Systems and methods for battery life maximization under fixed-route applications
An embodiment of the invention provides a method of charging an energy storage system for an electric vehicle. The method includes determining the estimated consumption for a specific route of the electric vehicle at different times and setting a target end point for the energy storage system based upon a minimum state of charge level for the energy storage system. The method further includes determining charge set points for the energy storage system based upon the target end point and the determined estimated consumption and determining the actual end point of the energy storage system after operation of the electric vehicle on the given route. The method also includes comparing the actual end point to the target end point and determining the difference in state of charge for the energy storage system between the actual end point and the target end point. In addition, the method includes using the difference between the actual end point and the target end point to adjust the charge set points for the energy storage system.
1. A method of charging an energy storage system of an electric vehicle, the electric vehicle being configured to be charged at multiple charging events during an operating period, the multiple charging events including a first charging event and a second charging event subsequent to the first charging event, comprising:
selecting a minimum desired state of charge for the energy storage system, wherein the minimum desired state of charge is a predetermined positive value of charge;
calculating a target maximum state of charge based on at least (a) an estimated energy consumption of the electric vehicle between the first charging event and the second charging event and (b) the selected minimum desired state of charge, such that energy storage system retains the minimum desired state of charge at the second charging event; and
charging the electric vehicle to the calculated target maximum state of charge during the first charging event.
2. The method of claim 1 further including, determining an actual minimum state of charge of the electric vehicle at the second charging event, wherein the actual minimum state of charge is the actual value of charge retained in the energy storage system at the second charging event.
3. The method of claim 2 , further including adjusting the target maximum state of charge based on a difference between the target and actual minimum states of charge.
4. The method of claim 1 , further including determining the estimated energy consumption of the vehicle between the first and second charging events.
5. The method of claim 4 , wherein determining the estimated energy consumption includes predicting the energy consumption based on one or more of route information, expected passenger volume, and weather data.
6. The method of claim 1 , wherein the operating period is a single day.
7. The method of claim 6 , further including determining the estimated energy consumption of the electric vehicle between each two successive charging events of the multiple charging events of a day.
8. The method of claim 1 , wherein the minimum desired state of charge is a function of fluctuation in energy cost during the operating period.
9. The method of claim 1 , further including adjusting the target maximum state of charge based on the type of configuration of the energy storage system.
10. The method of claim 1 , wherein the minimum desired state of charge is between about 10%-40% of a capacity of the energy storage system.
11. A method of charging an electric vehicle configured to be charged at multiple charging events during a day, comprising:
determining an estimated energy consumption of the electric vehicle between a first and a second charging event during the day;
selecting a target minimum state of charge of the electric vehicle, the minimum state of charge being a desired minimum value of charge to be retained in an energy storage system of the electric vehicle;
determining a target maximum state of charge of the electric vehicle based at least on the determined energy consumption and the selected target minimum state of charge;
charging the electric vehicle to the target maximum state of charge at the first charging event;
determining an actual minimum state of charge of the electric vehicle at the second charging event, wherein the actual minimum state of charge is the actual value of charge retained in the energy storage system at the second charging event; and
adjusting the target maximum state of charge for the second charging event based on a difference between the target and actual minimum states of charge.
12. The method of claim 11 , wherein the first and second charging events are two successive charging events, and wherein determining the estimated energy consumption includes determining the energy consumption between each two successive charging events during the day.
13. The method of claim 11 , wherein determining an estimated energy consumption includes predicting the energy consumption based on one or more of route information, expected passenger volume, and weather data.
14. The method of claim 11 , wherein determining a target maximum state of charge includes adjusting the target maximum state of charge to reduce the variation in target maximum states of charge at different charging events during the day.
15. The method of claim 11 , wherein determining a target maximum state of charge includes adjusting the target maximum state of charge to eliminate a charging event that occurs during a time of high energy cost.
16. The method of claim 11 , wherein determining a target maximum state of charge includes adjusting the target maximum state of charge based on the type of configuration of the energy storage system.
17. The method of claim 11 , wherein selecting the target minimum state of charge and determining the target maximum state of charge includes adjusting the target minimum state of charge and the target maximum state of charge to increase life of the energy storage system.
18. A method of charging an electric vehicle configured to be charged at multiple charging events during a day, comprising:
determining an estimated energy consumption of the electric vehicle between two charging events during the day;
selecting a target minimum state of charge of the electric vehicle, the minimum state of charge being a desired minimum value of charge to be retained in an energy storage system of the electric vehicle;
determining a target maximum state of charge of the electric vehicle based at least on the determined energy consumption and the selected target minimum state of charge;
adjusting the target maximum state of charge to eliminate a charging event that occurs at a time of high energy cost during the day; and
charging the electric vehicle to the adjusted target maximum state of charge.
19. The method of claim 18 , further including determining a difference between the selected target minimum state of charge and an actual value of charge retained in the energy storage system at a charging event.
20. The method of claim 19 , further including adjusting the target maximum state of charge for a later charging event based on the determined difference.