Sensorless operation of permanent magnet motor using direct voltage sensing circuit

In this paper, position-sensorless operation of the permanent magnet motor is introduced. To estimate the rotor position and speed, a new closed-loop flux observer is proposed for wide speed operation. To extend the operation range of the proposed algorithm, a direct voltage sensing circuit is proposed that enables correct disturbance voltage rejection and stable operation of the proposed flux observer at extremely low speed. Experimental results of position-sensorless torque control are shown in order to verify the feasibility of the new algorithm using the proposed voltage sensing circuit.