Fuzzy inference correction of calculated position angles of the sensorless direct drive servomotor

An improved sensorless servo system using the direct drive (DD) motor is proposed. The calculated values of the rotor position angles of the sensorless DD motor system contain uncertain values. Fuzzy inference is adopted to correct the uncertain calculated position-angles of the DD motors. It is shown that the accuracy of the detected rotor position angles is improved with this system. Experimental results show that the adoption of the fuzzy correction improves the accuracy of the calculated values of the rotor position angles at a standstill or at a lower speed condition. The proposed sensorless system may be applied to the rotor position sensor of the DD motor