Permanent-magnet synchronous motors with three-zone distributed tooth-coil winding

Abstract:
Permanent-magnet synchronous motors are increasingly being used for high-speed drives. Due to the high operating speed, the available power electronics and the desired high energy efficiency, a low-pole motor design is required. In case of pronounced short motors the use of conventional winding systems becomes problematic. For these often 4-pole PM synchronous motors, winding systems that lead to the shortest possible winding overhangs would be desirable. Unfortunately, the fractional-slot tooth-coil windings used as standard in PM servo motors are not possible here, as they tend in significantly higher numbers of pole pairs. Three-zone distributed tooth-coil windings are one possible solution. After introducing the problems of low-pole short motors, the systematics of three-zone distributed tooth-coil windings is presented and the fundamental and harmonic field behavior is analyzed. As part of a design study, a high-speed PM synchronous motor with different winding variants is designed and the steady-state operating behavior is simulated taking into account the rotor eddy current losses. The operating data in the rated point allow a direct comparison of the winding variants considered, whereby the three-zone distributed tooth-coil winding has clear advantages.