Research on Armature Winding Characteristic of a Double Rotor Permanent Magnet Motor from Perspective of the Magnetic-Field Modulation

In this article, a research method for armature winding characteristic of double rotor permanent magnet (DRPM) motor is proposed, in which the key is to analyze and investigate the filter effect from the perspective of air-gap magnetic-field harmonic. Considering that the back electromotive force (EMF) is the intuitive manifestation of the winding characteristic, the relationship between air-gap harmonics and back EMF is studied. Based on this, an effective air-gap harmonic evaluation factor is defined, which is mainly aimed to effectively evaluate the winding filter effect. Meanwhile, in order to comprehensively investigate the filter effect caused by the winding, two types of winding configurations, including double-layer winding (DLW) and single-layer winding (SLW), are incorporated into the design of the DRPM motor. Then, the leading evaluation factor is purposefully selected as one of optimization objectives to achieve optimal design of the motor, for further improvement of the winding characteristic. In addition, the leading evaluation factor related to the effective air-gap harmonic and other basic performances are evaluated, including no-load back EMF and torque. Finally, a prototype motor is manufactured and tested for validation.