Battery cooling device

Abstract

The invention provides a battery cooling device capable of appropriately cooling a battery pack. A battery cooling device is provided with: a blower for cooling a battery pack; a plurality of first sensors for detecting the temperature of each of the corresponding battery cells; a second sensor that detects an intake air temperature of the battery pack by the blower; and a controller that specifies the battery cell having the highest temperature among the plurality of battery cells as a first battery cell on the basis of the temperatures detected by the plurality of first sensors, and that specifies the battery cell having the highest temperature among the plurality of battery cells as a second battery cell at the temperature of the first battery cell detected by the first sensor for the first battery cell and the intake air temperature detected by the second sensor for the second battery cell. The number of rotations of the blower at which the cooling performance of the first battery cell is maximized is determined from the plurality of candidates, and the blower is controlled to rotate at the determined number of rotations.

Description

Technical Field

[0001] This invention relates to a battery cooling device. Background Technology

[0002] Battery cooling devices are known in the past. For example, in the device of Patent Document 1, the cooling device includes a fan for cooling the battery, a temperature sensor for measuring the battery temperature, and a controller for controlling the fan based on the detected temperature from the temperature sensor. The controller calculates the cooling capacity of the fan and the heat generated by the battery using a prescribed arithmetic formula, and then calculates an estimated temperature of the battery based on these calculated values. The controller also determines a correction coefficient to make the estimated temperature consistent with the detected temperature; this correction coefficient is the correction coefficient in the formula for calculating the cooling capacity. Then, the controller determines the target speed of the fan based on the determined correction coefficient.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2013-069470 Summary of the Invention

[0004] In Patent Document 1, it is impossible to properly cool a battery pack with multiple battery cells. This is because each battery cell has different cooling performance.

[0005] Therefore, the object of the present invention is to provide a battery cooling device capable of properly cooling a battery pack.

[0006] According to one aspect of the present invention, a battery cooling device as shown below is provided.

[0007] The battery cooling device of the present invention cools a battery pack having a battery stack composed of multiple battery cells. The battery cooling device comprises: a blower for cooling the battery pack; a plurality of first sensors for detecting the temperature of corresponding battery cells; a second sensor for detecting the intake air temperature of the battery pack based on the blower; and a controller that, based on the temperature detected by the plurality of first sensors, determines the battery cell with the highest temperature among the plurality of battery cells as the first battery cell, and, based on the temperature of the first battery cell detected by the first sensors and the intake air temperature detected by the second sensors, determines the speed of the blower from a plurality of candidates to maximize the cooling performance of the first battery cell, and controls the blower to rotate at the determined speed.

[0008] According to the above structure, among the multiple battery cells, the blower is controlled to rotate at the speed at which the cooling performance of the first battery cell is maximized, based on the temperature of the first battery cell (which is the battery cell with the highest temperature) detected by the first sensor and the intake air temperature detected by the second sensor. This allows the blower to be cooled appropriately.

[0009] Invention Effects

[0010] According to the present invention, the battery pack can be cooled appropriately. Attached Figure Description

[0011] Figure 1 This is a diagram illustrating an example of the overall structure of a vehicle equipped with the battery cooling device according to the embodiment.

[0012] Figure 2 This diagram illustrates the cooling issues of the battery pack 20.

[0013] Figure 3 This is a graph showing the relationship between the rotational speed of the blower 21 and the cooling performance of the battery cell CL.

[0014] Figure 4 (a) is a diagram showing an example of a cooling map for a battery cell CL(1). Figure 4 (b) is a diagram showing an example of a cooling map for a battery cell CL(n).

[0015] Figure 5 This is a flowchart illustrating the cooling steps of the battery pack 20 in an embodiment. Detailed Implementation

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0017] [Implementation Method]

[0018] Figure 1 This diagram illustrates an example of the overall structure of a vehicle equipped with the battery cooling device according to the embodiment. Vehicle 1 is, for example, a plug-in hybrid vehicle capable of being charged (plug-in charging) by electricity supplied from an external source. Vehicle 1 can be any vehicle equipped with a battery pack for driving, or it can be a conventional hybrid vehicle that does not support plug-in charging. Vehicle 1 can also be a pure electric vehicle or a fuel cell vehicle.

[0019] Vehicle 1 includes a driving unit 10, a battery pack 20, a charging unit 30, a battery cooling device 50, and an electronic control unit (ECU) 100. The driving unit 10 includes electric generators 11 and 12, a PCU 13, an engine 14, a power distribution device 15, and drive wheels 16. The charging unit 30 includes an air intake 31, an AC / DC converter 32, and a charging relay (CHR) 33.

[0020] Electric generators 11 and 12 are AC rotating motors, such as three-phase AC synchronous motors with permanent magnets embedded in the rotor. Electric generator 11 is mainly used as a generator driven by engine 14 via power distribution unit 15. The power generated by electric generator 11 is supplied to electric generator 12 or battery pack 20 via PCU 13. Furthermore, electric generator 11 can also start engine 14.

[0021] The electric generator 12 primarily functions as an electric motor, driving the drive wheel 16. The electric generator 12 is driven by receiving power from the battery pack 20 and power generated by the electric generator 11. The driving force of the electric generator 12 is transmitted to the drive shaft. On the other hand, when the vehicle 1 brakes or when acceleration decreases while going downhill, the electric generator 12 operates as a generator, performing regenerative power generation. The power generated by the electric generator 12 is supplied to the battery pack 20 via the PCU 13.

[0022] PCU13 is configured to perform bidirectional power conversion between battery pack 20 and electric generators 11 and 12, or between electric generators 11 and 12, based on control commands from ECU100.

[0023] Engine 14 outputs power by converting the combustion energy generated when the air-fuel mixture is burned into the kinetic energy of the moving parts (piston or rotor, etc.).

[0024] The power distribution device 15 is, for example, a planetary gear system. Although not shown, the power distribution device 15 includes a sun gear, a ring gear, a pinion, and a planet carrier. The planet carrier is connected to the engine 14. The sun gear is connected to the electric generator 11. The ring gear is connected to the electric generator 12 and the drive wheel 16 via a drive shaft. The pinion meshes with the sun gear and the ring gear. The planet carrier holds the pinion in a free-rotating and revolving manner.

[0025] The battery pack 20 includes a battery stack 28 having multiple (typically dozens to hundreds) battery cells CL(1) to CL(n) stacked together. The battery cells CL are secondary batteries such as lithium-ion batteries or nickel-metal hydride batteries. The battery stack 28 has a cooling flow path through which cooling air from the blower 21 passes.

[0026] The battery pack 20 stores power for driving the electric generators 11 and 12, and supplies power to the electric generators 11 and 12 via the PCU 13. The battery pack 20 is charged by receiving generated power through the PCU 13 when the electric generators 11 and 12 are generating electricity.

[0027] The AC / DC converter 32 is electrically connected between the air intake 31 and the charging relay 33. The AC / DC converter 32 converts AC power supplied from an external power source (charging rack, etc.) via the air intake 31 into DC power according to control commands from the ECU 100. Alternatively, a DC / DC converter may be provided in addition to the AC / DC converter 32.

[0028] The charging relay 33 is electrically connected between the AC / DC converter 32 and the battery pack 20. When the charging relay 33 is closed according to the control command from the ECU 100, it becomes a state in which power can be transferred between the air intake 31 and the battery pack 20.

[0029] The ECU 100 includes a processor 101 such as a central processing unit (CPU), a memory 102 such as a read-only memory (ROM) and a random access memory (RAM), and input / output ports (not shown) for inputting and outputting various signals. The ECU 100 controls the vehicle 1 to a desired state based on signals received from various sensors and programs and mapping tables stored in the memory 102.

[0030] The battery cooling device 50 is configured to cool the battery pack 20. The battery cooling device 50 consists of a blower 21, multiple battery cell temperature measuring sensors 23(1) to 23(n), an intake air temperature measuring sensor 22, and an ECU 100 (the battery cooling control section in the ECU 100).

[0031] The blower 21 is located at the air inlet of the battery pack 20.

[0032] The temperature Tb(i) of the corresponding battery cell CL(i) is detected by sensor 23(i) for battery cell temperature measurement.

[0033] The intake air temperature sensor 22 detects the intake air temperature Ta based on the blower 21.

[0034] Figure 2 (a) and (b) are diagrams used to illustrate the problem points of cooling of battery pack 20.

[0035] Multiple battery units CL(1) to CL(n) are arranged in the cooling flow path through which the cooling air based on the blower 21 passes. The distance between the blower 21 and each battery unit is different. The battery unit CL(1) is located at the position closest to the blower 21, and the battery unit CL(n) is located at the position farthest from the blower 21.

[0036] Battery cells CL(1) to CL(n) are cooled by cooling air from blower 21. Figure 2 In (a), assuming that the battery cell CL(1) located closest to the blower 21 is at a high temperature, the rotational speed R of the blower 21 is increased. If the rotational speed of the blower 21 is increased, then as follows... Figure 2 As shown in (b), the cooling air reaches a position far from the blower 21, thus reducing the amount of cooling air delivered to the battery cell CL(1) located closest to the blower 21. As a result, the temperature of the battery cell CL(1) neither decreases nor increases.

[0037] Figure 3 This is a graph showing the relationship between the rotational speed of the blower 21 and the cooling performance of the battery cell CL.

[0038] If the blower 21 rotates at a high speed, the cooling airflow increases, making it easier to cool battery cells CL located far from the blower 21. If the blower 21 rotates at a low speed, the cooling airflow decreases, making it easier to cool battery cells CL located close to the blower 21.

[0039] In this embodiment, in order to solve this problem, the cooling performance of each battery cell is obtained in advance, taking into account the intake air temperature Ta, the battery cell temperature Tb and the speed R of the blower 21, thereby effectively cooling the high-temperature battery cell CL.

[0040] The ECU100 determines the battery cell with the highest temperature as the first battery cell CL(k) based on the temperatures Tb(1) to Tb(n) detected by multiple battery cell temperature measuring sensors 23(1) to 23(n). The ECU100 determines the speed R of the blower 21, which has the greatest cooling performance for the first battery cell CL(k), from multiple candidates based on the temperature Tb(k) of the first battery cell CL(k) detected by the battery cell temperature measuring sensor 23(k) and the intake air temperature Tb detected by the intake air temperature measuring sensor 22, and controls the blower 21 to rotate at the determined speed R.

[0041] More specifically, the ECU100 references the cooling mapping table MP of the battery cell CL with the highest temperature, and calculates the speed R of the blower 21 based on the battery cell temperature Tb and the intake air temperature Ta. The battery pack 20 is then cooled using the calculated blower speed R. By determining the blower speed R based on the cooling mapping table MP of the battery cell CL with the highest temperature, cooling corresponding to the high-temperature battery cell CL can be performed.

[0042] The memory 102 stores multiple cooling mapping tables MP(1) to MP(n). Cooling mapping table MP(i) specifies the cooling performance W corresponding to the battery cell CL(i) in the combination of temperature Tb(i), blower speed R, and intake air temperature Tb. Cooling mapping tables MP(1) to MP(n) are prepared in advance through experiments. Cooling performance is an index representing the degree of cooling (cooling ease) of the battery cell CL(i) under given conditions (temperature Tb(i), Ta, speed R). Cooling performance W can be calculated, for example, based on the difference between the temperature of the battery cell CL(i) before cooling and the temperature of the battery cell CL(i) after cooling based on the battery cooling device 50.

[0043] Figure 4 (a) is a diagram showing an example of a cooling map for a battery cell CL(1). Figure 4 (b) is a diagram showing an example of the cooling map table for battery cell CL(n). For battery cell CL(1), the cooling performance is set to be higher when the speed R of blower 21 is low.

[0044] Figure 5 This is a flowchart illustrating the cooling steps of the battery pack 20 in an embodiment.

[0045] In step S101, ECU100 acquires the battery cell temperatures Tb(1), Tb(2), ... Tb(n) detected by the battery cell temperature measuring sensors 23(1) to 23(n).

[0046] In step S102, ECU100 acquires the intake air temperature Ta detected by the intake air temperature measuring sensor 22.

[0047] In step S103, ECU100 determines the battery cell with the highest temperature as the first battery cell CL(k) based on the battery cell temperatures Tb(1), Tb(2), ..., Tb(n).

[0048] In step S105, ECU100 selects the cooling map MP(k) of the first battery cell CL(k). Referring to the cooling map MP(k) of the first battery cell, ECU100 determines the speed R of the blower 21 that maximizes the cooling performance of the first battery cell CL(k) based on the battery cell temperature Tb(k) detected by the battery cell temperature measuring sensor 23(k) of the first battery cell CL(k) and the intake air temperature Ta detected by the intake air temperature measuring sensor 22.

[0049] In step S105, ECU100 controls blower 21 to rotate blower 21 at a determined speed R.

[0050] As described above, according to this embodiment, the maximum blower speed can be determined to maximize the cooling performance of the high-temperature battery cells, thus enabling appropriate cooling of the battery pack. By obtaining a cooling performance mapping table in advance for each battery cell housed in the battery pack, taking into account the intake air temperature, battery temperature, and blower speed, the blower speed that can effectively cool the high-temperature battery cells can be selected, thereby reducing the battery temperature.

[0051] Furthermore, while a cooling mapping table for each battery cell was used in the above embodiment, it is not a limitation. An arithmetic formula pre-calculated for each battery cell can also be used. The cooling performance of the battery cell is calculated using this arithmetic formula based on the battery cell temperature, intake air temperature, and blower speed.

[0052] It should be considered that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the invention is not shown in the foregoing description, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0053] Symbol Explanation

[0054] 1-Vehicle, 8-Temperature sensor, 10-Driving unit, 11, 12-Electric generator, 14-Engine, 15-Power distribution unit, 16-Drive wheel, 20-Battery pack, 21-Blower, 22-Intake air temperature sensor, 23-Battery cell temperature sensor, 28-Battery stack, 30-Charging unit, 31-Air inlet, 32-Converter, 33-Charging relay, 50-Battery cooling device, 101-Processor, 102-Memory.

Claims

1. A battery cooling device for cooling a battery pack having a battery stack consisting of multiple battery cells, the battery cooling device being characterized by comprising: A blower, used to cool the battery pack; Multiple first sensors, each detecting the temperature of its corresponding battery cell; The second sensor detects the intake air temperature of the battery pack based on the blower; and The controller determines the battery cell with the highest temperature among the plurality of battery cells as the first battery cell based on the temperature detected by the plurality of first sensors. It then determines the speed of the blower from a plurality of candidates to maximize the cooling performance of the first battery cell, taking into account the temperature of the first battery cell detected by the first sensor and the intake air temperature detected by the second sensor. The controller then controls the blower to rotate at the determined speed.

2. The battery cooling device according to claim 1, characterized in that, The battery cooling device also includes a storage unit that stores multiple cooling mapping tables that specify the cooling performance of corresponding battery cells based on combinations of battery cell temperature, blower speed, and intake air temperature. The controller refers to the cooling mapping table of the first battery cell and determines the blower speed at which the cooling performance of the first battery cell is maximized when the temperature of the first battery cell is the detected temperature of the first battery cell and the intake temperature is the detected intake temperature.

3. The battery cooling device according to claim 1, characterized in that, The distance between the blower and each battery unit is different. The plurality of battery cells are configured on a cooling flow path through which the cooling air from the blower passes.

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