Minimization of AC Losses in Permanent Magnet Machines by Transposed Coil Connection

With the increasing demand for high power density and high-speed electrical machines, AC copper loss issue for electrical machines is becoming more and more serious. This paper investigates AC losses of PMSMs with fractional-slot concentrated-winding by the field-circuit coupled finite element analysis (FEA). It shows that the conductor position has a significant influence on AC losses. To reduce the AC losses, this paper proposes a new AC loss suppression technique by transposing the coil connection in the same branch. The AC losses can be reduced by 19% compared to the non-transposed one at 400Hz. An experiment is designed to validate the FEA method and the effectiveness of the new transposition.