reference voltage source; The output end of the operational amplifier is the output end of the negative feedback circuit, and the output end of the operational amplifier is connected to the control end of the first switch unit; the control end of the second switch unit is connected to the third output end of the control unit.

3. The battery management circuit according to claim 2, characterized in that: The slow-start circuit further includes: a filtering unit; The output end of the operational amplifier is connected to the control end of the first switch unit through the filter unit.

4. The battery management circuit according to claim 3, characterized in that: The filtering unit comprises: a filtering resistor and a filtering capacitor; The output end of the operational amplifier is connected to the control end of the first switch unit through the filter resistor, and the control end of the first switch unit is also connected to the other end of the current sampling unit through the filter capacitor.

5. The battery management circuit according to claim 2, characterized in that: The current sampling unit includes: a sampling resistor or a Hall voltage sensor.

6. The battery management circuit according to claim 1, characterized in that: The first switch unit is an NMOS switch tube, the first end of the first switch unit is a drain, the second end of the first switch unit is a source, and the control end of the first switch unit is a gate.

7. The battery management circuit according to claim 1, characterized in that: The first switch unit is an N-type transistor, the first end of the first switch unit is the collector of the N-type transistor, the second end of the first switch unit is the emitter of the N-type transistor, and the control end of the first switch unit is the base of the N-type transistor.

8. The battery management circuit according to claim 1, characterized in that: The discharge switch unit is an NMOS switch tube, the first end of the discharge switch unit is a drain, the second end of the discharge switch unit is a source, and the control end of the discharge switch unit is a gate.

9. The battery management circuit according to claim 1, characterized in that: The charging switch unit is an NMOS switch tube, the first end of the charging switch unit is a source, the second end of the charging switch unit is a drain, and the control end of the charging switch unit is a gate.

10. A battery management system, characterized in that: The battery management system comprises: a battery module, and a battery management circuit as described in any one of claims 1 to 9 above; The positive power supply terminal and the negative power supply terminal of the battery module are respectively connected to the positive power supply terminal and the negative power supply terminal of the battery management circuit.

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