Magnetization Characteristics and Electromagnetic Performance Analysis of a Straight-Type Series Variable-Flux Servo Machine

With wide speed range, variable-flux machine (VFM) is a potential candidate for servo system. The VFM includes series VFM and parallel VFM. As the series VFM has the advantage of simple magnetization-regulation control and high torque density, a straight-type series variable-flux servo machine (STS-VFSM) adopting 9-slot 8-pole structure is investigated in this paper. The flux-adjustment characteristics of the STS-VFSM is investigated through harmonic flux analysis and finite element analysis (FEA). A method for uniform magnetization is proposed. The electromagnetic performances of the machine are analyzed. The influences of PM pole parameters on torque production capacity and speed range are discussed. The STS-VFSM with reference parameters is proved with wide speed range while taking torque production capacity into account.