A Super Capacitor Charging Device Based on the Sliding Mode Control Strategy

In this paper, a sliding mode control strategy is proposed for the tram with supercapacitor to deal with the problems, such as the large output current fluctuation and the pool system robustness. Based on the average state model of the DC-DC converter and supercapacitor characteristics, a dynamic model of the charging system for the tram with supercapacitor energy storage is established. By selecting the appropriate sliding surface and Lyapunov function, the duty cycle output rule is determined to satisfy the system stability requirements. According to the requirements of the device, controllers are designed for the constant current charging mode and constant power charging mode respectively. The simulation experimental results show that the charging system adopting the method proposed in this paper can reach the steady state quickly. The current fluctuation and system disturbance can be suppressed effectively, which can increase the system stability and reliability of the system.