An adaptive stator resistance estimation technique for sensorless permanent magnet synchronous motor drive

A proper estimation of stator resistance is extremely important for various reasons in permanent magnet synchronous motor drives. The increase of the resistance is an indirect measure of the temperature rise or thermal loading of the stator. Therefore, an accurate and online estimation technique will help in condition monitoring of the machine. This paper proposes a new adaptive stator resistance estimation technique by processing the active power in the synchronously rotating reference frame. A Model Reference Adaptive System (MRAS) is formulated for this purpose. The algorithm is operated on a reactive power-based speed sensorless drive. The sensorless algorithm utilises a different MRAS using reactive power as the functional candidate in the same. The algorithm for the stator resistance estimation is applied in the steady state while the sensorless routine is always activated. The validity of the proposed technique is tested extensively in MATLAB/SIMULINK.