Direct Speed Estimation of Synchronous Reluctance Machines using Model Reference Adaptive System

Position sensorless control of synchronous reluctance machines (SynRMs) without high frequency signal injection generally utilizes induced voltages and calculates fundamental components of the flux linkages resulting from rotation and saliency of the rotor. However, conventional methods estimate the rotor position from the fundamental flux linkages obtained by integrating the induced voltages. Therefore, response speed of the position estimation is slow compared to position sensorless control for permanent magnet synchronous machines and induction machines that estimates the rotor position without integration directly from induced voltages of the back electro-motive force (EMF) proportional to the machine speed. This paper proposes an adaptive observer based on model reference adaptive system to estimate the machine speed directly from induced voltages of the motional EMF. The direct speed estimation improves response speed of the position estimation compared to the conventional methods for SynRMs. Experimental investigation validated design of the adaptive observer and confirmed stable operation with speed acceleration and deceleration. At the beginning and end of change of the machine speed, the direct speed estimation reduced errors in the estimated position to half or less.