Practical implementation of a remote and sensorless stator resistance-based thermal protection method

A remote and sensorless stator winding resistance estimation method for thermal monitoring has been proposed for soft-starter-connected induction motors by the authors. As an continuation of the previous work, this paper specifically focuses on the practical implementation of the proposed method. In this paper, a compensation method for the measurement offsets is introduced to improve the performance of the resistance estimation. The design of a low pass analog filter is discussed to reduce the requirements of data acquisition system. In addition, a cable resistance compensation method is proposed to decrease the estimation error caused by the cable resistance, and achieve remote monitoring. The proposed method is validated by the experimental results. The stator resistance estimation error is within 1.5% without high requirements on the data acquisition system.