Study of Manufacturing Tolerance of Modular Permanent Magnet Machines: Segment Radial Displacement

In this paper, the investigation about the influence of manufacturing tolerance on the electromagnetic performance of modular PM machines with segmented stator has been carried out. Two typical slot/pole number combinations such as 12-slot/10-pole and 12-slot/14-pole have been chosen for case studies. The manufacturing tolerances scenarios are focused on the radial stator segment displacement. Firstly, the influence on the phase back-EMF as well as the on-load torque is investigated. By doing so, the cases where the influence of manufacturing tolerance are the most significant can be identified. This allows for further studying the influence of flux gap widths on the performance of the modular PM machines. Through the analyses of the back-EMF, the on-load torque, the cogging torque and the unbalanced magnetic force, the manufacturing tolerance withstand capability of the 12-slot/10-pole and 12-slot/14-pole modular PM machines can be assessed. It is found that the 12-slot/10-pole modular PM machines have better manufacturing tolerance withstand capability compared with the 12-slot/14-pole modular PM machines.