Patent ID: 7071651

Claim:
A position-of-magnetic-pole detecting device for detecting the position of a magnetic pole at the time of starting up a motor of a salient-pole type, comprising: a direction-of-magnetic-pole detecting means for detecting the direction of a magnetic pole on the basis of a feed back current of a driving current flowing through said motor which is returned after a high-frequency voltage is applied to said motor in order to drive said motor while an excitation phase is changed, the high-frequency voltage, and the excitation phase; and a polarity-of-magnetic-pole acquiring means for detecting the polarity of a magnetic pole on the basis of the peak values of the feed back currents of positive and negative driving currents flowing through said motor which are returned after positive and negative rectangular-wave voltages are applied to said motor in order to drive said motor with the excitation phase fixed to the direction of a magnetic pole detected by said position-of-magnetic-pole detecting means.