Battery control system for a vehicle

Abstract

The present disclosure provides a battery control system of a vehicle in which a total outputtable power comparison determination unit calculates total outputtable powers of battery modules using upper limit current values of the battery modules for all connection modes that can be achieved between a plurality of battery groups and a load by a battery connection / disconnection unit, and determines whether there is a high output mode in which the total outputtable power is greater than a current connection mode. In addition, a battery connection / disconnection control unit changes the connection mode of the battery connection / disconnection unit from the current connection mode to the high output mode when the total outputtable power comparison determination unit determines that there is the high output mode.

Description

Vehicle battery control system Technical Field

[0001] This disclosure relates to a battery control system for vehicles. Background Technology

[0002] Patent Document 1 discloses an electric vehicle comprising a first battery pack and a second battery pack constituting a battery module and a drive motor. The first battery pack and the second battery pack are connected in parallel, and a first contactor and a second contactor are provided between the first battery pack, the second battery pack and the drive motor.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent document 1: Japanese Patent Application Publication No. 2020-167864. Summary of the Invention

[0006] The problem the invention aims to solve

[0007] For battery packs, there is a suitable operating temperature range. Using the battery pack at temperatures exceeding this range will accelerate its degradation. Therefore, reducing the amount of current flowing through the battery pack at high temperatures (the battery pack's current value) to suppress temperature rise is effective in protecting the battery pack. For example, by pre-calculating the correspondence between the battery pack's temperature and voltage values ​​and the upper limit current value that is effective for battery pack protection, and by sequentially detecting the temperature and voltage values ​​of the battery pack in use, and using the detected temperature and voltage values ​​to determine the upper limit current value, the battery pack's current value can be controlled below the upper limit current value, thereby suppressing battery pack degradation.

[0008] When multiple battery packs constituting a battery module are connected in parallel with a load, as in Patent Document 1, the current flowing through each battery pack is the same (the current value of each battery pack is equal). Therefore, the upper limit current value when limiting the current value of each battery pack is the smallest upper limit current value among the upper limit current values ​​determined individually for each battery pack. As a result, the total power output from the battery module at high temperatures (total output power) may be significantly limited.

[0009] Therefore, the purpose of this disclosure is to provide a battery control system that, in a vehicle having multiple battery packs connected in parallel with a load, can protect the battery packs while suppressing a decrease in the total output power at high temperatures.

[0010] Solution to the problem

[0011] To achieve the above objectives, this disclosure provides a battery control system for a vehicle, the vehicle being equipped with a battery module having multiple battery packs connected in parallel with a load, the battery control system for the vehicle including a battery connection disconnection unit, an upper limit current calculation unit, a current control unit, an output power comparison and determination unit, and a battery connection disconnection control unit.

[0012] The battery connection / disconnection unit is located between the battery module and the load, configured to individually connect and disconnect each of the multiple battery packs from the load. The upper limit current calculation unit uses the temperature and voltage values ​​of the battery packs to calculate the upper limit current value of the battery packs. The current control unit controls the current value of the battery packs to be below the upper limit current value.

[0013] In the first embodiment of this disclosure, the output power comparison and determination unit calculates the total output power of the battery module for all possible connection modes between multiple battery packs and the load using the upper limit current value of the battery pack, and determines whether there is a high output mode where the total output power is greater than the current connection mode. If the output power comparison and determination unit determines that a high output mode exists, the battery connection disconnection control unit changes the battery connection disconnection unit from the current connection mode to the high output mode.

[0014] The second aspect of this disclosure, based on the battery control system of the first aspect, involves changing the connection mode of the battery connection disconnection unit to the maximum output mode with the largest total output power when multiple high output modes exist.

[0015] The third method of this disclosure, based on the battery control system of the first or second method, changes the connection mode of the battery connection disconnection section only when the following conditions are met: if the change is made, the number of connected battery packs will be reduced to a number less than the number of connected battery packs in the current connection mode, and a portion of the battery packs will be disconnected from the current connection mode.

[0016] In the fourth aspect of this disclosure, the output power comparison and determination unit calculates the total output power of the battery module using the upper limit current value of the battery pack for each of the current connection modes implemented between multiple battery packs and the load, and for connection modes in the following situations: and determines whether there exists a high output mode where the total output power is greater than the current connection mode, where a battery pack has been disconnected from the current connection mode. If the output power comparison and determination unit determines that a high output mode exists, the battery connection disconnection control unit changes the connection mode of the battery connection disconnection unit to the high output mode.

[0017] Invention Effects

[0018] According to the battery control system disclosed herein, in a vehicle having multiple battery packs connected in parallel with a load, the battery packs can be protected while suppressing the decrease in total output power at high temperatures. Attached Figure Description

[0019] Figure 1 is a schematic side view of a vehicle equipped with a battery module according to one embodiment of the present disclosure.

[0020] Figure 2 is a block diagram illustrating the battery control system of the embodiment shown in Figure 1.

[0021] Figure 3 is a flowchart illustrating the current control process.

[0022] Figure 4 is a flowchart illustrating the battery pack connection / disconnection control process.

[0023] Explanation of reference numerals in the attached figures

[0024] 1: Battery module;

[0025] 2: Battery pack;

[0026] 3: Battery connection disconnection point;

[0027] 4: Load;

[0028] 5: Temperature sensor;

[0029] 6: Contactor;

[0030] 10: Battery control device;

[0031] 11: Temperature Acquisition Unit;

[0032] 12: Voltage acquisition unit;

[0033] 13: Upper limit current calculation unit;

[0034] 14: Current control unit;

[0035] 15: Output power comparison and determination unit;

[0036] 16: Battery connection disconnection control unit. Detailed Implementation

[0037] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The battery control system of this embodiment is installed in vehicles such as electric vehicles and hybrid vehicles.

[0038] As shown in Figure 1, the vehicle is equipped with multiple (three in this embodiment) battery packs 2. These multiple battery packs 2 constitute a battery module 1. It should be noted that Figure 1 illustrates an example of a battery module 1 installed in a truck, but the vehicle is not limited to trucks.

[0039] As shown in Figure 2, the battery control system includes: a battery module 1, a battery connection disconnection part 3, a load 4, and a battery control device 10.

[0040] Multiple battery packs 2 are connected in parallel with a load 4. Each battery pack 2 is equipped with a temperature sensor 5 to detect its temperature. The load 4 includes a drive motor (not shown) that propels the vehicle. The drive motor is powered by electricity supplied from the battery module 1.

[0041] The battery connection disconnection section 3 consists of the same number of contactors 6 as the battery pack 2, and is located between the battery module 1 and the load 4. Each of the multiple battery packs 2 is individually connected to and disconnected from the load 4 by turning the contactors 6 on and off. In this embodiment, the state where all battery packs 2 are connected to the load 4 (all contactors 6 are on) is described as the standard connection mode (normal state) of the battery connection disconnection section 3.

[0042] The battery control device 10 is, for example, an ECU (Electronic Control Unit), which includes a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and input / output circuits. The battery control device 10 functions as a temperature acquisition unit 11, a voltage acquisition unit 12, an upper limit current calculation unit 13, a current control unit 14, an output power comparison and determination unit 15, and a battery connection / disconnection control unit 16 by executing a pre-stored control program.

[0043] The temperature acquisition unit 11 sequentially acquires the temperature of each battery pack 2 from the temperature sensor 5. The voltage acquisition unit 12 sequentially acquires the voltage between the terminals of each battery pack 2 (the voltage value of the battery pack 2) from the voltage sensor (not shown).

[0044] The battery control device 10 stores upper limit current value information (e.g., mapping) that represents the correspondence between the temperature and voltage values ​​of the battery pack 2 and the upper limit current value. The upper limit current value is the current value that effectively limits the protection of the battery pack 2; when the voltage value is constant, the upper limit current value decreases as the temperature rises. The battery pack 2 has a suitable operating temperature range; if the temperature rises above the operating temperature range, the upper limit current value will decrease significantly. The upper limit current value information is calculated in advance through simulation or the like and stored in the battery control device 10.

[0045] The upper limit current calculation unit 13 uses the temperature of the battery pack 2 obtained by the temperature acquisition unit 11, the voltage value of the battery pack 2 obtained by the voltage acquisition unit 12, and the upper limit current value information to calculate the upper limit current value of each battery pack 2.

[0046] The current control unit 14 controls the current value of the battery pack 2 to be below the upper limit current value. Since the battery packs 2 are connected in parallel, the total current value flowing through the battery module 1 is evenly distributed to each battery pack 2, and the current value of each battery pack 2 is equal. The current control unit 14 controls the total current value so that the current below the smallest upper limit current value among the upper limit current values ​​of the parallel-connected battery packs 2 flows through each battery pack 2. Therefore, if a battery pack 2 with a lower upper limit current value than other battery packs 2 due to high temperature is connected, the upper limit current value of the high-temperature battery pack 2 may become a bottleneck, resulting in a significant reduction in the total output power of the battery module 1 (the total output power of the parallel-connected battery packs 2).

[0047] The output power comparison and determination unit 15 uses the upper limit current value and voltage value of each battery pack 2 to calculate the output power of each battery pack 2. For all connection modes (including the current connection mode) that can be realized between the multiple battery packs 2 and the load 4 for the battery connection disconnection unit 3, it calculates the total output power of the battery module 1 and determines whether there is a high output mode with a total output power greater than the current connection mode. The connection modes in this embodiment include a total of 7 modes, namely, a standard connection mode (one) that connects all three battery packs 2, two sets of connection modes (three) that connect any two of the three battery packs 2, and a single connection mode (three) that connects only one battery pack 2. The total output power is calculated for each mode and compared with the current connection mode.

[0048] When the output power comparison determination unit 15 determines that a high output mode exists, the battery connection disconnection control unit 16 changes the connection mode of the battery connection disconnection unit 3 from the current connection mode to the high output mode. The number of connections to the battery pack 2 can be increased, decreased, or remain unchanged depending on the change to the high output mode.

[0049] Furthermore, when multiple high-output modes exist, the connection mode of the battery connection disconnection unit 3 is changed to the maximum output mode with the highest total output power. It should be noted that the battery connection disconnection control unit 16 may also change the connection mode of the battery connection disconnection unit 3 only if, upon making this change, the number of connected battery packs 2 is reduced to a number less than the current connection mode's number, and some battery packs 2 are disconnected from the current connection mode. Through this restriction, for example, in cases where there are battery packs 2 whose connections are restricted or prohibited by controls other than this control, connections to battery packs 2 whose connections are restricted or prohibited can be excluded.

[0050] Next, the current control processing and battery pack 2 connection / disconnection control processing performed by the battery control device 10 will be described with reference to the flowcharts in Figures 3 and 4. During the period when power is supplied from the battery module 1 to the load 4, the battery control device 10 repeatedly performs the current control processing and the battery pack 2 connection / disconnection control processing. It should be noted that the following description focuses on the case where the current connection mode of the battery connection / disconnection unit 3 is the standard connection mode (a connection mode in which all three battery packs 2 are connected), but the current connection mode can also be a mode other than the standard connection mode.

[0051] As shown in Figure 3, in the current control process, the temperature and voltage values ​​of the three battery packs 2 are obtained respectively (step S1), and the upper limit current value of each battery pack 2 is calculated using the obtained temperature and voltage values ​​and upper limit current value information of the battery pack 2 respectively (step S2).

[0052] After calculating the upper limit current values ​​of the three battery packs 2, the total current value of the battery module 1 is controlled in such a way that the current equal to or lower than the smallest of the calculated upper limit current values ​​flows through each battery pack 2 (step S3).

[0053] As shown in Figure 4, in the connection disconnection control process, the temperature and voltage values ​​of the three battery packs 2 are obtained respectively (step S11), and the upper limit current value of each battery pack 2 is calculated using the obtained temperature and voltage values ​​and upper limit current value information of the battery pack 2 respectively (step S12).

[0054] After calculating the upper limit current value of each of the three battery packs 2, the output power of the three battery packs 2 is calculated using the upper limit current value and voltage value of each battery pack 2 (step S13).

[0055] Next, for all connection modes (7 connection modes) that can be realized between the three battery packs 2 and the load 4 in the battery connection disconnection section 3, the total output power of the battery module 1 is calculated, and it is determined whether there is a high output mode with a total output power greater than the current connection mode (step S14).

[0056] If a high output mode is determined to exist, the connection mode of the battery connection disconnection unit 3 is changed from the current connection mode to the high output mode (step S15). Furthermore, if multiple high output modes exist, the connection mode of the battery connection disconnection unit 3 is changed to the maximum output mode with the highest total output power. For example, if the total output power is highest when disconnecting the connection mode of the battery pack 2 with the highest temperature among the three battery packs 2, the battery pack 2 with the highest temperature is disconnected.

[0057] In this embodiment, for all possible connection modes between the multiple battery packs 2 and the load 4 at the battery connection disconnection section 3, the total output power of the battery module 1 is calculated, and it is determined whether there is a high output mode with a higher total output power than the current connection mode. If a high output mode is determined to exist, the connection mode of the battery connection disconnection section 3 is changed from the current connection mode to the high output mode. Therefore, even when a battery pack 2 with a lower upper limit current value than other battery packs 2 due to high temperature is connected, and the upper limit current value of the high-temperature battery pack 2 becomes a bottleneck, the reduction in the total output power of the battery module 1 can be suppressed.

[0058] In addition, when multiple high output modes exist, the connection mode of the battery connection disconnection unit 3 is changed to the maximum output mode with the largest total output power. Therefore, the reduction in the total output power can be minimized.

[0059] Next, a modified example of this disclosure will be described. This modified example differs from the above embodiment in that it can output the processing performed by the power comparison and determination unit 15.

[0060] In the modified example, the output power comparison and determination unit 15 calculates the total output power of the battery module 1 for the current connection mode implemented between the multiple battery packs 2 and the load 4, and for connection modes in the following situations: the total output power is greater than the current connection mode. It then determines whether there exists a high-output mode where the total output power is greater than the current connection mode, specifically when one of the battery packs 2 has been disconnected from the current connection mode. Since the number of connection modes to be determined is less than the number of connection modes in the above embodiment, the processing can be simplified.

[0061] The present disclosure has been described above based on the aforementioned embodiments, but the present disclosure is not limited to the content of the above embodiments, and of course, appropriate modifications can be made without departing from the scope of the present disclosure. That is, other embodiments, examples, and application techniques implemented by those skilled in the art based on the embodiments are all included in the scope of the present disclosure.

[0062] For example, in the above embodiment, an example was described where a battery module 1 is composed of three battery packs 2, and all three (all) battery packs 2 are connected in parallel with the load 4 in the normal state. However, the number of battery packs 2 constituting the battery module 1 is not limited to the above description, and any number is acceptable. Alternatively, some of the battery packs 2 may be connected to the load 4 in the normal state.

[0063] Industrial applicability

[0064] This disclosure can be applied to vehicles having multiple battery packs connected in parallel with the load.

Claims

1. A battery control system for a vehicle, the vehicle being equipped with a battery module having multiple battery packs and the multiple battery packs being connected in parallel with a load, the battery control system for the vehicle being characterized by comprising: a battery connection disconnection unit, located between the battery module and the load, capable of individually connecting and disconnecting each of the multiple battery packs from the load; and an upper limit current calculation unit, which calculates an upper limit current value of the battery pack using the temperature and voltage values ​​of the battery packs; The current control unit controls the current value of the battery pack below the upper limit current value; The output power comparison and determination unit calculates the total output power of the battery module for all connection modes that can be achieved between the plurality of battery packs and the load using the upper limit current value of the battery pack, and determines whether there is a high output mode with a total output power greater than the current connection mode. And the battery connection disconnection control unit, when the output power comparison determination unit determines that the high output mode exists, changes the connection mode of the battery connection disconnection unit to the high output mode.

2. The battery control system for a vehicle as described in claim 1, wherein, In the presence of multiple high output modes, the battery connection disconnection control unit changes the connection mode of the battery connection disconnection unit to the maximum output mode with the largest total output power.

3. The battery control system for a vehicle as described in claim 1, wherein, The battery connection disconnection control unit changes the connection mode of the battery connection disconnection unit only under the following circumstances: if the change is made, the number of connected battery packs will be reduced to a number less than the number of connected battery packs under the current connection mode, and a portion of the battery packs will be disconnected from the current connection mode.

4. A battery control system for a vehicle, the vehicle being equipped with a battery module having multiple battery packs and the multiple battery packs being connected in parallel with a load, the battery control system for the vehicle being characterized by comprising: a battery connection disconnection unit, located between the battery module and the load, capable of individually connecting and disconnecting each of the multiple battery packs from the load; and an upper limit current calculation unit, which calculates an upper limit current value of the battery pack using the temperature and voltage values ​​of the battery packs; The current control unit controls the current value of the battery pack below the upper limit current value; The output power comparison and determination unit calculates the total output power of the battery module using the upper limit current value of the battery pack for the current connection mode that has been implemented between the plurality of battery packs and the load, and the connection mode under the following conditions, and determines whether there is a high output mode where the total output power is greater than the current connection mode, and the case is where one of the battery packs has been disconnected from the current connection mode. And the battery connection disconnection control unit, when the output power comparison determination unit determines that the high output mode exists, changes the connection mode of the battery connection disconnection unit to the high output mode.

Images