On-vehicle control device

Abstract

To more properly perform protection control for suppressing overheat of a charger.SOLUTION: An on-vehicle control device is mounted on a vehicle including a battery, a charger that charges the battery using external power, and a temperature sensor attached near an element of the charger, and controls the charger so as to impose a limit on charging power by the charger when a voltage of the battery is less than a threshold voltage serving as a reference voltage when the battery is charged using the charger. Then, allowable heat capacity of the element of the charger is calculated based on temperature detected by the temperature sensor, a protection voltage is set so as to decrease as the allowable heat capacity increases, and when the protection voltage is less than the reference voltage, the protection voltage is used as the threshold voltage to execute protection control.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an in-vehicle control device, and more particularly to an in-vehicle control device mounted on a vehicle equipped with a battery and a charger. [Background technology]

[0002] Conventionally, this type of on-board control device has been proposed to perform scheduled charging control when charging a battery so that the lower the outside temperature is, the closer the charging will end to the scheduled work start time (see, for example, Patent Document 1). This makes it possible to charge the battery in a state that allows work to be carried out smoothly and without hassle, regardless of differences in outside temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-113436 Summary of the Invention [Problem to be solved by the invention]

[0004] In vehicle control devices, when the battery voltage is low, the charging current may exceed the charging command current, causing the charger to overheat. For this reason, protective control is performed to reduce the charging power when the battery voltage is low to prevent the charger from overheating. However, if protective control is performed when the battery voltage is below a certain voltage, the charging time may become longer.

[0005] The main object of the on-board control device of the present disclosure is to more appropriately perform protection control that prevents overheating of elements in a charger. [Means for solving the problem]

[0006] The in-vehicle control device of the present disclosure employs the following means to achieve the above-mentioned main object.

[0007] The in-vehicle control device of the present disclosure includes: A battery, a charger that charges the battery using external power; a temperature sensor attached near an element of the charger; and an on-board control device that executes protection control to impose a limit on charging power by the charger when a voltage of the battery is lower than a threshold voltage set as a reference voltage when the battery is being charged using the charger, calculating an allowable heat capacity of an element of the charger based on the temperature detected by the temperature sensor, and setting a protection voltage that tends to decrease as the allowable heat capacity increases; and when the protection voltage is lower than the reference voltage, executing the protection control using the protection voltage as the threshold voltage. It is characterized by:

[0008] The on-board control device of the present disclosure is mounted on a vehicle including a battery, a charger that charges the battery using external power, and a temperature sensor attached near the charger's elements. When charging the battery using the charger, the control device controls the charger to impose a limit on the charging power of the charger when the battery voltage is below a threshold voltage set as a reference voltage. The control device calculates the allowable heat capacity of the charger's elements based on the temperature detected by the temperature sensor and sets a protection voltage that tends to decrease as the allowable heat capacity increases. When the protection voltage is below the reference voltage, the control device executes protection control using the protection voltage as the threshold voltage. In other words, the control device executes protection control according to the allowable heat capacity of the charger's elements. This allows for more appropriate protection control. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing an outline of the configuration of an electric vehicle 20 equipped with an on-board control device according to an embodiment of the present disclosure and a charging stand 80.

[0023] FIG. [Figure 2] 4 is a flowchart showing an example of a protection threshold voltage setting process executed by a vehicle ECU 60. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, a mode (embodiment) for carrying out the present disclosure will be described. Fig. 1 is a configuration diagram showing an outline of the configuration of an electric vehicle 20 equipped with an on-board control device according to one embodiment of the present disclosure, and a charging stand 80. As shown in the figure, the electric vehicle 20 of the embodiment includes a driving motor 32, an inverter 34, a battery 36 as a power 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. The vehicle ECU 60 corresponds to the on-board control device.

[0011] The motor 32 is configured as, for example, a synchronous generator motor, and the rotor of the motor 32 is connected to a drive shaft DS that is connected to the drive wheels 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] Battery 36 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and is connected to drive power line 38. System main relay 40 is provided on drive power line 38 and connects and disconnects inverter 34 and battery 36.

[0013] Charger 50 is connected by charging power line 51 to the inverter 34 side of drive power line 38 relative to system main relay 40, and is also connected to vehicle connector 52. Charger 50 is made up of multiple elements (such as switching elements) that adjust the charging power, and charges battery 36 by adjusting the charging power supplied from charging stand 80. Vehicle connector 52 is configured to be connectable to stand connector 82 of charging stand 80 at home, a charging station, or the like. A charging relay 54 is provided on charging power line 51 between charger 50 and vehicle connector 52, and charging relay 54 connects and disconnects the vehicle connector 52 side and the drive power line 38 side.

[0014] Although not shown, the vehicle ECU 60 includes a microprocessor having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. Signals from various sensors are input to the vehicle ECU 60 via the input port. Examples of signals input to the vehicle ECU 60 include a rotational position θm of the rotor of the motor 32 from a rotational position sensor (e.g., a resolver) 32a that detects the rotational position of the rotor of the motor 32. Examples of signals input to the vehicle ECU 60 include a voltage Vb of the battery 36 from a voltage sensor 36a attached between the terminals of the battery 36, a current Ib of the battery 36 from a current sensor 36b attached to the output terminal of the battery 36, a temperature Tb of the battery 36 from a temperature sensor 36c attached to the battery 36, and a temperature Tchg near the elements of the charger 50 from a temperature sensor 50a attached near the elements. Another example of a signal input to the vehicle ECU 60 is a connection signal from a connection sensor 53 provided in the vehicle connector 52. Since the vehicle ECU 60 also functions as a drive control device for the vehicle, information necessary for driving control is also input to the vehicle ECU 60. Examples of this information include a start signal from a start switch, a shift position from a shift position sensor that detects the operating position of the shift lever, an accelerator opening from an accelerator pedal position sensor that detects the amount of depression of the accelerator pedal, a brake pedal position from a brake pedal position sensor that detects the amount of depression of the brake pedal, and vehicle speed from a vehicle speed sensor.

[0015] Various control signals are output from the vehicle ECU 60 via the output port. The signals output from the vehicle ECU 60 include, for example, signals to a plurality of switching elements of the inverter 34. Examples of such signals include a switching control signal, a control signal to the system main relay 40, a drive control signal to the charger 50, and a control signal to the charging relay 54. 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 is capable of wireless communication with a station electronic control unit (hereinafter referred to as "station ECU") 86 of the charging station 80 at home, at a charging station, or the like.

[0016] The charging stand 80 includes a stand connector 82, a power converter 84, and a stand ECU 86. The stand connector 82 is configured to be connectable to the vehicle connector 52 of the electric vehicle 20. The power converter 84 is connected to the stand connector 82 and an external power source 90 configured as an AC power source such as a household power source or a commercial power source. When the vehicle connector 52 and the stand connector 82 are connected and a command to charge the battery 36 is issued, the power converter 84 converts AC power from the external power source 90 into DC power and adjusts the power (voltage and current) before supplying it to the electric vehicle 20.

[0017] Although not shown, the stand ECU 86 includes a microprocessor having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports. Signals from various sensors are input to the stand ECU 86 via the input port. Examples of the signals input to the stand ECU 86 include the output voltage Vout of the power converter 84 from a voltage sensor 84a attached between the output terminals of the power converter 84, and the output current Iout of the power converter 84 from a current sensor 84b attached to the output terminal of the power converter 84. Various control signals are output from the stand ECU 86 via the output port. Examples of signals output from the stand ECU 86 include a control signal to the power converter 84. The stand ECU 86 is capable of wireless communication with the vehicle ECU 60 of the electric vehicle 20.

[0018] In the electric vehicle 20 of this embodiment configured as described above, when the vehicle connector 52 and the stand connector 82 are connected while the vehicle is parked at home, a charging station, or the like with the system off, a connection signal is sent from the connection sensor 53 to the vehicle ECU 60, and the vehicle ECU 60 detects the connection between the vehicle connector 52 and the stand connector 82. When the user subsequently issues a command for external charging to charge the battery 36 using power from an external power source 90 (charging stand 80), the vehicle ECU 60 first turns on the system main relay 40 and the charging relay 54. The vehicle ECU 60 then sends a current command Ic* for external charging to the stand ECU 86, and the stand ECU 86 controls the power converter 84 so that the output current Iout of the power converter 84 becomes the current command Ic*. In this manner, external charging is performed. Then, when the charger 50 adjusts the charging power and the battery 36's power storage percentage SOC reaches a predetermined percentage Sch (e.g., approximately 80% to 95%), the vehicle ECU 60 transmits an external charging termination command to the station ECU 86. Upon receiving this command, the station ECU 86 stops the power converter 84. In this manner, external charging is terminated. Thereafter, the vehicle ECU 60 turns off the system main relay 40 and the charging relay 54. If the output voltage Vb of the battery 36 is low when charging the battery 36, a state may occur in which the charging current Ic exceeds the current command Ic* and becomes excessively large, causing the elements of the charger 50 to overheat. In the electric vehicle 20 of this embodiment, in order to prevent such overheating of the elements of the charger 50, when the output voltage Vb of the battery 36 is equal to or lower than a protection threshold voltage Vlow, the electric vehicle 20 executes protective control to control the charger 50 to reduce the charging power so that the charging current Ic is equal to or lower than an upper limit current that is slightly higher than the current command Ic*.

[0019] Next, the operation of the electric vehicle 20 of this embodiment configured as described above, in particular the operation when setting the protection threshold voltage Vlow used for protection control when external charging is started, will be described. Fig. 2 is a flowchart showing an example of a protection threshold voltage setting process executed by the vehicle ECU 60 when external charging is started.

[0020] When the protection threshold voltage setting process is executed, the vehicle ECU 60 first estimates the outside air temperature Tout based on the temperature Tchg near the elements of the charger 50 detected by the temperature sensor 50a (step S100). In this embodiment, the outside air temperature Tout is estimated by determining the relationship between the temperature Tchg near the elements and the outside air temperature Tout through experiments, machine learning, or the like, and storing the relationship in advance as an outside air temperature setting map, and deriving the corresponding outside air temperature Tout from the map when the temperature Tchg near the elements is given.

[0021] Next, the allowable heat capacity ΔT of the element is calculated based on the estimated outside air temperature Tout (step S110). The allowable heat capacity of the element is the heat capacity required to bring the element to the allowable maximum temperature, and can be obtained based on the element temperature and the outside air temperature Tout. Specifically, the relationship between the element temperature, the outside air temperature Tout, and the allowable heat capacity of the element is determined by experimentation, machine learning, or the like, and stored in advance as an allowable heat capacity setting map, and when the element temperature and the outside air temperature Tout are given, the corresponding allowable heat amount can be derived from the map.

[0022] Next, a protection voltage Vpro is set based on the allowable heat capacity ΔT (step S120). The protection voltage Vpro is used as a protection threshold voltage Vlow at which protection control is initiated. In this embodiment, the protection voltage Vpro is set to decrease as the allowable heat capacity ΔT increases. This is based on the fact that the larger the allowable heat capacity ΔT, the slower the overheating of the element occurs.

[0023] Then, it is determined whether the protection voltage Vpro is less than the reference voltage Vstnd (step S130). The reference voltage Vstnd is an initial voltage predetermined as the protection threshold voltage Vlow. If it is determined that the protection voltage Vpro is less than the reference voltage Vstnd, the protection threshold voltage Vlow is set to the protection voltage Vpro (step S140), and this process ends. On the other hand, if it is determined that the protection voltage Vpro is equal to or greater than the reference voltage Vstnd, the protection threshold voltage Vlow is set to the reference voltage Vstnd (step S150), and this process ends.

[0024] In the electric vehicle 20 of the embodiment described above, when external charging begins, the outside air temperature Tout is estimated based on the temperature Tchg near the elements of the charger 50, and the allowable heat capacity ΔT of the elements of the charger 50 is calculated based on this estimated outside air temperature Tout. The protection voltage Vpro is set so that it decreases as the allowable heat capacity ΔT of the elements of the charger 50 increases. When the protection voltage Vpro is lower than the reference voltage Vstnd, which is a predetermined initial voltage as the protection threshold voltage Vlow, the protection voltage Vpro is used as the protection threshold voltage Vlow for protection control. As a result, protection control that suppresses overheating of the elements of the charger 50 can be more appropriately performed in accordance with the temperature Tchg near the elements and the outside air temperature Tout.

[0025] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be explained below. In the embodiment, the battery 36 corresponds to the "battery", the charger 50 corresponds to the "charger", the temperature sensor 50a corresponds to the "temperature sensor", and the vehicle electronic control unit (vehicle ECU) 60 corresponds to the "vehicle control device".

[0026] The correspondence between the main elements of the embodiments and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the embodiments are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the embodiments are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0027] The present disclosure has been described above using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be embodied in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0028] The present disclosure is applicable to the manufacturing industry of in-vehicle control devices, etc. [Explanation of symbols]

[0029] 20 electric vehicle, 32 motor, 34 inverter, 36 battery, 36a voltage sensor, 36b current sensor, 36c temperature sensor, 38 drive power line, 40 system main relay, 50 charger, 51 charging power line, 52 vehicle connector, 53 connection sensor, 54 charging relay, 60 vehicle ECU, 80 charging stand, 82 stand connector, 84 power converter, 84a voltage sensor, 84b current sensor, 86 stand ECU, 90 external power supply.

Claims

1. A battery, a charger that charges the battery using external power; a temperature sensor attached near an element of the charger; and an on-board control device that executes protection control to impose a limit on charging power by the charger when a voltage of the battery is lower than a threshold voltage set as a reference voltage when the battery is being charged using the charger, calculating an allowable heat capacity of an element of the charger based on the temperature detected by the temperature sensor, and setting a protection voltage that tends to decrease as the allowable heat capacity increases; and when the protection voltage is lower than the reference voltage, executing the protection control using the protection voltage as the threshold voltage.

1. An in-vehicle control device comprising:

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