DC Fast Onboard Integrated Battery Charger Based on a Dual Three-Phase Open-Winding Machine with V2G Function

This paper proposes a new type of fast direct current (DC) integrated battery charger for electric vehicles (EVs) based on dual three-phase open-end winding machine drive system (D3OMDS) with Vehicle-to-Grid (V2G) functionality. The charging is achieved by controlling the D3OMDS as DC-DC buck converter, while the V2G is realized by controlling the D3OMDS as DC-DC boost converter. This allows the vehicle's battery to step up or step down to the same or different DC voltages, enabling bidirectional energy flow between the electric vehicle and the grid. Compared to traditional integrated solutions, this topology effectively enhances the bidirectional power transfer capability, improves system integration, and reduces automotive costs. In the charging/V2G mode, the electromagnetic torque is zero, which significantly enhances the stability of the V2G function and greatly increases power transfer efficiency by eliminating interference from electromagnetic torque. Adcitionally, the dual three-phase motor inductance is used as a filter to handle the ripple currents on the converter side. System topology and mathematical models are presented. Simulation and experimental results are provided to verify the theoretical analysis.