Fault detection method for battery balancing circuit and battery balancing circuit

Abstract

According to embodiments of the present invention, a fault detection method and circuit for a battery balancing circuit are disclosed. When a battery balancing module needs to be detected for faults, the method switches on or off a balancing switch, and the voltage between the first and second ports of the battery balancing module is measured before and after balancing is initiated to determine whether the battery balancing module has failed and what type of fault has occurred. This method utilizes the battery balancing circuit in a battery management system for fault detection, improving circuit power density, saving chip area, and reducing costs. The method can also detect five common faults: open and short circuits in the chip's external balancing resistors, and open, short circuits, and faulty open conditions in the chip's internal balancing switches.

Description

Technical Field

[0001] The present invention relates to the field of power electronics, and more particularly to a fault detection method for a battery balancing circuit and a battery balancing circuit. Background Art

[0002] With the widespread adoption of new energy products, electric vehicles are becoming a mainstream segment of the future automotive market. Electric vehicles require a battery pack consisting of multiple cells coupled in series for power. Therefore, the battery management system (BMS), which detects and manages the battery charge within the battery pack, plays a crucial role. The analog front end (AFE) in the battery management system is used to monitor, protect, and balance the battery voltage, current, and temperature. To address the issue of varying charge levels among cells within a battery pack, the battery balancing circuit in the battery management system balances the charge of each cell, maximizing the battery pack's capacity and ensuring that the energy in the pack is utilized as much as possible, thereby extending battery life. To meet the functional safety requirements of the ISO 26262 automotive specification, safety failure analysis and fault diagnosis mechanisms must be implemented in the design. For each balancing channel, a fault in the balancing resistor or balancing switch can prevent proper balancing within that channel, impacting the balancing effect.

[0003] In the prior art, each balancing channel is equipped with an independent pull-down current source. When a balancing channel requires diagnosis, the pull-down current source is turned on and the voltage across the balancing switch is converted to analog-to-digital (ADC) form. However, this prior art can only diagnose open-circuit balancing resistors and cannot cover all fault conditions during the entire balancing process, resulting in practical limitations. Summary of the Invention

[0004] In view of this, the present invention proposes a fault detection method for a battery balancing circuit to solve the technical problem that the prior art can only diagnose the situation where the balancing resistor is open, but cannot cover all fault situations.

[0005] An embodiment of the present invention provides a fault detection method for a battery balancing circuit. The battery balancing circuit is configured to perform voltage balancing on a plurality of single cells coupled in series. The battery balancing circuit includes a plurality of battery balancing modules corresponding one to each of the single cells. Each battery balancing module includes a first port, a second port, a first balancing resistor, a second balancing resistor, a balancing switch, and a first capacitor to balance the voltage of the corresponding single cell. The positive electrode of the single cell is coupled to the first port via the first balancing resistor, and the negative electrode is coupled to the second port via the second balancing resistor. The balancing switch and the first capacitor are both coupled between the first port and the second port. The fault detection method includes:

[0006] The balancing switch is controlled to be turned off to obtain a first voltage between the first port and the second port; the balancing switch is controlled to be turned on to obtain a second voltage between the first port and the second port; and whether the battery balancing module fails is determined based only on the first voltage and the second voltage.

[0007] In one embodiment, when it is detected that the first voltage is close to the voltage of the single battery and the second voltage is close to zero, it is determined that the first balancing resistor and / or the second balancing resistor are open-circuited.

[0008] In one embodiment, when it is detected that the first voltage is close to the voltage of the single cell and the second voltage is close to a third voltage, it is determined that one of the first balancing resistor and the second balancing resistor is short-circuited. When the balancing switch is controlled to be turned on, the on-resistance of the balancing switch and the other of the first balancing resistor and the second balancing resistor divide the voltage of the single cell, and the third voltage is configured as the on-state voltage drop of the balancing switch.

[0009] In one embodiment, when it is detected that the first voltage is close to the second voltage, it is determined that the balancing switch fails.

[0010] In one embodiment, when it is detected that both the first voltage and the second voltage are close to the voltage of the single battery, it is determined that the balancing switch is open.

[0011] In one embodiment, when it is detected that the first voltage and the second voltage are both close to zero, it is determined that the balancing switch is short-circuited.

[0012] In one embodiment, when it is detected that both the first voltage and the second voltage are close to a fourth voltage, it is determined that the balancing switch is normally open due to a fault; wherein, when the balancing switch is controlled to be turned off and on, the on-resistance of the balancing switch, the first balancing resistor, and the second balancing resistor divide the voltage of the single battery, and the fourth voltage is configured as the on-state voltage drop of the balancing switch.

[0013] In one embodiment, when it is detected that the first voltage is close to the voltage of the single cell and the second voltage is close to a fourth voltage, it is determined that the battery balancing module has not failed. When the balancing switch is controlled to be turned on, the on-resistance of the balancing switch, the first balancing resistor, and the second balancing resistor divide the voltage of the single cell, and the fourth voltage is configured as the on-state voltage drop of the balancing switch.

[0014] An embodiment of the present invention further provides a battery balancing circuit for voltage balancing a plurality of single cells coupled in series, comprising: a plurality of battery balancing modules corresponding one-to-one to the plurality of single cells, wherein each battery balancing module comprises: a first port, a second port, a first balancing resistor, a second balancing resistor, a balancing switch, and a first capacitor, for voltage balancing the corresponding single cells, wherein the positive electrode of the single cell is coupled to the first port via the first balancing resistor, and the negative electrode of the single cell is coupled to the second port via the second balancing resistor, and the balancing switch and the first capacitor are both coupled between the first port and the second port; the first port of a preceding battery balancing module serves as the second port of a succeeding battery balancing module, and the first balancing resistor of the preceding battery balancing module serves as the second balancing resistor of the succeeding battery balancing module, and any one of the above-described fault detection methods is used to determine whether the battery balancing circuit has a fault.

[0015] Compared with the prior art, the technical solution of the present invention has the following advantages: In the present invention, when it is necessary to detect whether a cell balancing module has failed, the balancing switch is controlled to be turned off or on, and the voltage between the first and second ports of the cell balancing module is measured before and after balancing is enabled to determine whether the cell balancing module has failed and what type of fault has occurred. The fault detection method proposed in the present invention can accurately diagnose the location and type of fault in the balancing channel based solely on the first and second voltages before and after balancing is enabled. The present invention utilizes the cell balancing circuit in the battery management system for fault detection, eliminating the independent current source required for each cell balancing module in the prior art. This improves the circuit's power density, saves chip area, and reduces costs. Furthermore, the present invention can detect five common faults: open and short circuits in the chip's external balancing resistors, and open, short circuits, and faulty open conditions in the chip's internal balancing switches. This presents a significant advantage over the prior art, which can only detect open balancing resistors. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0017] Figure 1 is a circuit diagram of an embodiment of a battery balancing circuit of the present invention;

[0018] Figure 2 A circuit diagram of an embodiment of a battery balancing module according to the present invention;

[0019] Figure 3 A circuit diagram of an embodiment of the present invention in which the balancing resistor in the battery balancing module is open;

[0020] Figure 4A circuit diagram of an embodiment of a battery balancing module according to the present invention in which a balancing resistor is short-circuited;

[0021] Figure 5 A circuit diagram of an embodiment of the present invention in which the balancing switch in the battery balancing module is open;

[0022] Figure 6 A circuit diagram of an embodiment of a short-circuit balancing switch in a battery balancing module according to the present invention;

[0023] Figure 7 This is a circuit diagram of an embodiment of a battery balancing module of the present invention in which a balancing switch is normally open due to a fault; DETAILED DESCRIPTION

[0024] The present invention is described below based on the following embodiments, but the present invention is not limited to these embodiments. In the detailed description of the present invention below, certain specific details are described in detail. Those skilled in the art can fully understand the present invention without these details. To avoid obscuring the essence of the present invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0025] Furthermore, persons of ordinary skill in the art will appreciate that the figures provided herein are for illustration purposes only and are not necessarily drawn to scale.

[0026] At the same time, it should be understood that in the following description, "circuit" refers to a conductive loop composed of at least one element or subcircuit connected electrically or electromagnetically. When an element or circuit is said to be "connected to" another element or an element / circuit is said to be "connected" between two nodes, it can be directly coupled or connected to the other element or there can be intermediate elements. The connection between the elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there are no intermediate elements between the two.

[0027] Unless the context clearly requires otherwise, throughout the specification and claims, the words "include," "comprising," and similar words should be construed in an inclusive sense rather than an exclusive or exhaustive sense; that is, in the sense of "including but not limited to."

[0028] In the description of the present invention, it should be understood that the terms "first", "second", etc. are used for descriptive purposes only and should not be understood to indicate or imply relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0029] Figure 1This is a circuit diagram of an embodiment of a battery balancing circuit according to the present invention. The battery balancing circuit includes N battery balancing modules for balancing the voltages of corresponding cells in a first battery pack. The first battery pack includes N battery cells BAT1 to BATN coupled in series. The first battery balancing module includes a first port B1, a second port B0, a first balancing resistor RB1, a second balancing resistor RB0, a balancing switch FET1, and a first capacitor CB1. The module is configured to balance the charge of the cell BAT1. The positive electrode of the cell BAT1 is coupled to the first port B1 via the first balancing resistor RB1, and the negative electrode is coupled to the second port B0 via the second balancing resistor RB0. The balancing switch FET1 and the first capacitor CB1 are both coupled between the first port B1 and the second port B0. The second battery balancing module includes: a first port B2, a second port B1, a first balancing resistor RB2, a second balancing resistor RB1, a balancing switch FET2, and a first capacitor CB2, and is used to balance the charge of the single battery BAT2. The positive electrode of the single battery BAT2 is coupled to the first port B2 via the first balancing resistor RB2, and the negative electrode is coupled to the second port B1 via the second balancing resistor RB1. The balancing switch FET2 and the first capacitor CB2 are both coupled between the first port B2 and the second port B1. In other words, the first port B1 of the first battery balancing module serves as the second port of the second battery balancing module, and the first balancing resistor RB1 of the first balancing channel serves as the second balancing resistor of the second battery balancing module. The third battery balancing module includes a first port B3, a second port B2, a first balancing resistor RB3, a second balancing resistor RB2, a balancing switch FET3, and a first capacitor CB3, and is configured to balance the charge of a single battery cell BAT3. The positive electrode of each single battery cell BAT3 is coupled to the first port B3 via the first balancing resistor RB3, and the negative electrode is coupled to the second port B2 via the second balancing resistor RB2. The balancing switch FET3 and the first capacitor CB3 are both coupled between the first port B3 and the second port B2. In other words, the first port B2 of the second battery balancing module serves as the second port of the third battery balancing module, and the first balancing resistor RB2 of the second balancing channel serves as the second balancing resistor of the third battery balancing module. The Nth battery balancing module includes: a first port BN, a second port B(N-1), a first balancing resistor RBN, a second balancing resistor RB(N-1), a balancing switch FETN, and a first capacitor CBN, and is configured to balance the charge of the single battery BATN. The positive electrode of the single battery BATN is coupled to the first port BN via the first balancing resistor RBN, and the negative electrode is coupled to the second port B(N-1) via the second balancing resistor RB(N-1). The balancing switch FETN and the first capacitor CBN are both coupled between the first port BN and the second port B(N-1).

[0030] Thus, Figure 2 As shown, the i-th battery balancing module includes a first port Bi, a second port B(i-1), a first balancing resistor RBi, a second balancing resistor RB(i-1), a balancing switch FETi, and a first capacitor CBi, configured to balance the charge of individual batteries BATi. The positive electrode of each individual battery BATi is coupled to the first port Bi via the first balancing resistor RBi, and the negative electrode is coupled to the second port B(i-1) via the second balancing resistor RB(i-1). The balancing switch FETi and the first capacitor Ci are both coupled between the first port Bi and the second port B(i-1), where i = 1 to N. Furthermore, the first port Bi of the i-th battery balancing module serves as the second port of the i+1-th battery balancing module, and the first balancing resistor RBi of the i-th battery balancing module serves as the second balancing resistor of the i+1-th balancing channel. That is, the first port of the previous battery balancing module serves as the second port of the next battery balancing module, and the first balancing resistor of the previous battery balancing module serves as the second balancing resistor of the next battery balancing module. The terms "front" and "rear" are relative. In this embodiment, the battery balancing module corresponding to the battery with a higher positive electrode voltage among two adjacent batteries is called the "rear" and the other one is called the "front". This is for illustration purposes only.

[0031] In this embodiment, the right side of line L is inside the AFE chip, and the left side of line L is outside the AFE chip. Consequently, the balancing resistors RB0 to RBN are located outside the AFE chip, the balancing switches FET1 to FETN are located inside the AFE chip, and the first capacitors CB1 to CBN are located outside the AFE chip. Ports B0 to BN on line L serve as the chip's balancing pins. The AFE chip also monitors the voltages of the individual cells BAT1 to BATN via sampling pins C0 to CN on line L.

[0032] In this embodiment, when it is detected that the voltage of a single cell BATi is higher (e.g., higher than the voltage of the remaining cells), the corresponding balancing switch FETi is turned on to discharge excess charge from the single cell BATi, thereby performing cell balancing. This process can be controlled by a control module in the AFE chip or by a host computer, and is not limited in this invention.

[0033] use Figure 2The i-th cell balancing module in FIG. 1 is used to illustrate how to detect whether each cell balancing module has a fault. When it is necessary to detect whether the i-th cell balancing module has a fault, the balancing switch FETi is controlled to be turned off or on. Before and after balancing is enabled, the voltage between the first port Bi and the second port B(i-1) of the i-th cell balancing module is detected to determine whether the i-th cell balancing module has a fault and what type of fault has occurred.

[0034] Specifically, the balancing switch FETi is controlled to be turned off to obtain a first voltage between the first port Bi and the second port B(i-1); the balancing switch FETi is controlled to be turned on to obtain a second voltage between the first port Bi and the second port B(i-1); and whether the battery balancing module has failed is determined solely based on the first and second voltages. It should be noted that controlling the balancing switch FETi to be turned off or on here refers to providing a turn-off control signal or a turn-on control signal to the balancing switch FETi. However, in practice, whether the balancing switch FETi is turned on or off also depends on whether the balancing switch FETi has failed.

[0035] exist Figure 2 In the example, when the i-th battery balancing module is not faulty, before balancing is enabled, that is, when the balancing switch FETi is turned off, the first voltage is equal to the voltage VBATi of the single battery BATi. If the voltage of each single battery is Vo, the first voltage is equal to Vo. After balancing is enabled, that is, when the balancing switch FETi is turned on, the on-resistance Rdson of the balancing switch FETi, the first balancing resistor RBi, and the second balancing resistor RB(i-1) divide the voltage VBATi of the single battery BATi. At this time, the second voltage is equal to the on-state voltage drop of the balancing switch FETi, that is, VBATi*Rdson / (Rdson+RB(i-1)+RBi). If the voltage of each single battery is Vo and the resistance of all balancing resistors is Ro, the second voltage is equal to Vo*Rdson / (Rdson+2Ro).

[0036] like Figure 3 As shown, for the i-th battery balancing module, when the first balancing resistor RBi is open,

[0037] Before balancing is turned on, that is, when the balancing switch FETi is controlled to be off, although the first port Bi is out of the clamp of the battery BATi, the first capacitor CBi and the first capacitor CB(i+1) will evenly divide the sum of the voltage VBAT(i+1) of the battery BAT(i+1) and the voltage VBATi of the battery BATi. Therefore, at this time, the first voltage is equal to the voltage across the first capacitor CBi, which is (VBAT(i+1)+VBATi) / 2. If the voltage of each battery cell is Vo, then the first voltage is equal to Vo;

[0038] After balancing is turned on, that is, when the balancing switch FETi is controlled to be turned on, the first capacitor CBi is discharged, and the second voltage is equal to the voltage across the first capacitor CBi, so that the second voltage is equal to 0V.

[0039] Figure 3 Only the analysis process when the first balancing resistor RBi is open is given. The detection when the second balancing resistor RB(i-1) is open and the detection when both the first balancing resistor RBi and the second balancing resistor RB(i-1) are open are similar to the detection when the first balancing resistor RBi is open, and are not repeated here.

[0040] like Figure 4 As shown, for the i-th battery balancing module, when the first balancing resistor RBi is short-circuited,

[0041] Before balancing is turned on, that is, when the balancing switch FETi is turned off, since the i-th battery balancing module is intact, the first port Bi and the second port B(i-1) are clamped by the battery BATi, so that the first voltage is equal to the voltage VBATi of the battery BATi. If the voltage of each battery cell is Vo, the first voltage is equal to Vo;

[0042] After balancing is turned on, that is, when the balancing switch FETi is controlled to be turned on, the on-resistance Rdson of the balancing switch FETi and the second balancing resistor RB(i-1) divide the voltage VBATi of the single battery BATi. The second voltage is the on-state voltage drop of the balancing switch FETi, that is, VBATi*Rdson / (Rdson+RB(i-1)). If the voltage of each battery cell is Vo and the resistance value of all balancing resistors is Ro, the second voltage is Vo*Rdson / (Rdson+Ro).

[0043] Figure 4 Only the analysis process of the short circuit of the first balancing resistor RBi is given. The detection of the short circuit of the second balancing resistor RB(i-1) is similar to the detection of the short circuit of the first balancing resistor RBi, and is not repeated here.

[0044] like Figure 5As shown, for the i-th battery balancing module, when the balancing switch FETi is open, the balancing switch FETi is controlled to be turned off or on. The balancing switch FETi is always turned off, so whether balancing is turned on or off does not affect the values ​​of the first voltage and the second voltage. The first port Bi and the second port B(i-1) are clamped by the battery BATi. The first voltage and the second voltage are equal to the voltage VBATi of the battery BATi before and after balancing is turned on. If the voltage of each battery is Vo, the first voltage and the second voltage are equal to Vo.

[0045] like Figure 6 As shown, for the i-th cell balancing module, when the balancing switch FETi is short-circuited, the balancing switch FETi is controlled to be turned off or on. The balancing switch FETi is always like a wire, and the voltage drop across it can be ignored. Therefore, whether balancing is turned on or off does not affect the values ​​of the first voltage and the second voltage. The first voltage and the second voltage are both equal to 0V before and after balancing is turned on.

[0046] like Figure 7 As shown, for the i-th battery balancing module, when the balancing switch FETi is normally open due to a fault, the balancing switch FETi is controlled to be turned off or on, and the balancing switch FETi is always on. Therefore, whether balancing is enabled or not does not affect the values ​​of the first voltage and the second voltage. When the balancing switch FETi is controlled to be turned off and on, the on-resistance Rdson of the balancing switch FETi, the first balancing resistor RBi, and the second balancing resistor RB(i-1) divide the voltage VBATi of the single battery BATi. The first voltage and the second voltage are both equal to the on-state voltage drop of the balancing switch, that is, VBATi*Rdson / (Rdson+RB(i-1)+RBi). If the voltage of each battery cell is Vo and the resistance of each balancing resistor is Ro, the second voltage is Vo*Rdson / (Rdson+2Ro).

[0047] In summary, it can be concluded that: when it is detected that the first voltage is close to Vo, and the second voltage is close to Vo*Rdson / (Rdson+2Ro), it is determined that the i-th battery balancing module has not failed and is operating normally;

[0048] When it is detected that the first voltage is close to Vo and the second voltage is close to 0V, it is determined that the first balancing resistor RBi and / or the second balancing resistor RB(i-1) is open;

[0049] When it is detected that the first voltage is close to Vo and the second voltage is close to Vo*Rdson / (Rdson+Ro), it is determined that the first balancing resistor RBi or the second balancing resistor RB(i-1) is short-circuited;

[0050] When it is detected that the first voltage and the second voltage are close to each other, it is determined that the balancing switch FETi has failed; specifically:

[0051] When it is detected that the first voltage is close to Vo and the second voltage is close to Vo, it is determined that the balancing switch FETi is open;

[0052] When it is detected that the first voltage is close to 0V and the second voltage is close to 0V, it is determined that the balancing switch FETi is short-circuited;

[0053] When it is detected that the first voltage is close to Vo*Rdson / (Rdson+2Ro) and the second voltage is close to Vo*Rdson / (Rdson+2Ro), the balancing switch FETi is normally open due to a fault.

[0054] The a and b mentioned in the present invention are close, which means that a and b are equal within a certain error range, for example, ab<0.02, which has a certain relationship with the accuracy of the instrument. The present invention does not limit the range of error, which is hereby explained.

[0055] In actual applications, when it is necessary to detect whether the i-th cell balancing module has a fault, the control module in the host or the AFE chip reads the voltage between the first port and the second port of the i-th cell balancing module before and after balancing is enabled, respectively. Based directly and solely on the voltage between the first port and the second port of the i-th cell balancing module before and after balancing is enabled, the fault type is quickly and accurately determined, and fault intervention processing is performed.

[0056] Although the embodiments are described and explained separately above, some common technologies are involved. It is the opinion of ordinary technicians in this field that they can be replaced and integrated between the embodiments. If there is anything not clearly recorded in one of the embodiments, reference can be made to another recorded embodiment.

[0057] While embodiments of the present invention have been described above, these embodiments do not exhaustively describe all details and do not limit the invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the above description. These embodiments are selected and described in detail in this specification in order to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better utilize the invention and its modifications. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for detecting a fault in a battery balancing circuit, wherein the battery balancing circuit is configured to balance the voltages of a plurality of battery cells coupled in series, and includes a plurality of battery balancing modules corresponding one to each of the battery cells. Each battery balancing module includes a first port, a second port, a first balancing resistor, a second balancing resistor, a balancing switch, and a first capacitor to balance the voltages of the corresponding battery cells. The positive electrode of the battery cell is coupled to the first port via the first balancing resistor, and the negative electrode is coupled to the second port via the second balancing resistor. The balancing switch and the first capacitor are both coupled between the first port and the second port. The method is characterized in that: Controlling the balancing switch to turn off, and obtaining a first voltage between the first port and the second port; Controlling the balancing switch to be turned on to obtain a second voltage between the first port and the second port; Whether the battery balancing module fails is determined only based on the first voltage and the second voltage.

2. The battery balancing circuit fault detection method according to claim 1, wherein: When it is detected that the first voltage is close to the voltage of the single battery and the second voltage is close to zero, it is determined that the first balancing resistor and / or the second balancing resistor is open-circuited.

3. The battery balancing circuit fault detection method according to claim 1, wherein: When it is detected that the first voltage is close to the voltage of the single battery and the second voltage is close to the third voltage, it is determined that one of the first balancing resistor and the second balancing resistor is short-circuited. When the balancing switch is controlled to be turned on, the on-resistance of the balancing switch and the other of the first balancing resistor and the second balancing resistor divide the voltage of the single battery, and the third voltage is configured as the on-state voltage drop of the balancing switch.

4. The battery balancing circuit fault detection method according to claim 1, wherein: When it is detected that the first voltage is close to the second voltage, it is determined that the balancing switch fails.

5. The battery balancing circuit fault detection method according to claim 4, wherein: When it is detected that both the first voltage and the second voltage are close to the voltage of the single battery, it is determined that the balancing switch is open.

6. The battery balancing circuit fault detection method according to claim 4, wherein: When it is detected that the first voltage and the second voltage are both close to zero, it is determined that the balancing switch is short-circuited.

7. The battery balancing circuit fault detection method according to claim 4, wherein: When it is detected that both the first voltage and the second voltage are close to a fourth voltage, determining that the balancing switch is normally open due to a fault; When the balancing switch is controlled to be turned off and on, the on-resistance of the balancing switch, the first balancing resistor and the second balancing resistor divide the voltage of the single battery, and the fourth voltage is configured as the on-state voltage drop of the balancing switch.

8. The battery balancing circuit fault detection method according to claim 1, wherein: When it is detected that the first voltage is close to the voltage of the single battery and the second voltage is close to a fourth voltage, it is determined that the battery balancing module has not failed; When the balancing switch is controlled to be turned on, the on-resistance of the balancing switch, the first balancing resistor, and the second balancing resistor divide the voltage of the single battery, and the fourth voltage is configured as the on-voltage drop of the balancing switch.

9. A battery balancing circuit for performing voltage balancing on a plurality of single batteries coupled in series, characterized in that: include: Multiple battery balancing modules corresponding to multiple single cells. For each battery balancing module, The battery balancing module includes: a first port, a second port, a first balancing resistor, a second balancing resistor, a balancing switch, and a first capacitor, for performing voltage balancing on corresponding single cells. The positive electrode of the single cell is coupled to the first port via the first balancing resistor, and the negative electrode is coupled to the second port via the second balancing resistor. The balancing switch and the first capacitor are both coupled between the first port and the second port. The first port of the preceding battery balancing module serves as the second port of the succeeding battery balancing module, and the first balancing resistor of the preceding battery balancing module serves as the second balancing resistor of the succeeding battery balancing module. The fault detection method according to any one of claims 1 to 8 is used to determine whether the battery balancing circuit has a fault.

Images