Integrated Boost-Converter for 400 V - 800 V Fast-Charging Compatibility

The automotive industry is increasing the voltage of the batteries from 400 V to 800 V to reduce the current rating of the vehicle cabling and the connectors to the external DC fast charger. Although 800 V vehicles are already on the market, the operating charging stations in Europe that support the 800 V charging level are only 1% of the total. Therefore, the electric vehicles must be intrinsically compatible with 400 V DC charging stations with a marginal increase in the cost and the weight of the drive train components. The solution analyzed in this paper reconfigures the electric motor and the three-phase inverter into a multiphase DC/DC boost converter, adapting the battery voltage to the off-board charger. The unconventional use of an electric machine as a coupled inductor requires careful electromagnetic analysis and a dedicated control scheme to control the rotor angular position during the recharge process.