Design Optimization of Multistack Coreless Disk-Type Hysteresis Motor

Coreless dual disks hysteresis motors (CDDHM) have been recently introduced. The CDDHM presents some improvements in power factor and efficiency compared to general hysteresis machines. However, there is not much design or manufacturing experience available and an initial design methodology has not yet been proposed for the new machine. According to this and existing inherent complexity in the model of hysteresis motors, it is difficult to achieve an optimal design solution by applying a conventional optimization method. In this paper, an initial design approach is proposed. Then, a genetic algorithm-based method is developed to find the high-efficiency solution for an optimal CDDHM. The optimized motor has been manufactured and fitted in a test facility with a torque meter. Some experiments are carried out to prove the optimal design. Furthermore, start-up characteristics of the motor are predicted from the model and validated by a routine test.

I. Introduction

Multiphase hysteresis motors are brushless and self-starting synchronous motors with flat speed-torque characteristics, smooth operation, and low noise level. The rotor is constructed very simply as a robust solid ring or disk of a heat treated alloy steel. Commonly, the start-up current is within 1.2–1.5 times the full-load current. Nevertheless, ordinary hysteresis motors have low power factor and efficiency [1], [2].