Comparative Study of Winding Configurations in Dual-Pole Permanent Magnet Synchronous Motors

Pole-changing is an alternative methodology to variable frequency drives for enabling two-speed operation in Permanent Magnet (PM) synchronous motors. However, existing dual-pole PM synchronous motors typically operate on an integer pole-changing ratio of 1:2 (e.g., 4p/8p) and are energized by a standard full-pitch lap winding arrangement. This paper aims to expand the speed relation between the two operating modes by enabling the speed jump at a fractional ratio of 2:3. In addition, two different types of winding are applied to investigate the impact of the winding layout on the motor response. For this purpose, a dual-pole rotor layout with fractional pole changing ratio of 2:3 (i.e., 4p/6p) is presented and energized by a dual-pole (i.e., 4p/6p) single-phase fractional slot winding arrangement. The performance characteristic of the proposed design is analyzed in finite element (FE) and compared against a case study with a similar rotor layout but with standard lap winding configuration. It is revealed that the use of the proposed winding arrangement, which has a shorter average winding length and consequently lower stator resistance, enhances the starting and steady state performance of the motor. The simulation results are validated via a series of experimental tests on the motor prototype.