The document discusses stepper motor technology, including how stepper motors work by using electromagnetic coils and permanent magnets to rotate the motor in discrete steps. It describes the different types of stepper motors like permanent magnet, variable reluctance, and hybrid motors. It also covers topics like bipolar and unipolar coil windings, basic motor testing with an ohmmeter, and the electronic components that control and power stepper motors.

1. NPM
Unraveling The Mystery of
Stepper Motor Technology
Jeramé Chamberlain
Nippon Pulse America, Inc., USA
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2. NPM What is a Open Loop
Stepper Motor System?
What Are Stepper Motors?
How Do Stepper Motors Work?
Troubleshoot & Test Stepper Motors
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3. NPM Basic Stepper Application
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4. NPM Stepper Motor Coil
PHASE A
S
N
● PHASE B
PHASE B
S
N
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PHASE A
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5. NPM PHASE A
One Phase
PHASE A
Step Sequence
S
N
PHASE B
●
PHASE B PHASE B N S PHASE B
N
S
●
●
S
N
STEP 1 STEP 2
PHASE A
Two Phase PHASE A
PHASE A
Stepper Motor PHASE A
N
S
PHASE B
●
●
PHASE B PHASE B S N PHASE B
N
●
S
N
N
S
STEP 4
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STEP 3
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PHASE A PHASE A
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6. NPM Types of Stepper Motors
Permanent-Magnet (PM)
• PM rotor & electromagnetic coil
Variable Reluctance (VR)
• No PM, no residual torque
Hybrid – NEMA Sizing
• Combined PM & VR Technology
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7. Cross Section of A Two
NPM Phase Hybrid Motor
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8. NPM PM & Hybrid Stepper Motors
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9. NPM Bipolar Coil Winding
Each phase
is a single
winding
Current flow and electromagnetic
polarity is reverses in the windings
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10. NPM Unipolar Coil Winding
Sometimes
called
four-phase
steppers
Current flow and electromagnetic polarity is
NOT reversed in the windings. Polarity
comes from alternately energized windings
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11. NPM Motors Need Maintenance
Steppers – Not So Much
Stalled motors burn up
• Steppers operate in stall condition
Most brushes go bad
• Steppers are brushless
All bearings go bad
• Quality Stepper bearings are
rated from 90-100K hours
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12. NPM Ohmmeter Test With Steppers
Bipolar
Always 4 leads
Resistance is
the same in
both windings
and both
directions
Some 8 lead motors can be connected
as bipolar Sold & Serviced By:
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13. NPM Ohmmeter Test With Steppers
Unipolar
5 or 6 leads
Resistance from
each phase to
Common is the
same in both
directions
If 5 leads, two commons connected
Some 8 lead motors can be Unipolar
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14. NPM Unipolar Windings & Wire Colors
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15. NPM Bipolar Windings & Wire Colors
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16. NPM Stepper Motor Electronic System
CPU, Controller, Sequencer, Driver
One or more parts can be combined,
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17. NPM Controller Receives & Coordinates
A dedicated controller generates
motion profiles that produce smoother
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18. NPM Controller Manages & Interpolates
Some controllers provide interpolation
between motors to produce smooth
XYZ motions – CNC Machines
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19. NPM Two Outputs Types to Sequencer
Pulse & Direction – Speed & Rotation
CW/CCW – Speed & Rotation Sold & Serviced By:
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20. NPM One Controller – Two Output Types
Pulse & Direction –
Speed & Rotation
CW/CCW – Speed &
Rotation
Pulse & Direction is the most
common format used in the USA
PCL6045B can output both formats
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21. NPM Stepper Motor Sequencers
Sequencers read speed and direction
from controller and deliver excitation
sequence to the driver
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22. NPM Bipolar Stepper Drivers
When Q1a and
Q4a (green)
are on, current
flows in one
direction
When Q2a and
Q3a (red) are
turned on,
current flow is
reversed Sold & Serviced By:
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23. NPM Unipolar Stepper Drivers
Half the drive
electronics of
bipolar, and
30% less torque
However,
unipolar coils
allow a higher
pulse rate than
bipolar, before
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24. NPM Constant Current - Constant Voltage
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25. NPM Current Lags Voltage in an Inductor
Torque from stepper
motors is generated by
current, not voltage
PWM or Chopper drive
manages current
through a switch,
applied at higher
voltages to induce
more winding current
Chopper delivers more
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26. NPM Half Stepping A Stepper Motor
Easiest way to accomplish half stepping
is by using 1-2 phase excitation
Divides a stepper’s full step angle by
two 7.5°/2 = 3.25° per half step
30% loss of torque depending on step
rate when compared to full step
Winding is not energized during each
alternating half step
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27. NPM PHASE A
Half Stepping
PHASE A
Sequence
S
N
PHASE B
●
PHASE B PHASE B N S PHASE B
N
S
●
●
S
N
STEP 1 STEP 3
PHASE A
Two Phase PHASE A
PHASE A
Stepper Motor PHASE A
N N
N
N N
S
PHASE B S PHASE B PHASE B S PHASE B
●
●
S
N
S S
STEP 4
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STEP 2
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PHASE A PHASE A
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28. NPM Microstepping A Stepper Motor
Full step can be broken into as many as
512 parts
Current is limited through each winding.
Unequal pull on the magnet means it
moves toward the weaker winding
Torque falls rapidly as speed increases
Steps are not constant for positioning
Microstepping should only be used for
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29. NPM Combined Sequencer & Translator
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