Battery pack and power supply system

Abstract

The invention provides a battery pack and a power supply system. A battery pack (10) having a substantially hermetic structure is provided with a plurality of unit cells (11-16), each of which is provided with a release unit for discharging internal gas when the internal pressure has increased. Non-reset type pressure switch units (30, 31) are connected to a controller (50) via a signal line, and change irreversibly from an active state to an inactive state when the pressure in the battery pack (10) exceeds a predetermined pressure threshold value.

Description

[0001] This application is a divisional application of the invention application with an international application date of November 8, 2019 and a national application number of 201980080827.9. The invention name of the invention application is battery pack, power supply system. Technical Field

[0002] The present invention relates to a battery pack and a power supply system containing a plurality of single cells. Background Art

[0003] In recent years, hybrid vehicles (HV), plug-in hybrid vehicles (PHV), and electric vehicles (EV) have become popular. In these electric vehicles, secondary batteries are installed as key equipment. In a vehicle-mounted battery pack that uses dozens to thousands of single cells electrically connected, if an abnormality occurs in a single cell in the battery pack, it is necessary to quickly detect the abnormality, interrupt the use of the battery pack, or perform a given safety process.

[0004] One method of detecting battery abnormality is to measure the temperature of the battery. In order to measure the temperature and detect the battery abnormality with high accuracy, it is necessary to measure the temperature of all the single cells in the battery pack, which increases the cost and the number of parts.

[0005] In addition, as another method for detecting battery abnormality, there is a method of monitoring the pressure in the battery pack by a pressure sensor (for example, see Patent Document 1). This method utilizes the fact that the pressure in the battery pack rises uniformly due to the gas ejected from the single cell when the single cell is abnormal, and can detect the abnormality with high accuracy using a small number of detection devices.

[0006] Prior Art Literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2010-45001 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, the pressure rise in the battery pack during an abnormality is a phenomenon that occurs within one to several seconds. Therefore, in order to detect the abnormality with the pressure sensor, the detection system needs to perform scanning at a cycle shorter than this period, which increases the load on the detection system.

[0011] Furthermore, in vehicle applications, the detection system is generally turned off / on standby while the vehicle is parked. In this state, even if an abnormality occurs in a single cell in the battery pack, the pressure in the battery pack returns to normal pressure within a few seconds, so not only can the abnormality not be detected in real time, but there is also a possibility that the abnormality cannot be detected even when the electric vehicle is started.

[0012] The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technology for detecting abnormalities of single cells in a battery pack with high accuracy using a small number of detection devices.

[0013] Means for solving problems

[0014] In order to solve the above-mentioned problems, a battery pack of a certain embodiment of the present invention is a battery pack of a substantially sealed structure, comprising: a plurality of single cells, each of which is provided with a release portion for discharging internal gas when the internal pressure rises; and a non-reset type pressure switch portion connected to a controller via a signal line. When the pressure in the battery pack exceeds a given pressure threshold, the pressure switch portion irreversibly changes from an effective state to an ineffective state.

[0015] In addition, arbitrary combinations of the above-described constituent elements and embodiments in which the expressions of the present invention are converted into methods, apparatuses, systems, and the like are also effective as embodiments of the present invention.

[0016] Effects of the Invention

[0017] According to the present invention, it is possible to detect abnormality of a single cell in a battery pack with high accuracy using a small number of detection devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a diagram for explaining a power supply system according to an embodiment of the present invention.

[0019] Figure 2 It is a diagram showing a sequence when gas is discharged from a single cell in the power supply system according to the embodiment of the present invention.

[0020] Figure 3 This is a flowchart showing the flow of a first processing example when gas is discharged from a cell in the power supply system according to the embodiment of the present invention.

[0021] Figure 4 This is a flowchart showing the flow of a second processing example when gas is discharged from a cell in the power supply system according to the embodiment of the present invention. DETAILED DESCRIPTION

[0022] Figure 1 1 is a diagram for explaining a power supply system 1 according to an embodiment of the present invention. In this embodiment, an example in which the power supply system 1 is a driving battery mounted on an electric vehicle will be described. The power supply system 1 includes a battery pack 10 having a substantially sealed structure in which a battery module M1 is housed. Figure 1In order to simplify the drawing, only one battery module M1 is depicted, but in reality, a plurality of battery modules are often accommodated. The plurality of battery modules are connected in series, in parallel, or in series and parallel.

[0023] The battery module M1 includes a plurality of single cells 11-16. Figure 1 In the example in which the battery module M1 contains six single cells, the number of the single cells contained may be more than six or less than six. In addition, the multiple single cells 11-16 may be electrically connected in series, in parallel, or in series-parallel connection. In the following description, a series connection is assumed.

[0024] The single cell is a secondary battery of square, cylindrical, laminated, etc., and lithium-ion batteries, nickel-metal hydride batteries, lead batteries, etc. can be used. In the following, the example of using a square lithium-ion battery is assumed in this specification. Multiple single cells 11-16 are stacked in a row with the surface with the largest area as the stacking surface. Two end plates P1 and P2 are provided at the two end surfaces in the stacking direction of the multiple single cells 11-16 to sandwich the multiple single cells 11-16. The end plates P1 and P2 at both ends are connected by multiple side tie bars. Specifically, at least one side tie bar B1 and B2 are respectively provided on both sides of the multiple stacked single cells 11-16.

[0025] When a single cell has an abnormality such as an internal short circuit or overcharge, the internal pressure rises and high-temperature gas is generated. In square and cylindrical single cells, a safety valve (not shown) is generally provided on the top surface of the outer casing to discharge the internal gas when the internal pressure rises. In laminated single cells, most are designed to discharge the internal gas by rupturing the sealed portion of the laminate material if the internal pressure rises. In either case, a release portion is provided for discharging the internal gas. Below, in this embodiment, it is assumed that a square single cell with a safety valve provided on the top surface of the outer casing is used in multiple single cells 11-16.

[0026] The battery pack 10 is provided with a pressure release mechanism 20. The pressure release mechanism 20 operates if the internal pressure value in the battery pack 10 is higher than a given value (operating pressure value), and discharges the gas in the battery pack 10 to the outside. The pressure release mechanism 20 has, for example, a discharge valve that opens if the internal pressure value is higher than the operating pressure value. If any safety valve in the plurality of single cells 11-16 is opened and gas is discharged from the inside of the single cell, the internal pressure in the battery pack 10 also rises, and if it exceeds the operating pressure value of the pressure release mechanism 20, the pressure release mechanism 20 operates. For example, the operating pressure value of the pressure release mechanism 20 is set to 10 to 50 kPa (gauge pressure).

[0027] A pressure switch element 30 is provided near the pressure release mechanism 20 and at a position where the gas discharged from the plurality of single cells 11-16 passes. In addition, the pressure switch element 30 is preferably installed at a position where the influence of heat is small. In addition, each of the safety valves of the plurality of single cells 11-16 may be connected to the pressure release mechanism 20 through a closed exhaust path. In this case, the pressure switch element 30 is provided inside the exhaust path.

[0028] Both ends of the pressure switch element 30 are connected to the detection circuit 31. The pressure switch element 30 and the detection circuit 31 constitute a pressure switch unit. The pressure switch unit is a non-reset type switch that irreversibly changes from an effective state to an ineffective state when the internal pressure value in the battery pack 10 exceeds a given pressure threshold. The pressure threshold is set to a value lower than the operating pressure value of the pressure release mechanism 20.

[0029] For example, a mechanical non-reset type switch that switches the switching state by displacing a mechanical movable contact piece can be used as the pressure switch element 30. Specifically, the pressure switch element 30 is set at a position where the pressure difference between the inside and outside of the battery pack 10 can be detected, so that an opening that can be ventilated and provided on the wall surface of the battery pack 10 is blocked, and the movable contact piece is displaced by the pressure change in the battery pack 10. The detection circuit 31 detects the displacement of the movable contact piece and detects the switching of the pressure switch element 30.

[0030] In addition, for example, a pressure-sensitive sensor using the piezoresistive effect can be used in the pressure switch element 30. In the pressure-sensitive sensor, the resistance value changes according to the pressure applied to the sensing part. Specifically, if the pressure increases, the resistance value decreases. The detection circuit 31 applies a given constant voltage to both ends of the pressure switch element 30. A switch that is irreversibly disconnected if a current exceeding a current threshold corresponding to the above-mentioned pressure threshold flows is inserted in the closed loop of the detection circuit 31 and the pressure switch element 30. If the pressure applied to the above-mentioned sensing part exceeds the above-mentioned pressure threshold, a current exceeding the current threshold flows, and the above-mentioned switch is turned off. In addition, instead of the switch, a fuse that melts if a current exceeding the current threshold flows can be used.

[0031] If the switch is turned off, the detection circuit 31 sends an abnormal signal to the BMU (1ang=EN-US>Battery Management Unit, battery management unit) 50. For example, the detection circuit 31 is connected to the BMU 50 via a signal line, and the detection circuit 31 continuously outputs a low level as a normal signal when the switch is turned on. The detection circuit 31 continuously outputs a high level as an abnormal signal when the switch is turned off. Conversely, the detection circuit 31 may also continuously output a high level as a normal signal when the switch is turned on, and continuously output a low level as an abnormal signal when the switch is turned off.

[0032] In addition, the structure of the pressure switch part is an example. It can also be configured that a bias voltage is applied to both ends of the pressure switch element 30, and a switch is applied to both ends from the detection circuit 31. If the current flowing in the pressure switch element 30 exceeds the current threshold corresponding to the above pressure threshold, the switch is irreversibly turned on due to electromagnetic induction. If the above switch is turned on, the detection circuit 31 sends an abnormal signal to the BMU 50.

[0033] In addition, the pressure switch element 30 may also be four piezoresistive elements forming a general Wheatstone bridge circuit. In this case, once the output voltage of the Wheatstone bridge circuit exceeds the voltage threshold corresponding to the above-mentioned pressure threshold, the detection circuit 31 continuously sends an abnormal signal to the BMU 50. Even if the output voltage of the Wheatstone bridge circuit drops, the detection circuit 31 continuously sends an abnormal signal to the BMU 50.

[0034] The BMU 50 is a controller for managing the power supply system 1. The voltage value, current value, and temperature value of the plurality of single cells 11-16 are input to the BMU 50. For example, the voltage value is measured by a voltage sensor (not shown) including an ASIC or an analog front end, the current value is measured by a current sensor (not shown) using a shunt resistor or a Hall element, and the temperature value is measured by a temperature sensor (not shown) using a thermistor. Based on the voltage value, current value, and temperature value of the plurality of single cells 11-16, the BMU 50 monitors whether overvoltage, undervoltage, overcurrent, or temperature abnormality occurs in the plurality of single cells 11-16.

[0035] In this embodiment, the signal line from the detection circuit 31 is connected to a port that receives a start signal from the BMU 50. When the BMU 50 receives an abnormality signal from the detection circuit 31 in the shutdown state / standby state, it starts up and determines that an abnormality has occurred in the single cells 11-16 in the battery pack 10.

[0036] When the BMU 50 determines that an abnormality has occurred in the cells 11 to 16 in the battery pack 10 , it notifies an ECU (Electronic Control Unit) 2 of the abnormality occurrence signal of the cell via an on-vehicle network such as CAN.

[0037] In addition, if it is determined that an abnormality has occurred in the single cell 11-16 in the battery pack 10, the BMU 50 turns on the sensor 40. For example, the sensor 40 can be a pressure sensor with higher performance than the pressure switch unit. For example, it can also be a pressure sensor formed by a Wheatstone bridge circuit including four piezoresistive elements. If it is determined that an abnormality has occurred in the single cell 11-16 in the battery pack 10, the BMU 50 allows a given constant current to flow through the input terminal of the Wheatstone bridge circuit. If current is supplied to the input terminal, a voltage corresponding to the detected pressure is generated at the output terminal of the Wheatstone bridge circuit and supplied to the BMU 50. The BMU 50 estimates the pressure value in the battery pack 10 based on the voltage value input from the sensor 40.

[0038] ECU2 is a controller for controlling the entire electric vehicle, and may include, for example, an integrated VCM (1ang=EN-US>Vehicle Control Module). If ECU2 receives a signal of abnormality of a single cell from BMU50, it causes the in-vehicle warning device 3 in the electric vehicle to report the abnormality of the battery pack 10. The in-vehicle warning device 3 is a user interface for warning the occupants of the abnormality of the battery pack 10. For example, ECU2 turns on the abnormality lamp of the battery pack 10 provided on the instrument panel. In addition, the occupants may be notified of the abnormality of the battery pack 10 through a voice message.

[0039] When the power supply system 1 is a driving battery mounted on a hybrid vehicle, upon receiving a cell abnormality occurrence signal from the BMU 50 during motor running, the ECU 2 stops the motor running and switches to engine running.

[0040] When the power supply system 1 is a driving battery mounted on a pure electric vehicle, safety and convenience are achieved by allowing the vehicle to travel to a car dealer or repair shop while ensuring safety. As a method of ensuring safety, cooling the power supply system 1 may be considered.

[0041] When the ECU 2 receives a signal of abnormal occurrence of a single cell from the BMU 50, the cooling device 4 is operated to cool the single cells 11-16 in the battery pack 10. In the case of water cooling, the cooling device 4 has an electric fan for cooling a radiator such as a heat sink and a cooling liquid (hereinafter referred to as coolant). In addition, a structure that is linked to the air conditioning system in the vehicle and cools the coolant by the cooling wind of the air conditioning system may be used instead of the electric fan.

[0042] The cooling device 4 is connected to the power system 1 through a cooling pipe (not shown). A cooling plate (not shown) is installed on the battery module M1 of the power system 1. The cooling plate is installed on the battery module M1 via an insulating heat conductive sheet (not shown). In addition, when the outer casing of the single battery contains an insulating material, the cooling plate can also be directly installed on the battery module M1. In addition, in the case of air cooling, the cooling air generated by the electric fan and the air conditioning system is directly supplied to the single battery 11-16 in the battery pack 10.

[0043] If the ECU 2 receives a signal of abnormality of a single cell from the BMU 50 when the cooling device 4 is in operation, the ECU 2 may instruct the cooling device 4 to increase the cooling capacity. For example, when an electric fan is used, in order to reduce the temperature of the coolant, the ECU 2 may instruct the electric fan to increase its rotation speed. For example, the ECU 2 may instruct the electric fan to rotate at the maximum rotation speed. In addition, when the coolant is cooled by an air conditioner, the ECU 2 may instruct the cooling air temperature to be reduced / the cooling air volume to be increased.

[0044] Figure 2 1 is a diagram showing a sequence of gas discharge from a single cell in the power supply system 1 according to an embodiment of the present invention. If an abnormality occurs in the internal pressure of the single cell, the safety valve opens and the gas is discharged into the battery pack 10. If the pressure of the battery pack 10 exceeds the pressure threshold of the pressure switch unit, the power supply to the pressure switch element 30 is cut off. As a result, the output signal of the detection circuit 31 indicating the occurrence of an abnormality in the single cell is turned on, the BMU 50 is started, and the BMU 50 becomes turned on. The BMU 50 turns on the sensor 40 to obtain more detailed pressure data. The BMU 50 notifies the ECU 2 of the occurrence of an abnormality in the single cell, and the ECU 2 activates the cooling device 4.

[0045] Figure 3 1 is a flowchart showing the flow of a first processing example when gas is discharged from a single cell in the power supply system 1 according to the embodiment of the present invention. When the pressure in the battery pack 10 exceeds the pressure threshold of the pressure switch unit ("Yes" in S10), the power supply to the pressure switch element 30 is cut off (S11), and the abnormality signal supplied from the detection circuit 31 to the BMU 50 is turned on (S12). When the BMU 50 is in the shutdown state / standby state ("No" in S13), the turning on of the abnormality signal is triggered and the BMU 50 is started (S14). When the BMU 50 is starting ("Yes" in S13), the processing of step S14 is skipped.

[0046] The BMU 50 notifies the ECU 2 of the abnormality occurrence signal of the single cell (S15). The ECU 2 causes the in-vehicle warning device 3 to notify the occupant of the abnormality of the battery pack 10 (S16). The ECU 2 activates the cooling device 4 to cool the single cells in the battery pack 10 (S17).

[0047] Figure 4 This is a flowchart showing the flow of the second processing example when the gas is discharged from the single cell in the power supply system 1 according to the embodiment of the present invention. In the description so far, it is assumed that the signal line from the detection circuit 31 is connected to the port that receives the start signal of the BMU 50. In the second processing example, it is assumed that the signal line from the detection circuit 31 is not connected to the port that receives the start signal of the BMU 50, but is connected to the port that receives the sensor input. That is, it is assumed that the BMU 50 is not immediately started even if the detection circuit 31 outputs an abnormal signal when the BMU 50 is in the shutdown state / standby state.

[0048] If the pressure in the battery pack 10 exceeds the pressure threshold of the pressure switch unit (Yes in S10), the power supply to the pressure switch element 30 is cut off (S11), and the abnormal signal supplied from the detection circuit 31 to the BMU 50 is turned on (S12). When the BMU 50 is in the shutdown state / standby state (No in S13), if the regular start timing of the BMU 50 arrives (Yes in S131), the BMU 50 is started (S14).

[0049] When the electric vehicle is parked and the battery module is not being externally charged, in order to reduce the power consumption of BMU50, BMU50 is turned off / standby. Even if BMU50 is turned off / standby, in order to monitor whether the multiple single cells 11-16 in the battery pack 10 have abnormalities, BMU50 is started regularly. BMU50 is started regularly to obtain the voltage value, current value, and temperature value of the multiple single cells 11-16 to determine whether there are abnormalities. In this embodiment, it is also determined whether there is an abnormal signal from the detection circuit 31. BMU50 is started every 5 to 60 minutes to determine whether there is an abnormality.

[0050] If the driver turns on the power of the electric vehicle (equivalent to turning on the ignition of the engine vehicle) (Yes in S132) while the regular start timing of the BMU 50 has not arrived (No in S131), the BMU 50 starts (S14). If the BMU 50 is starting (Yes in S13), the processing of steps S131, S132, and S14 is skipped.

[0051] The BMU 50 notifies the ECU 2 of the abnormality occurrence signal of the single cell (S15). The ECU 2 causes the in-vehicle warning device 3 to notify the occupant of the abnormality of the battery pack 10 (S16). The ECU 2 activates the cooling device 4 to cool the single cells in the battery pack 10 (S17).

[0052] As described above, according to the present embodiment, by using the pressure in the battery pack 10 that changes uniformly due to the gas discharge from the safety valve of the single cell as the detection object, it is possible to detect the abnormality of the single cell with high accuracy using a small number of detection devices. For example, when using a thermistor to detect the discharge of high-temperature gas from the safety valve of the single cell by temperature, a large number of thermistors need to be provided, which increases the cost and the number of components.

[0053] Furthermore, by using a non-reset type pressure switch as the detection device, it is possible to detect changes in the pressure in the battery pack 10 with a short change time with high accuracy. The pressure rise in the battery pack caused by the gas discharge from the safety valve of the single cell will return to the normal pressure within a few seconds. For example, if the BMU 50 scans the value of the pressure sensor at intervals of more than 5 seconds in order to reduce the load, it is highly likely that the pressure rise cannot be detected by monitoring the pressure value using a general pressure sensor.

[0054] For example, if the value of the pressure sensor is scanned at one-second intervals, the pressure rise can be detected, but the load on the BMU 50 increases. In addition, when the BMU 50 is in the off state / standby state, it is almost impossible to detect the pressure rise at the time of regular startup. In contrast, according to the present embodiment, since a non-reset type pressure switch is used, the pressure rise can be detected at the next scanning timing of the pressure rise during the startup of the BMU 50, and when the BMU 50 is not started, the pressure rise can be detected at the next startup.

[0055] Furthermore, by using an electric switch as the detection device, the detection device itself can be used as a start switch of the BMU 50, and the BMU 50 can be started when the pressure rises. In addition, even in a configuration in which the detection device is not used as a start switch of the BMU 50, at least the pressure rise can be detected when the driver turns on the electric vehicle key. In contrast, in a configuration using a general pressure sensor, since there is no record of the pressure rise remaining, the pressure rise cannot be detected afterwards.

[0056] In addition, it is also possible to detect a single cell with an open safety valve from the single cell voltage, but when the single cell with an open safety valve is connected in parallel with other single cells, it is difficult to detect the abnormality of the single cell from the voltage. Thus, according to this embodiment, the abnormality of the single cell can be detected at low cost and low load with high accuracy.

[0057] The present invention has been described above based on the embodiments. Those skilled in the art will appreciate that the embodiments are illustrative only and that various modifications are possible in the combination of the constituent elements and the processing steps, and that such modifications are also within the scope of the present invention.

[0058] In the above-mentioned embodiment, an example of using a non-reset type pressure switch is described. In this regard, in a configuration where the signal line from the detection circuit 31 is connected to the port that receives the start signal of the BMU 50 as in the first processing example, a reset type pressure switch can also be used. The BMU 50 can grasp the pressure rise at the moment when the pressure switch changes from the valid state to the invalid state, so even if the pressure switch returns to the original state, the situation where the pressure rise cannot be detected can be avoided. In this case, a general pressure sensor can be used, and the pressure switch can also be reused.

[0059] In the above Figure 1 In the embodiment, the detection circuit 31 and the BMU 50 are depicted outside the battery pack 10, but the detection circuit 31 and the BMU 50 may also be accommodated in the battery pack 10. Figure 1 In FIG. 1 , an example in which the ECU 2 controls the cooling device 4 is described, but a configuration in which the BMU 50 directly controls the cooling device 4 may also be adopted.

[0060] In addition, in the above Figure 1 The sensor 40 is depicted in the figure, but the sensor 40 is not essential and can be omitted. In addition, the example in which the sensor 40 is a pressure sensor is described, but the sensor 40 can be a temperature sensor or a voltage sensor. In either case, any detection device that can detect the state of the single cell in more detail is acceptable.

[0061] Furthermore, in the above-described embodiment, an example in which the power supply system 1 is used for vehicle-mounted applications has been described, but the power supply system 1 can also be used for stationary power storage applications, or for electronic devices such as notebook PCs and smartphones.

[0062] In addition, the implementation mode can also be determined by the following items.

[0063] [Project 1]

[0064] A battery pack (10) is of a substantially sealed structure, characterized in that:

[0065] The battery pack (10) includes:

[0066] A plurality of single cells (11-16) are each provided with a release portion for discharging internal gas when the internal pressure increases; and

[0067] The non-reset type pressure switch unit (30, 31) is connected to the controller (50) via a signal line.

[0068] The pressure switch unit (30, 31) irreversibly changes from an effective state to an ineffective state when the pressure in the battery pack (10) exceeds a given pressure threshold.

[0069] Thus, the gas discharge from the single cells (11-16) can be detected with high accuracy by basically using one pressure switch unit (30, 31) without increasing the load on the controller (50).

[0070] [Project 2]

[0071] The battery pack (10) according to item 1 is characterized in that:

[0072] The battery pack (10) further comprises: a pressure release mechanism (20) which operates if the pressure in the battery pack (10) exceeds a given pressure.

[0073] The pressure threshold value for the state change of the pressure switch unit (30, 31) is set to a value lower than the operating pressure of the pressure release mechanism (20).

[0074] Thus, the state of the pressure switch unit (30, 31) can be changed before the pressure release mechanism (20) is opened.

[0075] [Item 3]

[0076] A power supply system (1) comprising:

[0077] The battery pack (10) according to item 1 or 2; and

[0078] The controller (50) is connected to the pressure switch parts (30, 31) via a signal line.

[0079] Thus, a power supply system (1) can be constructed which can detect gas discharge from single cells (11-16) with high accuracy basically by using a single pressure switch unit (30, 31) without increasing the load on the controller (50).

[0080] [Item 4]

[0081] The power supply system (1) is characterized in that the controller (50) is activated by being triggered by the change of the pressure switch part (30, 31) from an effective state to an ineffective state.

[0082] Thus, even when the controller (50) is in the shutdown state or the standby state, the gas discharge from the single cells (11-16) can be detected in real time.

[0083] [Item 5]

[0084] The power supply system (1) according to item 3 or 4 is characterized in that if the controller (50) detects that the pressure switch unit (30, 31) changes from a valid state to an invalid state, it obtains the output value of other sensors (40) in the battery pack (10).

[0085] Thus, the controller (50) can understand the conditions inside the battery pack (10) in more detail.

[0086] [Item 6]

[0087] The power supply system (1) according to any one of items 3 to 5, characterized in that:

[0088] The power supply system (1) is mounted on an electric vehicle.

[0089] If the controller (50) determines that the battery pack (10) is abnormal based on the state of the pressure switch unit (30, 31), it sends an abnormality occurrence signal to the controller (2) on the vehicle side.

[0090] When the controller (2) on the vehicle side receives the abnormality occurrence signal, it causes the user interface (3) in the electric vehicle to report the abnormality of the battery pack (10).

[0091] This enables the occupant to recognize abnormality of the battery pack (10).

[0092] [Item 7]

[0093] The power supply system (1) according to any one of items 3 to 6 is characterized in that if the controller (50) determines that the battery pack (10) is abnormal based on the state of the pressure switch unit (30, 31), the cooling device (4) for cooling the battery pack (10) is operated.

[0094] This can prevent abnormality of a single cell of the battery pack (10) from spreading to other single cells.

[0095] [Item 8]

[0096] A battery pack (10) is of a substantially sealed structure, characterized in that:

[0097] The battery pack (10) includes:

[0098] A plurality of single cells (11-16) are each provided with a release portion for discharging internal gas when the internal pressure increases; and

[0099] The pressure switch parts (30, 31) are connected to the controller (50) via a signal line.

[0100] When the pressure in the battery pack (10) exceeds a given pressure threshold, the pressure switch unit (30, 31) changes from a valid state to an invalid state, and notifies the controller (50) of the change in state via the signal line.

[0101] Thus, the gas discharge from the single cells (11-16) can be detected in real time with high accuracy basically by one pressure switch unit (30, 31) without increasing the load on the controller (50).

[0102] Description of Reference Numerals

[0103] 1: Power system;

[0104] 10: Battery pack;

[0105] 20: Pressure release mechanism;

[0106] 30: Pressure switch element;

[0107] 31: detection circuit;

[0108] 40: sensor;

[0109] 50: BMU;

[0110] M1: battery module;

[0111] 11-16: Single cell;

[0112] B1, B2: tie bars;

[0113] P1, P2: end plates;

[0114] 2: ECU;

[0115] 3: In-vehicle warning device;

[0116] 4: Cooling device.

Claims

1. A battery pack having a substantially closed structure, The battery pack includes: The plurality of single cells are each provided with a release portion for discharging internal gas when the internal pressure increases; as well as The non-reset type pressure switch is connected to the controller via a signal line. When the pressure in the battery pack exceeds a predetermined pressure threshold, the pressure switch unit irreversibly changes from an effective state to an ineffective state. The controller determines whether a state of the pressure switch unit has changed.

2. The battery pack according to claim 1, wherein: The battery pack further includes a pressure release mechanism, which is activated if the pressure inside the battery pack exceeds a given pressure. The pressure threshold value for the state change of the pressure switch unit is set to a value lower than the operating pressure of the pressure release mechanism.

3. The battery pack according to claim 1, wherein: If the state of the pressure switch unit changes in the shutdown state / standby state, the controller determines the state of the pressure switch unit at the next startup.

4. The battery pack according to claim 1, wherein: The pressure switch unit includes a pressure switch element and a detection circuit. When the pressure in the battery pack exceeds the given pressure threshold, the detection circuit continuously sends an abnormal signal to the controller.

5. A power supply system comprising: The battery pack according to claim 1 or 2; and The controller is connected to the pressure switch unit via a signal line.

6. The power supply system according to claim 5, wherein: The controller is activated by a trigger when the pressure switch unit changes from an effective state to an ineffective state.

7. The power supply system according to claim 5, wherein: When the controller detects that the pressure switch unit changes from a valid state to a non-valid state, the controller acquires output values ​​of other sensors in the battery pack.

8. The power supply system according to claim 5, wherein: The power supply system is mounted on an electric vehicle, If the controller determines that the battery pack is abnormal based on the state of the pressure switch unit, the controller sends an abnormality occurrence signal to a controller on the vehicle side. When receiving the abnormality occurrence signal, the controller on the vehicle side causes a user interface in the electric vehicle to report the abnormality of the battery pack.

9. The power supply system according to claim 5, wherein: The controller operates a cooling device for cooling the battery pack when determining that the battery pack is abnormal based on the state of the pressure switch unit.

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