An Isolated High-Power Integrated Charger in Electrified Vehicle Applications
Journal article, 2011
For electric and hybrid vehicles using grid power to charge the battery, traction circuit components are not normally engaged during the charging time; hence, there is a possibility to use them in the charger circuit to have an on-board integrated charger. An isolated high-power integrated charger based on a special electrical machine with a double set of stator windings is described. Through reconfiguration of the motor stator windings in the charging mode, a six-terminal machine is achieved. The so-called motor/generator acts as an isolated three-phase power source after synchronization with the utility grid in the charging mode. This rotary isolated power source constitutes a three-phase boost rectifier (battery charger) with full utilization of the inverter. The motor windings are reconfigured by a relay-based switching device for the charging and traction modes. This paper presents the mathematical model of the motor/generator and explains the system's functionality for the traction and charging modes. Further, the charger grid synchronization and charge control are described. Finally, the simulation results are presented for a practically designed system with a traction power of 25 kW and a possible charge power of 12.5 kW.