A Novel Motor Drive and Battery Charger System using Eight-Switch Converter for EVs Incorporating Symmetrical Six-Phase Machines

This paper proposes a new configuration for onboard battery charging of electric vehicles incorporating symmetrical six-phase machines based on an eight-switch voltage-source converter. The configuration leverages the spatial phase opposition of symmetrical six-phase machine winding to perform propulsion and battery charging functions with minimized system component count. In propulsion mode, the eight-switch converter drives the six-phase machine with the same torque capability as the conventional twelve-switch converter while mitigating voltage fluctuations across dc-link capacitors by eliminating the need for dc-link midpoint connection. In battery charging mode, the converter is reconfigured as a single-phase active rectifier and connected to single-phase AC mains through the machine windings with zero developed electromagnetic torque. Switching between propulsion and charging modes is maintained using a simple hardware reconfiguration. Control schemes for both propulsion and charging modes are presented. Experimental prototyping based on a 4 kW six-phase induction machine validates the effectiveness of the proposed configuration in both propulsion and charging modes of electric vehicles.