Double‐Layer Windings for Optimised Torque and Force Production in Dual Three‐Phase Induction Motors

This paper investigates the design methodology and optimisation of double‐layer windings of dual three‐phase induction motors that can generate torque and electromagnetic forces simultaneously. In high‐power variable speed drives, the possibility of controlling the electromagnetic forces on the rotor enables these machines to operate at critical speed. Four winding topologies are developed to maximise both the torque and force through a systematic shift of return path of the winding coils and optimisation of the winding factors of both torque and force producing harmonics. The performance of the optimised winding configurations is also analysed for certain slot‐pole combinations and the optimum scheme is presented. In addition to winding factors, the evaluation criteria consider key parameters such as mean torque, mean force, respective ripples and overall efficiency of machine. An experimental setup has been developed to validate the results and compare them with those from finite element analysis. The research shows that depending on the chosen topology, there is an optimal slot‐pole combination that delivers enhanced torque and force performance or vice versa, for a given slot‐pole combination, there is an optimal winding topology. These results are relevant for industry applications where an existing machine needs to be redesigned for better stability.