stepper motor
TRANSCRIPT
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STEPPER MOTOR
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STEPPER MOTORA brushless DC electric motor
that divides a full rotation into a number of equal steps.
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STEPPER MOTORA brushless, synchronous
electric motor that converts digital pulses into mechanical shaft.
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STEPPER MOTOR
Is the “digital” version of the electrical motor.
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Actual picture of a Stepper Motor
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Actual picture of a Stepper Motor
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BASIC CONSTRUCTION
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BASIC CONSTRUCTION
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THE ROTOR
Made from two discs placed together so we get a series of alternating n
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THE STATOR• Placed around
the edge of the rotor.
• Are electromagnets that can be switched on and off individually.
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OPERATION
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TYPES OF STEPPER MOTOR
1. PERMANENT MAGNET STEPPER2. HYBRID SYNCHRONOUS STEPPER3. VARIABLE RELUCTANCE STEPPER
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PERMANENT MAGNET• Magnetized rotor.• Greater
resolution as pole pairs increase or “additional phases”.
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VARIABLE RELUCTANCE• Non-magnetic
rotor.• Greater
resolution as more teeth are added.
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VARIABLE RELUCTANCE• Normally have
three or five stator windings that energized one at a time.
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HYBRID• Has the
characteristics of both permanent magnet and variable reluctance.
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STEPPER MOTOR DRIVERS
Receives step and direction signals from a control system, typically a computer, and converts them into electronic signals which run the stepper motor.
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STEPPER MOTOR DRIVERS
The speed and torque of a stepper motor is determined by the flow of current from the stepping motor driver to the stepping motor winding.
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STEPPER MOTOR DRIVERS
Most stepper motor driver circuits is designed to supply a greater amount of voltage than the stepper motor’s voltage.
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STEPPER MOTOR DRIVERSThe higher the output voltage from
the stepper motor driver, the higher the level of torque versus speed.
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STEPPING SEQUENCE OF STEPPER MOTORS• Wave Drive Sequence• Full Step Sequence• Half Step Sequence• Micro Stepping
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MICROCONTROLLER-BASEDSTEPPER DRIVERSCan achieve very high rotation
speeds in stepper motor.
Using a microcontroller, it is possible to have extreme control over exactly how each individual coil is energized inside the motor.
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OPEN SOURCE STEPPER DRIVERS• AVRSTMD
–An open source microcontroller-based stepper driver.
–Uses an atmega48 processor and two LMD18245T current limited h-bridge chips.
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OPEN SOURCE STEPPER DRIVERS• DR. IGUANA
–Based on a dsPic23 microcontroller and two L298N H-bridge chips.
–Can achieve speeds up to 800 rpm.
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RepRap Stepper Motor Driver v1. x
-Uses L297/L298 stepper motor driver combo.
-Handles up to 2A.
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RepRap Stepper Motor Driver v2. x- Uses Allegro A3982 chip which does a lot of nice things and makes the board much simpler.
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STEPPER MOTOR
• Precise control• Wide range of rotational speeds.• Very low speed rotation is possible.• Quite reliable because there is no
contact brushes.• Good at starting, stopping, and
reversing direction.
ADVANTAGES
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• Provides precise positioning and repeatability of movement.
• Energized stepper motor maintains full torque at standstill position.
• Low cost for control achieved• Simplicity of construction
ADVANTAGES
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• Require a dedicated control circuit.• Use more current than DC motors.• Torque reduces at higher speeds.• Resonances can occur if not
properly controlled.• Not easy to operate at extremely
high speeds
DISADVANTAGES
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APPLICATIONS• In the field of lasers and optics they
frequently used in precision positioning equipment such as linear actuators, linear stages, rotation stages, goniometers, and mirror mounts.
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APPLICATIONS• In packaging machinery, and
positioning of valve pilot stages for fluid control system.
• Floppy Disk Drives• Flatbed Scanners• Computer Printers
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APPLICATIONS• Plotters• Slot Machines• Image Scanners• Compact Disc Drives• Intelligent Lighting
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APPLICATIONS• Camera Lenses• CNC Machines• 3D Machines