Temperature control device for battery

Abstract

To provide a temperature control device for a battery capable of keeping the battery at proper temperature at start of charging.SOLUTION: A temperature control device of a battery includes a processor having a memory and hardware, and the processor obtains charging standby time which is difference from a current time to a charging start time of the battery, obtains temperature rise required time required for raising a temperature of the battery from current temperature to appropriate charging temperature, and starts temperature rise control of the battery when the charging standby time is shorter than the temperature rise required time.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a battery temperature control device. [Background technology]

[0002] Vehicles that can run using battery power are known. In order to charge the battery, it is preferable that the battery be at an optimum charging temperature. Patent Document 1 describes that if it is predicted that the battery will heat up during charging, the currently set charging start time is advanced to prevent insufficient charge at the time charging stops. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-191784 Summary of the Invention [Problem to be solved by the invention]

[0004] It is preferable to charge a battery at home during the nighttime hours when electricity is cheap. However, the temperature drops at night, and it is expected that the battery will fall below the optimum temperature. Patent Document 1 assumes that if the temperature drops during charging, a heater will be used to raise the temperature. However, if heating is started at that point, there is a concern that the cheaper nighttime hours will not be utilized effectively.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide a battery temperature control device that can keep the battery at an appropriate temperature when charging starts. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the objectives, the battery temperature control device of the present invention includes a processor having memory and hardware, and the processor calculates a charging wait time, which is the difference between the current time and the time when charging of the battery begins, calculates a required heating time required to heat the battery from its current temperature to an appropriate charging temperature, and starts heating control of the battery when the charging wait time falls short of the required heating time. [Effects of the Invention]

[0007] The battery temperature control device according to the present invention can keep the battery at an appropriate temperature when charging begins. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic block diagram of a charging system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart of the battery charging and temperature control executed by the ECU. [Figure 3] FIG. 3 is a timing chart of the battery charging and heating process executed by the ECU. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic block diagram of a charging system 10 according to an embodiment. The charging system 10 is a system that charges a battery 14 mounted on an electric vehicle 12 from a house 16 via a V2H (Vehicle to Home) device 18. In the charging system 10, power can be supplied to the house 16 via the V2H device 18 by discharging the battery 14. A converter between the AC power of the house 16 and the DC power of the battery 14 may be located in the house 16, the V2H device 18, or the electric vehicle 12. In the house 16, electricity is set at a discount from a nighttime time H0 (see FIG. 3) until a specified time the following morning, according to a contract with an electric power company.

[0010] Examples of the electric vehicle 12 include a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), a fuel cell electric vehicle (FCEV), and an electric vehicle (BEV). The electric vehicle 12 can run on the power of its own battery 14 or on power generated in cooperation with an engine. The battery 14 is a secondary battery such as a lithium-ion battery. The battery 14 is connected to the V2H device 18 via a connector 20 and a cable 22.

[0011] The battery 14 is provided with a heater 24, a temperature sensor 26, and a voltage sensor 28. The electric vehicle 12 is provided with an ECU (Electronic Control Unit, temperature control device) 30 that controls charging and temperature of the battery 14. The ECU 30 includes a processor 30a configured by using, alone or in combination, hardware such as a general-purpose processor such as a CPU (Central Processing Unit) or a dedicated integrated circuit that executes a specific function such as an FPGA (Field Programmable Gate Array), and a storage unit 30b. The processor 30a has hardware and executes various arithmetic processes by reading various programs stored in the storage unit 30b. The ECU 30 may also be used to perform other controls, such as motor control.

[0012] The ECU 30 can heat the battery 14 by controlling the heater 24 on and off or by proportionally controlling it. The temperature T of the battery 14 is supplied to the ECU 30 by a temperature sensor 26. The ECU 30 can determine the SOC (State of Charge) of the battery 14 from the voltage V supplied from a voltage sensor 28. The SOC may also be determined by other means. A display 32 is connected to the ECU 30, allowing predetermined input and output operations. The display 32 is, for example, built into the dashboard, but may also be an independent device such as a smartphone. The ECU 30 and the V2H device 18 can communicate with each other via wired or wireless communication, allowing for cooperative control. The ECU 30 has a clock function.

[0013] 2 is a flowchart of charging and temperature control of the battery 14 executed by the ECU 30. As described above, the charging system 10 can supply power from the electric vehicle 12 to the house 16, but a description of the control will be omitted.

[0014] In step S1, the nighttime low-cost electricity time period is set on the display 32 in accordance with the contract status with the electric power company. The low-cost electricity time period starts from time H0 (for example, 11:00 p.m.). This setting is done once and can be omitted from the next time unless there is a change. In step S2, it is determined whether the V2H device 18 has started operating. If it has started (Yes), proceed to step S3; otherwise (No), wait.

[0015] In step S3, the current time H is obtained. In step S4, it is determined whether the time H0 of the cheap electricity time period has been reached. If it has been reached (Yes), the process proceeds to step S5, and if it has not been reached (No), the process proceeds to step S7. In step S5, it is determined whether the SOC is below a predetermined value. If it is below the predetermined value (Yes), the process proceeds to step S6, and if it is equal to or greater than the predetermined value, the process proceeds to step S7. In step S6, the heater 24 starts to heat the battery 14, and the process proceeds to step S7. In steps S5 and S6, heating is not performed because there is a possibility that charging will not occur if the SOC is high.

[0016] In step S7, it is determined whether the conditions for ending temperature increase by the heater 24 have been met. If they have been met (Yes), the process proceeds to step S8, and if they have not been met (No), the process proceeds to step S9. In step S8, it is determined whether the operation of the V2H device 18 has been stopped. If it has been stopped (Yes), the process shown in FIG. 2 ends, and if not (No), the process returns to step S3. In steps S7 and S8, the temperature increase is also ended when the cheaper electricity period ends.

[0017] Strictly speaking, the time determination in step S4 is based on a time somewhat earlier than time H0, and the start of temperature increase in determination step S6 is performed prior to the start of charging of the battery 14. Next, this process will be further described.

[0018] 3 is a timing chart of the charging and heating of the battery 14 executed by the ECU 30. The optimum temperature range for charging the battery 14 is set to tmin to tmax. tmin is, for example, approximately 15°C. Because the air temperature drops at night, the temperature T of the battery 14 can drop considerably below tmin. The ECU 30 pre-heats the battery 14 so that the battery 14 can be properly charged from the start time H0 of the low electricity rate period. This will be explained further below.

[0019] ECU 30 starts determining whether the temperature is rising from time Ha, which is sufficiently earlier than time H0. Time Ha may be set to an earlier time in advance based on time H0, or may be the time when electric vehicle 12 and V2H device 18 are connected via cable 22 and preparations for charging are completed.

[0020] At time Ha, the current time and the temperature T of the battery 14 are acquired. Then, the charge waiting time Sw (=H0-H) is calculated, which is the difference between the current time H and the time when charging of the battery 14 starts, i.e., time H0, and further, the required temperature rise time Sh required for the heater 24 to raise the temperature of the battery 14 from the current temperature T to tmin, which is the lower limit of the optimum charging temperature, is calculated.

[0021] Here, T = -10°C. The required temperature rise time Sh is calculated from the temperature difference between the current temperature T and tmin, the capacity of the heater 24, the heat capacity of the battery 14, and the like. Here, Sh = 1200 seconds. The rated power of the V2H device 18 is 6 kW. While FIG. 3 shows the V2H device 18 switching from 0 kW to 6 kW at time Ha, this is conceptual, and the output of the V2H device 18 remains substantially 0 kW at this point.

[0022] The ECU 30 then controls the heater 24 at time Hb when the charging standby time Sw falls below the required heating time Sh to start heating control of the battery 14. The ECU 30 may determine the timing to start heating control of the battery 14 at time Hb. For example, the charging standby time Sw may be calculated in real time and compared with the required heating time Sh to determine which is larger, or a timer may be set to reach 0 at time Hb, or time Hb may be calculated in advance and the current time H may be compared with Hb. The required heating time Sh may be recalculated and updated as the temperature T changes. The type of heater 24 is not important.

[0023] From time Hb, the heater 24 heats the battery 14, causing the temperature T to rise, and by time H0 when charging begins, the battery 14 reaches the lower limit tmin of the appropriate temperature range. Therefore, charging of the battery 14 can begin immediately from time H0, the start of the cheap electricity period.

[0024] The heater 24 continues to heat the battery 14 after time H0, and when the temperature T subsequently reaches the upper limit tmax of the appropriate temperature range, the heater 24 is stopped at time Hc. When the temperature T subsequently reaches the upper limit tmin of the appropriate temperature range, the heater 24 resumes heating at time Hd, and thereafter the heater 24 is controlled so that the temperature T is maintained within the range from tmin to tmax.

[0025] As described above, the control by the ECU 30 can maintain the battery 14 at an appropriate temperature at the charging start time H0. This allows charging of the battery 14 to begin immediately from the time H0, enabling efficient charging using inexpensive nighttime electricity. Furthermore, because the time H0 coincides with the lower limit tmin of the appropriate range, the battery temperature is not raised more quickly than necessary, eliminating waste of power. Furthermore, although the V2H device 18 cannot determine when charging of the battery 14 will begin, the ECU 30 can start raising the battery temperature at the appropriate timing, preventing unnecessary temperature rise and resulting in efficient charging. Furthermore, the ECU 30 can basically control the battery 14 to reach an appropriate temperature during inexpensive nighttime hours, and can also prohibit raising the battery temperature during daytime power supply.

[0026] The charging system 10 described above charges and discharges the battery 14 via the V2H device 18, but the V2H device 18 may be omitted if there is no need to supply power to the house 16. The ECU 30 controls the heater 24 to heat the battery 14, but the V2H device 18 may be the main controller. The heater 24 is powered by the battery 14, but power supplied from the V2H device 18 may be used depending on the system conditions, SOC, and other conditions of the battery 14. The time H0 at which charging of the battery 14 begins is generally the start of a low-cost overnight time slot, but may be set to another time slot at the user's discretion.

[0027] Further advantages and modifications will readily occur to those skilled in the art. The invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0028] 10 Charging System 12 Electric vehicles 14 Battery 16 Houses 18 V2H equipment 22 Cable 24 Heater 30 ECU (battery temperature control unit) 26 Temperature Sensor Sh Required time for temperature rise Sw Charging standby time T temperature

Claims

[Claim 1] a processor having a memory and hardware; The processor: Calculate the charging standby time, which is the difference between the current time and the time when battery charging starts, A required temperature rise time required to raise the temperature of the battery from the current temperature to an appropriate charging temperature is calculated; a temperature control device for a battery that starts temperature increase control of the battery when the charging standby time falls below the required temperature increase time;

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