Rotor position estimation method of sensorless PM motor at rest with no sensitivity to armature resistance

A new rotor position estimation method of a sensorless PM motor at rest is proposed, which has no sensitivity to the armature resistance. The method is based on a saliency of the rotor, and utilizes the alternating magnetic field which is excited by current control. The phase difference between the magnetizing current and the voltage references makes it possible to estimate the rotor direction accurately without motor parameters except the ratio of d-axis and q-axis inductances. In addition, the magnetic pole can be identified evidently using the voltage reference vibration phenomena caused by magnetic saturation