Chapter 8 - Stepper motors

Abstract

In industrial applications, stepper motors are not widely used as the main robotic or machine-tool drive, but they are widely used as an auxiliary drive or within a computer peripheral. One area where stepper motors have found widespread use is the drives within small educational robots; this is largely due to their simplicity of control and the low system cost. The essential feature of a stepper motor is its ability to translate the changes in stator winding's excitation into precisely defined changes, steps, of the rotor's position. The positioning is achieved by the magnetic alignment between the teeth of a stepper motor's stator and rotor. There is a wide range of stepper motors on the market, but they are all variations of two basic designs: variable-reluctance stepper motors or hybrid stepper motors. Variable-reluctance stepper motors can be also found as either multistack or single-stack motors. In the variable-reluctance design, the magnetic flux is provided solely by stator excitation, whereas the hybrid design uses the interaction between the magnetic flux produced by a rotor-mounted permanent magnet and that resulting from the stator winding's excitation.