Torque elimination for integrated battery charger based on two permanent magnet synchronous motor drives for electric vehicles

摘要

The study proposes a non-isolated three-phase integrated battery charger (IBC) based on electric vehicle drivetrains that have two permanent magnet synchronous motors with shafts coupled via a torque coupler. The windings of both machines are used as input filter inductances after reconfiguration and connected to a three-phase grid in charging mode. Their existing traction inverters are operated as a three-phase charger that controls the charging power from the grid. The total torque produced on the shaft during operation is analysed and a strategy to eliminate it is proposed. The strategy not only maintains a zero-average torque but also eliminates the pulsating torque component on the shaft during operation. The topology allows conversion of the existing drive to an IBC through minor reconfiguration and provides an opportunity to reduce the effective THD injection into the grid via interleaving for machines with low winding inductance. A power balancing control is also proposed to reduce the second harmonic on the DC power output due to machine non-ideality. Simulation and experimental results validate that the topology can be used as both a battery charger and as a distributed resource, while the resultant torque on the shaft remains eliminated by the proposed strategy.