An Integrated 20-kW Motor Drive and Isolated Battery Charger for Plug-In Vehicles

Abstract

For vehicles using grid power to charge the battery, traction circuit components are not normally engaged during the charging time, so there is a possibility to use them in the charger circuit to have an on-board integrated motor drive and battery charger. An isolated high-power three-phase integrated motor drive and charger based on a split-phase permanent magnet motor is presented in this paper. The motor winding connections are reversible by a relay-based switching device for traction and battery charging. In traction mode, the motor is a classical three-phase motor, but in charging mode it is a rotating isolating transformer providing a three-phase voltage source for the inverter to charge the battery. A mathematical model of the motor with six stator windings is presented for an arbitrary phase shift in windings. For the charging mode, the split-phase motor grid synchronization process and charge control are explained including the developed controller. A 20 -kW system is designed and implemented to verify the proper operation of the proposed system. Simulation and practical results are provided to show the system performance in terms of functionality, dynamic response, and efficiency. Moreover, some discussions, recommendations, and limitations are provided to give more practical insights.