US-12620819-B2 - Discharge circuit, battery management system, battery, protection method, and electrical apparatus

US12620819B2US 12620819 B2US12620819 B2US 12620819B2US-12620819-B2

Abstract

A discharge circuit includes a first branch configured to be connected to a protected unit and a second branch connected in parallel to the first branch. The first branch includes a first overvoltage protection device configured to passively discharge a surge voltage. The second branch includes a second overvoltage protection device and a control switch connected in series. The control switch is configured to be connected to a control unit, and to be opened or closed based on a control signal of the control unit.

Inventors

Hui Chen
Yanhui FU
Le CHU
Maobo GUO

Assignees

CONTEMPORARY AMPEREX TECHNOLOGY (HONG KONG) LIMITED

Dates

Publication Date: 20260505
Application Date: 20220908
Priority Date: 20211101

Claims (15)

1 . A discharge circuit, comprising: a first branch configured to be connected to a protected unit, and comprising a first overvoltage protection device configured to passively discharge a surge voltage; and a second branch comprising a second overvoltage protection device and a control switch connected in series, the second branch being connected in parallel to the first branch; wherein: the control switch is configured to be connected to a control unit, and to be opened or closed based on a control signal of the control unit; the first branch comprises N sub-branches, N being a positive integer greater than or equal to 2; the first overvoltage protection device is one of N first overvoltage protection devices each connected in series to one of the sub-branches; the N first overvoltage protection devices are connected in parallel; each of the sub-branches further comprises a resistor connected in series to the corresponding first overvoltage protection device; and when the first branch is connected to the protected unit, the resistor is located on a side closer to the protected unit than the corresponding first overvoltage protection device.
2 . The discharge circuit according to claim 1 , wherein a 1 st sub-branch of the first branch is connected to the protected unit, one end of each of a 2 nd sub-branch to an N th sub-branch is connected between the resistor and the first overvoltage protection device of a previous sub-branch, and another end of each of the 2 nd sub-branch to the N th sub-branch is grounded.
3 . The discharge circuit according to claim 1 , wherein: the second branch comprises M sub-branches connected in parallel, M being a positive integer greater than or equal to 2; the second overvoltage protection device is one of M second overvoltage protection devices each belonging to one of the sub-branches; the control switch is one of M control switches each belonging to one of the sub-branches and connected in series to the corresponding second overvoltage protection device; and all of the control switches are configured to be connected to the control unit.
4 . The discharge circuit according to claim 1 , wherein: the N sub-branches are N first sub-branches; the resistors are first resistors of the first sub-branches; the second branch comprises M second sub-branches connected in parallel, M being a positive integer greater than or equal to 2; the second overvoltage protection device is one of M second overvoltage protection devices each belonging to one of the second sub-branches; the control switch is one of M control switches each belonging to one of the second sub-branches and connected in series to the corresponding second overvoltage protection device; all of the control switches are configured to be connected to the control unit each of the second sub-branches further comprises a second resistor connected in series to the corresponding second overvoltage protection device; and one end of each of the M second sub-branches closer to the corresponding second resistor is connected to a position between the first resistor and the first overvoltage protector of an N th first sub-branch, and one end of each of the M second sub-branches closer to the corresponding second overvoltage protection device is grounded.
5 . The discharge circuit according to claim 1 , wherein the first overvoltage protection device and the second overvoltage protection device each include a transient voltage suppression diode.
6 . The discharge circuit according to claim 1 , wherein the control switch includes a MOS transistor.
7 . A battery management system, comprising: a discharge circuit comprising: a first branch configured to be connected to a protected unit, and comprising a first overvoltage protection device configured to passively discharge a surge voltage; and a second branch connected in parallel to the first branch and comprising a second overvoltage protection device and a control switch connected in series, the control switch being configured to be connected to a control unit, and to be opened or closed based on a control signal of the control unit; a microcontroller; a voltage sampling unit; and a multi-stage voltage comparison unit; wherein: at least one of the microcontroller, the voltage sampling unit, or the multi-stage voltage comparison unit is connected to the control switch of the second branch of the discharge circuit, and the control switch receives a control signal from the at least one of the microcontroller, the voltage sampling unit, or the multi-stage voltage comparison unit, and is opened or closed based on the control signal; the first branch comprises N sub-branches, N being a positive integer greater than or equal to 2; the first overvoltage protection device is one of N first overvoltage protection devices each connected in series to one of the sub-branches; the N first overvoltage protection devices are connected in parallel; each of the sub-branches further comprises a resistor connected in series to the corresponding first overvoltage protection device; and when the first branch is connected to the protected unit, the resistor is located on a side closer to the protected unit than the corresponding first overvoltage protection device.
8 . The battery management system according to claim 7 , further comprising: a switch control unit connected to a control terminal of the control switch of the second branch of the discharge circuit; wherein the at least one of the microcontroller, the voltage sampling unit, or the multi-stage voltage comparison unit is connected to the switch control unit.
9 . The battery management system according to claim 7 , wherein a 1 st sub-branch of the first branch is connected to the protected unit, one end of each of a 2 nd sub-branch to an N th sub-branch is connected between the resistor and the first overvoltage protection device of a previous sub-branch, and another end of each of the 2 nd sub-branch to the N th sub-branch is grounded.
10 . The battery management system according to claim 7 , wherein: the second branch comprises M sub-branches connected in parallel, M being a positive integer greater than or equal to 2; the second overvoltage protection device is one of M second overvoltage protection devices each belonging to one of the sub-branches; the control switch is one of M control switches each belonging to one of the sub-branches and connected in series to the corresponding second overvoltage protection device; and all of the control switches are configured to be connected to the control unit.
11 . A discharge protection method, applied to the battery management system according to claim 7 , and comprising: obtaining a voltage of the protected unit; determining whether the voltage exceeds an overvoltage threshold; and in response to the voltage exceeding the overvoltage threshold, sending a control signal to the second branch of the discharge circuit, to control the control switch of the second branch to be closed, such that the discharge circuit discharges a surge voltage in a combined active-passive manner.
12 . The discharge protection method according to claim 11 , wherein the protected unit includes a positive terminal of a battery; the method further comprising, before obtaining the voltage of the protected unit and determining whether the voltage exceeds the overvoltage threshold: obtaining the voltage and a current of the positive terminal; determining whether the voltage and the current reach a protection threshold; in response to the voltage and the current reaching the protection threshold, controlling a controllable switch between the positive terminal of the battery and a positive terminal of a battery pack to be opened; and sending a control signal to the second branch of the discharge circuit, to control the control switch of the second branch to be closed, such that the discharge circuit discharges the surge voltage in the combined active-passive manner.
13 . The discharge protection method according to claim 11 , wherein the method is performed cyclically, until the voltage of the protected unit does not exceed the overvoltage threshold.
14 . The discharge protection method according to claim 13 , wherein: the obtained voltage of the protected unit is divided into a plurality of levels from low to high in response to the obtained voltage of the protected unit exceeding the overvoltage threshold; and a quantity of sub-branches in the discharge circuit that are connected is controlled to gradually increase, corresponding to the plurality of voltage levels from high to low.
15 . A discharge circuit, comprising: a first branch configured to be connected to a protected unit, and comprising a first overvoltage protection device configured to passively discharge a surge voltage; and a second branch comprising a second overvoltage protection device and a control switch connected in series, the second branch being connected in parallel to the first branch; wherein: the control switch is configured to be connected to a control unit, and to be opened or closed based on a control signal of the control unit; the second branch comprises M sub-branches connected in parallel, M being a positive integer greater than or equal to 2; the second overvoltage protection device is one of M second overvoltage protection devices each belonging to one of the sub-branches; the control switch is one of M control switches each belonging to one of the sub-branches and connected in series to the corresponding second overvoltage protection device; and all of the control switches are configured to be connected to the control unit.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a continuation of International Application No. PCT/CN2022/089068, filed on Apr. 25, 2022, which claims priority to Chinese Patent Application No. 202111283737.5, entitled “DISCHARGE CIRCUIT, BATTERY MANAGEMENT SYSTEM, BATTERY, PROTECTION METHOD, AND ELECTRICAL APPARATUS”, filed on Nov. 1, 2021, the entire contents of both of which are incorporated herein by reference. TECHNICAL FIELD The present application relates to the field of battery technologies, and specifically to a discharge circuit, a battery management system, a battery, a protection method, and an electrical apparatus. BACKGROUND ART As new energy technologies advance, battery technology, especially lithium battery technology, has developed rapidly. In the existing technologies, a battery management system (BMS) is used to effectively manage a battery. However, the battery management system is a low-voltage system, has a specific limit on a voltage withstand requirement for a high voltage, and cannot be completely galvanically isolated. The battery management system will be damaged when the high voltage exceeds a withstand voltage limit of the battery management system. Therefore, how to effectively protect the battery management system from overvoltage and overcurrent is a technical problem that needs to be solved urgently. SUMMARY OF THE DISCLOSURE In view of the above problem, the present application provides a discharge circuit, a battery management system, a battery, a protection method, and an electrical apparatus, which can solve the problem of the battery management system being damaged due to a high-voltage surge. According to a first aspect, the present application provides a discharge circuit, including: a first branch configured to be connected to a protected unit, and including a first overvoltage protection device configured to passively discharge a surge voltage; and a second branch including a second overvoltage protection device and a control switch connected in series, the second branch being connected in parallel with the first branch, where the control switch is configured to be connected to a control unit, and to be opened or closed based on a control signal of the control unit. In the technical solution of this embodiment of the present application, two branches are provided in the discharge circuit. The first branch can use the first overvoltage protection device to passively discharge the surge voltage, thereby protecting the protected unit from overvoltage. The second branch is not only provided with the second overvoltage protection device but also provided with the control switch. The control unit of the battery management system may be used to control the control switch to be opened or closed, such that the second branch participates in actively discharging the surge voltage, and the discharge circuit discharges the surge voltage of the protected unit in a combined active-passive manner. This ensures that no overvoltage occurs in the protected unit, thereby further protecting the battery management system from being damaged due to a relatively large surge. In some embodiments, the first branch includes N first sub-branches, and the first overvoltage protection device is connected in series to each of the first sub-branches. The first overvoltage protection devices of the N first sub-branches are connected in parallel, N being a positive integer greater than or equal to 2. In this embodiment, the first branch is provided as the N first sub-branches, and the N first overvoltage protection devices are provided in parallel in the first branch, so that the N first overvoltage protection devices can cooperatively discharge the surge received by the protected unit, thereby improving the capability of passively discharging the surge. In some embodiments, the first sub-branch further includes a first resistor connected in series to the first overvoltage protection device. When the first branch is connected to the protected unit, the first resistor is located on a side closer to the protected unit than the first overvoltage protection device. In this embodiment of the present application, the first resistor can effectively play a current limiting role. That is, the first resistor is a current limiting resistor, and can effectively reduce power consumption of the first overvoltage protection device. In some embodiments, a 1st first sub-branch of the first branch is connected to the protected unit, one end of each of a 2nd first sub-branch to an Nth first sub-branch is connected between the first resistor and the first overvoltage protection device of a previous first sub-branch, and the other end of each of the 2nd first sub-branch to the Nth first sub-branch is grounded, N being a positive integer greater than or equal to 2. In this embodiment of the present application, the N first sub-branches are sequentially connected in the above manner, and the first bran