Energy Management Applications in Battery and Supercapacitor Hybrid Electric Vehicles Using Fuzzy Logic

The battery is primarily used in electric vehicles as an energy storage unit because it has a large energy storage capacity. The disadvantages of the typical battery are that it has a small power density, a limited-service life, and a relatively high price. Due to the driving cycle characteristics of electric vehicles, which are often not constant, because an excessive charge-discharge process causes them, it decreases battery life. Additional energy storage systems such as the supercapacitor are recently applied to overcome energy fulfilment. Since the battery and the supercapacitor have different characteristics in charging and discharging operation, a proper energy management system should be applied. An intelligent method to share the energy consumption of both battery and supercapacitor is proposed in this research. This paper proposed a fuzzy logic controller (FLC) be applied to the power distribution control for the hybrid energy storage system. The proposed power distribution is carried out by attaching a buck converter to the battery. The duty cycle value of the buck converter is controlled using FLC according to vehicle starting, normal, and regenerative braking operation. The simulation uses MATLAB Simulink software. The simulation result shows that the FLC can successfully manage the energy sharing between the battery and supercapacitor according to vehicle operation when in the starting condition, the supercapacitor fully supplies the power demand. Under normal conditions, most of the power demand is supplied by the battery. Under the regenerative braking condition, the supercapacitor fully receives the current and power.