Analysis, design, fabrication and testing of three actuators based electromagnetic levitation system for vehicle applications

In this paper the analysis, design and fabrication of 3-coil based DC attraction type levitation scheme has been presented. In vehicle applications majority works have been reported based on four actuators based electromagnetic levitation system (EMLS). But in this prototype three electromagnets have been used at the three sides of the platform. The use of one magnet-coil, power amplifier and associated gate driver, controller circuit, position and current sensor is dispensed with the prototype. So there is considerable reduction of cost and weight of the proposed system and the hardware circuit is also simpler than four-coil structure. The objective is to levitate a platform under ferromagnetic guide-way normally used in electromagnetically levitated vehicle structure. The prototype (total mass 7.528kg) consists of three identical electromagnets placed at the three sides of a platform and the structure is made to remain suspended at different air-gap positions under a ferromagnetic guide-way - the arrangement that is normally used for EMLS. The structure of the levitated system has been constructed in-house. The three actuators have been controlled simultaneously by three similar single input single output (SISO) controllers utilizing the cascade Lead compensation control scheme. The design and implementation of the controller for such an unstable and non-linear system is the main aim of this study. The stable levitation has been demonstrated of the platform around an operating point.