Design of in-wheel motor powertrain systems for a micro electric car applying permanent magnet synchronous motors

Abstract

The use of in-wheel motor (IWM) based powertrains can provide great flexibility in design freedom. In addition, the use of all-wheel-drive (AWD) IWM allows independent torque control from each wheel and maximizing driving safety. In this thesis, three different all-wheel-drive (AWD) in-wheel-motor (IWM) powertrain configurations for a micro electric vehicle have been considered in view of efficiency, maximum speed, and other vehicle design requirements. The first AWD IWM powertrain, denoted as “Armadillo-T (AT) Baseline”, uses Permanent Magnet Synchronous Motors (PMSM). The second will be called as “AIT proposed” which is based on collaboration with the Austrian Institute of Technology (AIT). The powertrain in “AIT Proposed” configuration has IWMs which use PMSMs without iron cores. These two powertrains have their advantages and disadvantages; the “AT Baseline” powertrain showed better acceleration performance but had lower efficiency of energy consumption, whereas the “AIT proposed” powertrain showed higher efficiency in energy consumption, but lacked acceleration performance. One additional powertrain configuration is newly proposed which is the unique major contribution of this thesis; one that combines the electric drives from the “AT Baseline” and the “AIT Baseline” configurations into one powertrain which has been named as “Combined Proposed” powertrain. An algorithm for the front-and-rear drives has also been proposed and evaluated to further improve the vehicle operational energy efficiency, while delivering the demanded torque on FTP-75 and NEDC driving cycles. This powertrain configuration has shown to be a balance between the overall energy efficiency and acceleration performance of the vehicle based on simulation results, being able to match the efficiency rating of the “AIT Proposed” powertrain, and nearly match the acceleration profile of the “AT Baseline” configuration. The “Combined Proposed” powertrain has shown that the vehicle’s overall acc...