Implementation issues affecting the performance of carrier signal injection based sensorless controlled AC drives

This paper assesses and analyzes the practical implementation issues affecting the performance of carrier signal injection based sensorless control methods for AC drives. Included in this assessment and analysis are the following topics: selection of the carrier signal frequency and magnitude; the nonlinear behavior of pulse-width modulation and power electronics; and the signal processing required for the estimation, including analog filtering, sampling and analog-to-digital conversion. Variations in the characteristics and behavior of the saliency used for the estimation as a function of the machine's design and operating point are also addressed. The influence that each of these topics has on the robustness and accuracy of the estimate is discussed. Finally, conclusions are drawn on how the negative effects can be minimized and the performance of the estimation improved.