Scalability investigation of proximity losses in fractional-slot concentrated winding surface PM machines during high-speed operation

In previous work, an integrated analysis tool for predicting the strand- and bundle-level proximity losses was developed and experimentally verified using a 30 kW (continuous) surface permanent magnet (SPM) machine designed with fractional-slot concentrated windings. In this extended work, a new 200 kW (continuous) FSCW-SPM machine has been designed based on commercial specifications for a high-performance electric traction machine. Predicted proximity losses developed by applying the integrated analysis tool to this 200 kW machine match finite element analysis predictions very well over the speed range from 1500 r/min (corner point) to 6000 r/min (maximum speed). In addition to confirming the scalability of the proximity loss analysis tool to higher power machines, this investigation has also demonstrated that these larger FSCW-SPM machines are vulnerable to high proximity losses at high speeds. Special design features such as transposing the stator winding strands must be taken to suppress these losses that can otherwise reach unacceptably high levels without these techniques.