Charge / discharge control device

Abstract

To provide a charging / discharging control device capable of suppressing battery deterioration in a high temperature and high SOC state.SOLUTION: A charging / discharging control device includes: a battery state sensor 41 for detecting temperature of a battery 4; a cooling unit 5 for cooling the battery 4 using electric power from the battery 4; and a control unit 9 for limiting a SOC of the battery 4 to a predetermined SOC upper limit value, setting the SOC upper limit value lower as the temperature of the battery 4 is higher, and driving the cooling unit 5 when the SOC of the battery 4 is equal to or higher than the SOC upper limit value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a charge / discharge control device. [Background technology]

[0002] Patent Document 1 describes that if the temperature of the power storage device is equal to or higher than a predetermined temperature when the vehicle ignition switch is switched from on to off and the time that has elapsed since the ignition switch was switched off is less than a predetermined time, the interior air conditioning device and cooling device are operated to cool the power storage device, and then charging of the power storage device by an AC power source is started. This discloses a technology that prevents the power storage device from becoming too hot during charging, which would otherwise cause the power storage device to deteriorate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-095985 Summary of the Invention [Problem to be solved by the invention]

[0004] As described in Patent Document 1, maintaining a battery at a high temperature and a high SOC (State Of Charge) accelerates battery degradation. However, Patent Document 1 does not disclose how to suppress battery degradation when the battery is at a high temperature in a high SOC state.

[0005] Therefore, an object of the present invention is to provide a charge / discharge control device that can suppress battery degradation in high temperature and high SOC states. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a battery control system that includes a temperature detection unit that detects the temperature of a battery, a cooling unit that cools the battery using power from the battery, and a control unit that limits the SOC of the battery to a predetermined SOC upper limit value, wherein the control unit sets the SOC upper limit value lower as the temperature of the battery increases, and activates the cooling unit when the SOC of the battery is equal to or higher than the SOC upper limit value. When the SOC of the battery reaches the SOC upper limit value based on the temperature of the battery at the time when the cooling unit starts to operate, the cooling unit is stopped. This is what is done. [Effects of the Invention]

[0007] In this way, according to the present invention, it is possible to suppress battery degradation in high temperature and high SOC states. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a vehicle equipped with a charge / discharge control device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart showing the procedure of the battery cooling control process of the charge / discharge control device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A charge / discharge control device according to one embodiment of the present invention includes a temperature detection unit that detects the temperature of a battery, a cooling unit that cools the battery using power from the battery, and a control unit that limits the SOC of the battery to a predetermined SOC upper limit value, and the control unit is configured to set a lower SOC upper limit value the higher the battery temperature, and to activate the cooling unit when the SOC of the battery is equal to or higher than the SOC upper limit value.

[0010] As a result, the charge / discharge control device according to one embodiment of the present invention can suppress battery degradation in high temperature and high SOC states. [Example]

[0011] Hereinafter, a charge / discharge control device according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0012] In FIG. 1, a vehicle 1 equipped with a charge / discharge control device according to an embodiment of the present invention includes a motor 2, an inverter 3, a battery 4, a cooling unit 5, and a control unit 9.

[0013] The motor 2 is configured as a synchronous motor, for example, equipped with a rotor in which multiple permanent magnets are embedded and a stator around which a stator coil is wound. When three-phase AC power is applied to the stator coil, a rotating magnetic field is formed in the stator, which rotates the rotor and generates a driving force.

[0014] Furthermore, the motor 2 is driven so that the rotational resistance generated during power generation is used to brake the vehicle 1. This allows the motor 2 to generate power through regeneration. In this way, the motor 2 also functions as a generator, and is capable of generating power to charge the battery 4.

[0015] The inverter 3 supplies three-phase AC power to the motor 2. The inverter 3 also converts the three-phase AC power generated by the motor 2 into DC power and charges the battery 4.

[0016] The battery 4 is, for example, a nickel storage battery or a lithium storage battery, and is configured by connecting multiple cells in series. The battery 4 supplies power to the motor 2 via the inverter 3. The battery 4 is provided with a battery state sensor 41 as a temperature detection unit. The battery state sensor 41 detects the charge / discharge current, voltage, and battery temperature of the battery 4. The battery state sensor 41 is connected to the control unit 9. The control unit 9 can detect the temperature and state of charge (hereinafter referred to as "SOC") of the battery 4 from the output of the battery state sensor 41.

[0017] A charger 42 and a charging connector 43 are connected to the battery 4. The charging connector 43 connects the charger 42 to an external power source of a power supply facility 110 installed outside the vehicle 1. The charger 42 is connected to the charging connector 43 and includes a converter that converts AC power supplied from the external power source via the charging connector 43 into DC power, and a boost circuit that boosts the DC power.

[0018] The power of the battery 4 is supplied to the cooling unit 5, the lead battery 7, and the auxiliary devices 8 via a DC-DC converter 44. The DC-DC converter 44 converts the voltage of the power output from the battery 4 and supplies it to the cooling unit 5, the lead battery 7, and the auxiliary devices 8. The lead battery 7 has an output voltage of about 12 V, and supplies power to drive various auxiliary devices 8 consisting of the electrical system of the vehicle 1, etc.

[0019] The cooling unit 5 cools the battery 4 by utilizing the power of the battery 4. The cooling unit 5 is configured by, for example, a compressor, a blower fan, etc. The cooling unit 5 is driven or stopped under the control of the control unit 9.

[0020] The communication unit 6 communicates with the smartphone 100 and the like via a communication medium such as wireless communication or short-range wireless communication to transmit and receive information. The control unit 9 can transmit and receive information with the smartphone 100 and the like via the communication unit 6.

[0021] The control unit 9 is composed of a computer unit equipped with a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory for storing backup data, etc., input ports, and output ports.

[0022] The ROM of this computer unit stores various constants, various maps, and the like, as well as a program for causing the computer unit to function as the control unit 9.

[0023] That is, the CPU executes the program stored in the ROM using the RAM as a work area, and the computer unit functions as the control unit 9 in this embodiment.

[0024] In addition to the battery state sensor 41, various sensors including an outside air temperature sensor 91 and various switches are connected to the input port of the control unit 9. The outside air temperature sensor 91 detects the temperature of the outside air around the vehicle 1.

[0025] The output port of the control unit 9 is connected to various control targets including the inverter 3, the cooling unit 5, and the charger 42 described above.

[0026] In this embodiment, the control unit 9 limits the SOC of the battery 4 to a predetermined SOC upper limit value.

[0027] The control unit 9 sets a lower SOC upper limit value as the temperature of the battery 4 increases, and drives the cooling unit 5 to cool the battery 4 when the SOC of the battery 4 is equal to or higher than the SOC upper limit value.

[0028] When the SOC of the battery 4 reaches the SOC upper limit, the control unit 9 does not drive the cooling unit 5 until a predetermined time has elapsed.

[0029] The control unit 9 stops the cooling unit 5 when the SOC of the battery 4 reaches an upper SOC limit value based on the temperature of the battery 4 at the time when the cooling unit 5 starts to operate.

[0030] When the battery 4 is being charged by an external power source, the control unit 9 starts charging the battery 4 if the SOC of the battery 4 is below the SOC upper limit after a predetermined period of time has elapsed since the cooling unit 5 was stopped.

[0031] The control unit 9 extends the predetermined period as the outside air temperature becomes higher than the temperature of the battery 4 when the cooling unit 5 is stopped.

[0032] When a user requests charging, the control unit 9 charges the battery 4 to full charge or to a user-specified SOC regardless of the current temperature of the battery 4, and prohibits the cooling unit 5 from operating at an SOC upper limit value according to the temperature of the battery 4.

[0033] The user issues a charging request to the control unit 9 and specifies the SOC to be charged, for example, by an application running on the smartphone 100. The application running on the smartphone 100 may also allow the user to know the SOC and temperature of the battery 4.

[0034] Furthermore, a dedicated device may be used to issue a charge request or specify the SOC to be charged to the control unit 9, instead of an app running on the smartphone 100. Alternatively, a switch or the like provided on the vehicle 1 may be used to issue a charge request or specify the SOC to be charged.

[0035] The control unit 9 cancels the prohibition on driving the cooling unit 5 based on the SOC upper limit value according to the temperature of the battery 4 in response to an instruction from the user.

[0036] The battery cooling control process performed by the charge / discharge control device according to this embodiment configured as described above will be described with reference to Fig. 2. The battery cooling control process described below starts when the control unit 9 starts operating, and is executed at preset time intervals.

[0037] In step S1, the control unit 9 acquires the temperature of the battery 4. After executing the process of step S1, the control unit 9 executes the process of step S2.

[0038] In step S2, the control unit 9 sets the SOC upper limit value based on the temperature of the battery 4. After executing the process of step S2, the control unit 9 executes the process of step S3.

[0039] In step S3, the control unit 9 acquires the SOC of the battery 4. After executing the process of step S3, the control unit 9 executes the process of step S4.

[0040] In step S4, the control unit 9 determines whether the SOC of the battery 4 is equal to or greater than the SOC upper limit.

[0041] If it is determined that the SOC of the battery 4 is equal to or greater than the SOC upper limit, the control unit 9 executes the process of step S5. If it is determined that the SOC of the battery 4 is not equal to or greater than the SOC upper limit, the control unit 9 ends the battery cooling control process.

[0042] In step S5, the control unit 9 drives the cooling unit 5. After executing the process of step S5, the control unit 9 ends the battery cooling control process.

[0043] Thus, in this embodiment, the control unit 9 sets a lower SOC upper limit value as the temperature of the battery 4 increases, and when the SOC of the battery 4 is equal to or higher than the SOC upper limit value, the control unit 9 drives the cooling unit 5 to cool the battery 4.

[0044] As a result, by setting the SOC upper limit lower as the temperature of the battery 4 increases, it is possible to prevent the SOC from becoming high at high temperatures and accelerating deterioration of the battery 4.

[0045] Furthermore, if the temperature of the battery 4 rises due to an increase in ambient temperature or the like after charging to the SOC upper limit, the actual SOC may exceed the SOC upper limit. In this case, deterioration of the battery 4 may be accelerated. Therefore, by cooling the battery 4, it is possible to adjust the temperature of the battery 4 to a temperature at which the actual SOC becomes an appropriate SOC, and thus it is possible to prevent the deterioration of the battery 4 from being accelerated.

[0046] Furthermore, when the SOC of the battery 4 reaches the SOC upper limit, the control unit 9 does not drive the cooling unit 5 until a predetermined time has elapsed.

[0047] As a result, the cooling unit 5 is not driven until a predetermined time has elapsed during which it is assumed that the impact on the battery 4 will be small, and consumption of the SOC of the battery 4 can be suppressed.

[0048] Furthermore, the control unit 9 stops the cooling unit 5 when the SOC of the battery 4 reaches an SOC upper limit value based on the temperature of the battery 4 at the time when the cooling unit 5 starts to operate.

[0049] As a result, if the cooling unit 5 is controlled so that the actual SOC is equal to the SOC upper limit based on the temperature of the battery 4 during cooling, the SOC upper limit will rise as the battery 4 is cooled, and the cooling unit 5 will immediately be stopped. At this time, the temperature of the battery 4 rises again due to the stopping of the cooling unit 5, and the SOC upper limit will fall, and the cooling unit 5 will be started again. Thus, if the SOC upper limit is set based on the temperature of the battery 4 during cooling, the cooling unit 5 will frequently be turned on and off. In this case, the cooling unit 5 performs cooling using a compressor, a blower fan, etc., and these devices are driven by the motor 2. Furthermore, since the motor 2 generally consumes the most power during startup, frequent on-off switching of the motor 2 may result in excessive power consumption without achieving sufficient cooling effect, which may result in a decrease in the actual SOC.

[0050] Therefore, in this embodiment, the cooling unit 5 is continuously driven up to the SOC upper limit based on the temperature of the battery 4 at the time when the cooling unit 5 starts to be driven, and the battery 4 can be cooled efficiently.

[0051] Furthermore, when the battery 4 is being charged by an external power source, the control unit 9 starts charging the battery 4 if the SOC of the battery 4 is below the SOC upper limit after a predetermined period of time has elapsed since the cooling unit 5 was stopped.

[0052] The SOC of the battery 4 when the cooling unit 5 is stopped is the SOC upper limit value based on the temperature of the battery 4 before cooling. Therefore, if a predetermined period is not set, charging may start immediately after the cooling unit 5 is stopped. In this case, if the temperature of the battery 4 rises again due to charging, etc., the actual SOC may exceed the SOC upper limit value, charging may be stopped, and the cooling unit 5 may be driven again. In other words, charging and discharging may be repeated frequently.

[0053] Therefore, by keeping charging stopped for a predetermined period after the cooling unit 5 has stopped, it is possible to prevent the battery 4 from deteriorating due to frequent repetition of charging and discharging.

[0054] Moreover, the control unit 9 extends the predetermined period as the outside air temperature becomes higher than the temperature of the battery 4 when the cooling unit 5 is stopped.

[0055] The higher the outside air temperature is, the higher the probability that the temperature of the battery 4 will rise significantly after the cooling unit 5 is stopped. Therefore, if charging is resumed immediately, the SOC upper limit value will drop due to the rise in the temperature of the battery 4, and the cooling unit 5 will be immediately activated, requiring cooling and discharging. In this case, charging and discharging will be repeated frequently.

[0056] At this time, the higher the outside air temperature is, the longer the time until charging is resumed, thereby preventing deterioration of the battery 4 due to frequent repetition of charging and discharging.

[0057] In addition, when a user requests charging, the control unit 9 charges the battery 4 to full charge or to a user-specified SOC regardless of the current temperature of the battery 4, and prohibits the cooling unit 5 from operating at an SOC upper limit value according to the temperature of the battery 4.

[0058] This allows the battery to be charged to a specified SOC upon request of the user, and the battery can be brought to the specified SOC state without inconvenience to the user or without having to wait when getting on the vehicle.

[0059] Furthermore, the control unit 9 cancels the prohibition on driving the cooling unit 5 based on the SOC upper limit value according to the temperature of the battery 4 in response to an instruction from the user.

[0060] This allows the prohibition of driving the cooling unit 5 based on the SOC upper limit value according to the current temperature of the battery 4 to be lifted in response to a user instruction, thereby improving usability for the user.

[0061] In this embodiment, an example has been described in which the control unit 9 performs various judgments and calculations based on various sensor information, but this is not limited to this. The vehicle 1 may be provided with a communication unit capable of communicating with an external device such as an external server, and various judgments and calculations may be performed by the external device based on the detection information of the various sensors transmitted from the communication unit. The judgment results and calculation results may be received by the communication unit, and various controls may be performed using the received judgment results and calculation results.

[0062] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0063] 1 vehicle 4 Battery 5 Cooling section 6. Communications Department 9 Control Unit 41 Battery status sensor (temperature detection section) 91 Outside air temperature sensor

Claims

1. a temperature detection unit that detects the temperature of the battery; a cooling unit that cools the battery using power from the battery; a control unit that limits the SOC of the battery to a predetermined SOC upper limit value, The control unit sets the SOC upper limit value lower as the temperature of the battery increases, and when the SOC of the battery is equal to or higher than the SOC upper limit value, activates the cooling unit, and when the SOC of the battery reaches the SOC upper limit value based on the temperature of the battery at the time when the cooling unit starts to operate, stops the cooling unit.

2. 2. The charge / discharge control device according to claim 1, wherein the control unit does not drive the cooling unit until a predetermined time has elapsed after the SOC of the battery reaches the SOC upper limit value.

3. The battery is configured to be chargeable from an external power source outside the vehicle, 3. The charge / discharge control device according to claim 1, wherein the control unit starts charging the battery when the SOC of the battery is below the SOC upper limit value after a predetermined period of time has elapsed since the cooling unit was stopped while the battery is being charged by the external power source.

4. An outside air temperature sensor is provided to detect the outside air temperature of the vehicle. The charge / discharge control device according to claim 3 , wherein the control unit extends the predetermined period as the outside air temperature increases to a temperature higher than the temperature of the battery when the cooling unit is stopped.

5. 5. The charge / discharge control device according to claim 3, wherein the control unit, when receiving a charging request from a user, charges the battery to full charge or to an SOC specified by the user regardless of the current temperature of the battery, and prohibits operation of the cooling unit at the SOC upper limit value corresponding to the temperature of the battery.

6. The charge / discharge control device according to claim 5 , wherein the control unit cancels the prohibition of driving the cooling unit based on the SOC upper limit value according to the temperature of the battery, in response to an instruction from a user.

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