Transcript Micro Motors

DC Motors
Micro Motors
Mark Lyon
Brent Peterson
Outline

Motor Overview
 DC vs. AC
 Brushless DC Motors
 Design Considerations
 Application Considerations
 DC Micro Motors
How a DC motor Works
lancet.mit.edu/motor/motor3.html
DC vs. AC Motors
DC Motor
AC Motor
http://mot-sps.com/motor/tutorial/blac.html
AC Advantages/Disadvantages
Advantages
 Simple Design
 Low Cost
 Reliable Operation
 Easily Found
Replacements
 Many Different
Environmental
Enclosures
Disadvantages
 Expensive Speed
Control
 Inability to Operate at
Slow Speeds
 Poor Positioning
Control
DC Advantages/Disadvantages
Advantages
 Easy to Understand
Design
 Easy to Control Speed
 Easy to Control
Torque
Disadvantages
 Expensive to Produce
 Can’t Reliably Control
at Lower Speeds
 Physically Larger
 High Maintenance
Brushless DC Motor
http://mot-sps.com/motor/tutorial/blac.html
DC Motor Torque/Speed
http://lancet.mit.edu/motors/motors3.html#torque
DC Motor Power/Speed
http://lancet.mit.edu/motors/motors3.html#torque
DC Motor Electrical Power
Constant Voltage
Constant Current
http://www.4p8.com/eric.brasseur/emamem.html
Motor Application Considerations
Service Life
http://www.micromo.com/03application_notes/tutorial4.asp
Motor Application Considerations

Audible Noise
 Electrical Noise
 Efficiency
Emax = (1 - ((Mf/(Mst + Mf)).5)2
where:
Emax = maximum motor efficiency
Mf = motor friction torque
Mst = motor stall torque
http://www.micromo.com/03application_notes/tutorial4.asp
DC Micro Motors
Max. Power (Watts)
12
10
8
6
4
2
0
0
0.2
0.4
0.6
Weight (oz.)
0.8
1
1.2
Efficency (%)
DC Micro Motors
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.2
0.4
0.6
Weight (oz.)
0.8
1
1.2