Power Distribution Strategy for Electric Vehicle Hybrid Power System

Abstract. Aiming at the load power fluctuates greatly during the driving process of the electric vehicles, a large load current is required, it is difficult to meet the load demand by the lithium battery alone, so the super-capacitor is introduced. In order to give full play to advantages of both, and to reduce the transient high current fluctuation of lithium battery, a power allocation strategy based on adaptive frequency is proposed. The power supply current, super-capacitor and bus voltage are controlled with double closed-loop control, and the filter time constant is dynamically adjusted according to the state of charge and load requirements of the super-capacitor, the battery bears the low-frequency component of the load current, and the super-capacitor provides the residual component, therefore, the charge and discharge current of the battery can be reduced and reducing the large current fluctuation. The Matlab/Simulink the results show that the method fully utilizes the super-capacitor smooth load fluctuation, which effectively reduces the charge and discharge current of the lithium battery and reduces the fluctuation range, thus prolonging the service life.