FEA based investigation of the magnetic forces developed by fractional slot PM synchronous machines
Purpose - The paper is aimed at the investigation of the magnetic forces generated by fractional slot surface mounted PM machines, considering a comparative study between two topologies: a 9 slot/10 pole machine and a 12 slot/10 pole machine. Design/methodology/approach - Following the distribution of the armature windings using the star of slots approach, an investigation of the magnetic forces developed by both machines under study, using 3D finite element analysis (FEA). Prior to such investigation, a 2D FEA based sizing procedure is carried out in order to select a set of suitable geometrical parameters. Then, the comparison between both machines is extended to the torque production capability. Findings - It has been found that the 9 slot/10 pole machine has a pic value of the average magnetic force reaching almost 40N which is located in one side of the air gap. Such a peak does not exceed 7N in the 12 slot/10 pole machine and is located in two diametrically-opposite areas of the air gap. Research limitations/implications - This work should be extended by an experimental validation of the FEA results regarding the magnetic force generation. Practical implications - The list of the selection criteria of fractional slot PM machines should be extended to the magnetic force generation in order to fulfil the requirements of many applications such as the propulsion systems. Originality/value - The paper proposes a combined electromagnetic-mechanical approach to investigate the magnetic forces generated by fractional slot surface mounted PM machines using 2D and 3D finite element analysis.
magnetic forces fractional slot surface mounted pm machines comparative study finite element analysis torque electromagnetic torque von mises strain/stress magnetic measurement