- Stepper motors are brushless DC motors that rotate in discrete steps in response to control signals. They are excellent for positioning applications as their rotation can be accurately controlled. - There are three main types of stepper motors: permanent magnet, variable reluctance, and hybrid. Permanent magnet motors are the most common. - Key components include the rotor, stator, and windings. Pulses sent to the windings energize the stator poles and rotate the motor. - Stepper motors have advantages like low cost control, simplicity, and ability to operate without feedback but disadvantages like higher current draw and need for a driver circuit. - Common applications include printers, CNC machines, robotics, and

1. Xubair Khan

2. Agenda:
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Introduction to Stepper Motors
Types of Stepper Motors
Main components of a stepper motor
How do these components work together
Control sequence to turn a stepper motor
Advantages and disadvantages of stepper motors
Practical Applications of stepper motor
Step Angle
Summary

3. Introduction to Stepper Motors:
• A stepper motor is a brushless, synchronous electric motor that converts digital pulses
into mechanical movement.
• The stepper motor rotates a specific incremental distance per each step. The number
of steps that are executed controls the degree of rotation of the motor’s shaft. This
characteristic makes step motors excellent for positioning applications.
• For example, a 1.8° stepper motor executing 100 steps will rotate exactly 180° with
some small amount of non-cumulative error. The speed of step execution controls the
rate of motor rotation. A 1.8° step motor executing steps at a speed of 200 steps per
second will rotate at exactly 1 revolution per second.

4. Types of Stepper Motors:
Permanent Magnet
Magnetic rotor
Variable Reluctance
Non-magnetic, geared rotor
Hybrid
Combines characteristics from PM and VR
magnetic, geared rotor

5. Permanent magnet motor:
The permanent magnet (PM) or tin can (fig. 2) motor is perhaps the most widely used
stepping motor in non-industrial applications. In it's simplest form the motor consists of a
radially magnetized permanent magnet rotor and a stator similar to the V.R. motor.
Due to the manufacturing techniques used in constructing the stator they are also
sometimes known as 'claw pole' motors

6. The variable reluctance motor:
The variable reluctance or V.R. (fig 1) motor consist of a rotor and stator each with a
different number of teeth. As the rotor does not have a permanent magnet it spins freely
i.e. it has no detent torque. Although the torque to inertia ratio is good, the rated torque
for a given frame size is restricted. Therefore small frame sizes are generally used and then
very seldom for industrial applications.
Energized A & A’
Energized C & C’

7. Advantages and disadvantages of stepper motors:
Advantages
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Low cost for control achieved
Simplicity of construction
Can operate in an open loop control system
Low maintenance (no brushes)
Less likely to stall or slip
Will work in any environment
Disadvantages
• Require a dedicated control circuit
• Use more current than D.C. motors
• High torque output achieved at low speeds

8. Stepper Motor Construction:
YouTube Video link : www.youtube.com/watch?v=MHdz3c6KLrg

9. How to Stepper motor works?
YouTube Video link : www.youtube.com/watch?v=t-3VnLadIbc

10. Two Main Configuration of Stepper Motors :
Two Phase Bipolar Stepper Motor:
• Leads on each coil can be brought out in two ways
• Each lead taken separately
• Bi-directional current flow through entire winding

11. Applying a voltage to lead A’ and grounding lead
A generates current flow resulting in the stator
polarities shown above.
Applying a voltage to lead A and grounding lead
A’ generates current flow resulting in the stator
polarities shown above.

12. Applying a voltage to lead B and grounding lead
B’ generates current flow resulting in the stator
polarities shown above.
Applying a voltage to lead B’ and grounding lead
B generates current flow resulting in the stator
polarities shown above.

13. Four Phase Unipolar stepper Motor:
• A center tap added between the two leads
• Center Tap connected to Ground or Voltage source
• Unidirectional current flow in each ½ of winding

14. Driving one of the leads on winding A to ground allows
current to flow in one half of the winding generating a
polarity on the stator poles and the rotor rotates
accordingly.
Driving one of the leads on winding B to ground allows
current to flow in one half of the winding generating a
polarity on the stator poles and the rotor rotates
accordingly.

15. Driving one of the leads on winding A to ground allows
current to flow in one half of the winding generating a
polarity on the stator poles and the rotor rotates
accordingly.
Next, the grounding source is removed from the winding A
lead and one of winding B’s leads is driven to ground. Again,
current flows in half the winding and the appropriate stator
poles are energized. This continues to rotate the motor 360
degrees.

16. Let’s compare both winding configurations.
Unipolar and Bipolar Motors
• Bipolar uses entire winding
−Unipolar uses half the winding at one time
• Unipolar motor coil wire is thinner
− More wire needed = increased resistance
• Bipolar requires more complex circuitry
− Increased cost
− More real estate

18. Application :
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Paper Feeder On Printers
CNC Machine
Stepping Motor to move read-write head in computer CD drive
Labeling Machine
Moving Positioning System
Medical Equipment
Automotive and scientific equipment etc.
Packing Machine
Robotic Arm
Fiber Optic Splicing Machine

19. Stepper motor move clockwise:

20. Stepper motor move counter clockwise:

21. Step Angle:
How much movement is associate with a single step ? This depends on the internal
construction of the motor in particular the number of teeth on the stator and the rotor.
The step angles for various motor have different step angles table shown
Notice the term steps per revolution this is the
Total number of steps needed to rotate one
complete rotation or 360 degrees
(e.g.,180 steps x 2 degrees = 360)

22. Stepper Motors Interface With microcontroller :

23. How Can I Determine Stepper Motor Wiring Without the Stepper Motor Pin out?
1.
Each of the two phases should have the same
resistance when measured with a multimeter.
When measuring the resistance across one wire
from each of the two phases, the resistance
should be infinite because the circuit is open.
Locate the two pairs of wires that represent
the two phases; both pairs of wires will have
similar internal resistance.
2.
Connect each phase to the amplifier and ignore
the polarity (+ / -), for now. You have a 50
percent chance of guessing right.
3.
Send a command to move the motor. If the motor
rotates in the wrong direction, then switch either phase
A and A- or B and B- (effectively reversing directions).

24. Determine Stepper Motor Wiring using color code chart:

25. Thank You!!
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