Protection circuit and battery management system

Abstract

The utility model discloses a protection circuit and a battery management system. The battery management system comprises a protection unit and a switch transistor, the protection unit is used for outputting a protection signal to the switch transistor to turn off the switch transistor, the protection circuit comprises a discharge adjustment unit and a discharge control unit, and the discharge adjustment unit and the discharge control unit are connected in series at a first electrode and a control electrode of the switch transistor. The discharge control unit is further connected with the protection unit and is used for being closed when receiving the protection signal so as to form a discharge loop with the discharge adjusting unit and the switching transistor, and the discharge adjusting unit can control the discharge time of the discharge loop. According to the protection circuit, the closed loop is formed by the switch transistor, the discharge adjusting unit and the switch transistor when the switch transistor is turned off, and the discharge time of the closed loop is controlled through the discharge adjusting unit, so that the impulse voltage when the switch transistor is turned off can be reduced, and the switch transistor is prevented from being damaged.

Description

Technical Field

[0001] This application relates to the technical field of energy storage, and particularly to a protection circuit and a battery management system. Background Art

[0002] Currently, most battery management systems (BMS) have short-circuit protection and over-current protection functions. When the battery management system triggers protection, it is necessary to quickly disconnect the charge and discharge metal-oxide-semiconductor field-effect transistor (MOSFET) to avoid overheating damage of the MOSFET due to too long turn-off time. In order to accelerate the turn-off of the charge and discharge MOSFET, a charge discharge circuit will be added between the MOSFET - GS. However, if the MOSFET turns off too quickly, due to the existence of loop parasitic inductance, an instantaneous impact voltage will be generated at the MOSFET - DS at the moment when the MOSFET turns off. When the impact voltage exceeds the maximum withstand voltage value of the MOSFET - DS, the MOSFET will be broken down and damaged. Summary of the Invention

[0003] This application aims to solve at least one of the technical problems existing in the prior art. For this reason, this application provides a protection circuit and a battery management system.

[0004] The protection circuit of the embodiment of this application is used for a battery management system, and is characterized in that the battery management system includes a protection unit and a switching transistor, the protection unit is used to output a protection signal to the switching transistor to turn off the switching transistor, the protection circuit includes a discharge adjustment unit and a discharge control unit, and the discharge adjustment unit and the discharge control unit are connected in series between the first pole and the control pole of the switching transistor;

[0005] The discharge control unit is also connected to the protection unit and is used to close when receiving the protection signal to form a discharge loop with the discharge adjustment unit and the switching transistor;

[0006] The discharge adjustment unit is used to adjust the discharge time of the discharge loop.

[0007] In some embodiments, the discharge adjustment unit includes:

[0008] A variable resistor, one end of the variable resistor is connected to the first pole of the switching transistor, and the other end of the variable resistor is connected to the discharge control unit.

[0009] In some embodiments, the discharge regulating unit includes a plurality of switches and a plurality of regulating resistors. Each switch is connected to one of the regulating resistors to form a resistance regulating loop, and multiple such resistance regulating loops are connected in parallel between the first pole of the switching transistor and both ends of the discharge control unit.

[0010] In some embodiments, the discharge control unit includes:

[0011] A discharge transistor, the first pole of the discharge transistor is connected to the discharge regulating unit, the second pole of the discharge transistor is connected to the second pole of the switching transistor, and the control pole of the discharge transistor is connected to the protection unit. The discharge transistor is closed when receiving the protection signal;

[0012] A diode, the positive input terminal of the diode is connected to the control pole of the discharge transistor, and the negative pole of the diode is connected to the second pole of the discharge transistor.

[0013] In some embodiments, the protection circuit further includes:

[0014] A protection resistor, one end of the protection resistor is connected to the first pole of the switching transistor, and the other end of the protection resistor is connected to the control pole of the switching transistor.

[0015] In some embodiments, the switching transistor is an N-type metal-oxide-semiconductor field-effect transistor, and the discharge transistor is a P-type metal-oxide-semiconductor field-effect transistor; or, the switching transistor is a P-type metal-oxide-semiconductor field-effect transistor, and the discharge transistor is an N-type metal-oxide-semiconductor field-effect transistor.

[0016] The battery management system according to the embodiments of the present application includes a switching transistor and the protection circuit as described above.

[0017] In some embodiments, the battery management system further includes an absorption capacitor and an absorption resistor, and the absorption capacitor and the absorption resistor are connected in series between the first pole and the second pole of the switching transistor.

[0018] In some embodiments, the battery management system further includes a transient voltage suppressor, and the transient voltage suppressor is respectively connected to the first pole and the second pole of the switching transistor.

[0019] In some embodiments, there are a plurality of the switching transistors, and there are a plurality of the protection circuits, and each protection circuit corresponds to one of the switching transistors.

[0020] In the protection circuit and battery management system according to the embodiments of the present application, by connecting the discharge adjustment unit and the discharge control unit in series between the first pole and the control pole of the switching transistor, and connecting the discharge control unit to the protection unit, when the switching transistor is turned off, a closed loop is formed by the switching transistor, the discharge adjustment unit and the switching transistor, and the discharge adjustment unit controls the discharge time of the closed loop, so that the turn-off time of the switching transistor can be controlled, and the impact voltage of the switching transistor when turned off is reduced. In this way, on the one hand, the overvoltage risk of the switching transistor is reduced, and the safety of the switching transistor is protected. On the other hand, under the condition that the switching transistor can work in the safe operating area, the battery management system can select a switching transistor with a lower withstand voltage, thereby reducing the cost of the battery management system.

[0021] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 is a schematic block diagram of the battery management system according to the embodiment of the present application.

[0024] Figure 2 is a schematic circuit diagram of the battery management system according to the embodiment of the present application.

[0025] Figure 3 is another schematic circuit diagram of the battery management system according to the embodiment of the present application.

[0026] Figure 4 is yet another schematic circuit diagram of the battery management system according to the embodiment of the present application.

[0027] MAIN ELEMENT SYMBOL DESCRIPTION:

[0028] Battery management system 100, power supply 20, protection unit 30, switching transistor Q1, current limiting resistor R1, transient voltage suppressor TVS, absorption capacitor C1, absorption resistor R2;

[0029] Protection circuit 10, discharge adjustment unit 11, variable resistor R3, switch SW, adjustment resistor R4, discharge control unit 12, discharge transistor Q1, diode D1, protection resistor R5. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where like or similar reference numerals denote like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary only for explaining the present application and should not be construed as limiting the present application.

[0031] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. These 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. Therefore, it should not be construed as limiting the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "a plurality" means two or more unless otherwise specifically defined.

[0032] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, the terms "mounted", "connected" and "coupled" should be construed in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection, an electrical connection or a connection that can communicate with each other; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0033] In the present application, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through other features between them. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely means that the horizontal height of the first feature is lower than that of the second feature.

[0034] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. To simplify the disclosure of the present application, components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present application. In addition, the present application may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0035] Please refer to Figure 1 , an embodiment of the present application provides a battery management system 100. The battery management system 100 includes a switching transistor Q1 and a protection unit 30. The protection unit 30 is electrically connected to the control electrode of the switching transistor Q1 and is configured to output a protection signal to the switching transistor Q1 to turn off the switching transistor Q1.

[0036] An embodiment of the present application also provides a protection circuit 10. The protection circuit 10 is used for the above-mentioned battery management system 100, or rather, the battery management system 100 may include the protection circuit 10. The protection circuit 10 includes a discharge adjustment unit 11 and a discharge control unit 12. The discharge adjustment unit 11 and the discharge control unit 12 are connected in series between the first electrode and the control electrode of the switching transistor Q1; the discharge control unit 12 is also connected to the protection unit 30 and is configured to close when receiving the protection signal to form a discharge loop with the discharge adjustment unit 11 and the switching transistor Q1. The discharge adjustment unit 11 can control the discharge time of the discharge loop.

[0037] In the battery management system 100 and the protection circuit 10 according to the embodiments of the present application, the discharge adjustment unit 11 and the discharge control unit 12 are connected in series between the first electrode and the control electrode of the switching transistor Q1, and the discharge control unit 12 is connected to the protection unit 30. When the protection unit 30 outputs a protection signal, the switching transistor Q1 is turned off according to the protection signal, and the discharge control unit 12 forms a closed loop with the discharge adjustment unit 11 and the switching transistor Q1 according to the protection signal. The discharge adjustment unit 11 can control the discharge time of the closed loop, thereby realizing the control of the turn-off speed of the switching transistor Q1, so that the switching transistor Q1 can meet the conditions of operating in the safe operating area and reduce the impact voltage when the switching transistor Q1 is turned off. In this way, on the one hand, the overvoltage risk of the switching transistor Q1 is reduced, protecting the safety of the switching transistor Q1. On the other hand, under the condition that the switching transistor Q1 can operate in the safe operating area, the battery management system 100 can select a switching transistor Q1 with a lower withstand voltage, thereby reducing the cost of the battery management system 100.

[0038] It should be noted that the transistors used in this application can all be field effect transistors or other switching devices with the same characteristics. For example, the transistor can be a metal-oxide-semiconductor field effect transistor. In addition, the first pole and the second pole described in this application refer to the source and drain of the transistor, and the control pole refers to the gate of the transistor.

[0039] The battery management system 100 (Battery Management System, BMS) is a complex system used to monitor and manage the state of a battery pack, which can ensure that the battery operates in a safe and efficient state. The battery management system 100 can implement functions such as battery parameter detection, state of charge estimation, battery equalization management, charge and discharge management, thermal management, communication and data recording, short circuit protection, or overcurrent protection.

[0040] Please refer to Figures 2-3 , specifically, the battery management system 100 may include a power supply 20, a switching transistor Q1, a protection unit 30, and a current limiting resistor R1. Among them, the first pole of the switching transistor Q1 is electrically connected to the power supply 20. The switching transistor Q1 is used to control the charge and discharge of the power supply 20. When the switching transistor Q1 is turned on, the power supply 20 can achieve the charge and discharge function. When the switching transistor Q1 is turned off, the power supply 20 stops charging and discharging. The current limiting resistor R1 is connected in series between the protection unit 30 and the control pole of the switching unit. The current limiting resistor R1 is used to limit the magnitude of the output current of the protection unit 30. When the protection unit 30 detects a short circuit or overcurrent phenomenon in the power supply 20, it can generate a protection signal and output it to the control pole of the switching transistor Q1 through the current limiting resistor R1, so that the switching transistor Q1 is turned off, thereby realizing the short circuit protection function or overcurrent protection function of the battery management system 100. It can be understood that when the switching transistor Q1 is turned on, a parasitic capacitance is formed between the first pole and the control pole of the switching transistor Q1. When the switching transistor Q1 is turned off, if the switching transistor Q1 turns off too quickly, due to the existence of loop parasitic charges, therefore, at the moment when the switching transistor Q1 turns off, an instantaneous impact voltage will be generated between the first pole and the second pole of the switching transistor Q1. When the impact voltage exceeds the maximum withstand voltage value of the switching transistor Q1, the switching transistor Q1 will be broken down, resulting in damage to the switching transistor Q1.

[0041] Therefore, the battery management system 100 may further include a protection circuit 10 for the switching transistor Q1. The protection circuit 10 is connected to the switching transistor Q1 and is used to achieve the turn-off protection of the switching transistor Q1 to avoid the voltage breakdown phenomenon of the switching transistor Q1 when it turns off too quickly.

[0042] The switching transistor Q1 may include one or more. Understandably, if the switching transistor Q1 includes multiple ones and the protection circuits 10 also include multiple ones, then the protection circuits 10 may also be multiple, and each protection circuit 10 corresponds to one switching transistor Q1. For example, please refer to Figure 4 , in some examples, the switching transistor Q1 may be two, and then the protection circuits 10 are also two.

[0043] The protection circuit 10 includes a discharge regulation unit 11 and a discharge control unit 12. Among them, the discharge regulation unit 11 and the discharge control unit 12 are connected in series between the first pole and the control pole of the switching transistor Q1. Moreover, the discharge control unit 12 is connected to the current-limiting resistor R1 to achieve connection with the protection unit 30, that is, the protection signal output by the protection unit 30 is also output to the discharge control unit 12 through the current-limiting resistor R1. The discharge control unit 12 is turned off when it does not receive the protection signal output by the protection unit 30 and is turned on after receiving the protection signal output by the protection unit 30.

[0044] When the discharge control unit 12 is turned on upon receiving the protection signal, the discharge control unit 12, the discharge regulation unit 11 and the switching transistor Q1 form a discharge loop. The discharge regulation unit 11 serves as the load of the discharge loop and can consume the parasitic charges generated by the switching transistor Q1. The discharge regulation unit 11 can control the discharge time of the discharge loop, so that the switching transistor Q1 meets the conditions of operating in the Safe Operating Area (SOA), thereby avoiding overheating damage caused by too long turn-off time of the switching transistor Q1, and avoiding the impact voltage caused by too short turn-off time of the switching transistor Q1, resulting in breakdown of the switching transistor Q1 due to overvoltage. In this way, the safety of the switching transistor Q1 is protected. Moreover, under the condition of meeting the requirement that the switching transistor Q1 operates in the safe operating area, a switching transistor Q1 with a lower withstand voltage can also be selected. Thus, the material cost of the battery management system 100 is reduced.

[0045] Furthermore, the discharge regulation unit 11 can adjust the discharge time of the discharge loop by adjusting its own resistance value. For example, when the switching transistor Q1 is turned off and the impact voltage across the first and second poles of the switching transistor Q1 is too high, its own resistance value can be reduced to slow down the discharge time of the parasitic charges in the switching transistor Q1. Another example is that when the switching transistor Q1 is turned off and the turn-off time of the switching transistor Q1 is too long and prone to overheating damage, its own resistance value can be increased to speed up the discharge time of the parasitic charges in the switching transistor Q1.

[0046] Please refer to Figure 2, in some embodiments, the discharge adjustment unit 11 includes a variable resistor R3. One end of the variable resistor R3 is connected to the first pole of the switching transistor Q1, and the other end of the variable resistor R3 is connected to the discharge control unit 12.

[0047] In this way, by adjusting the resistance value of the variable resistor R3, the control of the discharge time of the discharge loop can be realized, so that the switching transistor Q1 operates in the safe operating area, ensuring the safety of the switching transistor Q1 during the turn-off process.

[0048] Please combine Figure 3 , in some embodiments, the discharge adjustment unit 11 includes a plurality of switches SW and a plurality of adjustment resistors R4. Each switch SW is connected to an adjustment resistor R4 to form a resistance value adjustment loop, and multiple resistance value adjustment loops are connected in parallel across the first pole of the switching transistor Q1 and the discharge control unit 12.

[0049] The resistance values of the multiple adjustment resistors R4 can be the same or different. When the resistance values of the multiple adjustment resistors R4 are the same, the resistance value of the discharge adjustment unit 11 can be changed by controlling the number of closed switches SW. When the resistance values of the multiple adjustment resistors R4 are different, the switch SW to be closed can be selected to change the resistance value of the discharge adjustment unit 11, thereby realizing the control of the discharge time of the discharge loop. Thereby realizing the control of the discharge time of the discharge loop.

[0050] In this way, by controlling the turn-off and turn-on of the switch SW, the adjustment of the resistance value of the discharge adjustment unit 11 can be realized, thereby realizing the control of the discharge time of the discharge loop and ensuring the safety of the switching transistor Q1 during the turn-off process.

[0051] In some embodiments, the discharge control unit 12 includes a discharge transistor Q1 and a diode D1. The first pole of the discharge transistor Q1 is connected to the discharge adjustment unit 11, the second pole of the discharge transistor Q1 is connected to the second pole of the switching transistor Q1, the control pole of the discharge transistor Q1 is connected to the protection unit 30, the discharge transistor Q1 closes when receiving a protection signal, the positive input terminal of the diode D1 is connected to the control pole of the discharge transistor Q1, and the negative pole of the diode D1 is connected to the second pole of the discharge transistor Q1.

[0052] In this way, through the setting of the discharge transistor Q1 and the diode D1 in the discharge control unit 12, the discharge transistor Q1 can close when receiving a protection signal, forming a discharge loop with the discharge adjustment unit 11 and the switching transistor Q1, thereby consuming the parasitic charge generated by the switching transistor Q1 and ensuring the safety of the switching transistor Q1.

[0053] The switching transistor Q1 is an N-type metal-oxide-semiconductor field-effect transistor, and the discharging transistor Q1 is a P-type metal-oxide-semiconductor field-effect transistor; or, the switching transistor Q1 is a P-type metal-oxide-semiconductor field-effect transistor, and the discharging transistor Q1 is an N-type metal-oxide-semiconductor field-effect transistor. Thus, it is ensured that the discharging transistor Q1 is turned off when the switching transistor Q1 is closed, and the discharging transistor Q1 is turned on when the switching transistor Q1 is turned off.

[0054] Referring to FIGS. 2-4, in some embodiments, the protection circuit 10 further includes a protection resistor R5. One end of the protection resistor R5 is connected to the first pole of the switching transistor Q1, and the other end of the protection resistor R5 is connected to the control pole of the switching transistor Q1.

[0055] In this way, by setting the protection resistor R5 between the control pole and the first pole of the switching transistor Q1, the stability of the discharging transistor Q1 when it is turned on or off can be improved.

[0056] In some embodiments, the battery management system 100 further includes a snubber capacitor C1 and a snubber resistor R2. The snubber capacitor C1 and the snubber resistor R2 are connected in series across the first and second poles of the switching transistor Q1.

[0057] In this way, by setting the snubber capacitor C1 and the snubber resistor R2, the spike voltage generated when the switching transistor Q1 is turned off can be absorbed, reducing the risk of damage to the switching transistor Q1.

[0058] In some embodiments, the battery management system 100 further includes a transient voltage suppressor TVS. The transient voltage suppressor TVS is connected to the first and second poles of the switching transistor Q1 respectively.

[0059] The transient voltage suppressor TVS can protect the switching transistor from damage caused by externally occurring transient voltages (such as lightning, electrostatic discharge, power supply 20 fluctuations, etc.).

[0060] In this way, by setting the transient voltage suppressor TVS, the risk of damage to the switching transistor Q1 caused by externally occurring transient voltages is reduced.

[0061] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0062] Although embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present application. The scope of the present application is defined by the claims and their equivalents.

Claims

1. A protection circuit for a battery management system, characterized in that, The battery management system includes a protection unit and a switching transistor. The protection unit is configured to output a protection signal to the switching transistor to control the switching transistor to turn off. The protection circuit includes a discharge regulation unit and a discharge control unit. The discharge regulation unit and the discharge control unit are connected in series between the first pole and the control pole of the switching transistor. The discharge control unit is further connected to the protection unit and is configured to close when receiving the protection signal, so as to form a discharge loop with the discharge regulation unit and the switching transistor. The discharge regulation unit can control the discharge time of the discharge loop.

2. The protection circuit according to claim 1, characterized in that, The discharge regulation unit includes: A variable resistor, one end of the variable resistor is connected to the first pole of the switching transistor, and the other end of the variable resistor is connected to the discharge control unit.

3. The protection circuit according to claim 1, wherein The discharge regulation unit includes a plurality of switches and a plurality of regulating resistors. Each switch is connected to one of the regulating resistors to form a resistance value regulation loop, and multiple such resistance value regulation loops are connected in parallel between the first pole of the switching transistor and both ends of the discharge control unit.

4. The protection circuit according to claim 1, wherein The discharge control unit includes: A discharge transistor, the first pole of the discharge transistor is connected to the discharge regulation unit, the second pole of the discharge transistor is connected to the second pole of the switching transistor, and the control pole of the discharge transistor is connected to the protection unit. The discharge transistor closes when receiving the protection signal. A diode, the positive input terminal of the diode is connected to the control pole of the discharge transistor, and the negative terminal of the diode is connected to the second pole of the discharge transistor.

5. The protection circuit according to claim 4, characterized in that, The protection circuit further includes: A protection resistor, one end of the protection resistor is connected to the first pole of the switching transistor, and the other end of the protection resistor is connected to the control pole of the switching transistor.

6. The protection circuit according to claim 4, wherein The switching transistor is an N-type metal-oxide-semiconductor field effect transistor, and the discharge transistor is a P-type metal-oxide-semiconductor field effect transistor; or, the switching transistor is a P-type metal-oxide-semiconductor field effect transistor, and the discharge transistor is an N-type metal-oxide-semiconductor field effect transistor.

7. A battery management system, characterized in that, It includes a switching transistor and the protection circuit according to any one of claims 1-6.

8. The battery management system according to claim 7, characterized in that, The battery management system further includes an absorption capacitor and an absorption resistor. The absorption capacitor and the absorption resistor are connected in series between the first pole and the second pole of the switching transistor.

9. The battery management system according to claim 7, characterized in that, The battery management system further includes a transient voltage suppressor, and the transient voltage suppressor is respectively connected to the first pole and the second pole of the switching transistor.

10. The battery management system according to claim 7, characterized in that, There are a plurality of the switching transistors, and there are a plurality of the protection circuits. Each protection circuit corresponds to one of the switching transistors.

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