Modeling And Sensorless Control Of An Advanced Concentrated Winding Vernier Pm Machine

Due to the advantages of high torque density and simple mechanical structure, vernier permanent magnet (VPM) machines have attracted more and more research interests. In this paper, the inductance non-linearity of an advanced concentrated winding (CW) VPM machine is investigated with consideration of both magnetic saturation and cross coupling saturation. Then, the mathematical model with variable inductance of the VPM machine is established through incorporation of finite element analysis (FEA) and surface fitting method. Further, a back-EMF based sensorless control method is developed for this VPM machine model with design of a current dependent state observer. Simulation results show that the VPM machine can be well controlled for steady and dynamic state operation, and the position estimation error is effectively decreased. Finally, the proposed sensorless control algorithm is validated through experimental tests of the VPM prototype machine.