An evaluation of model-based stator resistance estimation for induction motor stator winding temperature monitoring

Summary form only given, as follows. In this paper, the feasibility of using an estimate of the stator resistance (R_s) as an indicator of stator winding temperature (T_s) is evaluated. The advantages of resistance-based temperature monitoring over conventional thermal model-based methods are presented. Since obtaining an accurate estimate of R_s is critical for this approach, an investigation of existing R_s estimation schemes, and an analysis showing the sensitivity of model-based R_s estimation due to the uncertainties in motor parameters and variables, are given. It is shown that R_s estimation is difficult during high-speed operation, because estimated R_s becomes sensitive to errors in motor electrical parameters and variables, as the input excitation frequency (speed) increases. A new R_s estimation scheme for the purpose of monitoring the temperature in steady state is proposed. Experimental results on a line-connected induction machine verify the validity of the proposed method and the analysis.