Jeff Shelton 10 March 2015 1 - Purdue EngineeringJeff Shelton – 10 March 2015 Electric Motors DC Motors Permanent Magnet Series Wound Compounded Shunt Wound Separately Excited Brushed

Jeff Shelton – 10 March 2015 1

Jeff Shelton – 10 March 2015

Shaft (Rotor) Angle

I1

I2

I3

2

Jeff Shelton – 10 March 2015

Electric Motors

DC Motors

Permanent Magnet

Series Wound

Compounded

Shunt Wound

Separately Excited

Brushed

Brushless

Stepper

AC Motors

Reluctance

Hysteresis

Synchronous

Induction

Wound Rotor

Squirrel Cage

Permanent Magnet

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Jeff Shelton – 10 March 2015 4

Image: http://electronics.howstuffworks.com/brushless-motor.htm

Jeff Shelton – 10 March 2015 5

Image: http://www.rcuniverse.com/magazine/reviews/1344/BrushlessMotors7.jpg

Jeff Shelton – 10 March 2015

Shaft (Rotor) Angle

I1

I2

I3

6

Jeff Shelton – 10 March 2015

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Jeff Shelton – 10 March 2015

Electric Motors

DC Motors AC Motors

Permanent Magnet

Brushed

Brushless

Reluctance

Hysteresis

Stepper

Synchronous

Induction

Wound Rotor

Squirrel Cage

Series Wound

Compounded

Shunt Wound

Separately Excited

Permanent Magnet

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What does it all mean?

Image: http://www.pololu.com/category/87/stepper-motors

Jeff Shelton – 10 March 2015

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Image: http://www.engineersgarage.com/articles/stepper-motors

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Motor Driver

Current to Windings

Indexer Step Pulses

Controller

Movement Sequence

Images: http://www.automationdirect.com/adc/Overview/Catalog/Motion_Control/Stepper_Systems

Jeff Shelton – 10 March 2015

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Jeff Shelton – 10 March 2015

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Jeff Shelton – 10 March 2015

N N

N

A

A'

B B'

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N N

N

A

A'

B B'

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N N

N

A

A'

B B'

Jeff Shelton – 10 March 2015

N

N

N N

N

Initial equilibrium state

Horizontal winding field reversed (no motion yet)

Motion starts toward new equilibrium

Reach new equilibrium

N N

S

S N

N

N

N S

N N

S

N N

N

S

N

S

N

N

N S

S

N

N

N

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S N S N N S

Jeff Shelton – 10 March 2015

ℱ

19

+ –

ℱ = 𝑁𝑖

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+ –

ℱ = Φ ℜ𝑚

𝑉 = 𝑖 𝑅

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+ –

Core

ℱ = Φ ℜ𝑚

Jeff Shelton – 10 March 2015

Φ

ℜ𝑚

22

Φ =𝑁𝐼

ℜ𝑚

+ –

Core

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Φ =𝑁𝐼

ℜ𝑚

+ –

Core

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N S

Jeff Shelton – 10 March 2015

β

27

𝛽 =𝑁𝑠 − 𝑁𝑟

𝑁𝑠 ∙ 𝑁𝑟× 360°

30°

Jeff Shelton – 10 March 2015

1 1

2

2

3

3

1 1

2

2

3

3

1 1

2 3

1 1

2 3

2 3 2 3

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Jeff Shelton – 10 March 2015

S

S S N

N N

N

S

S

S

S

N

N

N

S S

S

N

N N

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N S

N

S

N S

Jeff Shelton – 10 March 2015 31

Comparison adopted from: http://www.automotsys.com.au/stepserv.html

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Comparison adopted from: http://www.automotsys.com.au/stepserv.html

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Comparison adopted from: http://www.automotsys.com.au/stepserv.html

Jeff Shelton – 10 March 2015

A

B

(a) (b) (c) (d)

A

B ON

OFF ON

OFF ON

OFF ON

OFF

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Jeff Shelton – 10 March 2015

A

B

(a) (b) (c) (d)

A

B

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Vs

GND

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Vs

GND

Have to swap leads to reverse magnetic polarity

Jeff Shelton – 10 March 2015 39

Vs

GND

Have to swap leads to reverse magnetic polarity

Vs

GND

Vs or GND

Jeff Shelton – 10 March 2015 40

Vs

GND

Have to swap leads to reverse magnetic polarity

Vs

GND

Vs or GND

No lead swapping, but less torque production

Jeff Shelton – 10 March 2015

⟹

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On the same frame, bipolar motors can deliver about 40% more torque than

unipolar motors

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1 2 3 4

Phase 1

Phase 2

Jeff Shelton – 10 March 2015

1 2 3 4

Phase 1A (Q1)

Phase 1B (Q2)

Phase 2C (Q3)

Phase 2D (Q4)

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Jeff Shelton – 10 March 2015

Q5 Q6

Q7 Q8

A

B

(1) (2) (3) (4)

A B

A

B

(1) (2) (3) (4) (5) (6) (7) (8)

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Jeff Shelton – 10 March 2015

Pulse

Direction

Q1 Q2 Q3 Q4

Input: P & D

Output: Q1 & Q3

2 1 and 4 3Q Q Q Q

S0

S3 S2

S1

11 10

00 01

11

11

11

11

10

10

10

10

1 2 3 4

Phase 1A (Q1)

Phase 1B (Q2)

Phase 2C (Q3)

Phase 2D (Q4)

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Jeff Shelton – 10 March 2015

Time

Step

(A

ngu

lar

Posi

tio

n)

50

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Jeff Shelton – 10 March 2015

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Jeff Shelton – 10 March 2015

Torque

Spee

d (

Step

Rat

e)

Start/Stop Curve (limit)

Slew Curve (limit)

53

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