Integrated Battery Charger for EV by Using Three-Phase Induction Motor Stator Windings as Filter

This article presents an on-board charger for the electric vehicles (EVs) by integrating the drive-train components into the charging process. The stator windings of three-phase induction motor (IM) can be used as a grid interfacing inductor with the constraint that the rotor should be in the stationary position during the charging mode. This article proposes the stator winding configurations of three-phase IM split into two equal parts at zero electrical degree for the on-board integrated battery charger. The effective filtering with these two three-phase windings combination, either in series or parallel while the rotor is in a stationary position, is analyzed. The equivalent inductance provided by the stator windings for filtering is increased by generating the pulsating magnetic field (PMF) in the motor. However, it results in the unbalanced impedances in filter causing odd harmonics in the grid current. This is resolved by using a modified double synchronous reference frame control algorithm, which maintains the balanced current operation with the unity power factor at the grid interface during the charging mode. This configuration is obtained by using the existing three-phase-based drive-train components, thereby providing the saving in space and reducing the weight of EV. Experimental results for the proposed winding configurations are presented with filter losses and system efficiency.