Saliency-based sensorless predictive torque control with reduced torque ripple

The proposed sensorless predictive torque control (PTC) scheme relies on the anisotropy of the inductance, assuming a continuous presence of a slight current ripple. At high speed, this condition is fulfilled inherently, while at low speed it has to be ensured by an arbitrary voltage injection. Eliminating injection at high speed enables this saliency-based scheme to reach full speed. The main contribution of this paper is a general approach to estimate the extended mean admittance under arbitrary voltages. As a result, the sensorless technique becomes applicable to variable switching time PTC schemes, which cause significantly less noise and torque ripple. Experimental results demonstrate a very good dynamics, full speed range capability, machine parameter independence, and distinct noise and loss reduction achieved by the proposed sensorless PTC method.