Design and selection of AC machines for saliency-based sensorless control

This paper presents a design method for introducing a measurable saliency in the spatial impedances of structurally symmetrical AC machines without any periodic modulation and considerations in selection of AC machines for saliency-based sensorless control. In the structurally symmetrical AC machines such as surface mounted permanent magnet synchronous machine (SMPMM) and induction machine (IM), the saliency in the spatial impedances is built by the spatial saturation on the leakage flux paths. It is explained by the machine model considering the spatial saturation, analyzed by finite element method, and verified experimentally on the test machines. In the design or the selection of AC machines, the consideration of this phenomenon can make any saliency-based sensorless control for zero or low speed operation viable. The selection of AC machines and the control accuracy assessment for saliency-based sensorless control are discussed.