dishant 824
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[1]
STEPPER MOTOR
Under the Guidance of
[guide teacher name]
By
Dishant Kumar (2K8/EE/824)
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[2]
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 shafts rotation.
Speed of rotation is directly related to thefrequency of input pulses applied
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[3]
STEPPER MOTOR THEORY OF OPERATION
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
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[4]
CLOCKWISE & COUNTERCLOCKWISE CONTROL
CounterClockwise Rotation
ControlSequence
ControlSequence
Clockwise Rotation
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THEORY
When current flows holding torque is produced
Without power, rotor will detent oralign 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
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[6]
STEPPER MOTOR TYPES
There are three basic stepper motor
types.
Variable-reluctance
Permanent-magnet
Hybrid
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VARIABLE-RELUCTANCE TYPE
Consists of a soft ironmulti-toothed rotor and awound stator.
When the stator windingsare energized with DCcurrent &the poles becomemagnetized
Rotation occurs when therotor teeth are attracted tothe energized stator poles.
Crossectional view
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PERMANENT MAGNET (PM) TYPE
Rotor of PM typeCrossectional view
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HYBRID TYPE
Step Angles For HbStepper Motor RangeFrom 3.6to 0.9 DegreeWith100 400 Steps PerRevolution
Detent, holding anddynamic torquecharacteristics of themotor are bettercompared to both the VRand PM types. Crossectional View
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APPLICATION
Used in controlledrotation angle, speed,
position applications.
Printers, Plotters, HighEnd Office Equipment,Hard Disk Drives,Medical Equipment,
Fax Machines,Robotics, automotiveAnd Many More. Paper drive mechanism
Using stepper machine
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SOME PRACTICAL FIGURES
Used in CD-ROMDriveUsed in Dot Matrix Printer
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STEPPING MODES
Full Step Drive ----200 full steps per
revolution and 1.8 full step angle
Half Step----- 400 full steps per revolution
and 0.9 full step angle
Microstepping (Continiously varying motor
currents )----more than 50000 full steps per
revolution and (1/256) full step angle
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TORQUE VS ROTOR ANGLE & SPEED
CHARCTERISTICS
Graph between Torque
and speed
Torque vs. Rotor angle
graph
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SINGLE STEP RESPONSE
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
microsteppingPositional Accuracy Of
A Stepper Motor
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STEP ANGLE ACCURACY
Stepper motor is popular
due to its accuracy and
repeatability
Step angle accuracy is 3-5% of one step
Positional Error
Step Position Error
Positional accuracy
of a stepper motor
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ADVANTAGES OF STEPPER MOTORS
The rotation angle of the motor is proportional to the inputpulse
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 cumulativefrom one step to the next
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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
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THANK YOU
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