DESIGNING METHOD FOR INTEGRATED BATTERY CHARGERS IN ELECTRICAL VEHICLES

Electrical vehicles often make use of multi-phase induction motors. At the same time, the vehicles have an on-board charger, the power electronics device that converts the ac power from the mains and charges the traction battery. The traction inverter can be integrated with the charger, reducing in this way the component count, weight and cost, while the windings of the ac motor can be used as the inductors required to complete the charger topology, thus saving on passive components, iron and copper. The integrated charger performances depend on the configuration of the stator windings as well as on the topology of the power converter. The objective in charging mode is reaching a high efficiency while keeping the charging-mode electromagnetic torque at zero. In traction mode, the goals include the efficiency and the torque-per-Amps ratio. In order to compare and distinguish between the available topologies and configurations, the paper starts with the analysis of the magnetic field in the air-gap ofthe electric machine in both charging and traction modes. Based upon that, a novel algorithm is proposed which determines the space-time distribution of the air-gap field, eventually deriving all the relevant pulsating and revolving component of the magnetic field, thus providing the grounds for studying the losses, efficiency and torque pulsations in both charging and traction modes.