Proposal of an Alternating Magnetic Field Type Step Motor

The author formerly proposed a rotating magnetic field type step motor. This step motor holds the follwing advantages:(i) When one input pulse arrives, the rotating angle of the rotor that corresponds to this input pulse can be controlled by a simple eletric circuit, and therefore this angle can easily be varied in a wide range.(ii) The heat loss at the time of lightload, compared with the conventional step motor, is extremely small. Especially, at standstill and no load(when output torque is zero), the electric current in the step motor is exciting current only, so the heat loss of this motor is negligible.(iii) By the use of a universal wound-rotor induction motor, a high power step motor can easily be obtained.An alternating magnetic field type step motor possessing the same advantages as the rotating magnetic type step motor is now proposed for the first time. The principle of the alternating type step motor is as follows. At first, an alternating magnetic field is made on the stator of the motor which has two phase windings. This magnetic field is shifted by the digital control circuit as each input pulse arrives, and then the rotor is attracted.In this paper, the control method of the new step motor is discussed, and the torque is calculated by tensor analysis. By using this control circuit, the induction motor was driven as the step motor and the basic experiment was conducted. The results of this experiment were successful.