Analysis of a Vernier Machine With Buried Halbach-Array Permanent Magnets

Existing vernier permanent magnet (PM) machines usually exhibit unsatisfactory torque and efficiency performances under strong cooling and wide-speed operations. This article presents a novel vernier machine with buried Halbach-array PMs, aiming to achieve improved torque and efficiency performances in high electrical load and wide-speed conditions. The proposed vernier machine has a low pole ratio and fractional slot concentrated winding. Besides, the rotor PMs are a combination of spoke-type and inset-type PMs. In this article, the operation principle of the proposed vernier machine is introduced and analyzed. Besides, the torque performances of the proposed vernier machine are examined under rated load, overload, and flux weakening conditions. Furthermore, the proposed vernier machine is compared with two regular vernier machines, i.e., one is the typical surface-mounted vernier PM machine, and the other one is a consequent-pole V-type vernier PM machine. It shows that the proposed vernier machine exhibits the highest torque density and efficiency. Finally, experiments are conducted to verify the output torque and efficiency of the proposed vernier machine.