An Isolated High-Power Integrated Charger in Electrified Vehicle Applications

Artikel i vetenskaplig tidskrift, 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.