Electrical Engineering ⇒ Topic : Construction and Working of stepper motor
Construction and Working
1. Permanent-manget stepper motor : -
Fig.(a) shows the phases or stacks of a 2-phase, 4-pole permanent-magnet stepper motor.
Fig.(a) Permanent-magnet stepper motor The rotor is made of ferrite or rare-earth material which is permanently magnetised. The stator stack of phase II is staggered form that òf phase 1 by an angle of 90°. When the phase-T is excited, the rotor aligned as shown in fig(1). If now the phase II is also excited, the effective stator poles Shift anti-clockwise by 22.5 [Fig.(a) (ii)] causing the rotor to move accordingly. Now, keeping the'phase"Il' still energised, if the phase 'I' is now de-energised, the rotor will move another -step- of 22.5"The reversal of phase 'I' winding current Will-Produce a further forward movement of 22.5°, and So on. It can be a easily observed/visualised as to how the direction of movement can be reversed. Each phase is provided With-double Coils to simplify the switching arrangment (which is electronically accomp
2.Variable-reluctance stepper motor
Stepping angle, irrespective of the type' of stepper motor is given as.
3.Hybrid stepped motor :
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