STEPPERS AND SERVOS

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STEPPERS AND SERVOS
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Types of stepper motors

• Based on construction
• Variable reluctance
• Permanent magnet
• Hybrid
• Based on winding
• Unipolar
• Bipolar

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Variable Reluctance

• This motor dose not have a permanent magnet
• These motors have four stater pole sets as shown
  below

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Permanent magnet

• These motors have permanent magnet rotor
• It is a relatively low speed, low torque device
• It has a large step angle of either 45 or 90
  degrees

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Hybrid

• This is a combination of variable reluctance and
  permanent magnet motors
• These motors have multi toothed starter poles and
  permanent magnet rotor
• These motors normally have very small step angle.

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Bipolar and Unipolar

• Bipolar stepper comes with 4 wires and have no
  tapping at the center of the windings
• Unipolar steppers comes with 5,6 or 8 wires.

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Driving a unipolar stepper
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Servos
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Driving a servo

• A servo runs on a PWM signal as shown below
• W1.5 ms for normal position
• W1 ms for 0 degree
• W2ms for 180 degrees

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Thank You