STEPPER MOTORS

Cleverness with Magnets and Coils

Stepper Motors

Different types of stepper motors

Differences in Characteristics

Snubbing for Stepper Motors

Stepper Drive Techniques

Stepper Dynamics

The Permanent Magnet (PM) Stepper Motor

PM Stepper Operation

S

N

S N

S

N

SN

S

N

Torque v.s. Angular Displacement

The Variable Reluctance (VR) Stepper Motor

The Hybrid Stepper Motor

The Hybrid Motor Rotor

Offset Teeth in Hybrid Rotor

Variations in Output Torque

Stepper Motor Wiring

1 23 45 6

c

d

e

Winding Direction is Important

2-Phase Universal Wound v.s. 4-Phase

a b

Driving Stepper Motors

Stepper Sequences: Full Step

V +

V +

G n d

G n dS

N

S

N S

N

S

N

Driving Full Step

Stepper Sequences: Wave Drive

V+

G nd

S

NS N

S

NSN

S

N

Driving: Wave Drive

V+

V+

G nd

G nd

A

B

C D

Stepper Sequences: Half-Step

S N

S

NS

N

S

N

SN

S

N

S

N

Driving: Half-Step

Stepper Sequences: Micro-Stepping

V+

V+

G nd

G nd

A

B

C DS

N

S N

S

N

S

NS

N

S

N

Generating the Drive

LogicSequencer

CoilDrive

Stepping Dynamics

Load Affects the Step Dynamics

Drive Affects the Step Dynamics

ab

Stepper Motor Performance Curves

Current Dynamics

L/nR Drive

Current Rise in Detail

0

Performance Improvement with L/nR Drive

2-Level Drive

Chopper Drive

Vo

ltage

Cur

ren

t

t0

t0

t1

t1 tim e

Diode Snubber for an H-Bridge

Zener Diode Snubber for and H-Bridge

Several other alternatives+V

12V

Ext F ile

0/0V 2N3055

1.2m H DIO DE

50

11.427

+V12V

E xt F ile

0 /0V 2N 3055

1.2m HDIO D E

ZE NE R

50

11 .4

+V

Ext F ile

0/0V 2N3055

1.2m H

1N474950

11.4

Snubber Summary

3 0 3 u3 7 2 u 4 4 2 u 5 1 1 u 5 8 0 u 6 4 9 u 7 1 8 u- 1 . 0 6

- 8 7 5 m

- 6 9 0 m

- 5 0 6 m

- 3 2 1 m

- 1 3 7 m

4 7 . 6 m

R e f = G r o u n d X = 6 9 . 2 u S / D i v 2 4 1 %

Diode Only

Resistor + Diode

Diode + Zener

Zener Only

No Snubber

Affects of Snubbing on Performance