electric vehicles

Abstract

This helps to reduce the lifespan of onboard chargers. [Solution] A control device for an electric vehicle equipped with a charger that charges a power storage device using an external power source sets the charging power and charging time when charging the power storage device based on the charge storage rate of the power storage device, estimates the self-heating of the charger based on the charging power and charging time, and sets the charging start time and charging end time so as to suppress the rise in the temperature of the charger during charging of the power storage device based on the cooling state of the charger, the self-heating of the charger, the change in ambient temperature over time and the charging time.

Description

Technical Field

[0001] The present disclosure relates to an electric vehicle, and more particularly to an electric vehicle equipped with a charger that charges a power storage device using an external power source.

Background Art

[0002] Conventionally, as this type of electric vehicle, the battery temperature during driving and after parking is predicted based on the battery temperature, outside air temperature, and predicted outside air temperature after parking. The upper and lower limit values of the battery charge amount are set based on the predicted battery temperature after parking. When the battery charge amount reaches the lower limit value of the charge amount, charging of the battery is started, and when the battery charge amount reaches the upper limit value of the charge amount, charging of the battery is terminated (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described electric vehicle, the life of the in-vehicle charger may be reduced depending on the charging start time and the charging time. The aluminum electrolytic capacitor generally used in the charger has its life reduced when exposed to high temperatures. Therefore, in order to suppress the reduction in the life of the charger, it is necessary to prevent the charger from becoming hot.

[0005] The main object of the electric vehicle of the present disclosure is to suppress the reduction in the life of the in-vehicle charger.

Means for Solving the Problems

[0006] The electric vehicle of the present disclosure has adopted the following means to achieve the above main object.

[0007] The electric vehicle disclosed herein is An electric vehicle comprising: an electric motor that outputs power for driving; a power storage device that exchanges power with the electric motor; a charger that charges the power storage device using an external power source; and a control device that controls the charging of the power storage device by the charger, The control device sets the charging power and charging time when charging the energy storage device based on the energy storage device's charge level, estimates the self-heating of the charger based on the charging power and charging time, and sets the charging start time and charging end time based on the cooling state of the charger, the self-heating of the charger, the time change of ambient temperature, and the charging time, so as to suppress the rise in the temperature of the charger during charging of the energy storage device. It is characterized by the following:

[0008] In the electric vehicle of this disclosure, the charging power and charging time when charging the energy storage device are set based on the energy storage device's charge level, and the self-heating of the charger is estimated based on the charging power and charging time. Then, the charging start time and charging end time are set so as to suppress the rise in the charger's temperature during charging of the energy storage device, based on the charging device's cooling state, the charging device's self-heating, the change in ambient temperature over time, and the charging time. By suppressing the rise in the charger's temperature during charging of the energy storage device in this way, the reduction in the charger's lifespan can be suppressed. The charging device's cooling state includes water cooling with cooling water and air cooling with ambient air. If the charging device is water-cooled, the rise in cooling water temperature is estimated based on the charging device's self-heating, and the charging start time and charging end time should be set considering the rise in cooling water temperature and the change in ambient temperature over time. If the charging device is air-cooled, the rise in charger temperature is estimated based on the charging device's self-heating, and the charging start time and charging end time should be set considering the rise in charger temperature and the change in ambient temperature over time. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing the configuration of an electric vehicle 20 as one embodiment of the present disclosure. [Figure 2]This flowchart shows an example of the charging time setting process performed by the vehicle ECU 60. [Figure 3] This flowchart shows an example of the charging time setting process for a modified example. [Modes for carrying out the invention]

[0010] Next, embodiments for implementing this disclosure will be described. Figure 1 is a schematic diagram showing the configuration of an electric vehicle 20 as one embodiment of this disclosure. As shown in the figure, the electric vehicle 20 of the embodiment includes a motor 32 for driving, an inverter 34, a battery 36 as an energy storage device, a drive power line 38, a system main relay 40, a charger 50, a vehicle connector 52 connected to a charging power line 51, a charging relay 54, and a vehicle electronic control unit (hereinafter referred to as "vehicle ECU") 60.

[0011] The motor 32 is configured, for example, as a synchronous generator-motor, and the rotor of the motor 32 is connected to a drive shaft DS which is connected to a drive wheel DW via a differential gear. The inverter 34 is connected to the motor 32 and also to a drive power line 38. The motor 32 is rotationally driven by switching control of a plurality of switching elements (not shown) of the inverter 34.

[0012] The battery 36 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery and is connected to the drive power line 38. The system main relay 40 is provided on the drive power line 38 and connects and disconnects the inverter 34 side and the battery 36 side.

[0013] The charger 50 is connected to the inverter 34 side of the drive power line 38, beyond the system main relay 40, via a charging power line 51, and is also connected to the vehicle connector 52. The charger 50 converts power supplied from an external power source, such as a commercial power supply, into DC power of the desired voltage to charge the battery 36. The vehicle connector 52 is configured to be connectable to a connector of an external power source, such as a home or charging station. A charging relay 54 is provided between the charger 50 and the vehicle connector 52 on the charging power line 51, and the charging relay 54 connects and disconnects the vehicle connector 52 side and the drive power line 38 side. The charger 50 is cooled by a cooling device 55 that circulates cooling water while the battery 36 is being charged.

[0014] The vehicle ECU 60, although not shown in the diagram, includes a microprocessor with a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. Signals from various sensors are input to the vehicle ECU 60 via its input ports. Examples of signals input to the vehicle ECU 60 include the rotational position θm of the motor 32 rotor from a rotational position sensor (e.g., resolver) 32a that detects the rotational position of the motor 32's rotor. Other examples include the voltage Vb of the battery 36 from a voltage sensor 36a attached between the terminals of the battery 36, the current Ib of the battery 36 from a current sensor 36b attached to the output terminal of the battery 36, and the temperature Tb of the battery 36 from a temperature sensor 36c attached to the battery 36. Connection signals from a connection sensor 53 provided on the vehicle connector 52 and the coolant temperature Tw supplied to the charger 50 by the cooling device 55 are also included. Since the vehicle ECU 60 also functions as a vehicle drive control device, it also receives information necessary for driving control. Examples of this information include the start signal from the start switch, the shift position from the shift position sensor which detects the position of the shift lever, the accelerator opening from the accelerator pedal position sensor which detects the amount the accelerator pedal is pressed, the brake pedal position from the brake pedal position sensor which detects the amount the brake pedal is pressed, and the vehicle speed from the vehicle speed sensor.

[0015] Various control signals are output from the vehicle ECU 60 via its output ports. Examples of signals output from the vehicle ECU 60 include switching control signals to multiple switching elements of the inverter 34, control signals to the system main relay 40, drive control signals to the charger 50, control signals to the charging relay 54, and drive control signals to the cooling device 55. The vehicle ECU 60 calculates the state of charge (SOC) of the battery 36 based on the current Ib of the battery 36 from the current sensor 36b. The vehicle ECU 60 communicates wirelessly with an external information center 100, enabling it to acquire various information such as weather information.

[0016] In the electric vehicle 20 of this embodiment, when the vehicle is stopped with the system off, if the vehicle connector 52 and the connector on the external power supply side are connected, a connection signal is sent from the connection sensor 53 to the vehicle ECU 60. When the user instructs external charging to charge the battery 36 using power from an external power supply, the vehicle ECU 60 executes the charging time setting process illustrated in Figure 2, and charges the battery 36 based on the charging start time and charging end time set by this process.

[0017] When the charging time setting process is executed, the vehicle ECU 60 first calculates the state of charge (SOC) of the battery 36 from the voltage Vb of the battery 36 (step S100). The SOC can be obtained, for example, by pre-determining the relationship between the voltage Vb of the battery 36 and the SOC through experiments or machine learning, storing it as a map for deriving the SOC, and then deriving the corresponding SOC from the map when the voltage Vb of the battery 36 is given.

[0018] Next, the charging power Wchg and charging time Tchg are set based on the state of charge (SOC) of the battery 36 (step S110). The charging power Wchg and charging time Tchg can be set by, for example, determining the relationship between the state of charge (SOC) of the battery 36, the charging power Wchg, and the charging time Tchg in advance through experiments or machine learning, storing it as a map for setting the charging power and time, and then deriving the corresponding charging power Wchg and charging time Tchg from the map when the state of charge (SOC) of the battery 36 is given.

[0019] Next, the self-heating of the charger 50 is estimated based on the charging power Wchg and charging time Tchg (step S120). Self-heating can be estimated, for example, by pre-determining the relationship between the charging power Wchg, charging time Tchg, and the self-heating of the charger 50 through experiments or machine learning, storing it as a self-heating estimation map, and then deriving the corresponding self-heating of the charger 50 from the map when the charging power Wchg and charging time Tchg are given.

[0020] When estimating the self-heating of the charger 50, an increase in the cooling water temperature is estimated based on this self-heating and the temperature Tw of the cooling water supplied from the cooling device 55 (step S130). The increase in the cooling water temperature can be estimated, for example, by previously obtaining the relationship between the self-heating of the charger 50, the cooling water temperature Tw, the charging time Tchg, and the increase in the cooling water temperature through experiments, machine learning, etc., storing it as a map for estimating the increase in the cooling water temperature, and deriving the corresponding increase in the cooling water temperature Tw from the map when the self-heating of the charger 50, the cooling water temperature Tw, and the charging time Tchg are given.

[0021] Then, the change in the outside air temperature over time at the current position from the current time to a predetermined time (for example, 12 hours later) exceeding the charging time Tchg is acquired from the information center 100 (step S140), and the charging start time and the charging end time are set so as to suppress the temperature rise of the charger 50 based on the increase in the cooling water temperature Tw, the change in the outside air temperature over time, and the charging time Tchg (step S150). The setting of the charging start time and the charging end time can be, for example, including the time of the minimum value of the change in the outside air temperature over time at a predetermined time, and setting the start point and the end point of the time that matches when the outside air temperature at the charging start time and the temperature obtained by multiplying the increase in the cooling water temperature after the charging time Tchg by a coefficient are used as the outside air temperature as the charging start time and the charging end time.

[0022] In the electric vehicle 20 of the embodiment described above, when charging the battery 36 based on the state of charge SOC of the battery 36, the charging power Wchg and the charging time Tchg are set, and the self-heating of the charger 50 is estimated based on the charging power Wchg and the charging time Tchg. An increase in the cooling water temperature Tw is estimated based on the self-heating of the charger 50 and the cooling water temperature Tw. Then, the charging start time and the charging end time are set so as to suppress the temperature rise of the charger 50 to a low level based on the increase in the cooling water temperature Tw, the change in the outside air temperature over time, and the charging time Tchg. Thereby, it is possible to suppress the temperature rise of the charger 50 during charging of the battery 36 and suppress the decrease in the life of the charger 50.

[0023] In the electric vehicle 20 of this embodiment, the charger 50 is cooled by a water-cooled cooling device 55, but the charger 50 may also be cooled by air cooling. In this case, the charging time setting process of the modified example shown in Figure 3 can be performed.

[0024] In the modified charging time setting process, the vehicle ECU 60 calculates the charge level (SOC) of the battery 36 from the voltage Vb of the battery 36 (step S100), similar to the charging time setting process in Figure 2, sets the charging power Wchg and charging time Tchg based on the charge level (SOC) of the battery 36 (step S110), and estimates the self-heating of the charger 50 based on the charging power Wchg and charging time Tchg (step S120). Subsequently, it estimates the temperature rise of the charger 50 based on the self-heating of the charger 50 and the ambient temperature (step S130B). The temperature rise of the charger 50 can be estimated, for example, by pre-determining the relationship between the self-heating of the charger 50, the ambient temperature, and the temperature rise of the charger 50 through experiments or machine learning, storing it as a map for estimating the charger temperature rise, and then deriving the corresponding temperature rise of the charger 50 from the map when the self-heating of the charger 50 and the ambient temperature are given.

[0025] Then, the information center 100 acquires the change in ambient temperature over time at the current location from the current time to a predetermined time (for example, 12 hours later) that exceeds the charging time Tchg (step S140), and sets the charging start time and charging end time to suppress the temperature rise of the charger 50 based on the rise of the charger 50, the change in ambient temperature over time, and the charging time Tchg (step S150B). The setting of the charging start time and charging end time can be, for example, set to include the time of the minimum value of the change in ambient temperature over time in the predetermined time, and set to the start and end points of the time that match when the ambient temperature at the charging start time and the temperature obtained by multiplying the temperature rise of the charger 50 by a coefficient after the charging time Tchg are taken as the ambient temperature.

[0026] Even in this modified electric vehicle 20B, the same effects as in the electric vehicle 20 of the embodiment can be achieved, namely, the effect of suppressing the rise in temperature of the charger 50 during charging of the battery 36 and suppressing the reduction in the lifespan of the charger 50.

[0027] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be explained. In the embodiment, the motor 32 corresponds to an "electric motor," the battery 36 corresponds to an "energy storage device," the charger 50 corresponds to a "charger," and the vehicle ECU 60 corresponds to a "control device."

[0028] Furthermore, the correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem is merely an example to specifically explain the form in which the embodiment implements the invention described in the section on means for solving the problem, and does not limit the elements of the invention described in the section on means for solving the problem. In other words, the interpretation of the invention described in the section on means for solving the problem should be based on the description in that section, and the embodiment is merely one specific example of the invention described in the section on means for solving the problem.

[0029] Although the present disclosure has been described above using embodiments, the present disclosure is not limited in any way to these embodiments, and can of course be implemented in various forms without departing from the gist of the present disclosure. [Industrial applicability]

[0030] This disclosure can be used in industries such as electric vehicle manufacturing. [Explanation of symbols]

[0031] 20 Electric vehicle, 32 Motor, 34 Inverter, 36 Battery, 36a Voltage sensor, 36b Current sensor, 36c Temperature sensor, 38 Power line for drive, 40 System main relay, 50 Charger, 51 Power line for charging, 52 Vehicle connector, 53 Connection sensor, 54 Charging relay, 55 Cooling device, 60 Vehicle ECU.

Claims

[Claim 1] An electric vehicle comprising: an electric motor that outputs power for driving; a power storage device that exchanges power with the electric motor; a charger that charges the power storage device using an external power source; and a control device that controls the charging of the power storage device by the charger, The control device sets the charging power and charging time when charging the energy storage device based on the energy storage device's charge level, estimates the self-heating of the charger based on the charging power and charging time, and sets the charging start time and charging end time based on the cooling state of the charger, the self-heating of the charger, the time change of ambient temperature, and the charging time, so as to suppress the rise in the temperature of the charger during charging of the energy storage device. An electric vehicle characterized by the following features.

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