Flux-Adjustable Permanent Magnet Machines in Traction Applications

This paper overviews the recent advances in flux-adjustable permanent magnet (PM) machines for traction applications. The PM benefit from synergies of high torque density and efficiency conventional as well controllable air-gap field wound-field machines, which are attractive applications requiring enhanced capabilities speed regulation uncontrolled voltage mitigation. In general, three solutions have been presented, namely hybrid excited (HE), mechanically regulated (MR), variable flux memory (VFM) machines. Numerous innovations were proposed on these topics during last two decades, while each machine topology has its own merits demerits. purpose this is to review development history trend with particular reference their topologies, working mechanism, electromagnetic performance.