A fast on-board integrated battery charger for four-motor EVs

A novel type of fast on-board battery charger, applicable for four-motor electric vehicles (EVs), is presented in the paper. The charger consists exclusively of components that are already present on-board the vehicle. Having no new elements, it has a positive impact on the cost, weight and space saving in the vehicle. A three-phase grid is directly attached to the neutral points of three propulsion machines, so that hardware reconfiguration with respect to the propulsion mode of operation is not required. The charger operates with unity power factor and both charging and vehicle-to-grid (V2G) modes are feasible. The torque is not produced in the machines during the charging/V2G process. The charger is particularly suited for the interleaving process, which is used to improve the quality of the current that is taken/injected into the grid. A complete control algorithm for the charging/V2G operation is given, and performance of the charger, including torque-free operation feature, is validated by simulations.