A Novel Yokeless Permanent Magnet Vernier Machine with Compensated Rotor Structure

This paper presents a novel yokeless Vernier permanent magnet (PM) machine for low-speed direct-drive systems. The key novelty is that the compensated rotor structure is integrated with the yokeless complementary rotor structure. The torque production between two rotors can be balanced, the stator yoke is no longer necessary, and therefore the machine space can be better utilized. In this paper, the machine structure and working principle are introduced under bidirectional flux modulation theory and magnetic flux path analysis, respectively. The electromagnetic performances of the proposed structure, including flux distribution, open-circuit back EMF and torque performances, are given under the proposed machine design. And the design suggestions are given accordingly.