A Comparative Study of Vernier Machine with Short Pitch Winding Configuration

Rare earth magnets have long been the cornerstone of high-performance electrical machines owing to their exceptional magnetic properties. However, their utilization presents challenges, notably in terms of cost and limited availability of resources. In response, ferrite magnets have emerged as a promising alternative due to their cost-effectiveness and abundant supply. Vernier permanent-magnet (VPM) machines typically exhibit low power factors due to high winding reactance. Given the weaker magnetic properties of ferrite magnets compared to rare earth counterparts, ferrite-based machines inherently suffer from poorer power factors. Short pitch winding is a known strategy to mitigate this issue and enhance power factor. This paper investigates the impact of employing short pitch winding in ferrite VPM machines, alongside an exploration of different gear ratios. The research findings indicate that when a high-power factor is desired, employing short pitch winding can lead to higher torque/power and efficiency compared to full pitch winding in ferrite VPM machines. Moreover, the advantages of short pitch winding are more prominent with higher gear ratios. Finite element analysis is employed to optimize both the machine's topology and performance, providing insights into the intricate interplay between winding configurations, gear ratios, and magnetic materials.