Stepper Motor

ELE 101 / 102 Basic Electrical Technology Dept of E & E, MIT Manipal

Introduction

• Incremental motion machine, does not rotate

continuously

• Designed to rotate through a specific angle for each

electrical pulse

• Each pulse initiates the drive circuit to produce 1

step of angular movement

• Popular types of stepper motor

Variable Reluctance (VR) type

Permanent Magnet (PM) type

Hybrid type (combination of VR & PM)

ELE 101 / 102 Basic Electrical Technology Dept of E & E, MIT Manipal

Connection diagram

ELE 101 / 102 Basic Electrical Technology Dept of E & E, MIT Manipal

Construction

• Stator : Slotted, Multi pole, multi phase winding

• Rotor : No winding

• Number of poles depends upon required angular change per

input pulse

• Operate with an external drive logic circuit

ELE 101 / 102 Basic Electrical Technology Dept of E & E, MIT Manipal

Working

• Train of Pulses applied to drive circuit

• Drive circuit supplies currents to the stator winding of motor

• Axis of air gap field coincides with the input pulses

• Rotor follows axis of the air gap magnetic field depending upon

pulse rate

• Step Angle

Angle by which rotor moves when 1 pulse is applied to the

stator, degrees

Resolution of positioning is decided by step angle

Smaller the step angle, higher is the resolution

Higher the resolution, greater is the accuracy of object

positioning

srevolutionrotor ofNumber

Steps ofNumber Resolution

ELE 101 / 102 Basic Electrical Technology Dept of E & E, MIT Manipal

Applications & Advantages

• Applications

Use with computer controlled systems

Machine Tools, Tape drives, Floppy disc drives

Printers, X-Y plotters, Robotics, Electric Watches, Space

crafts

Science Fiction Movies, Commercial, Medical, Military

Applications

• Advantages

Compatibility with digital systems

Precise control of angular displacement without feedback

arrangement

No requirement of any sensors for position and speed

sensing

Readily interfaced with microprocessors