Influence of machine design parameters on flux-weakening performance of induction machine for electrical vehicle application

This study investigates the influence of machine design parameters, mainly the mutual and leakage inductances, on the flux-weakening performance of induction machines (IMs) for electrical vehicle application. In addition, the influences of other practical issues, such as iron saturation, stator and rotor resistances and so on, are investigated. A per-unit model is employed for the investigation, while during the analysis, the inductance ratio between the leakage and mutual inductance is introduced. It is shown that, in general, it is very difficult to achieve infinite flux weakening performance of IMs, and only with ideal zero inductance ratio, could IM achieve infinite constant power region and the maximum utilisation of inverter. Finally, analytically calculated torque/power-speed characteristics of a 12 kW IM are verified by finite element analyses and experiments.