Analysis of slot-pole combination of fractional-slots PMSM for embedded applications

During the design of permanent magnet synchronous machines (PMSM), the first step that engineers have to do, concern the choice of the topology, i.e. the slot/pole combination. Given that the performances of the machines are strongly related to this combination, the choice has to be fully justified. Fractional-slots (FS)-PMSM offers several advantages and have been focused by a lot of researches. However, depending on the topology, these machines could have major drawbacks as magnetic noises, high iron and eddy-current losses and low fault-tolerance. The aim of this paper is to give an overview of each machine considering the most common slot/pole combination in order to single out if a topology is suitable or not. A special focus is also done on the homopolar component which traduces the machine´s fault tolerant capability required for embedded applications.