Postfault Control of Scalar (V/f) Controlled Asymmetrical Six-Phase Induction Machines

With the accelerated development in semiconductor power devices along with the dictated rigorous reliability standards in some industrial sectors, the application of a medium-voltage high-power multiphase induction machine with multiple three-phase windings is now considered as a leading technology in high-power safety-critical applications. This paper proposes a parameter-independent postfault control scheme for an asymmetrical six-phase induction machine based on simple scalar V/f control, which can successfully ensure the most common postfault scenarios used in this respect, namely, equal stator copper loss and minimum copper loss modes. Moreover, the proposed controller can effectively be used in either open-loop or closed-loop speed control modes. The proposed controller is experimentally validated using a 1.5-kW prototype induction machine. The effect of the neutral arrangement on the dynamic performance is also explored.