| 摘要 |
PURPOSE:To enable restart from hunting state by providing means for switching phase current, means for measuring rising time of current, and means for performing slow-up operation at start. CONSTITUTION:Upon increase of load, difference between the position of exciting phase of stator and the rotor position having minimum excitation resistance increases to cause increase of magnetic resistance and thereby inductance of the exciting phase decreases to quicken rising of current. Upon decrease of load, the positional difference also decreases to cause decrease of magnetic resistance thus increasing inductance. Consequently, current rises slowly. In such a manner, variation of exciting current is measured based on the positional relation between the rotor and the stator and a judgment is made that a step motor is hunting if thus measured variation is lower than a predetermined value and then slow-up processing takes place to restart the step motor. |
