Magnetic Levitation Control of Doubly Fed Linear Motor With Multiphase AC Excited Mover

Abstract

The existing Transrapid (TR) maglev adopts a long-stator linear synchronous motor (LLSM), which establishes a relatively stationary magnetic field for dc levitation control. While the doubly fed linear motor (DFLM) adopts ac excitation on the mover side and realizes ac levitation by an asynchronous magnetic field with respect to the mover. Compared with dc levitation with LLSM, ac levitation with DFLM holds technical benefits but also faces challenges. In this article, ac levitation control based on DFLM is discussed. The principle of inherent pitch torque fluctuation is investigated. In conjunction with quasi-synchronous operation (QSO) principle of DFLM, the decoupling control for propulsion and levitation is discussed. To realize the stable ac levitation control, a compensation method for pitch torque is proposed. The efficacy of the proposed control method is verified through both simulation and bench tests.