STEPPER MOTORS

D.Citharthan Assistant Professor

EEE Department, CKECCoimbatore

TYPES

• VARIABLE RELUCTANCE STEPPER MOTOR a)Single stack

b)Multi-stack• PERMANENT MAGNET STEPPER MOTOR• HYBRID STEPPER MOTOR

i) Single phase ON method (step angle=90)1. a)SINGLE STACK VARIABLE RELUCTANCE STEPPER MOTOR

ii)Two phase ON method (step angle =90)

Advantage: HIGH torque compared to single phase ON method

Disadvantage :

1) High torque ripple (uneven torque due to high current excitation at position 2,4,6,8.2 ) So we need to regulate the current using PWM (pulse width modulation technique)

iii)Single phase and two phase ON method (Step angle=45)

MICROSTEPPING?

1) ANTICLOCKWISE DIRECTION OF ROTATION=??

In all modes of excitation we can get the anticlockwise direction by changing the excitation in the poles

2) DRIVE CIRCUITS??

UNIPOLAR DRIVE CIRCUITS (Because we don’t need to change the direction of Current (or) we don’t need to care about the poles (North or south) in the Stator windings.

1. b)MULTISTACK STEPPER MOTOR

WHEN PHASE A IS EXCITED

• Energizing phase (stack) A: when stack A winding is energized, the rotor teeth will move to align themselves with the stator teeth is stack A as shown in Figure

• Energizing phase (stack) B: when stack B winding is then energized while stack A winding is de-energized, the rotor teeth will move to align themselves with the stator teeth is stack B. This will result in a clockwise rotation of the rotor by 10° as shown in Figure

• Energizing phase (stack) C: when stack C winding is then energized while stack B winding is de-energized, the rotor teeth will move to align themselves with the stator teeth is stack C. This will result in another clockwise rotation of the rotor by 10°. After this stage the rotor has moved one rotor tooth pitch as illustrated

2.PERMANENT MAGNET STEPPER MOTOR

Fig - Construction and operation of two phase Permanent magnet stepper motor

(Step angle =90)

1) ANTICLOCKWISE ROTATION ?

2) STEP ANGLE =45 by alternate single and two phase on ? Tabular column ?

3) DRIVE CIRCUITS?? Bipolar Drive circuits

3.HYBRID STEPPER MOTOR

CONSTRUCTION OF 4 POLE STATOR AND 5 POLE ROTOR HBRID STEPPER MOTOR

CROSS SECTION VIEW OF 4 POLE STATOR AND 5 POLE ROTOR HYBRID STEPPER MOTOR

ADVANTAGES AND DISADVANTAGES OF

1) VARIABLE RELUCTANCE STEPPER MOTOR 2) PERMANENT MAGNET STEPPER MOTOR 3) HYBRID STEPPER MOTOR

ASSIGNMENT

Thanks