Three-phase induction motor impulse drive method

A three-phase induction motor is successfully driven in a stepwise motion, that is, one small rotating angle of the motor shaft at a time. This is accomplished by applying a three-phase power source voltage in pulse form through thyristors to the primary winding of the motor. The drive method based on this entirely new principle is dubbed "impulse drive." It is classified into six types with somewhat different characteristics depending on the construction of the thyristor circuit. The torque generated by each type consists of pulsed positive and negative portions in a pair for each cycle. Theoretical as well as experimental investigations of the torque generated are given, together with various characteristics of a positioning machine. This machine makes the most of this drive method which is especially suited for controlling speed in very low-speed regions below several r/min.