Single-phase on-board integrated battery charger based on a nine-phase machine

An obvious obstacle to a wider utilization of electric vehicles (EVs) is the absence of a widely available charging network. Direct charging of EV batteries with dc voltage in charging stations requires deployment of expensive power electronics equipment. On the other hand, placing the same equipment on-board an EV would enable access to any three-phase grid outlet, but would substantially increase the vehicle cost, weight and volume. A multitude of solutions have been proposed to integrate the charger using the already existing equipment, which normally serves the propulsion operating mode of the vehicle. However, only a few of them have the advantage of torque-free fast charging that is accomplished without any hardware reconfiguration. The primary aim of these integrated on-board chargers is to provide fast charging by enabling connection to a three-phase grid. These structures also enable slower charging by connection to a single-phase grid. This paper examines single-phase charging capabilities of an integrated charger using a nine-phase machine. The charger does not require any reconfiguration or additional elements other than those used in propulsion mode and it does not produce torque during the charging. Additionally, the charger can provide energy recuperation to the grid. The operating principle relies on additional degrees of freedom of multiphase machines, to draw currents through non-flux and non-torque producing planes of the machines.