An Integrated Battery Charger for EVs Based on a Symmetrical Six-Phase Machine

A new topology for integrated on-board battery charging is proposed in this paper. A symmetrical six-phase machine and inverter, which are used for propulsion, are incorporated into the charging process. The configuration achieves power transfer through the machine without developing an average torque in it during the charging mode. Additional degrees of freedom of six-phase machines are explained and it is shown how they can be utilized to transfer a part of the excitation from the torque producing plane into the non-flux/torque producing plane of the machine, so that rotation does not take place. The advantage is that the motor does not have to be mechanically locked during the charging process. The configuration is operated with a unity power factor and the appropriate control scheme is introduced for this purpose. Theoretical considerations are validated by simulations for both charging and vehicle-to-grid (V2G) modes of operation.