Phase resistance estimation for sensorless control of switched reluctance motors

The determination of phase resistance is a key factor for a number of sensorless position estimation algorithms of switched reluctance (SR) motors. The change of phase resistance during motor operation due to it´s temperature dependency causes error in the position estimation and thus it significantly affects the performance of the drive. An on-the-fly resistance estimation algorithm for SR motors has been developed. The algorithm is based on estimation of flux linkage and its relation to the actual phase current. The developed resistance estimation algorithm has been successfully implemented and tested on a sensorless SR drive. The overall error of the phase resistance estimation was reached in a range of 2% for the low- and mid-speed range. it significantly improves the sensorless position estimation and thus SR drive performance. Since the algorithm requires neither additional sensors nor excessive computational power, it is applicable in real sensorless SR drives.