An Integrated EV Battery Charger With Retrofit Capability

In this article, a fast onboard integrated battery charger that uses the stator windings of an asymmetrical six-phase machine (rewound from an existing three-phase motor) is proposed. The proposed scheme uses the existing three-legged traction inverter for both charging and driving modes. This reduces the total cost of the system compared with the existing battery charging systems for electric vehicles. The leakage inductances of the rewound asymmetrical six-phase machine are used instead of additional inductors as the interface between the grid and the inverter, for charging the battery. During the driving mode, the windings of the six-phase machine are connected in series, i.e., the 30° phase belts are connected in series, making it a three-phase machine. During charging, the windings of the six-phase machine are reconfigured to produce zero electromagnetic torque (a pulsating magnetic field is produced). In addition, different current control schemes, namely PI, PDF, and PR, are implemented and compared in this article. Experimental results for steady-state and transient operations are presented to validate the proposed scheme.