Improvement of Power Factor in Modular Stator Dual-Permanent-Magnet-Excited Vernier Machine

This article aims to propose and analyze a power factor increased modular stator dual-permanent-magnetexcited vernier (DPMEV) machine. Currently, the DPMEV machines suffer from a low power factor due to significant amplitude of armature non-working harmonics. With the modular stator design, the magnetic circuit of low-order non-working harmonics is interrupted, effectively reducing its amplitude without compromising working harmonics. Consequently, the proposed DPMEV machine achieves a notable improvement in power factor, increasing from 0.5 to 0.69 under rated conditions compared to non-modular machines. Firstly, the topology and working principle of proposed machine are introduced. Then, air gap flux density model is established for investigating the mechanism of power factor improvement. Furthermore, a comprehensive analysis is conducted using finite element analysis to study the influence of critical dimension parameters on the power factor, including PM thickness, PM pole arc and modulated pole angle. Lastly, a modular stator DPMEV prototype is manufactured and tested for validation. The experiments results closely align with the finite element analysis.