Battery management system open circuit detection circuit and detection method

Abstract

This invention discloses a battery management system (BMS) disconnection detection circuit and method. The BMS disconnection detection circuit includes a battery pack, a front-end management chip, a control chip, and multiple energy storage circuits. The battery pack includes multiple strings of cells for powering electrical devices. Each energy storage circuit is connected to one string of cells, and the energy storage circuits are connected in parallel. The front-end management chip is connected to all energy storage circuits and is used to collect the voltage value of each energy storage circuit and convert the voltage value into a digital voltage. The front-end management chip collects the voltage value of only one energy storage circuit at a time. The control chip is connected to the front-end management chip and is used to send control signals to control the front-end management chip to switch the collected energy storage circuits, and to determine whether there are abnormal values ​​in the received digital voltage. When an abnormal value is found, a disconnection in the BMS is confirmed. This invention can detect disconnections in a battery management system.

Description

Technical Field

[0001] This invention relates to the field of battery management technology, and in particular to a battery management system disconnection detection circuit and detection method. Background Technology

[0002] The Battery Management System (BMS) is primarily used to ensure battery safety and stable operation. Currently, the main battery problem is thermal runaway caused by overheating and overcharging. The main reasons for this problem are design flaws in the BMS and insufficient stability during operation. Among these factors, disconnection detection is a crucial aspect of ensuring stable BMS operation. Most BMSs currently rely on disconnection detection functionality provided by the front-end management chip. If the front-end management chip does not support disconnection detection, it cannot detect disconnections in the BMS. Furthermore, even front-end management chips with disconnection detection capabilities can sometimes misjudge connections. Summary of the Invention

[0003] This invention provides a battery management system disconnection detection circuit and detection method, which can detect disconnections in the battery management system.

[0004] In a first aspect, embodiments of the present invention provide a battery management system disconnection detection circuit, which includes a battery pack, a front-end management chip, a control chip, and multiple energy storage circuits; the battery pack includes multiple strings of cells for supplying power to electrical devices; each energy storage circuit is connected to a string of cells, and each energy storage circuit is connected in parallel with each other; the front-end management chip is connected to all the energy storage circuits, and is used to collect the voltage value of each energy storage circuit and convert the voltage value into a digital voltage, wherein the front-end management chip collects the voltage value of only one energy storage circuit at a time; and the control chip is connected to the front-end management chip, and is used to send a control signal to control the front-end management chip to switch the collected energy storage circuit, and to determine whether there is an abnormal value in the received digital voltage, and when the abnormal value exists, confirm that the battery management system is disconnected.

[0005] Furthermore, the energy storage circuit includes a first resistor, a first capacitor, and a first diode; one end of the first resistor is connected to the battery cell, and the other end is connected to the negative terminal of the first diode, one end of the first capacitor, and the front-end management chip, respectively; the positive terminal of the first diode and the other end of the first capacitor are both connected to another first resistor of the energy storage circuit.

[0006] Furthermore, the battery pack includes fifteen strings of cells, and the battery management system disconnection detection circuit includes fifteen energy storage circuits, with one energy storage circuit connected to one string of cells.

[0007] Furthermore, the battery pack includes fifteen strings of cells, and the battery management system disconnection detection circuit includes fifteen energy storage circuits, with one energy storage circuit connected to one string of cells.

[0008] Furthermore, it also includes a battery pack wake-up circuit, one end of which is connected to the control chip and the other end of which is connected to the battery pack.

[0009] Furthermore, it also includes an LED indicator circuit, which is connected to the control chip and is used to indicate whether there is a broken cell in the battery pack.

[0010] Secondly, embodiments of the present invention provide a method for detecting disconnection in a battery management system, the method comprising:

[0011] The front-end management chip is controlled to sequentially collect the voltage value of each energy storage circuit, so that the front-end management chip converts each collected voltage value into a corresponding digital voltage;

[0012] If the front-end management chip completes the acquisition and conversion of the voltage values ​​of all energy storage circuits, confirms the maximum value among all the digital voltages and uses it as the first digital voltage, and confirms the minimum value among all the digital voltages and uses it as the second digital voltage, wherein the minimum value is not zero;

[0013] If the ratio of the first digital voltage to the second digital voltage is greater than a preset value, it is confirmed that there is a disconnection in the battery management system.

[0014] This invention provides a battery management system disconnection detection circuit and method. The circuit can collect the voltage value of the energy storage circuit through the front-end management chip and convert the voltage value into a digital voltage. The control chip then collects the digital voltage of the front-end management chip. After one round of collection, the control chip determines whether there is a disconnection in the battery management system based on whether there are abnormal values ​​in the collected digital voltage. Thus, disconnection detection of the battery management system can be achieved when the front-end management chip does not have a disconnection detection function. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a structural block diagram of the battery management system disconnection detection circuit provided in an embodiment of the present invention;

[0017] Figure 2 This is a circuit diagram of the battery management system disconnection detection circuit provided in an embodiment of the present invention;

[0018] Figure 3 This is a flowchart illustrating the battery management system disconnection detection method provided in an embodiment of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be understood that, when used in this specification and the appended claims, the terms “comprising” and “including” indicate the presence of the described features, integrals, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, operations, elements, components and / or collections thereof.

[0021] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0022] Please see Figure 1 , Figure 1 This is a structural block diagram of the battery management system disconnection detection circuit provided in an embodiment of the present invention, as shown below. Figure 1As shown, the battery management system disconnection detection circuit includes a battery pack 10, a front-end management chip 30, a control chip 40, and multiple energy storage circuits 20. The battery pack 10 includes multiple strings of cells for powering electrical devices. Each energy storage circuit 20 is connected to a string of cells, and each energy storage circuit 20 is connected in parallel. The front-end management chip 30 is connected to all the energy storage circuits 20 and is used to collect the voltage value of each energy storage circuit 20 and convert the voltage value into a digital voltage. The front-end management chip 30 collects the voltage value of only one energy storage circuit 20 at a time. The control chip 40 is connected to the front-end management chip 30 and is used to send control signals to control the front-end management chip 30 to switch the collected energy storage circuit 20, and to determine whether there are abnormal values ​​in the received digital voltage. When an abnormal value is found, it is confirmed that the battery management system is disconnected.

[0023] Specifically, the battery pack 10 includes multiple strings of cells for powering electrical devices. Each cell is connected to an energy storage circuit 20, and all energy storage circuits 20 are connected to a front-end management chip 30. After startup, the battery pack 10 charges the energy storage circuits 20. The front-end management chip 30 includes multiple pins, such as... Figure 1 As shown, B1 to B3 represent different pins used to acquire the voltage values ​​of connected energy storage circuits 20. The front-end management chip 30 connects to only one energy storage circuit 20 at a time and acquires the voltage value of that connected circuit. It then acquires the voltage value of the next energy storage circuit 20 based on the control signal from the control chip 40. The control chip 40 uses the received digital signals to determine if there is a disconnection in the battery management system.

[0024] See Figure 2 In one embodiment, the energy storage circuit 20 includes a first resistor R1, a first capacitor C1, and a first diode D1; one end of the first resistor R1 is connected to the battery cell, and the other end is connected to the negative terminal of the first diode D1, one end of the first capacitor C1, and the front-end management chip 30, respectively. The positive terminal of the first diode D1 and the other end of the first capacitor C1 are both connected to the first resistor R1 of another energy storage circuit 20.

[0025] In each energy storage circuit 20, the first diode D1 and the first capacitor C1 are connected to the first diode D1 and the first capacitor C1 of the next energy storage circuit 20, such as... Figure 2As shown, the battery cells are arranged sequentially from A1 to A15. The energy storage circuit 20 corresponding to A1 is the starting energy storage circuit 20, and the energy storage circuit 20 corresponding to A15 is the ending energy storage circuit 20. When the battery cell between A1 and A15 is disconnected, its corresponding energy storage circuit 20 will not receive power from the battery cell and will need to be charged by the previous battery cell. Taking A2 as an example, if A2 is disconnected, the energy storage circuit 20 connected to A2 will not receive power from A2. However, the first diode D1 in the energy storage circuit 20 of A2 is connected to the first diode D1 in the energy storage circuit 20 connected to A1. A1 can charge the energy storage circuit 20 connected to A2 through the first diode D1. Since A1 needs to supply power to both the energy storage circuit 20 connected to A1 and the energy storage circuit 20 connected to A2 at the same time, the voltage of the first capacitor C1 connected to A1 and the first capacitor C1 of the energy storage circuit 20 connected to A2 decreases. The front-end management chip 30 can collect the corresponding changes, i.e., the voltage value. Specifically, for the energy storage circuit 20 connected to A1, if A1 is disconnected, the voltage of the energy storage circuit 20 will be 0. If A15 is disconnected, the voltage of the energy storage circuit 20 corresponding to A15 will be significantly lower than the standard value.

[0026] In one embodiment, the battery pack 10 includes fifteen strings of battery cells, and the battery management system disconnection detection circuit includes fifteen energy storage circuits 20, with one energy storage circuit 20 connected to one string of battery cells.

[0027] Among them, such as Figure 2 As shown, each energy storage circuit 20 has the same structure and is connected to a battery cell.

[0028] In one embodiment, a battery pack wake-up circuit 50 is also included, one end of which is connected to the control chip 40 and the other end of which is connected to the battery pack 10.

[0029] The battery pack wake-up circuit 50 is used to receive instructions from the control chip 40 and wake up the battery pack 10 to work. That is, when charging is required, the control chip 40 controls the battery pack wake-up circuit 50 to wake up the battery pack 10. The structure of the battery pack wake-up circuit 50 is a wake-up circuit commonly used by those skilled in the art, and will not be described in detail here.

[0030] In one embodiment, an LED indicator circuit 60 is also included, which is connected to the control chip 40 and is used to indicate whether there is a broken cell in the battery pack 10.

[0031] The LED indicator circuit 60 may include multiple LEDs, each of which can flash at a certain frequency according to the signal from the control chip 40 to indicate different faults. For example, flashing at a frequency of 1Hz for 10 seconds indicates that there is a disconnection in the battery management system.

[0032] Please see Figure 3 , Figure 3 This is a flowchart illustrating a battery management system disconnection detection method provided in an embodiment of the present invention. This method can be applied to the control chip of a battery management system disconnection detection circuit. Figure 3 As shown, the method includes steps S110 to S130.

[0033] S110, control the front-end management chip to sequentially collect the voltage value of each of the energy storage circuits, so that the front-end management chip converts each collected voltage value into a corresponding digital voltage.

[0034] In this embodiment of the invention, the battery management system disconnection detection circuit may include a front-end management chip, an energy storage circuit, a battery pack, and a control chip. The battery pack may include multiple battery cells for supplying power to electrical devices. Each battery cell corresponds to one energy storage circuit connection. All energy storage circuits are connected to the front-end management chip. The front-end management chip collects voltage values ​​through the energy storage circuits; that is, multiple energy storage circuits correspond to multiple voltage values. The front-end management chip then converts the collected voltage values ​​into digital voltages and sends them to the control chip. The control chip determines whether there is a disconnection in the battery management system based on the received digital voltages. Specifically, if the battery pack contains fifteen battery cells, there are fifteen corresponding energy storage circuits. The number of voltage values ​​that the front-end management chip can collect in one round of acquisition is also fifteen. Therefore, the number of digital voltages that the control chip can receive is also fifteen.

[0035] S120, if the front-end management chip completes the acquisition and conversion of the voltage values ​​of all energy storage circuits, confirms the maximum value among all the digital voltages and uses it as the first digital voltage, and confirms the minimum value among all the digital voltages and uses it as the second digital voltage, wherein the minimum value is not zero.

[0036] In this embodiment of the invention, with fifteen battery cells, the control chip completes one round of digital voltage acquisition when it acquires fifteen digital voltages. After completing one round of digital voltage acquisition, the control chip confirms the maximum and minimum values ​​among the acquired digital voltages, sets the digital voltage corresponding to the maximum value as the first digital voltage, and sets the digital voltage corresponding to the minimum value as the second digital voltage. Generally, after the battery pack starts working, the voltage of all battery cells is not zero. Therefore, if there is a case where the digital voltage is zero, it indicates that the battery cell corresponding to that digital voltage has a disconnection. Thus, the battery management system also has a disconnection, and there is no need to further determine whether the battery management system has a disconnection.

[0037] S130, if the ratio of the first digital voltage to the second digital voltage is greater than a preset value, then it is confirmed that there is a disconnection in the battery management system.

[0038] In this embodiment of the invention, when the ratio of the first digital voltage to the second digital voltage is greater than a preset value, it can be confirmed that there is a disconnection in the battery management system. The preset value can be two. When the ratio of the first digital voltage to the second digital voltage is greater than two, it indicates that there is a disconnection in the battery management system.

[0039] In some embodiments, such as this embodiment, step S130 may include the following steps: sorting all the digital voltages according to the arrangement order of the cells in the battery management system disconnection detection circuit; setting any digital voltage other than the first and last digital voltages as the target voltage, and determining whether the difference between the target voltage and its two adjacent digital voltages is within a preset difference range; if the difference between the target voltage and its two adjacent digital voltages is not within the preset difference range, then confirming that the cell corresponding to the target voltage has a disconnection.

[0040] In this embodiment of the invention, after confirming a disconnection in the battery management system, the specific disconnected cell can be further identified. If the battery pack has fifteen cells, there are fifteen corresponding digital voltages. These fifteen digital voltages are sorted according to the series connection order of the cells. Assuming A0 to A14 represent the fifteen digital voltages, for any digital voltage other than A0 and A14, such as A2, A2 is set as the target voltage. It is then determined whether the voltage difference between A2 and A1 and the voltage difference between A2 and A3 are within a preset range. If the voltage difference between A2 and A1 and the voltage difference between A2 and A3 are not within the preset range, it indicates that A2 is disconnected.

[0041] In some embodiments, such as this embodiment, the battery management system disconnection detection circuit may further include the following steps: determining whether the acquisition time of the front-end management chip has reached a preset acquisition time; if the acquisition time of the front-end management chip has reached the preset acquisition time, controlling the front-end management chip to connect with the next energy storage circuit so that the front-end management chip acquires the voltage value of the next energy storage circuit and converts the voltage value into the digital voltage.

[0042] In this embodiment of the invention, the front-end management chip collects the voltage value of the energy storage circuit. After the battery cell starts working, it charges the energy storage circuit. In a short period of time, the charging speed of each energy storage circuit will not change significantly. Since the front-end management chip collects the voltage value one by one, the control chip can control the collection time of the front-end management chip for each energy storage circuit. For example, if the preset collection time is 100 microseconds, then after the front-end management chip collects the voltage value of one energy storage circuit for 100 microseconds, it will collect the voltage value of the next energy storage circuit.

[0043] In some embodiments, such as this embodiment, the battery management system disconnection detection circuit may further include the following steps: if the digital voltage corresponding to the first energy storage circuit in the battery management system disconnection detection circuit is zero, then it is confirmed that the battery management system is disconnected; if the digital voltage corresponding to the last energy storage circuit in the battery management system disconnection detection circuit is lower than a standard value, then it is confirmed that the battery management system is disconnected.

[0044] In this embodiment of the invention, if the battery pack contains fifteen cells, their corresponding digital voltages are A0 to A14. All energy storage circuits between A0 and A14 are connected in parallel, and current can only flow from A0 to A14, not in the opposite direction. When all cells are working normally, the voltages of each energy storage circuit are basically the same. If a cell is disconnected, the corresponding energy storage circuit needs to be powered by the cell adjacent to it. When the cell corresponding to the first energy storage circuit is disconnected, this energy storage circuit cannot obtain power from other cells, so its voltage is zero. When the cell corresponding to the last energy storage circuit is disconnected, this energy storage circuit can only obtain power from one adjacent cell, and its voltage value will be much lower than the normal value. Therefore, it can be determined whether its corresponding digital voltage is lower than the standard value. If it is lower, it indicates that there is a disconnection in the battery management system.

[0045] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0046] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Since these modifications and variations fall within the scope of the claims and their equivalents, this invention also intends to include these modifications and variations.

[0047] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A battery management system disconnection detection circuit, characterized in that, include: A battery pack, comprising multiple strings of cells, is used to power electrical devices; Multiple energy storage circuits, each of which is connected to a string of battery cells, and each of the energy storage circuits is connected in parallel with each other; A front-end management chip, connected to all the energy storage circuits, is used to acquire the voltage value of each energy storage circuit and convert the voltage value into a digital voltage, wherein the front-end management chip acquires the voltage value of only one energy storage circuit at a time; and A control chip, connected to the front-end management chip, is used to send control signals to control the front-end management chip to switch the collected energy storage circuit, and to determine whether there are abnormal values ​​in the received digital voltage. When there are abnormal values, it is confirmed that there is a disconnection in the battery management system. The energy storage circuit includes a first resistor, a first capacitor, and a first diode. One end of the first resistor is connected to the battery cell, and the other end is connected to the negative terminal of the first diode, one end of the first capacitor, and the front-end management chip. The positive terminal of the first diode and the other end of the first capacitor are both connected to the first resistor of another energy storage circuit.

2. The battery management system disconnection detection circuit as described in claim 1, characterized in that, The battery pack includes fifteen strings of cells, and the battery management system disconnection detection circuit includes fifteen energy storage circuits, with each energy storage circuit connected to one string of cells.

3. The battery management system disconnection detection circuit as described in claim 1, characterized in that, It also includes a battery pack wake-up circuit, one end of which is connected to the control chip and the other end of which is connected to the battery pack.

4. The battery management system disconnection detection circuit as described in claim 1, characterized in that, It also includes an LED indicator circuit, which is connected to the control chip and is used to indicate whether there is a broken cell in the battery pack.

5. A method for detecting a disconnection in a battery management system, applied to a control chip in a disconnection detection circuit of a battery management system as described in any one of claims 1-4, wherein the disconnection detection circuit of the battery management system includes a battery pack, a front-end management chip, the control chip, and multiple energy storage circuits, characterized in that, The method includes: The front-end management chip is controlled to sequentially collect the voltage value of each energy storage circuit, so that the front-end management chip converts each collected voltage value into a corresponding digital voltage; If the front-end management chip completes the acquisition and conversion of the voltage values ​​of all energy storage circuits, confirms the maximum value among all the digital voltages and uses it as the first digital voltage, and confirms the minimum value among all the digital voltages and uses it as the second digital voltage, wherein the minimum value is not zero; If the ratio of the first digital voltage to the second digital voltage is greater than a preset value, it is confirmed that there is a disconnection in the battery management system.

6. The battery management system disconnection detection method as described in claim 5, characterized in that, The step of controlling the front-end management chip to sequentially collect the voltage value of each energy storage circuit, so that the front-end management chip converts each collected voltage value into a corresponding digital voltage, includes: Determine whether the acquisition time of the front-end management chip has reached the preset acquisition time; If the acquisition time of the front-end management chip reaches the preset acquisition time, the front-end management chip is controlled to connect with the next energy storage circuit so that the front-end management chip acquires the voltage value of the next energy storage circuit and converts the voltage value into the digital voltage.

7. The battery management system disconnection detection method as described in claim 5, characterized in that, The method further includes: If the digital voltage corresponding to the first energy storage circuit in the battery management system disconnection detection circuit is zero, then the disconnection of the battery management system is confirmed.

8. The battery management system disconnection detection method as described in claim 7, characterized in that, The method further includes: If the digital voltage corresponding to the last energy storage circuit in the battery management system disconnection detection circuit is lower than the standard value, then the battery management system is confirmed to be disconnected.

9. The battery management system disconnection detection method as described in claim 5, characterized in that, After the step of confirming a disconnection in the battery management system if the ratio of the first digital voltage to the second digital voltage is greater than a preset value, the method further includes: All the digital voltages are sorted according to the arrangement order of the cells in the battery management system disconnection detection circuit; For any digital voltage other than the first and last digital voltages, set it as the target voltage, and determine whether the difference between the target voltage and its two adjacent digital voltages is within a preset difference range. If the difference between the target voltage and the two adjacent digital voltages is not within the preset difference range, it is confirmed that the cell corresponding to the target voltage has a broken wire.

Images