ABSTRACT
DC-excited linear synchronous motors (DCE-LSM) in flat active ac stator configuration are favored for MAGLEVs in low, medium, and high-speed active guideway applications. The double slotting on stator and on mover—for an airgap of 10–12 mm in MAGLEVs—produces magnetic flux density harmonics that cause thrust and normal pulsations, which, by careful design, may be kept to a reasonable p.u. level, in order to prevent strong vibrations and noise of DCE-LSM. Model linearization may be used to investigate stability under various controls but, due to strong nonlinearities in the system and large variation of variables, robust control systems are needed for DCE-LSM. The emf decoupling is introduced to improve the control at high speeds and allow open-loop space vector PWM in the converter, to exploit best the limited switching frequency to maximum fundamental frequency rather small ratio at high speeds, even when multilevel inverters are used on ground to supply the vehicle.
