Step Motors / Drivers Overview
Simple positioning control by high torque and sensorless motors
Abundant lineup correcsponding to various application
About Step Motor
Rotational speed of step motor is defined by pulse rate and its rotational angle is defined by the amount of pulses. These digital signals enable open loop control, which does not require feedback structure. On the other hand the unit step angle is defined by the mechanical structure of a rotor and a stator. The step motor is also called Stepping Motor, Stepper or Pulse Motor because no unified name is established. Tamagawa Seiki Co., Ltd. unifies to call it Step Motor.
A step motor consists of a cylindrical stator and a rotor. The rotor rotates in the stator. The center of the rotor is of a permanent magnet and the periphery of the rotor is "toothed" like a gear. The stator has, on the other hand, gear-shaped iron-cores, which correspond to the gear-shaped periphery of the rotor. Wires are wound around the iron-cores to form coils. If current is externally applied to the coils, they become magnets, and the rotor starts to rotate through the interaction (magnetic attraction and repulsion) with the permanent magnet in the rotor.
Fundamentals of operation
The rotation angle per input pulse is called "the unit step angle". The unit step angle is usually 1.8°for 2 phase step motors and 0.72°for 5 phase step motors. The total rotation angle is obtained by multiplying the unit step angle by the number of input pulses. The timing of switching current is given as a pulse from an external controller to a driver of a step motor. When one pulse is given, the current is switched once.