The document discusses stepper motors. It begins with an introduction that defines a stepper motor as a device that converts electrical pulses into discrete mechanical movements, with the shaft rotating in steps proportional to the input pulses. It then covers stepper motor operation, types including variable reluctance, permanent magnet and hybrid, advantages, applications in devices like printers and CD drives, and stepping modes like full step and microstepping.

1. SEMINAR
ON
STEPPER
MOTOR
A splendid innovation in the
techsavi society….

2. P P E N D IX
 STEPPER MOTOR-INTRODUCTION
 OPERATION
 TYPES
 ADVANTAGE
 REAL LIFE APPLICATIONS
 CONCLUSION
2
110907

3. INTRODUCTION TO STEPPER MOTOR
 Electromechanical device which converts
electrical pulses into discrete mechanical
movements
 Shaft of a stepper motor rotates in
discrete step increments when electrical
pulses are applied
 Sequence of the applied pulses is directly
related to the direction of motor shaft’s
rotation.
 Speed of rotation is directly related to
the frequency of input pulses applied
[3]

4.  PM type stepper
motor permanent
magnet is rotor and
coils are put on
stator.
 The rotor will move
precisely 90 degrees
for each pulse of
electricity that the
motor receives
[4]

5. CLOCKWISE & COUNTERCLOCKWISE CONTROL
Clockwise Rotation Counter
Clockwise Rotation
Control Control
Sequence Sequence
Steppers don't simply respond to a clock signal
They have several windings which need to be energized in the correct sequence before the [5]
motor's shaft will rotate.
Reversing the order of the sequence will cause the motor to rotate the other way.

6. THEORY
[6]
 When current flows holding torque is produced
 Without power, rotor will detent or align to magnetic
poles ,here 4 Such positions are present.
 changing the current flow to the next stator winding,
the magnetic field will be changed 90°& rotor will
move 90° before its magnetic fields will again align
with the change in the stator field.
 The turn of the motor is controlled by the electric
current which pours into different stator terminals

7. A circuit which is responsible for
converting step and direction signals
into winding energization patterns is
called a translator. Most stepper motor
control systems include a driver in
addition to the translator, to handle
the current drawn by the motor's
[7] windings.

8. Basing On Internal Wiring Condition
Stepper Motors are of two types :
[8]
UNIPOLAR STEPPER MOTOR BIPOLAR STEPPER MOTOR
Unipolar stepper motors are generally six leads in Bipolar Stepper motors are generally four leads and
two triplets - each triplet powering one coil with a two pairs each powering one coil
centre tap . Sometimes there are 5 leads due to Example : floppy disc drive read or write
internal connection of centre taps . By using an ohm Supply two coils with phase shifted pulse train in
meter and by checking equal resistances between order to rotate the motor
pair of leads it can be easily found out which The leads can be identified corresponding
leads corresponding to each unit . Just by ignoring To the windings of the motor with an ohm meter
centre taps unipolar motors can be operated as
bipolar fashion .

9. STEPPER MOTOR
TYPES There are three
basic stepper motor
types.
[9]

10. VARIABLE-RELUCTANCE TYPE
[10]
 Consists of a soft iron multi-
toothed rotor and a wound
stator.
 When the stator windings
are energized with DC
current &the poles become
magnetized
 Rotation occurs when the
rotor teeth are attracted to
the energized stator poles.
Crossectional view

11. PERMANENT MAGNET (PM) TYPE
Crossectional view Rotor of PM type
[11]

12. HYBRID TYPE :
• Step Angles For Hb
Stepper Motor Range
From 3.6to 0.9 Degree
With100 – 400 Steps
Per Revolution
• Detent, holding and
dynamic torque
characteristics of the
motor are better
compared to both the
VR and PM types. Crossectional View
[12]

13. [13]

14. C o mp ute r
B u s in e s s M a c h in e s
P e r ip h e r a ls
APPLICATION USE APLICATION USE ROBOTICS
Floppy Disc position magnetic pickup Card Reader position cards INSTRUMENTATION
APPLICATION
Copy Machine paper feed
Printer carriage drive NUMERICAL CONTROL
Banking Systems credit card positioning
Printer rotate character wheel OF MACHINE TOOLS
Banking Systems paper feed
Printer paper feed ELECTROMEDICAL
Typewriters head positioning
Printer ribbon wind/rewind
(automatic) NUCLEAR REACTOR
Printer position matrix print head
Typewriters paper feed
Tape Reader index tape
(automatic) AEROSPACE AND
INDUSTRIAL
Plotter X-Y-Z positioning Copy Machine lens positioning
APPLICATIONS
Plotter paper feed Card Sorter route card flow
CONSUMER
ELECTRONICS
P ro c e s s C o ntro l
Machine Tools
APPLICATION USE
APPLICATION USE
Carburetor Adjusting air-fuel mixture adjust
Milling Machines X-Y-Z table positioning Valve Control fluid gas metering
Drilling Machines X-Y table positioning Conveyor main drive
Grinding Machines down feed grinding wheel In-Process Gaging parts positioning
Assembly Lines parts positioning
Grinding Machines automatic wheel dressing
Silicon Processing I. C. wafer slicing
Electron Beam Welder X-Y-Z positioning I. C. Bonding chip positioning
Laser Cutting X-Y-Z positioning Laser Trimming X-Y positioning
Lathes X-Y positioning Liquid Gasket Dispensing valve cover positioning
Sewing X-Y table positioning Mail Handling Systems feeding and positioning letters [14]

15. Used in Dot Matrix Printer Used in CD-ROM Drive
[15]

16.  Full Step Drive ----200 full steps per
revolution and 1.8º full step angle
 Half Step----- 400 full steps per revolution
and 0.9º full step angle
 Micro stepping (Continuously varying motor
currents )----more than 50000 full steps per
revolution and (1/256) ºfull step angle
[16]

17. STEPPING MODES Frame 1: The top electromagnet (1) is
turned on, attracting the nearest tooth
cOnTd : of a gear-shaped iron rotor. With the
teeth aligned to electromagnet 1, they
will be slightly offset from
electromagnet 2.
Frame 2: The top electromagnet (1)
is turned off, and the right
electromagnet (2) is energized, pulling
the nearest teeth slightly to the right.
This results in a rotation of 3.6° in this
example.
Frame 3: The bottom electromagnet
(3) is energized; another 3.6° rotation
occurs.
Frame 4: The left electromagnet (4)
is enabled, rotating again by 3.6°.
When the top electromagnet (1) is
again enabled, the teeth in the sprocket
will have rotated by one tooth position;
since there are 25 teeth, it will take 100
steps to make a full rotation in this
example.
[17]

18. F u ll S t e p S t e p p e r H a lf S t e p
M o to r S te p p e r M o to r
The main difference is that the second
Just as the rotor aligns with phase is turned on before the first
one of the stator poles, the phase is turned off. Thus, sometimes
second phase is energized. both phases are energized at the same
The two phases alternate on time. During the half-steps the rotor is
and off and also reverse held in between the two full-step
polarity. There are four positions. [18]
steps

19. A stepper motor (or step motor) is a brushless,
synchronous electric motor that can divide a full
rotation into a large number of steps.
Control sequences :
Two control sequences for single stepping
a unipolar or bipolar stepper motor are shown
below (here positive voltages are denoted by red
bars, and negative / ground by blue):
powers two windings at a time and
produces a torque about 40% greater than
for the previous sequence while using twice
as much power
[19]

20. TORQUE VS ROTOR ANGLE & SPEED
CHARACTERISTICS
Torque vs. Rotor angle Graph between Torque
graph and speed
[20]

21.  The curve shows
behavior of rotor with
one step pulse
 step time dependent on
the ratio of torque to
inertia & the type of
driver used
 Acceleration causes
overshoots & ringing as
shown
 This behavior is reduced
by micro stepping Positional Accuracy Of
A Stepper Motor
[21]

22. STEP ANGLE ACCURACY
[22]
 Stepper motor is
popular due to it’s
accuracy and
repeatability
 Step angle accuracy is
3-5% of one step
 Positional Error
 Step Position Error
Positional accuracy
of a stepper motor

23. Overall Graphics of Working :
 Halls Sensors sense the
position of the coils
 The Decoder Circuit turns
appropriate switches on and
off
 The voltage through the
specific coils turns the motor
 No Commutators
 Position of Coils with respect
to the magnetic field is
sensed electronically.
 Current is commutated
through electronic switches to
appropriate phases.

24. ADVANTAGES OF STEPPER MOTORS
[24]
 The rotation angle of the motor is proportional to the input
pulse
 Excellent response to starting, stopping/reversing
 The motors response to digital input pulses provides open-loop
control
 It is possible to achieve very low speed synchronous rotation
 A wide range of rotational speeds can be realized
 Very reliable since there are no contact brushes in the motor
 Accuracy of 3 – 5% of a step and this error is non cumulative
from one step to the next

25. 166 OzIn 6-Wires 260 OzIn 4-Wires
80 OzIn 8-Wire
Stepper Motor Stepper Motor
Stepper Motor
NASA rover history -
August 09, 2006
Micro stepping RAMS (Robot-Assisted
Chopper Driver Micro-Surgery)
25

26. Application Examples : Stepping your way
Film Advance Indexing Circuit Board Engine Test
Scanning Stand
Table
Engraving Telescope Capsule Filling Surface Grinding
Machine Drive Machine Machine
[26
]

27. CONCLUSION
 All types and characteristics of a stepper motor are
studied throughout this paper.
 These are very popular in our day to day life due to a
lot of advantages and also in digital control circuits,
such as robotics because they are ideally suited for
receiving digital pulses for step control
[27]

28. Useful Links :
 http://en.wikipedia.org/wiki/Electric_motor
 http://electronics.howstuffworks.com/ stepper motor3.htm
 http://www.hernonmfg.com/stepper motor.htm
 http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html
 http://www.servomag.com/flash/4-pole/motor.html
 http://www.engineersedge.com/motors/stepper_motor.htm
 http://www.freescale.com/webapp/sps/site/application.jsp?nodeI
[28
]

29. ANY
QUESTION ??