A Distributed Winding Wound Field Pole-Changing Vernier Machine for Variable Speed Application

Abstract

This paper proposes a distributed winding wound field pole-changing vernier machine for variable speed application. The proposed machine uses a wound field rotor with two sets of windings. The direction of current in one set of the field windings is reversed to change the number of poles of the machine. Hence, the machine can run in two modes: a vernier mode and a wound field synchronous machine (WFSM) mode. The electromagnetic characteristics of the machine are thoroughly investigated at base speed initially. Then, the two modes of the machine are combined for variable speed operation. The 2-D finite-element analysis shows that the machine provides the advantages of high torque and high power of a vernier machine until the base speed is reached. After the base speed, the advantages of the WFSM mode are utilized, enabling wide speed range operation and restraining the efficiency of the machine from decreasing abruptly during variable speed operation.