Energy saving in Battery Electric Vehicles equipped with Induction Machines and Modular Multilevel Converters

This paper presents a detailed analysis of the energy saving in battery electric vehicles (BEV) equipped with an induction motor (IM) and modular multilevel converter (MMC) when their control methods are both optimized with respect to the energy losses. Specifically, the IM is driven according to a modified Field Oriented Control (FOC) which guarantees the Maximum Torque Per Ampere (MTPA) both during steady-state and transient operations. This strategy is aimed at the minimization of the stator energy losses and also determines a decrease of the rotor and iron losses. The MMC, based on battery-supplied half-bridge modules, is controlled with a Maximum Power Per Ampere (MPPA) strategy, obtained by the injection of an optimum common-mode voltage. This approach guarantees the minimization of the battery energy losses and, moreover, also reduces the converter switching losses. The whole powertrain is designed and tested during the Worldwide harmonized Light vehicles Test Procedure (WLTP) and the energy saving is quantified in comparison with traditional control methods.