Control method of a battery pack

Abstract

To provide a battery pack control method that takes into account the maintenance of the behavior of a vehicle when the battery pack is flooded. A battery pack control method including the steps of: in the case where it is determined by a flooding sensor that water has entered the battery pack, changing the connection of a plurality of battery modules within the battery pack from a series connection to a parallel connection; cutting off a portion of the circuit of the parallel connection, determining whether or not each battery module is short-circuited; and changing the connection between each battery module depending on whether or not each battery module is short-circuited.

Description

Technical Field

[0001] This invention relates to a control method for a battery pack. Background Technology

[0002] Patent document 1 discloses a technology that cuts off the power supply by melting a fuse connected in series with the power source when the battery pack is submerged in water.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2013-110813 Summary of the Invention

[0004] In the technology disclosed in Patent Document 1, the vehicle stops operating immediately when the battery pack is submerged in water. Therefore, the maintenance of vehicle operation during submersion is not considered, leaving room for improvement.

[0005] The present invention was made in view of the above circumstances, and its object is to provide a battery pack control method that takes into account the vehicle's operation maintenance when the battery pack is submerged in water.

[0006] The battery pack control method of the present invention includes the following steps: when the battery pack is determined to be submerged in water by the immersion sensor, the connection of multiple battery modules in the battery pack is changed from series connection to parallel connection; a part of the parallel connection circuit is disconnected to determine whether each battery module has a short circuit; and the connection between each battery module is changed according to whether each battery module has a short circuit.

[0007] Invention Effects

[0008] According to the present invention, when water immersion is detected in the battery pack, the connections between the battery modules are modified based on whether there is a short circuit in each battery module, and the short-circuited battery module is disconnected. This allows drive power to be supplied to the battery modules that have not experienced a short circuit, and prevents the vehicle from immediately stopping when the battery pack is submerged in water. Attached Figure Description

[0009] Figure 1 This is a diagram illustrating an example of the structure of a control system for a battery pack that implements the control method for the battery pack according to the embodiment.

[0010] Figure 2 This is a diagram showing the internal state of the battery pack involved in the embodiment as viewed from the side.

[0011] Figure 3 This is a diagram illustrating an example of the circuit structure of a battery module in a battery pack according to an embodiment.

[0012] Figure 4 This diagram illustrates an example of a series connection mode in the battery pack control method described in the embodiment, in which multiple battery modules are connected in series.

[0013] Figure 5 This diagram illustrates an example of a parallel mode (partial disconnection) in the control method of the battery pack involved in the embodiment, where a portion of multiple battery modules is disconnected and the remaining battery modules are connected in parallel.

[0014] Figure 6 This diagram illustrates an example of a parallel mode (all connected) in which multiple battery modules are connected in parallel in the control method of the battery pack according to the embodiment.

[0015] Figure 7 This is a flowchart illustrating a first mode of the control method for the battery pack according to the embodiment, and an example of the process of determining water immersion and short circuit during driving.

[0016] Figure 8 This is a flowchart illustrating a second mode of the control method for the battery pack involved in the implementation, and an example of the process for determining water immersion and short circuit during parking. Detailed Implementation

[0017] The control method for a battery pack according to embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, the constituent elements in the following embodiments include elements that can be easily replaced or are substantially the same by those skilled in the art.

[0018] (Battery pack control system)

[0019] refer to Figures 1-6 The structure of the control system for the battery pack according to the embodiments will be described. The control system for the battery pack according to the embodiments is a vehicle battery pack system. The control system for the battery pack according to the embodiments is, for example, installed in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs).

[0020] like Figure 1 As shown, the control system of the battery pack according to the embodiment includes a battery pack 1, an inverter 2, an electric generator 3, a control unit 4, a voltage sensor 5, a water immersion sensor 6, and a pump 7.

[0021] Battery pack 1 is a battery pack comprising multiple battery modules consisting of multiple battery cells. Battery pack 1 includes multiple battery modules 11, wiring 12, and relays 13a, 13b, and 13c. Furthermore, as... Figure 2As shown, the battery module 11 includes multiple battery cells 111 and a busbar 112 connecting each battery cell 111.

[0022] Multiple battery cells 111 are connected in series. The battery cells 111 are, for example, secondary batteries such as lithium-ion batteries. Furthermore, the battery cells 111 can be either liquid-based batteries or all-solid-state batteries. An insulating film is attached to the surface of each battery cell 111, and the battery pack 1 is insulated.

[0023] Thus, the battery module 11 is composed of multiple battery cells 111. Furthermore, the battery pack 1 is composed of multiple battery modules 11. In this embodiment, an example of the battery pack 1 having two battery modules 11 is described, but the battery pack 1 may also have three or more battery modules 11.

[0024] Wiring 12 connects multiple battery modules 11 between each other and between each battery module 11 and the inverter 2. Relays 13a, 13b, and 13c are installed on wiring 12. Relay 13a is installed between multiple battery modules 11. Relays 13b and 13c are installed between each battery module 11 and the inverter 2. Additionally, in... Figure 1 The diagram is omitted, but relays 13a, 13b, and 13c are connected to control unit 4 and operate under the control of control unit 4.

[0025] Inverter 2 converts DC power into AC power and supplies the AC power to generator 3. Generator 3 is, for example, an AC synchronous motor, which functions as both a motor and a generator.

[0026] Control Unit 4 is an electronic control unit that controls the various components of the vehicle. Control Unit 4 includes a processor and memory. The processor includes a Central Processing Unit (CPU), a Digital Signal Processor (DSP), and a Field-Programmable Gate Array (FPGA). The memory is the main storage device, including Random Access Memory (RAM) and Read Only Memory (ROM). Additionally, in... Figure 1 The diagram is omitted, but the control unit 4 is connected to relays 13a, 13b, and 13c, and controls the switching on and off of relays 13a, 13b, and 13c as needed.

[0027] Here, battery pack 1 is envisioned, for example, as a high-voltage battery pack of approximately 800V. Inside this battery pack 1, such as... Figure 2 As shown, multiple battery cells 111 are arranged on the same surface. An insulating film is attached to the surface of each battery cell 111, but sometimes holes or damage may accidentally form in the insulating film (see reference). Figure 2 (The black circle).

[0028] Thus, if there are holes in the insulating film, and for some reason the cooling water leaks from the cooling water passage and enters the interior of the battery pack 1, the battery cells 111 will be connected to each other through the holes in the insulating film, which may lead to a short circuit.

[0029] Because the pores in the insulating film are formed accidentally, short circuit paths sometimes form within a single battery module 11, and sometimes between multiple battery modules 11. In the most severe case, a short circuit path is formed between the battery cell 111 with the highest potential (e.g., 800V) and the battery cell 111 with the lowest potential (e.g., 0V).

[0030] Therefore, in this embodiment, when the battery pack 1 is immersed in water, the battery module 11 is divided into appropriate segments using relays 13a, 13b, and 13c in a manner that does not exceed the withstand voltage characteristics of the battery cell 111.

[0031] The voltage and current that battery cell 111 can withstand are determined based on the characteristics of battery cell 111. Therefore, in this embodiment, for example, Figure 3 As shown, the voltage that the battery cell 111 can withstand is derived based on the resistance of the battery cell 111 (internal, internal to the casing of the battery pack 1) and the resistance of the cooling water (calculated based on conductivity, short-circuit path length, diameter, etc.). Then, the battery module 11 is divided in a manner lower than this voltage.

[0032] In this embodiment, specifically, as follows: Figure 3 As shown, the battery module 11 is divided in a manner that satisfies the relationship "V < I×R1 + I×R2 + I×R3". Here, V is the voltage, I is the current, R1 is the resistance on the positive side of the battery cell 111, R2 is the resistance on the negative side of the battery cell 111, and R3 is the resistance of the cooling water.

[0033] The control unit 4, as the control method for the battery pack 1, specifically performs the first step, the second step, and the third step. The details of each step are explained below.

[0034] <First Step>

[0035] In the first step, if the control unit 4 determines that the battery pack 1 is flooded by the water immersion sensor 6, it changes the connection of the multiple battery modules 11 within the battery pack 1 from a series connection to a parallel connection. Specifically, the control unit 4 determines whether there is water immersion in the battery pack 1 based on the values ​​(pressure, flow rate) obtained from the water immersion sensor 6. Furthermore, the control unit 4 changes the connection of the multiple battery modules 11 from a series connection to a parallel connection by controlling relays 13a, 13b, and 13c.

[0036] Here, Figure 4 This is a circuit diagram showing the connection of multiple battery modules 11 in series. Here, relay 13a is controlled to be on, and relays 13b and 13c are controlled to be off. In this embodiment, as shown... Figure 4 The connection state of the battery module 11 shown is defined as "series mode". Additionally, in the initial state of the control method for the battery pack 1, such as... Figure 4 As shown, multiple battery modules 11 are configured in series.

[0037] Figure 5 This is a circuit diagram showing the disconnection of a portion of multiple battery modules 11 and the connection of the remaining portions in parallel. Here, relay 13a is controlled to be open, relay 13b is controlled to be closed, and relay 13c is controlled to be open. Figure 5 In this configuration, only the lower battery module 11 is connected to the inverter 2, while the upper battery module 11 is disconnected from the circuit. In this embodiment, the battery module 11 is connected as follows: Figure 5 The connection state of the battery module 11 shown is defined as "parallel mode (partial disconnection)". In the first step, the control unit 4 changes the connection of the multiple battery modules 11 from the initial series mode to the current state. Figure 5 The parallel connection mode shown (with a portion disconnected).

[0038] Figure 6 This is a circuit diagram showing the connection of all battery modules 11 in parallel. Here, relay 13a is controlled to be open, relay 13b is controlled to be closed, and relay 13c is controlled to be open. Figure 6 In this embodiment, the two battery modules 11 are not connected in series and are each connected to the inverter 2. Figure 6 The connection status of the battery module 11 shown is defined as "parallel mode (all connected)".

[0039] <Second Step>

[0040] In the second step, the control unit 4 disconnects a portion of the parallel-connected circuit and determines whether each battery module 11 has a short circuit. Specifically, the control unit 4 switches to the state where a portion of the parallel-connected circuit has been disconnected. Figure 5In the parallel mode (partial disconnection) shown, determine whether each battery module 11 has a short circuit.

[0041] For example, such as Figure 5 As shown, control unit 4 controls relay 13a to be open, control relay 13b to be on, and control relay 13c to be open. While the upper battery module 11 is disconnected from the circuit, it determines whether the lower battery module 11 is short-circuited. Furthermore, control unit 4, for example, connects with... Figure 5 Conversely, when control relay 13a is open, control relay 13b is open, and control relay 13c is closed, it is determined whether the upper battery module 11 is short-circuited while the lower battery module 11 is disconnected from the circuit.

[0042] Thus, the control unit 4 determines whether each battery module 11 is short-circuited by controlling the relays 13b and 13c that connect each battery module 11 to the inverter 2. Furthermore, in this embodiment, an example with two battery modules 11 has been described, but even if there are three or more battery modules 11, it is still possible to determine whether each battery module 11 is short-circuited by switching the relays connecting each battery module 11 to the inverter 2.

[0043] <Step 3>

[0044] In the third step, the control unit 4 changes the connection between each battery module 11 based on whether there is a short circuit in each battery module 11. Specifically, based on the determination result of whether there is a short circuit in each battery module 11, the control unit 4 disconnects all connections of each battery module 11 and switches to parallel mode (disconnecting a portion) (see reference). Figure 5 Parallel mode (all connected) (see reference) Figure 6 Any one of them.

[0045] For example, if a short circuit occurs in all battery modules 11 when the battery pack 1 is submerged in water, the control unit 4 disconnects all relays 13a, 13b, and 13c, cutting off all battery modules 11 from the circuit. Furthermore, if a short circuit occurs in some battery modules 11 when the battery pack 1 is submerged in water, the control unit 4 controls relays 13a, 13b, and 13c to switch to parallel mode (cutting off a portion) (see reference). Figure 5 The short-circuited battery module 11 will be disconnected from the circuit.

[0046] Furthermore, if no short circuit occurs in any of the battery modules 11 when the battery pack 1 is submerged in water, the control unit 4 controls relays 13a, 13b, and 13c to switch to parallel mode (all connected) (see reference). Figure 6 All battery modules 11 are connected in parallel.

[0047] Thus, the battery pack 1 has a circuit structure capable of switching the connection state of multiple battery modules 11 from a series connection to a parallel connection. Furthermore, in this embodiment, the vehicle's load can be operated even under the voltage of the battery modules 11 after being separated by relays 13a, 13b, and 13c, therefore the vehicle can continue to operate even when the battery pack 1 is submerged in water. That is, in this embodiment, "submersion in water ≠ liquid flow," and the vehicle is not immediately rendered inoperable based solely on the submersion determination, thus balancing convenience and safety.

[0048] Voltage sensor 5 is used to detect the voltage of battery module 11. Voltage sensor 5 is connected to each battery module 11 and detects the voltage of each battery module 11. Voltage sensor 5 detects the voltage of each battery module 11 and outputs the detected voltage to control unit 4. Thus, control unit 4 determines whether there is a short circuit within each battery module 11 and whether there is a short circuit between each battery module 11.

[0049] A water immersion sensor 6 is used to detect water immersion inside the battery pack 1. The water immersion sensor 6 is installed in the cooling water path of the battery pack 1. The water immersion sensor 6 is, for example, composed of a pressure sensor that detects the pressure of the cooling water in the cooling water path or a flow sensor that detects the flow rate of the cooling water in the cooling water path. The water immersion sensor 6 outputs the detected values ​​(pressure, flow rate) to the control unit 4. Therefore, the control unit 4 determines whether cooling water in the cooling water path has entered the battery pack 1.

[0050] Furthermore, as the water immersion sensor 6, a speed sensor that detects the rotational speed of the pump 7 can be used, for example. In this case, it is possible to determine whether there is a cooling water leak from the cooling water circuit or whether there is water immersion in the battery pack 1 based on whether the rotational speed of the pump 7 detected by the speed sensor is higher than a predetermined value.

[0051] Here, as an event where the battery pack 1 may be submerged in water, a leak of cooling water from the cooling water circuit can be considered. Therefore, the aforementioned submersion sensor 6 is used to detect changes in the flow rate, pressure, or rotational speed of the cooling water circuit, thereby detecting a leak of cooling water from the cooling water circuit.

[0052] For example, in the event of a cooling water leak from the cooling water circuit, the amount of cooling water in the circuit decreases, thus reducing the flow rate and pressure. Furthermore, if the cooling water level decreases, pump 7 will run idle, thereby increasing its rotational speed. Additionally, changes in pump 7's rotational speed can only be detected when cooling water is flowing. Therefore, even when cooling is not required, it is preferable to periodically run pump 7 to detect its rotational speed, in cases where water immersion is detected based on pump 7's rotational speed.

[0053] In addition to the methods mentioned above, other methods for detecting cooling water leaks from the cooling water system include installing a water level gauge in the reservoir. Furthermore, electrodes can be placed inside the battery pack 1, and water immersion can be determined by detecting the current between the electrodes.

[0054] Pump 7 is used to supply cooling water to the cooling water circuit. Pump 7 is, for example, an electric pump. Preferably, pump 7 is equipped with a speed sensor for detecting the rotational speed of pump 7. Alternatively, if pump 7 does not have a speed sensor, the rotational speed of pump 7 can be detected, for example, based on the duty cycle of the signal input to pump 7.

[0055] (Battery pack control method 1)

[0056] refer to Figure 7 The first embodiment of the battery pack control method according to the implementation method will be described. This embodiment shows an example of the process for determining water immersion and short circuit during vehicle operation. Furthermore, at the start of control in this embodiment, each battery module 11 is set in series mode (see reference). Figure 4 ).

[0057] First, the control unit 4 determines whether water immersion is possible in the battery pack 1 based on the value detected by the water immersion sensor 6 (step S1). In step S1, if it is determined that water immersion is possible in the battery pack 1 ("Yes" in step S1), the control unit 4 switches the connection of the battery module 11 to parallel mode (partially disconnecting) by controlling relays 13a, 13b, and 13c (see reference). Figure 5 (Step S2).

[0058] Next, the control unit 4 performs a short circuit determination in each battery module 11 (step S3). Here, the processing in steps S2 and S3 is performed separately for each of the multiple battery modules 11. For example, if the battery pack 1 has two battery modules 11, in step S2, the circuit of each battery module 11 is cut off, and in step S3, it is determined whether there is a short circuit in the battery module 11 that was not cut off in step S2.

[0059] Furthermore, in step S3, a short circuit is determined to have occurred, for example, if the voltage of the battery module 11 continues to drop, or if the voltage of the battery module 11 is lower than the value envisioned based on the state of charge (SOC).

[0060] Next, the control unit 4 determines whether a short circuit has occurred in each battery module 11 (i.e., whether a short circuit has occurred in any one battery module 11) (step S4). In step S4, if it is determined that a short circuit has occurred in each battery module 11 ("yes" in step S4), the control unit 4 determines whether a short circuit has occurred in all battery modules 11 (step S5).

[0061] In step S5, if it is determined that a short circuit has occurred in all battery modules 11 ("Yes" in step S5), the control unit 4 controls all relays 13a, 13b, and 13c to be disconnected, so that the drive power of the vehicle is completely disconnected (step S6), and the process is completed.

[0062] Here, in step S1, if it is determined that there is no possibility of water immersion in the battery pack 1 ("No" in step S1), the control unit 4 completes this process. Furthermore, in step S4, if it is determined that no short circuit has occurred in any of the battery modules 11 (= no short circuit has occurred in all battery modules 11) ("No" in step S4), the control unit 4 controls relays 13a, 13b, and 13c to switch the battery modules 11 from series mode to parallel mode (all connected) (see reference). Figure 6 Thus, driving power is supplied to the vehicle in a state where all battery modules 11 are connected in parallel (step S7), and this process is completed.

[0063] Furthermore, in step S5, if it is determined that no short circuit has occurred in all battery modules 11 (= a short circuit has occurred in a portion of battery modules 11) (in step S5, this is "No"), the control unit 4 controls relays 13a, 13b, and 13c to switch the battery modules 11 from series mode to parallel mode (disconnecting a portion) (see reference). Figure 5 Thus, driving power is supplied to the vehicle in a state where a portion of the battery modules 11 are connected in parallel (step S8), and this process is completed.

[0064] Thus, in this method, based on the premise that "water immersion ≠ short circuit," the vehicle can be driven while limiting output even after the battery modules 11 are disconnected. Furthermore, in this method, when each battery module 11 is sequentially disconnected from the output, a short circuit is considered to have occurred if the voltage of the battery module 11 continues to drop, or if the voltage of the battery module 11 falls below the value envisioned according to the State of Charge (SOC). Then, based on the occurrence of short circuits within each battery module 11, the battery modules 11 are disconnected to ensure safe vehicle operation.

[0065] In addition, in this method, if a short circuit occurs in all battery modules 11, all relays 13a, 13b, and 13c are controlled to be disconnected, so that the drive power of the vehicle is completely disconnected (step S6), but the control method is not limited to this.

[0066] For example, in the event of a short circuit in all battery modules 11, the driving power supplied to the vehicle can be limited to a very small amount (the minimum power required for the vehicle to operate) without disconnecting each battery module 11. Furthermore, in the event of a short circuit in all battery modules 11, all relays 13a, 13b, and 13c can be controlled to be disconnected, completely cutting off the driving power to the vehicle, and then further stopping the vehicle to put it into standby mode. Also, in the event of a short circuit in all battery modules 11, a portion of the multiple battery modules 11 can be connected in series, disconnecting the remaining portion.

[0067] (Battery pack control method 2)

[0068] refer to Figure 8 This section describes a second aspect of the battery pack control method according to the embodiment. This aspect illustrates an example of the process for determining water immersion and short circuit while the vehicle is parked. Furthermore, this aspect is based on... Figure 7 In step S8, the vehicle is stopped while the system is switched to parallel mode (partial disconnection). Therefore, at the start of control in this method, each battery module 11 is set to parallel mode (partial disconnection) (see reference). Figure 5 ).

[0069] First, the control unit 4 determines whether water may be immersing in the battery pack 1 based on the value detected by the water immersion sensor 6 (step S11). In step S11, if it is determined that water may be immersing in the battery pack 1 ("yes" in step S11), the control unit 4 determines whether a short circuit has occurred in each battery module 11 (= whether a short circuit has occurred in any battery module 11) (step S12).

[0070] The processing in step S12 is performed on each of the multiple battery modules 11. For example, if the battery pack 1 has two battery modules 11, the circuit of each battery module 11 is cut off, and it is determined whether there is a short circuit in the battery module 11 on the side that is not cut off.

[0071] In step S12, if it is determined that no short circuit has occurred in any of the battery modules 11 (= no short circuit has occurred in all battery modules 11) (No in step S12), the control unit 4 controls relays 13a, 13b, and 13c to switch the battery modules 11 to series mode (see reference). Figure 4 (Step S13).

[0072] Next, while the battery modules 11 are connected in series (in series mode), the control unit 4 determines whether a short circuit has occurred between the battery modules 11 (step S14). In step S14, if it is determined that no short circuit has occurred in the series mode ("No" in step S14), the control unit 4 determines that it can drive in series mode, supplies drive power to the vehicle in series mode (step S15), and completes this process.

[0073] Here, in step S11, if it is determined that there is no possibility of water immersion in the battery pack 1 ("No" in step S11), the control unit 4 completes this process. Furthermore, in step S12, if it is determined that a short circuit has occurred in any of the battery modules 11 (i.e., a short circuit has occurred in any one of the battery modules 11) ("Yes" in step S12), the control unit 4 sets the battery modules 11 to parallel mode (disconnecting a portion) (see reference). Figure 5 In the state of ( ), drive power is supplied to the vehicle (step S16), and this process is completed.

[0074] Furthermore, in step S14, if it is determined that a short circuit has occurred in the series connection state ("Yes" in step S14), the control unit 4 determines that it cannot be driven in series mode. Then, the control unit 4 controls relays 13a, 13b, and 13c to switch the battery module 11 from series mode to parallel mode (disconnecting a portion) (see reference). Figure 5 (S17) supplies drive power to the vehicle and completes the process.

[0075] Thus, in this method, when it is assumed that no short circuit has occurred in each battery module 11, and there is no output from the battery module 11 in the parking state, and the voltage is stable, the battery modules 11 are restored to the series mode. Furthermore, in this method, when the voltage of the battery module 11 does not continuously decrease and the voltage of the battery module 11 is above the value envisioned according to the SOC, the battery module 11 is restored to the series mode, which is considered that no short circuit has occurred anywhere.

[0076] Thus, even if there is a coolant leak but no water immersion, or if there are no holes or damage in the insulating film of the battery cell 111, or even if water immersion occurs but no short circuit occurs, the vehicle's performance can be prevented from being limited.

[0077] In vehicle battery pack systems, if cooling water leaks into the battery pack, the battery cells may become submerged and short-circuit, potentially causing malfunctions within the cells. Therefore, measures such as using high-resistance LCCs to reduce the voltage of the battery cells or the current in the short-circuit path are typically implemented to counteract this. However, if the battery pack voltage is increased, further countermeasures are needed, as this is considered to affect cost or manufacturing.

[0078] Therefore, in the battery pack control method according to the embodiment, when water immersion is detected in the battery pack 1, relays 13a, 13b, and 13c in the battery pack 1 are switched to reduce the voltage, thereby avoiding the impact of additional countermeasures caused by high voltage in the battery pack 1. Furthermore, in the battery pack control method according to the embodiment, the voltage of the battery pack 1 is limited so that operation can continue even after water immersion is detected, and this limitation is lifted in the event of a false detection or when it can be determined that there is no danger, thereby reducing the impact of water immersion and its detection.

[0079] In the battery pack control method described in the implementation method, the following control is specifically performed.

[0080] (1) Based on the withstand voltage characteristics of battery cell 111 (refer to) Figure 3 The battery module 11 is disconnected from the output to provide a voltage that will not cause a short circuit in the battery cell 111 due to water immersion.

[0081] (2) During vehicle operation, the possibility of battery pack 1 being submerged due to cooling water leakage is determined based on the flow rate or pressure of the cooling water circuit or the speed of pump 7.

[0082] (3) The circuit structure is designed to connect the battery modules 11 in parallel and to enable the vehicle to operate even when the battery modules 11 are at their voltage, so that the vehicle can operate even when the battery pack 1 is submerged in water.

[0083] (4) While driving, determine whether a short circuit has occurred in each battery module 11, and disconnect the output of the battery module 11 that is determined to have a short circuit, thereby ensuring safety while driving the vehicle.

[0084] (5) If there is no short circuit in each battery module 11, after parking, determine whether there is a short circuit by connecting all battery modules 11 in series. If there is no problem, restore the series connection state.

[0085] According to the battery pack control method described above, when water immersion is detected in the battery pack 1, the connection between each battery module 11 is changed based on whether there is a short circuit in each battery module 11, and the battery module 11 that has been short-circuited is disconnected from the circuit. Therefore, drive power can be supplied to the battery modules 11 that have never been short-circuited, and the vehicle can be prevented from immediately stopping when the battery pack 1 is immersed in water.

[0086] Further effects or variations can be readily derived by those skilled in the art. Therefore, the invention is presented in a broader manner as described above and is not limited to the specific details and representative embodiments described above. Thus, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended independent claims and their equivalents.

[0087] Symbol Explanation

[0088] 1-Battery pack, 11-Battery module, 111-Battery cell, 112-Busbar, 12-Wiring, 13a, 13b, 13c-Relays, 2-Inverter, 3-Electric generator, 4-Control unit, 5-Voltage sensor, 6-Immersion sensor, 7-Pump.

Claims

1. A control method for a battery pack, characterized in that, Includes the following steps: If the battery pack is determined to be submerged in water by the immersion sensor, the connection of the multiple battery modules in the battery pack will be changed from a series connection to a parallel connection. Disconnect a portion of the parallel-connected circuit to determine if any battery modules are short-circuited; and Adjust the connections between battery modules based on whether there is a short circuit in each battery module.

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