A Novel Speed Observer Based on Parameter-optimized MRAS for PMSMs

Nowadays, many efforts are made to realize the position/speed sensorless control strategy of permanent magnet synchronous motors (PMSM) to simplify the control structure and cut down the cost. A sensorless control scheme based on a model reference adaptive system (MRAS) with the theory of parameter optimization for the PMSM servo system is described in this paper. The scheme can promptly work out the speed of the rotor without any other position/speed sensor. Different from the other MRAS-based speed observers which constructed according the theory of stability customarily, by using the error between the measured phase currents of actual motors and theoretic phase currents acquired by the mathematical model of motors as the parameter to be optimized, the proposed method can gain the speed of rotor with fast response and better performance. The stability of MRAS is analyzed subsequently. In the scheme, only a few parameters are needed and satisfactory performance can be achieved. So this scheme is very simple to be used as the position/speed observer of the PMSM servo system. Finally the simulation and experimental results confirm the validity and advantage of the proposed method.