Analysis of influence on back-EMF based sensorless control of PMSM due to parameter variations and measurement errors

To achieve better performance of sensorless control of PMSM, a precise and stable estimation of rotor position and speed is required. Several parameter uncertainties and variable measurement errors may lead to estimation error, such as resistance and inductance variations due to temperature and flux saturation, current and voltage errors due to measurement uncertainties, and signal delay caused by hardwares. This paper reveals some inherent principles for the performance of the back-EMF based sensorless algorithm embedded in a surface mounted PMSM system adapting vector control strategy, gives mathematical analysis and experimental results to support the principles, and quantify the effects of each. It may be a guidance for designers to minify the estimation error and make proper on-line parameter estimations.