Control method for electric vehicles, and control system for electric vehicles

Abstract

This control method for an electric vehicle is for delivering power between a drive motor and a battery and limiting the charge / discharge power of the battery when the battery temperature reaches a predetermined upper limit temperature or when the battery temperature falls below a lower limit temperature that is lower than the upper limit temperature, the method involving: calculating a load transition that represents changes in the load of the battery when traveling on a travel route from the current location of the vehicle to a destination; calculating a temperature transition of the battery on the basis of the load transition and the current battery temperature; heating the battery before the load enters a high load state when the battery temperature is predicted to be lower than the lower limit temperature when the load is transitioning from a low load state to a high load state; and cooling the battery before the load enters the high load state when it is predicted that the battery temperature will reach the upper limit temperature when the load state is the high load state.

Claims

1. A control method for an electric vehicle that exchanges power between a drive motor and a battery, and limits the charging and discharging power of the battery when the battery temperature reaches a predetermined upper limit temperature or falls below a lower limit temperature that is lower than the upper limit temperature, By estimating a low-load driving route in which the vehicle travels with a low load on the battery, and a high-load driving route in which the vehicle travels with a load greater than the low load, from the vehicle's current location to its destination, the load transition representing the change in the battery's load as the vehicle travels along the driving route is calculated. Based on the load transition and the current battery temperature, the temperature transition of the battery is calculated. If it is predicted that the battery temperature will be lower than the lower limit temperature when the load transitions from the low load state to the high load state, the battery is heated before the load reaches the high load state. If it is predicted that the battery temperature will reach the upper limit temperature when the load is in the high load state, the battery is cooled before the load reaches the high load state. A control method for an electric vehicle, wherein when heating the battery, the battery is heated so that it reaches the lower limit temperature before the load transitions to the high load state, and the heating of the battery is stopped when the battery reaches the lower limit temperature before the load transitions to the high load state.

2. If the temperature of the battery is below the lower limit temperature and it is predicted that the load on the battery will not subsequently transition to the high load state, the battery will not be heated. A control method for an electric vehicle according to claim 1, wherein the battery is not cooled when the battery temperature is higher than the lower limit temperature and it is predicted that the load on the battery will not subsequently transition to the high load state.

3. A control method for an electric vehicle according to claim 1, wherein past low-load driving routes and high-load driving routes calculated using map information representing the driving route of the vehicle from its current location to the destination and past map information having the same driving route are extracted as the current low-load driving route and high-load driving route.

4. The high-load driving path includes a high-load output driving path in which the battery supplies power to the drive motor. The electric vehicle control method according to claim 1, wherein the low-load driving route and the high-load output driving route are estimated from map information representing the driving route from the vehicle's current location to the destination.

5. The map information includes information on the location of roads constituting the driving route, information on the gradient of the roads, and information on the predicted vehicle speed of the roads. The electric vehicle control method according to claim 4, wherein the portion of the road with an uphill gradient that continues for a predetermined distance or longer, and the portion where the predicted vehicle speed exceeds a predetermined speed, are estimated to be the high-load output driving route in the aforementioned map information.

6. The high-load driving path includes a high-load output driving path in which the battery supplies power to the drive motor. A control method for an electric vehicle according to claim 1, wherein the low-load driving path and the high-load output driving path are estimated based on the load at the current location, or the load from the vehicle's starting point to the current location.

7. The aforementioned high-load driving path includes a regenerative braking driving path in which the vehicle is braked while regenerative power is supplied from the drive motor to the battery. If the temperature of the battery is lower than the lower limit temperature when the vehicle enters the regenerative braking driving path, the battery is heated before the vehicle enters the regenerative braking driving path. A control method for an electric vehicle according to claim 1, wherein, when it is predicted that the temperature of the battery will reach the upper limit temperature while the vehicle is traveling along the regenerative braking travel path, the battery is cooled before the vehicle enters the regenerative braking travel path.

8. The regenerative braking travel path is estimated from map information representing the travel path of the vehicle from its current location to its destination. The map information includes information on the location of the roads constituting the driving route, information on the gradient of the roads, and information on the predicted vehicle speed of the roads. The electric vehicle control method according to claim 7, wherein the map information is used to estimate the regenerative braking driving path as the portion of the road on a downhill slope that continues for a predetermined distance or longer, or the portion of the road that transitions from a region with a high predicted vehicle speed to a region with a speed difference of more than a predetermined amount.

9. If the temperature of the battery before the vehicle enters the regenerative braking path is lower than the lower limit temperature, and it is predicted that the total amount of power required to heat the battery to the lower limit temperature is higher than the difference obtained by subtracting the total amount of regenerative power obtained when the vehicle travels the regenerative braking path without heating the battery before entering the regenerative braking path from the total amount of regenerative power obtained when the vehicle travels the regenerative braking path after the battery has been heated to the lower limit temperature, then the vehicle will not heat the battery before entering the regenerative braking path. In cases where the temperature of the battery before the vehicle enters the regenerative braking driving path is higher than the lower limit temperature, if it is predicted that the total amount of power required to cool the battery temperature down to the lower limit temperature is higher than the difference obtained by subtracting the total amount of regenerative power obtained when the vehicle drives the regenerative braking driving path without performing battery cooling before the vehicle enters the regenerative braking driving path from the total amount of regenerative power obtained when the vehicle drives the regenerative braking driving path after the battery temperature has been cooled down to the lower limit temperature, then the method for controlling an electric vehicle according to claim 7, wherein the vehicle does not perform battery cooling before entering the regenerative braking driving path.

10. In a case where the battery supplies the power necessary for cooling the battery, and the charging power of the battery is limited when the battery's charge level reaches a predetermined upper limit, A control method for an electric vehicle according to claim 7, wherein, when it is predicted that the charge level of the battery will reach the upper limit while the vehicle is traveling along the regenerative braking travel path, the battery is cooled before the vehicle enters the regenerative braking travel path.

11. When the charge level of the battery is above a predetermined lower limit, heating and cooling of the battery can be performed. A control method for an electric vehicle according to claim 1, wherein heating and cooling of the battery are disabled when the charge level is lower than the lower limit.

12. Further estimate the charging points along the aforementioned travel route that can charge the battery, If it is predicted that the battery temperature will be lower than the lower limit temperature when the vehicle reaches the charging point to charge the battery, the battery is heated before the vehicle arrives at the charging point. A control method for an electric vehicle according to claim 1, wherein if it is predicted that the temperature of the battery will reach the upper limit temperature while the battery is being charged at the charging point, the battery is cooled before the vehicle arrives at the charging point.

13. The method for controlling an electric vehicle according to claim 12, wherein the charging point is estimated from map information representing the driving route of the vehicle from its current location to its destination.

14. When the temperature of the battery rises above an intermediate temperature between the upper and lower limits, the battery is cooled, and when the temperature of the battery falls below the intermediate temperature, the cooling of the battery is stopped. A control method for an electric vehicle according to claim 1, wherein the vehicle starts traveling along the low-load travel path when the battery temperature is higher than the intermediate temperature, and it is predicted that the end point of the low-load travel path is the destination, the cooling of the battery is stopped.

15. When the vehicle is equipped with a chiller and radiator capable of cooling the battery, When the ambient temperature is above a predetermined threshold temperature, the battery is cooled by the chiller, and when the ambient temperature is below the threshold temperature, the battery is cooled by the radiator. A control method for an electric vehicle according to claim 1, wherein the threshold temperature is set to decrease as the load predicted from the load transition increases, and the threshold temperature is set to increase as the load predicted from the load transition decreases.

16. The drive motor and A battery that exchanges power with the aforementioned drive motor, A control system for an electric vehicle, comprising: a control unit that limits the charging and discharging power of the battery when the battery temperature reaches a predetermined upper limit temperature, or when the battery temperature falls below a predetermined lower limit temperature that is lower than the upper limit temperature; The control unit estimates, from the vehicle's current location to its destination, a low-load driving path in which the vehicle travels with a low load on the battery, and a high-load driving path in which the vehicle travels with a high load greater than the low load. Based on this estimation, the control unit calculates a load transition representing the change in the battery's load as the vehicle travels along the driving path. Based on the load transition and the current battery temperature, the temperature transition of the battery is calculated. If it is predicted that the battery temperature will be lower than the lower limit temperature when the load transitions from the low load state to the high load state, the battery is heated before the load reaches the high load state. If it is predicted that the battery temperature will reach the upper limit temperature when the load is in the high load state, the battery is cooled before the load reaches the high load state. A control system for an electric vehicle that, when heating the battery, heats the battery so that it reaches the lower limit temperature before the load transitions to the high load state, and stops heating the battery when the battery reaches the lower limit temperature before the load transitions to the high load state.

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