1. STEPPER MOTOR
CHAPTER 7

2. Stepper Motor
 Stepper motor is a brushless, synchronous
electric motor and an electromagnetic device
that uses magnetic field to move the rotor
with the aid of digital pulses that drives power
solid state devices ON and OFF
 Three types of stepper motor:
-Permanent magnet
-Hybrid
-Variable reluctance

3. Types of stepper motor
Variable reluctance
Permanent magnet
Hybrid
1) Soft iron multipole rotor
and a laminated core in
the wound stator
2) Has four "stator pole
sets" (A, B, C,) set 15
degrees apart
3) Rarely use in industry
because of less detent
torque.
1) Rotor has no teeth and
and a laminated core in
the wound stator
2) Has four phase and 90
degrees apart.
3) Ideal choice for non
industrial application
such as a line printer
print wheel positioner
and operate at fairly low
speed.
1) Standard Hybrid motor
has 200 rotor teeth and
bifilar stator windings.
2) Standard Hybrid motor
move at 1.8 step
angles.Other Hybrid
motor available in
0.9ºand 3.6º step angle
configurations.
3) Wide variety used for
industrial applications
because of high static
and dynamic torque and
run at very high step
rates.

4. Stepper Motor
-Stepper motor “step modes” include
full step,half step and microstep.

5. Full Step
ONE-ON full step operation

6. Full Step
Two-ON full step operation

7. Half Step(also known as one ON,two
ON operation)

8. Four operational mode of stepper
motor
 Rest mode – the stator windings are de-energized
and the motor is not running, resisting movement
until a load-originating torque exceeds the detent
torque.
 Stall mode – the stator windings are energized and
the rotor is not running resisting movement until a
load-originating torque exceeds the holding torque.
 Bidirectional mode – the rotor turns continually then
stops. It can continue in the same direction or the
reverse direction
 Unidirectional mode – the rotor is accelerated
(ramped up) beyond the bidirectional rate and cannot
be reversed instantaneously. In some of the literature
this mode is called the slew mode

9. Stepper motor resolution
The resolution of stepper motor depends on the type and energize method of
the stepper motor.
Res = 360
β
Where : Res = resolution of the stepper motor (step/rev)
β = step angle
360 = conversion factor ( 360°/rev)
Example:
Determined the resolution of a four-phase hybrid stepper motor with a 1.8° step
angle if the stepper motor operated:
a) full step
B)half step
Answer:
(a) β = 1.8° for full step rotation
Res = 360/1.8
= 200 steps/rev
(b) Half step,
β = 0.9°.
Res = 360/0.9
= 400 steps/rev.

10. Stepper Motors Sequence
 Full step sequence
showing how binary
numbers can control
the motor
 Half step
sequence of
binary control
numbers