DC MotorsDC MotorsMicro MotorsMicro Motors

Mark Lyon

Brent Peterson

OutlineOutline

Motor OverviewDC vs. ACBrushless DC MotorsDesign ConsiderationsApplication ConsiderationsDC Micro Motors

How a DC motor WorksHow a DC motor Works

lancet.mit.edu/motor/motor3.html

DC vs. AC MotorsDC vs. AC Motors

DC Motor AC Motor

http://mot-sps.com/motor/tutorial/blac.html

AC Advantages/DisadvantagesAC 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/DisadvantagesDC 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 MotorBrushless DC Motor

http://mot-sps.com/motor/tutorial/blac.html

DC Motor Torque/SpeedDC Motor Torque/Speed

http://lancet.mit.edu/motors/motors3.html#torque

DC Motor Power/SpeedDC Motor Power/Speed

http://lancet.mit.edu/motors/motors3.html#torque

DC Motor Electrical PowerDC Motor Electrical Power

Constant Voltage Constant Current

http://www.4p8.com/eric.brasseur/emamem.html

Motor Application ConsiderationsMotor Application ConsiderationsService LifeService Life

http://www.micromo.com/03application_notes/tutorial4.asp

Motor Application ConsiderationsMotor 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

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