Fuzzy algorithm for commutation of permanent magnet AC servo motors without absolute rotor position sensors

A fuzzy algorithm is proposed which makes it possible to estimate the absolute rotor position essential to the electrical commutation of the permanent magnet AC servo motor with an incremental encoder coupled to the shaft. This improved fuzzy algorithm estimates the absolute rotor position with the desirable convergence time and little oscillation in the transient state. Using this algorithm, the motor can be controlled with maximum torque per ampere of stator current without pulsation except the transient state of the estimation. The motor speed and motor position are measured by a method based on pulse interval measurements, which guarantees the same measurement resolution from a standstill to the rated speed. The proposed control algorithm has been implemented on a microprocessor control system. Experimental results show that the proposed control system is very effective in controlling the permanent-magnet AC servo motor with high dynamic performance