cmpe 118 mechatronics stepper motors cleverness with magnets and coils

CMPE 118 MECHATRONICSCMPE 118 MECHATRONICS

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 d

S

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

cmpe 118 mechatronics stepper motors cleverness with magnets and coils

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