Battery cooling device

Abstract

To provide a battery cooling device that can properly cool a battery pack. [Solution] The battery cooling device 50 includes a blower 21 for cooling the battery pack 20, a plurality of first sensors 23(1) to 23(n), each detecting the temperature of a corresponding battery cell CL, a second sensor 22 for detecting the intake air temperature of the battery pack 21 by the blower 21, and a controller 100 that identifies the battery cell CL with the highest temperature among the plurality of battery cells as the first battery cell based on the temperatures detected by the plurality of first sensors 23, identifies a rotation speed of the blower 21 from a plurality of candidates that maximizes the cooling performance of the first battery cell at the temperature of the first battery cell CL detected by the first sensor 23 for the first battery cell and the intake air temperature detected by the second sensor 22, and controls the blower 21 to rotate at the identified rotation speed.

Description

Technical Field

[0001] The present disclosure relates to a battery cooling device.

Background Art

[0002] Conventionally, battery cooling devices have been known. For example, the device of Patent Document 1 includes a fan for cooling a battery, a temperature sensor for measuring the battery temperature, and a controller for controlling the fan based on the detected temperature by the temperature sensor. The controller calculates the cooling capacity of the fan and the heat generation amount of the battery by a predetermined arithmetic expression, and further calculates the estimated temperature of the battery from those calculated values. The controller further obtains a correction coefficient for making the estimated temperature match the detected temperature, which is a correction coefficient in the expression for calculating the cooling capacity. Then, the controller determines the target rotation speed of the fan according to the obtained correction coefficient.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, a battery pack having a plurality of battery cells cannot be appropriately cooled. This is because the cooling performance differs for each battery cell.

[0005] Therefore, an object of the present disclosure is to provide a battery cooling device capable of appropriately cooling a battery pack.

Means for Solving the Problems

[0006] According to one aspect of the present disclosure, a battery cooling device as shown below is provided. The battery cooling device of this disclosure is a battery cooling device for cooling a battery pack having a battery stack consisting of a plurality of battery cells, and comprises a blower for cooling the battery pack, a plurality of first sensors each detecting the temperature of a corresponding battery cell, a second sensor for detecting the intake air temperature of the battery pack by the blower, and a controller that identifies the battery cell with the highest temperature among the plurality of battery cells as the first battery cell based on the temperatures detected by the plurality of first sensors, identifies a rotation speed of the blower from a plurality of candidates that maximizes the cooling performance of the first battery cell based on 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, and controls the blower to rotate at the identified rotation speed.

[0007] With the above configuration, the blower is controlled to rotate at a speed that maximizes the cooling performance of the first battery cell, based on the temperature of the first battery cell (the battery cell with the highest temperature among the multiple battery cells) detected by the first sensor and the intake air temperature detected by the second sensor, thereby enabling proper cooling of the battery pack. [Effects of the Invention]

[0008] According to this disclosure, the battery pack can be properly cooled. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of the overall configuration of a vehicle equipped with a battery cooling device according to an embodiment. [Figure 2] This diagram illustrates the cooling problems of the battery pack 20. [Figure 3] This diagram shows the relationship between the rotation speed of blower 21 and the cooling performance of battery cell CL. [Figure 4] (a) is a diagram showing an example of the cooling map of battery cell CL(1). (b) is a diagram showing an example of the cooling map of battery cell CL(n). [Figure 5]This is a flowchart illustrating the cooling procedure for the battery pack 20 of the embodiment. [Modes for carrying out the invention]

[0010] The embodiments of this disclosure will be described in detail below with reference to the drawings. [Embodiment] Figure 1 shows an example of the overall configuration of a vehicle equipped with a battery cooling device according to an embodiment. Vehicle 1 is, for example, a plug-in hybrid vehicle configured to allow charging by power supplied from outside Vehicle 1 (plug-in charging). However, Vehicle 1 may be any vehicle equipped with a battery pack for driving, and may be a normal hybrid vehicle that does not support plug-in charging. Vehicle 1 may also be an electric vehicle or a fuel cell vehicle.

[0011] Vehicle 1 comprises a running unit 10, a battery pack 20, a charging unit 30, a battery cooling device 50, and an ECU (Electronic Control Unit) 100. The running unit 10 includes motor generators 11 and 12, a PCU 13, an engine 14, a power split device 15, and drive wheels 16. The charging unit 30 includes an inlet 31, an AC / DC converter 32, and a charge relay (CHR) 33.

[0012] Each of the motor generators 11 and 12 is an AC rotating electric machine, for example, a three-phase AC synchronous motor with permanent magnets embedded in the rotor. Motor generator 11 is mainly used as a generator driven by engine 14 via power splitter 15. The power generated by motor generator 11 is supplied to motor generator 12 or battery pack 20 via PCU 13. Motor generator 11 can also crank engine 14.

[0013] The motor-generator 12 primarily operates as an electric motor, driving the drive wheels 16. The motor-generator 12 is powered by at least one of the power from the battery pack 20 and the power generated by the motor-generator 11. The driving force of the motor-generator 12 is transmitted to the drive shaft. On the other hand, when the vehicle 1 is braking or when acceleration is reduced on a downhill slope, the motor-generator 12 operates as a generator to perform regenerative power generation. The power generated by the motor-generator 12 is supplied to the battery pack 20 via the PCU 13.

[0014] The PCU13 is configured to perform bidirectional power conversion between the battery pack 20 and the motor generators 11 and 12, or between the motor generators 11 and 12, in accordance with control commands from the ECU100.

[0015] Engine 14 outputs power by converting the combustion energy generated when a mixture of air and fuel is burned into the kinetic energy of a moving element (such as a piston or rotor).

[0016] The power split device 15 is, for example, a planetary gear system. The power split device 15 includes, though not shown in the figures, a sun gear, a ring gear, a pinion gear, and a carrier. The carrier is connected to the engine 14. The sun gear is connected to the motor generator 11. The ring gear is connected to the motor generator 12 and the drive wheel 16 via a drive shaft. The pinion gear meshes with the sun gear and the ring gear. The carrier holds the pinion gear so that it can rotate and revolve freely.

[0017] The battery pack 20 includes a battery stack 28 in which multiple (typically tens to hundreds) battery cells CL(1) to CL(n) are stacked. The battery cells CL are secondary batteries such as lithium-ion batteries or nickel-metal hydride batteries. The battery stack 28 has a cooling channel through which cooling air from the blower 21 passes.

[0018] The battery pack 20 stores electric power for driving the motor generators 11 and 12, and supplies electric power to the motor generators 11 and 12 through the PCU 13. The battery pack 20 is charged by receiving the generated electric power through the PCU 13 during the power generation of the motor generators 11 and 12.

[0019] The AC / DC converter 32 is electrically connected between the inlet 31 and the charging relay 33. The AC / DC converter 32 converts the alternating current power supplied from an external power source (such as a charging stand) through the inlet 31 into direct current power according to a control command from the ECU 100. Instead of or in addition to the AC / DC converter 32, a DC / DC converter may be provided.

[0020] 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 in response to a control command from the ECU 100, power transmission between the inlet 31 and the battery pack 20 becomes possible.

[0021] The ECU 100 includes a processor 101 such as a CPU (Central Processing Unit), a memory 102 such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and an I / O port (not shown) for inputting and outputting various signals. The ECU 100 controls the vehicle 1 to a desired state based on the signals received from each sensor and the programs and maps stored in the memory 102.

[0022] The battery cooling device 50 is configured to cool the battery pack 20. The battery cooling device 50 is composed of a blower 21, a plurality of battery cell temperature measurement sensors 23(1) to 23(n), an intake air temperature measurement sensor 22, and the ECU 100 (the battery cooling control part in the ECU 100).

[0023] The blower 21 is installed at the intake port of the battery pack 20. The battery cell temperature sensor 23(i) detects the temperature Tb(i) of the corresponding battery cell CL(i).

[0024] The intake air temperature sensor 22 detects the intake air temperature Ta generated by the blower 21. Figures 2(a) and (b) illustrate the cooling problems of the battery pack 20.

[0025] Multiple battery cells CL(1) to CL(n) are arranged in a cooling channel through which cooling air from the blower 21 passes. The distances between the blower 21 and each battery cell differ. Battery cell CL(1) is located closest to the blower 21, and battery cell CL(n) is located furthest from the blower 21.

[0026] The cooling air from the blower 21 cools the battery cells CL(1) to CL(n). In Figure 2(a), if the battery cell CL(1), which is located closest to the blower 21, is hot, the rotation speed R of the blower 21 is increased. When the rotation speed of the blower 21 is increased, as shown in Figure 2(b), the cooling air reaches positions farther from the blower 21, so the amount of cooling air sent to the battery cell CL(1), which is located closest to the blower 21, decreases. As a result, the temperature of battery cell CL(1) may not decrease, or it may even increase.

[0027] Figure 3 shows the relationship between the rotation speed of the blower 21 and the cooling performance of the battery cell CL. When the rotation speed of blower 21 is high, the airflow of cooling air increases, and battery cells CL located farther from blower 21 cool down more easily. When the rotation speed of blower 21 is low, the airflow of cooling air decreases, and battery cells CL located closer to blower 21 cool down more easily.

[0028] In this embodiment, to solve these problems, the cooling performance of each battery cell, taking into account the intake air temperature Ta, the battery cell temperature Tb, and the rotation speed R of the blower 21, is obtained in advance through evaluation, thereby efficiently cooling the high-temperature battery cell CL.

[0029] Based on the temperatures Tb(1) to Tb(n) detected by multiple battery cell temperature measuring sensors 23(1) to 23(n), the ECU 100 identifies the battery cell with the highest temperature as the first battery cell CL(k). The ECU 100 identifies a rotational speed R for the blower 21 from among several candidates that maximizes the cooling performance of the first battery cell CL(k) at 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 identified rotational speed R.

[0030] More specifically, the ECU 100 refers to the cooling map MP of the hottest battery cell CL, determines the rotational speed R of the blower 21 based on the battery cell temperature Tb and intake air temperature Ta, and cools the battery pack 20 using the determined rotational speed R of the blower 21. By determining the rotational speed R of the blower 21 from the cooling map MP of the hottest battery cell CL, it becomes possible to cool the high-temperature battery cell CL accordingly.

[0031] Memory 102 stores multiple cooling maps MP(1) to MP(n). Cooling map MP(i) defines the cooling performance W of a corresponding battery cell CL(i) for a given combination of the corresponding battery cell CL(i) temperature Tb(i), the rotation speed R of the blower 21, and the intake air temperature Tb. Cooling maps MP(1) to MP(n) are created in advance through experiments. Cooling performance is an index that represents the degree of cooling (ease of cooling) of the battery cell CL(i) under given conditions (temperature Tb(i), Ta, rotation speed R). Cooling performance W can be calculated, for example, from the difference between the temperature of the battery cell CL(i) before cooling by the battery cooling device 50 and the temperature of the battery cell CL(i) after cooling by the battery cooling device 50.

[0032] Figure 4(a) shows an example of the cooling map for battery cell CL(1). Figure 4(b) shows an example of the cooling map for battery cell CL(n). For battery cell CL(1), the cooling performance is set to be higher when the rotation speed R of the blower 21 is lower.

[0033] Figure 5 is a flowchart illustrating the cooling procedure for the battery pack 20 of the embodiment. In step S101, the ECU 100 acquires the battery cell temperatures Tb(1), Tb(2), ...Tb(n) detected by the battery cell temperature measurement sensors 23(1) to 23(n).

[0034] In step S102, the ECU 100 obtains the intake air temperature Ta detected by the intake air temperature measuring sensor 22.

[0035] In step S103, the ECU 100 identifies 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).

[0036] In step S105, the ECU 100 selects the cooling map MP(k) for the first battery cell CL(k). The ECU 100 refers to the cooling map MP(k) for the first battery cell and determines the rotational speed R of the blower 21 that maximizes the cooling performance of the first battery cell CL(k) at the battery cell temperature Tb(k) detected by the battery cell temperature measuring sensor 23(k) and the intake air temperature Ta detected by the intake air temperature measuring sensor 22.

[0037] In step S105, the ECU 100 controls the blower 21 so that it rotates at a specified rotational speed R.

[0038] As described above, according to this embodiment, it is possible to identify the blower rotation speed that maximizes the cooling performance of high-temperature battery cells, thereby enabling proper cooling of the battery pack. By obtaining a cooling performance map in advance for each battery cell installed in the battery pack, taking into account the intake air temperature, battery temperature, and blower rotation speed, it is possible to select a blower rotation speed that can efficiently cool high-temperature battery cells, thereby reducing the battery temperature.

[0039] In the above embodiment, a cooling map for each battery cell was used, but the method is not limited to this. An arithmetic formula that has been determined in advance for each battery cell may also be used. The cooling performance of the battery cell is calculated from the temperature of the battery cell, the intake air temperature, and the rotation speed of the blower using the arithmetic formula.

[0040] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of Symbols]

[0041] 1 Vehicle, 8 Temperature sensors, 10 Running unit, 11,12 Motor generator, 14 Engine, 15 Power splitter, 16 Drive wheels, 20 Battery pack, 21 Blower, 22 Intake air temperature sensor, 23 Battery cell temperature sensor, 28 Battery stack, 30 Charging unit, 31 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, A blower for cooling the aforementioned battery pack, Each of the following is a set of first sensors that detect the temperature of the corresponding battery cell, A second sensor detects the intake air temperature of the battery pack by the blower, A battery cooling device comprising: a controller that identifies 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, identifies a rotation speed of the blower from a plurality of candidates that maximizes the cooling performance of the first battery cell based on 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, and controls the blower to rotate at the identified rotation speed.

2. The aforementioned battery cooling device, Each unit further includes a storage unit that stores multiple cooling maps, each defining the cooling performance of a corresponding battery cell for a given combination of the temperature of the corresponding battery cell, the rotation speed of the blower, and the intake air temperature. The battery cooling device according to claim 1, wherein the controller refers to the cooling map of the first battery cell and determines the rotation speed of the blower such that 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 air temperature is the detected intake air temperature.

3. The distance between the blower and each battery cell is different. The battery cooling device according to claim 1, wherein the plurality of battery cells are arranged on a cooling channel through which the cooling air from the blower passes.

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