Design of a Compact Permanent Magnet Vernier Machine for Portable Medical Applications

The demand for small high-torque machines is steadily growing due to the need for precise, low-speed motors operating in tight spaces, especially in applications such as robotics and medical devices. Permanent magnet vernier machines (PMVM) are an attractive topology due to their ability to deliver high torque at low speeds and the magnetic gearing effect that supersedes traditional gearboxes. This paper proposes a compact 12- slot, 22-pole PMVM developed for use with a portable magnetic resonance imaging (MRI) system that requires high torque density, low weight and form factor, and fine angular resolution. The proposed machine is optimized through finite element analysis (FEA) and demonstrates the potential to meet the system needs. In addition, a dedicated control scheme is introduced to enhance operational precision. Together, the electromagnetic design and control strategy establish a foundation for a machine prototype and practical deployment in high-torque, space-constrained applications.