INTRODUCTION

Terminology

Coil vs. winding vs. phase

Stepper Motor Types

Stepper Motor Specifications

Stepper Motor Selection Criteria

Stepper Motor Sizes

  • NEMA “Teen” Cubes
  • NEMA Size 23 Cylinders
  • Stacked Cans With Diamond-Shaped Mounting Flange

    Rough Motor Specs – Based On My Experiments

    Gear Puller

    GETTING STARTED

    4-Phase Stepper Motors

  • Exercise motor with four SPST toggle switches and a power supply

    Testing 5-wire and 6-wire motors
    – Full steps – one winding energized (wave drive)
    – Full steps – two adjacent windings energized in each
      detent position (normal mode)
    – Half steps – alternately one winding energized, two
      adjacent windings energized
    Testing an 8-wire motor

    2-Phase Stepper Motors

  • Determine wiring with ohmmeter
  • Exercise motor with two DPDT on-off-on toggle switches and a
        power supply
    – Full steps – one winding energized (wave drive)

    – Full steps – two windings energized (normal mode)

    – Half step sequence – alternately one winding energized,
      two windings energized

    MICROCONTROLLER-BASED STEPPER MOTOR CONTROL – INTRODUCTION

  • PICMicro (R) instruction set
  • Hexadecimal notation
  • Compare using PICMicro(R)
  • Interrupt service and saving context

    TEST CIRCUITS OVERVIEW

    Overview

    Test Board for Exercising Stepper Motors

  • Pulser
  • Switches And Pull-ups
  • Construction Techniques And Board Design
  • Pulser software
  • Testing the pulser

    Translators

  • PIC16F84A translator (unipolar bit pattern)
    – Software design

    – Hardware design

    – Code

    – Testing the PIC16F84A unipolar translator

  • PIC16F84A translator (bipolar bit pattern)
    – Design

    – Code

    – Testing the PIC16F84A bipolar translator

    Simple Drivers

    Unipolar

  • Simple ULN2803A driver
  • Exercising a unipolar stepper motor using a pulser, PIC16F84A
        translator and a ULN2803A unipolar driver
  • Simple TIP120 driver
  • Exercising a unipolar stepper motor using a pulser, PIC16F84A
        translator and a TIP120 unipolar driver
  • UCN5804B translator/driver
  • Exercising a unipolar stepper motor using a pulser and a UCN5804B translator/driver

    Bipolar

  • H-Bridge
  • L293D driver (dual H-bridge)
  • Exercising a bipolar stepper motor using a pulser, PIC16F84A
        translator and an L293D bipolar driver
  • L298N driver (dual H-bridge)
  • Exercising a bipolar stepper motor using a pulser, PIC16F84A,
        translator and an L298N biopolar driver

    TORQUE MEASUREMENT

  • Motor (what’s available) via lever arm and weights
    – Holding, add weight until slips
    – Moving, add weight until won’t turn
  • Application (what’s required) via lever arm and weights
  • Lever arms and fishing sinkers

    MAXIMUM STEP RATE MEASUREMENT

    MICROCONTROLLER-BASED STEPPER MOTOR CONTROL

    Unipolar

  • Simple unipolar stepper control – straight line code
    Full steps – one winding energized

    How to reverse direction

    Change delay time to change speed

  • Table lookup and counter to get bit pattern for each step
    Full steps – two windings energized

    Half step sequence

  • Exercising a unipolar stepper motor using a microcontroller,
        PIC16F84A translator and a ULN2803A or TIP 120 unipolar driver
  • Exercising a unipolar stepper motor using a microcontroller and a UCN5804B translator/driver

    Bipolar

  • Exercising a bipolar stepper motor using a microcontroller and
        an L293D or L298N bipolar driver

    HIGH PERFORMANCE DRIVE CIRCUITS – Current Control

  • Limitations of voltage control and need for high performance current control

    Unipolar

  • SLA7024M unipolar driver – Allegro
  • Exercising a unipolar stepper motor using a pulser, PIC16F84A
        translator and a SLA7024M driver
    – Maximum stepping rate at higher than rated voltage
    – Torque operating at higher than rated voltage

    Bipolar

  • L297/L298N bipolar translator/driver
  • Exercising a bipolar stepper motor using a pulser and a L297/L298N translator/driver
    – Maximum stepping rate at higher than rated voltage

    – Torque operating at higher than rated voltage

  • Exercising a bipolar stepper motor using a microcontroller and a     L297/L298N translator/driver

    Controlling A STEPPER MOTOR WITH A PC

  • Serial port, parallel port
  • Programming languages
  • Port board, not mother board

    MECHANICAL CONSIDERATIONS

    Mounting The Stepper Motor And Heat Dissipation

    Grabbing On To The Shaft = Mechanical Connection

  • Avoid damaging the shaft (clamp, flat, split hub)
  • Shaft couplings – alignment, flex
  • Avoid applying a thrust load to the shaft

    Converting Rotary Motion To Linear Motion

    Mechanics

  • Torque
  • Inertia

    Position – Home Or Starting Position Sensor

  • Test for accuracy

    Backlash

    NEMA 23 Tester

    PRINTER EXPERIMENT

  • Software design
  • Code snippet
  • Implement your design

    QUICK STEP’n

  • Test Hardware
  • Software design details
  • Home Position
  • Ramping up/down and rapid traverse
    – Ramping up – acceleration

    – Ramping down – deceleration
  • Speed – rapid traverse

  • Destination
  • More software details
  • Code

    APPENDIX A – Fast Diodes

    APPENDIX B – Parts Lists

    APPENDIX C – Sources

    APPENDIX D – Program Listings vs. Page Number





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    (C) Copyright 2002 Square 1 Electronics
    This site last updated August 31, 2005