Multi-source Bidirectional Quasi-Z-source Inverter using Fractional Order PI Controller for Electric Traction System

This paper proposes a new control configuration of hybrid energy storage system (HESS) using a battery pack and a supercapacitor for electric vehicle (EV). The HESS is designed based on bidirectional quasi-Z-source inverter (QZSI) and a DC-DC converter. The HESS configuration with its modeling is presented in this paper. The operation modes of HESS for EV and its control scheme using fractional order PI controller (FOPI) are presented. FOPI controller is combined with a filtering technique to contribute to battery degradation mitigation. The flux-weakening method is applied to provide correct operation with the maximum available torque at any speed request within current and voltage limits. The simulation results verify the performance and effectiveness of the HESS topology. The results also point out the ability of the inverter to give a fast response to the mechanical load and provide a DC bus constant voltage over the power-demand profile. The proposed HESS with these types of controller and converter can globally enhance the performance of the EV by allowing the efficient energy use of the battery for a longer distance coverage and extending its driving range.