A sensorless rotor position detecting method for self-controlled synchronous motors

A new sensorless rotor position detecting method for self-controlled synchronous motors is proposed. The proposed method is based on the idea that the induced electromotive forces in the armature windings due to the pulsation included in the field current when a chopper is used as a field circuit depend on the rotor position of the motor. The principle of the proposed method is explained first. Then the usefulness of this method is discussed through experimental and simulated results when the motor is operated at a constant speed. Finally, an experimental investigation with the proposed sensorless rotor position detecting method at starting is discussed.