Minimum Phase Converter-Based Hybrid Energy Storage System for Electric Vehicles and DC Loads

Battery and super-capacitor-based hybrid energy storage systems (HESS) are becoming prevalent due to the dynamically varying power demand of electric vehicles (EVs) and dc loads. The boost-derived topologies used in these systems suffer from the problem of the Right Half Plane (RHP) zero in their voltage control plant transfer function. The RHP zero restricts the bandwidth and reduces the phase margin (PM) of the voltage control loop of the system. PM is further reduced with an increase in load or with a decrease in super-capacitor voltage. This causes ringings at DC-link voltage resulting in instability and restricting the optimum utilization of super-capacitors. This article presents a minimum phase converters-based hybrid energy storage system for dynamically varying DC loads and BLDC motors used in EVs. The proposed system eliminates the RHP zero, achieving high bandwidth with an enhanced phase margin. Therefore, the system's fast, smooth, and stable operation with increased phase margin and optimum utilization of the supercapacitor is achieved. MATLAB simulation results for the complete system are presented to validate the proposed system. Experimental results for the working of a minimum phase converter are also provided.