A Wound-Field Pole-Changing Vernier Machine for Electric Vehicles

This paper proposes a wound field pole changing vernier machine with fractional slot concentrated winding for electric vehicles application. The main aim of the paper is to utilize the advantages of a vernier machine and a wound field synchronous machine in a single topology using a fractional slot concentrated armature winding. The proposed machine operates in a vernier mode at low speeds and a wound-field synchronous mode at high speeds to utilize the merits of both a vernier machine and a wound-field synchronous machine. The topology, operating principle and pole-changing method of the proposed machine are explained initially. Then, finite element analysis (FEA) is utilized to study the electromagnetic characteristics such as back EMF, torque, wide speed range operation and efficiency of the proposed topology in two modes. Further, a prototype of the machine is manufactured and the FEA results are validated through experiments. The FEA and experiment results show that the proposed machine is a promising candidate for electric vehicles application.