Design and Control of IPMSM Sensorless Drive for Mechanical Rotor Position Estimation Capability

In this paper, a design and control method of interior permanent magnet synchronous machines (IPMSMs), which is controlled in sensorless position control mode based on high frequency signal injection, for absolute position estimation and control capability has been addressed. Although conventional motor designs with symmetric structure work well in sensorless speed and torque control modes, their actual mechanical rotor position is unidentifiable since their inductance profile is repeated for every electrical revolution. To realize the mechanical rotor position estimation capability, from a given template six-pole/nine-slot IPMSM with symmetric structure, an IPMSM design with asymmetric winding and asymmetric rotor geometry is proposed and constructed as a prototype. Based on the proposed design, the mechanical rotor position can be identified at the cost of slight degradation of basic motor characteristics such as torque ripples, harmonics in back EMF, and so on. The overall performances of the proposed IPMSM have been evaluated by rigorous finite element method simulations and experiments.