Wide Speed-range Operation of a Dual-mode Wound Field Synchronous Machine

Abstract

This paper proposes a dual-mode wound field synchronous machine (WFSM) topology for wide speed operation. The machine stator has two winding, winding ABC-1 and ABC-2, and the current to each winding is supplied by a separate inverter. Contrary to the disadvantages in conventional brushed and brushless WFSM topologies, the proposed topology combines the advantage of achieving constant torque region by brushed operation in mode-I, and advantage of brushless in constant power region in mode-II. In mode-II, the difference in the two inverter currents creates an additional sub-harmonic magnetomotive-force (MMF). The additional sub-harmonic is utilized for brushless operation. The advantages of the proposed topology are, constant torque region, brushless operation in constant power region, and robust rotor structure as the machine operates brushless though out constant power region. The wide speed operation is achieved by negative-d-axis control along with the special inverter-current magnitude variation. A 2-D finite-element analysis is performed, and the proposed topology is analyzed. © 2019 The Korean Institute of Power Electronics (KIPE).