Strategies for control of a battery/supercapacitor system in an electric vehicle

Two control strategies for a battery/supercapacitor vehicle have been developed, one optimised to maximise vehicle efficiency and the other to extend battery life by reducing peak battery currents. Both strategies will also improve the vehiclepsilas ability to accelerate. The efficiency strategy improves the yield of the vehicle by up to 7.6%. The battery life strategy reduces battery currents by up to 72%. In both cases, the total extent of improvements depends on the specific drive cycle used. Typically the efficiency strategy also shows reduced battery currents by 50psila60%, while the battery life strategy shows an improved efficiency of up to 2.4% in some cycles. In other cycles the efficiency is decreased by the battery life strategy. In general it is not possible to optimise for both efficiency and battery life; one must be prioritised over the other. Drive cycles with higher peak power showed greater improvements to efficiency. Drive cycles with lower average power and shorter length showed greater improvements to peak battery current.