Battery management system and self-diagnosis method thereof

Abstract

The invention provides a battery management system and a self-diagnosis method thereof. The battery management system comprises a controller, a battery switch circuit, an energy storage unit and a delay switch circuit. The delay switch circuit is electrically connected with the energy storage unit, the controller and the battery switch circuit. The delay switch circuit conducts a loop between the energy storage unit and the battery switch circuit when the controller fails, so that the battery switch circuit continues to conduct a loop between the battery module and the load system within a preset delay time. According to the battery management system, the loop between the battery module and the load system can be temporarily maintained when the controller fails, and the time for taking necessary safety measures is given to the load system.

Description

Technical Field

[0001] This application relates to a battery management system and a self-diagnosis method thereof. Background Art

[0002] As Figure 1 shown, in the battery management system 10 of the prior art, the controller 14 can control the battery switch circuit 12 to conduct or disconnect the loop between the battery module 50 and the load system 60. However, for safety reasons, in some abnormal situations (such as the Limp Home mode), the battery management system should not immediately disconnect the aforementioned loop, but should briefly maintain the aforementioned loop so that the load system can take corresponding measures such as restarting the battery management system. Summary of the Invention

[0003] The purpose of this application is to provide a battery management system and a self-diagnosis method thereof so that the battery management system will not immediately disconnect the loop between the battery module and the load system when it fails.

[0004] To achieve the above object, this application provides a battery management system, including a controller, a battery switch circuit, an energy storage unit, and a delay switch circuit. The battery switch circuit is controlled by the controller to conduct or disconnect the loop between the battery module and the load system. The delay switch circuit is electrically connected to the energy storage unit, the controller, and the battery switch circuit respectively. Wherein, when the controller fails, the delay switch circuit conducts the loop between the energy storage unit and the battery switch circuit, and the energy storage unit supplies power to the battery switch circuit, so that the battery switch circuit conducts the loop between the battery module and the load system within a preset delay time.

[0005] This application also provides a self-diagnosis method that can be applied to the aforementioned battery management system. The steps include: obtaining a preset delay time according to the discharge time constant of the energy storage unit, where the energy of the energy storage unit corresponds to the discharge time constant; conducting the loop between the battery module and the load system, and obtaining a first voltage value at a detection point in the battery switch circuit; sending an instruction to disconnect the loop between the battery module and the load system through the controller, and obtaining a first timestamp; repeatedly obtaining a second voltage value and a corresponding second timestamp at the detection point every sampling time until the time difference between the second timestamp and the first timestamp is greater than or equal to the preset delay time; and during the period of repeatedly obtaining the second voltage value, if the second voltage value is not approximately equal to the first voltage value, it is determined that the delay-off function of the delay switch circuit is abnormal.

[0006] When the controller fails, the present application turns on the loop between the energy storage unit and the battery switch circuit through a delay switch circuit, preventing the battery module from immediately disconnecting the charging and discharging of the load system, and giving the load system time to take necessary safety measures, thereby enhancing the safety of the battery management system. The present application can also perform self-diagnosis of the delay-off function through the opening and closing of the delay switch circuit and the detection points of the battery switch circuit, thereby enhancing the reliability of the battery management system. Description of the Drawings

[0007] Figure 1 is a schematic diagram of a battery management system in the prior art;

[0008] Figure 2 is a schematic diagram of the battery management system of the present application;

[0009] Figure 3 is a circuit diagram of the delay switch circuit of the present application in some embodiments;

[0010] Figure 4 is a flowchart of the self-diagnosis method of the battery management system of the present application;

[0011] Figures 5 - 6 is a flowchart of the self-diagnosis method of the battery management system of the present application in different embodiments.

[0012] Description of the Reference Numerals: 10 - Battery management system; 12 - Battery switch circuit; 14 - Controller; 20 - Battery management system; 22 - Battery switch circuit; 23 - Constant voltage source; 24 - Controller; 26 - Delay switch circuit; 262 - First MOS switch circuit; 264 - Second MOS switch circuit; 28 - Energy storage unit; 50 - Battery module; 60 - Load system. Detailed Description of the Embodiments

[0013] The following describes the present application based on embodiments, but the present application is not limited to these embodiments. In the following detailed description of the present application, some specific details are described in detail. Those skilled in the art can fully understand the present application without the description of these details. In order to avoid obscuring the essence of the present application, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0014] Please refer to Figure 2, which shows a schematic diagram of the battery management system of the present application. The battery management system 20 includes a battery switch circuit 22, a controller 24, a delay switch circuit 26, and an energy storage unit 28. Both ends of the battery switch circuit 22 are electrically connected to the battery module 50 and the load system 60 respectively. The controller 24 is electrically connected to the battery switch circuit 22 to conduct or disconnect the loop between the battery module 50 and the load system 60. The controller 24 is also electrically connected to the battery module 50 and the load system 60 to detect the voltages at different nodes. Multiple endpoints of the delay switch circuit 26 are electrically connected to the energy storage unit 28, the controller 24, and the battery switch circuit 22 respectively. It should be noted that, in order to focus on the necessary components for implementing the delayed shutdown function in the battery management system 20, a part of the inherent devices in the battery management system 20 are appropriately omitted in the present application; for example, those skilled in the art know that the battery management system 20 also includes inherent devices such as a driver, and the driver is used to close and disconnect the switch in the battery switch circuit 22. The energy storage unit 28 is an electronic component or module that can be repeatedly charged and can be discharged briefly, such as a capacitor.

[0015] When the controller 24 operates, the battery switch circuit 22 can respond to the control of the controller 24 and immediately conduct or disconnect the loop between the battery module 50 and the load system 60 to perform the charging and discharging of the battery module 50. It is worth mentioning that the battery management system 20 of the present application has a delayed shutdown function. In the state where the delayed shutdown function is enabled, if the controller 24 malfunctions and stops controlling the battery switch circuit 22, at this time, the battery switch circuit 22 will not immediately disconnect the loop between the battery module 50 and the load system 60. For example, the switch pin of the delay switch circuit 26 electrically connected to the controller 24 is at a high potential (indicating that the delayed shutdown function is enabled), and the switch pin will change to a low potential after the controller 24 malfunctions and is reset. At this time, the delay switch circuit 26 conducts the loop between the energy storage unit 28 and the battery switch circuit 22. The battery switch circuit 22 will continuously conduct the loop between the battery module 50 and the load system 60 within a preset delay time, and the preset delay time depends on the discharge time constant of the energy storage unit 28. In other words, the load system 60 will not immediately lose power due to the failure of the controller 24, but will continue to operate for a preset delay time to take necessary safety measures. In addition, the controller 24 that has been reset due to the failure may resume operation before the end of the preset delay time. At this time, the controller 24 can turn off the delay switch circuit 26 and immediately turn off the battery switch circuit 22 through the control pin of the controller 24 electrically connected to the battery switch circuit 22.

[0016] In some embodiments, the controller 24 can charge the energy storage unit 28 so that after the delayed shutdown function is actuated, the energy storage unit 28 can supply power to the battery switch circuit 22. For example, the energy storage unit 28 is directly or indirectly electrically connected to the controller 24, and after the controller 24 disconnects the loop between the energy storage unit 28 and the battery switch circuit 22, it directly or via the delay switch circuit 26 charges the energy storage unit 28. This application is not limited thereto, and the energy storage unit 28 can also be charged via other devices or loops.

[0017] Please refer to Figure 3 , which shows the circuit diagram of the delay switch circuit 26 of the present application in some embodiments. Figure 3 is based on Figure 2 drawn partial schematic diagram. To make the drawing concise, Figure 3Other connection relationships such as the battery module 50 and the load system 60 are omitted. The delay switch circuit 26 includes a first MOS switch circuit 262 and a second MOS switch circuit 264. Multiple terminals of the first MOS switch circuit 262 are electrically connected to the constant voltage source 23, the ground terminal, the switch pin of the controller 24, and the second MOS switch circuit 264 respectively. When the switch pin of the controller 24 outputs a high potential, the first MOS switch circuit 262 outputs a low potential of the ground terminal; on the contrary, when the switch pin outputs a low potential, the first MOS switch circuit 262 outputs a high potential of the constant voltage source 23. Multiple terminals of the second MOS switch circuit 264 are electrically connected to the battery switch circuit 22, the first MOS switch circuit 262, the energy storage unit 28, and the control pin of the controller 24 respectively. The second MOS switch circuit 264 conducts or disconnects in response to the potential output by the first MOS switch circuit 262. The switch pin is used to turn on or off the delay-off function and charge the energy storage unit 28, and the control pin is used to turn on or off the battery switch circuit 22. The controller 24 can set the switch pin and the control pin to a first potential or a second potential to achieve the foregoing various operations. For example, the first potential is a low potential and the second potential is a high potential. In some embodiments, the first MOS switch circuit 262 is an inverter circuit architecture. For example, the first MOS switch circuit 262 includes a MOS transistor and a resistor. Two ends of the resistor are electrically connected to the constant voltage source 23 and the drain of the MOS transistor respectively. The gate, drain, and source of the MOS transistor are electrically connected to the switch pin of the controller 24, the second MOS switch circuit 264, and the ground terminal respectively. In some embodiments, the second MOS switch circuit 264 includes a first MOS transistor and a second MOS transistor. The gate, drain, and source of the first MOS transistor are electrically connected to the first MOS switch circuit 262, the battery switch circuit 22, and the drain of the second MOS transistor respectively. The gate, drain, and source of the second MOS transistor are electrically connected to the first MOS switch circuit 262, the energy storage unit 28, and the source of the first MOS transistor respectively. Resistors are also electrically connected to the sources of the first MOS transistor and the second MOS transistor, so that the energy storage unit 28 can generate a stable voltage on the resistor when the first MOS transistor and the second MOS transistor are closed. Diodes can also be respectively arranged between the energy storage unit 28 and the controller 24, and between the delay switch circuit and the controller 24 to prevent the charged energy storage unit from affecting the potentials of the switch pin and the control pin of the controller 24.

[0018] Under normal operation, the controller 24 can output a high potential at the switch pin to disconnect the second MOS switch circuit 264 through the low potential output by the first MOS switch circuit 262 and charge the energy storage unit 28. At the same time, the controller 24 can also output a high potential at the control pin to conduct the loop between the battery module 50 and the load system 60 through the battery switch circuit 22. However, when the controller 24 is reset due to failure, both the switch pin and the control pin turn into low potentials. At this time, the first MOS switch circuit 262 outputs a high potential and turns on the second MOS switch circuit 264, and the charged energy storage unit 28 supplies power to the battery switch circuit 22 through the second MOS switch circuit 264 within a preset delay time, thereby continuously conducting the loop between the battery module 50 and the load system 60.

[0019] The present application also provides a self-diagnosis method applied to the aforementioned battery management system 20. By detecting the voltage value of the battery switch circuit 22 when other loops are conducted or disconnected, the controller 24 can determine whether the delayed shutdown function is abnormal. Please refer to Figure 2 and Figure 4 , Figure 4 which shows the flowchart of the aforementioned self-diagnosis method. First, a delay switch circuit 26 is provided (such as step S100). The connection relationship between the delay switch circuit 26, the controller 24, the battery switch circuit 22, and the energy storage unit 28 has been described in the previous description, so it will not be elaborated here. As in step S110, the controller 24 calculates and obtains the preset delay time of the energy storage unit 28 according to the discharge time constant of the energy storage unit 28. For example, in Figure 3 , the discharge time constant is the time constant formed by the circuit composed of a capacitor and a resistor. According to practical requirements, the capacitor and the resistor can be respectively selected as a variable capacitor and a variable resistor, or the discharge time constant can be adjusted by modifying multiple circuit architectures. As in step S120, the controller 24 conducts the loop between the battery module 50 and the load system 60 through the battery switch circuit 22 and obtains a first voltage value through the detection point of the battery switch circuit 22. For example, the battery switch circuit 22 is composed of two MOS transistors (not shown in the figure). The sources of the two MOS transistors are connected in series to a resistor grounded at one end, the drains are respectively electrically connected to the battery module 50 and the load system 60, and the gates are both controlled by the controller 24 to form channels. At this time, the node where the sources are connected in series is defined as the detection point.

[0020] Next, to simulate the situation where the controller 24 fails and is reset, the controller 24 sets a specific pin to a low potential. As in step S130, the controller 24 sends an instruction to disconnect the circuit between the battery module 50 and the load system 60, and obtains a first timestamp. Specifically, the controller 24 sends an instruction to set both the control pin of the controller 24 electrically connected to the battery switch circuit 22 and the switch pin of the controller 24 electrically connected to the delay switch circuit 26 to a low voltage. If it is a prior art battery management system, then at this time the battery switch circuit will be turned off due to the control pin changing to a low voltage, and the circuit between the battery module and the load system will be disconnected. However, in this application, due to the circuit configuration of the delay switch circuit 26 and the energy storage unit 28, the switch pin will turn on the delay switch circuit 26 instead after changing to a low voltage, thereby conducting the circuit between the battery switch circuit 22 and the energy storage unit 28. Therefore, even if the control pin changes to a low voltage, the battery switch circuit 22 can still maintain operation through the energy storage unit 28 within a preset delay time, that is, the delay-off function delays the closing of the battery switch circuit 22. On the other hand, in order to diagnose whether the delay-off function is abnormal in subsequent steps, the controller 24 also obtains the time point when the circuit between the battery switch circuit 22 and the energy storage unit 28 is conducted, or rather the time point when the controller 24 sends an instruction to disconnect the circuit between the battery module 50 and the load system 60, as the first timestamp.

[0021] As in step S140, every other sampling time, the controller 24 obtains the second voltage value and its corresponding second timestamp from the detection point. For example, if the discharge time constant of the energy storage unit 28 is RC, then the preset delay time is five times RC, that is, the energy of the energy storage unit 28 will be released completely at the time point of five times RC. Here, it is assumed that RC is 2 seconds and the preset delay time is 10 seconds. Therefore, the controller 24 can obtain the voltage value of the current detection point (hereinafter collectively referred to as the second voltage value) every 2 seconds, and take the time point of the current detection as the second timestamp. In other words, the controller 24 repeatedly obtains the second voltage value and its corresponding second timestamp until the time difference between the second timestamp and the first timestamp is greater than or equal to the preset delay time. As in step S150, after each acquisition of the second voltage value and its corresponding second timestamp, the controller 24 determines whether the second voltage value is approximately equal to the first voltage value. Taking the second timestamp as the 2nd second as an example, if the second voltage value at this time is approximately equal to the first voltage value, it means that the residual energy of the energy storage unit 28 is sufficient to enable the energy storage unit 28 to continuously supply power to the battery switch circuit 22. In order to further determine whether the residual energy of the energy storage unit 28 can enable the energy storage unit 28 to supply power until the 10th second corresponding to the preset delay time, the process proceeds to step S160. On the contrary, if the second voltage value is not approximately equal to the first voltage value, it means that the actual energy of the energy storage unit 28 is not sufficient to enable the energy storage unit 28 to continuously supply power to the battery switch circuit 22 within the preset delay time, that is, the delay-off function has an abnormality (as in step S152). In step S160, the controller 24 determines whether the time difference between the second timestamp and the first timestamp is greater than or equal to the preset delay time. If it is equal, the diagnosis ends; if it is not equal, the process returns to step S140, and the controller 24 will re-obtain the current second voltage value and its corresponding second timestamp at the next sampling time. In other words, if the second voltage values detected at the 2nd, 4th, 6th, and 8th seconds are all approximately equal to the first voltage value, the controller 24 will return to step S140 to start a new round of detection and judgment. As long as the second voltage value at any time point is not approximately equal to the first voltage value, the controller 24 determines that the delay-off function of the delay switch circuit 26 is abnormal and ends the diagnosis.

[0022] In some embodiments, the controller 24 can also determine whether the delay-off function of the delay switch circuit 26 is normal. Please refer to Figure 5 which is continued in Figure 4Flowchart after step S160 and before ending the diagnosis. At step S162, the controller 24 determines that the time difference between the second timestamp and the first timestamp is greater than a preset delay time, indicating that there is no abnormality in the delayed shutdown function. At step S170, the controller 24 determines whether the second voltage value is approximately equal to the ground voltage value. If so, it indicates that the delayed shutdown function is normal (as in step S172), because the energy storage unit 28 has no energy to continue powering the battery switch circuit 22, so the shutdown of the battery switch circuit 22 disconnects the loop between the battery module 50 and the load system 60. In other words, after the controller 24 fails, the time point at which the energy storage unit 28 delays the shutdown of the battery switch circuit 22 conforms to the time point of the preset delay time. At this time, the battery management system 20 ends the diagnosis. On the contrary, if the second voltage value is not approximately equal to the ground voltage value, it indicates that there is an abnormality in the loop or switching function of the battery switch circuit 22 (as in step S174), and the diagnosis is ended. This is because the battery switch circuit 22 powered by the energy storage unit 28 will shut down after the energy of the energy storage unit 28 is released, and disconnect the loop between the battery module 50 and the load system 60. The reason for the abnormal switching function may be that the loop between the battery switch circuit 22 and the battery module 50 is damaged, or the loop or components inside the battery switch circuit 22 are damaged. For example, the switch electrically connected to the battery module 50 in the battery switch circuit 22 is short-circuited, resulting in the voltage at the detection point being the same as the voltage of the battery module 50. After the controller 24 ends the diagnosis, it can also send the detection result to the load system 60 to take necessary safety measures.

[0023] In some embodiments, in order to accurately find out the reason for the abnormal switching function, after determining that the delayed shutdown function is normal, the controller 24 can also diagnose the battery switch circuit 22 to determine whether its switching function is abnormal. Please refer to Figure 6 , which is continued in Figure 5Flowchart after step S172 and before ending the diagnosis. As in step S180, the controller 24 first conducts the loop between the battery module 50 and the load system 60, and then disconnects the loop between the battery switch circuit 22 and the energy storage unit 28. This is because when diagnosing the switching function of the battery switch circuit 22, the loop between the battery switch circuit 22 and the energy storage unit 28 should not be conducted. As in step S190, the controller 24 attempts to disconnect the loop between the battery module 50 and the load system 60, that is, sets the control pin electrically connected to the battery switch circuit 22 to a low voltage, and obtains a third voltage value at the detection point. As in step S200, the controller 24 determines whether the third voltage value is approximately equal to the ground voltage value; if so, it indicates that the battery switch circuit 22 does respond to the control of the controller 24 to close the switch therein and disconnect the loop between the battery module 50 and the load system 60. At this time, it is determined that the switching function of the battery switch circuit 22 is normal (step S202), and the diagnosis ends; if not, it indicates that the loop between the battery module 50 and the load system 60 has not been disconnected. At this time, it is determined that the switching function of the battery switch circuit 22 is abnormal (step S204), and the diagnosis ends. After the controller 24 ends the diagnosis, it can also send the detection result to the load system 60 to take necessary safety measures.

[0024] As described above, it is only an example to illustrate the preferred embodiments of the present application, and is not intended to limit the scope of implementation. Any simple substitution and equivalent change made according to the claims and the content of the specification of the present application shall fall within the protection scope of the present application.

Claims

1. A battery management system, comprising a controller and a battery switch circuit, wherein the battery switch circuit is controlled by the controller to conduct or disconnect a loop between a battery module and a load system, and is characterized in that The battery management system further includes: An energy storage unit; and A delay switch circuit, electrically connected to the energy storage unit, the controller, and the battery switch circuit respectively. When the controller fails, the delay switch circuit conducts the loop between the energy storage unit and the battery switch circuit, and the energy storage unit supplies power to the battery switch circuit, so that the battery switch circuit conducts the loop between the battery module and the load system within a preset delay time.

2. The battery management system according to claim 1, wherein The controller disconnects the loop between the energy storage unit and the battery switch circuit and charges the energy storage unit.

3. The battery management system according to claim 1, characterized in that, The delay switch circuit includes: A first MOS switch circuit, with multiple terminals electrically connected to the switch pin of the controller, a certain voltage source, and a ground respectively; A second MOS switch circuit, with multiple terminals electrically connected to the control pin of the controller, the first MOS switch circuit, the battery switch circuit, and the energy storage unit respectively. When the controller fails, the states of the switch pin and the control pin are at a first potential, so that the first MOS switch circuit forms an open circuit, and the second MOS switch circuit is turned on by the constant voltage source to conduct the loop between the energy storage unit and the battery switch circuit.

4. The battery management system according to claim 3, wherein When the switch pin is at a second potential, the controller turns on the first MOS switch circuit, the second MOS switch circuit forms an open circuit, the battery switch circuit disconnects the delay switch circuit, and the controller charges the energy storage unit. The second potential is different from the first potential.

5. The battery management system according to claim 3, wherein The first MOS switch circuit has an inverter circuit architecture.

6. A self-diagnosis method applied to a battery management system, the battery management system having a controller and a battery switch circuit, the controller controlling the battery switch circuit to conduct or disconnect a loop between a battery module and a load system, characterized in that, The self-diagnosis method includes: Providing a delay switch circuit, and the controller controls the delay switch circuit to conduct or disconnect the loop between the battery switch circuit and an energy storage unit; Obtaining a preset delay time according to the discharge time constant of the energy storage unit, and the energy of the energy storage unit corresponds to the discharge time constant; Conducting the loop between the battery module and the load system, and obtaining a first voltage value at a detection point in the battery switch circuit; Sending an instruction to disconnect the loop between the battery module and the load system through the controller and obtaining a first timestamp; Repeatedly obtaining a second voltage value and a corresponding second timestamp at the detection point every sampling time until the time difference between the second timestamp and the first timestamp is greater than or equal to the preset delay time; and During the period of repeatedly obtaining the second voltage value, if the second voltage value is not approximately equal to the first voltage value, it is determined that the delay-off function of the delay switch circuit is abnormal.

7. The self-diagnosis method according to claim 6, characterized in that, When the time difference between the second timestamp and the first timestamp is greater than the preset delay time, if the second voltage value is not approximately equal to the ground voltage value, it is determined that the switching function of the battery switch circuit is abnormal.

8. The self-diagnosis method according to claim 6, characterized in that When the time difference between the second timestamp and the first timestamp is greater than the preset delay time, if the second voltage value is approximately equal to the ground voltage value, it is determined that the delay-off function of the delay switch circuit is normal.

9. The self-diagnosis method according to claim 8, wherein After determining that the delay-off function is normal, the method further includes the steps of: After the controller turns on the loop between the battery module and the load system, disconnect the loop between the battery switch circuit and the energy storage unit; After reconnecting to disconnect the loop between the battery module and the load system, obtain a third voltage value at the detection point. If the third voltage value is approximately equal to the ground voltage value, it is determined that the switching function of the battery switch circuit is normal; otherwise, it is determined that the switching function is abnormal.

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