Transcript phys - EvanW.org

Motorin': Whats Your Price for
Flight
The trade-offs of electric motors
Evan Widloski and Will Hime
The Era of Electricity
Electricity has changed the world drastically in the past 150
years, and one of the many ways it has is the introduction of
Electric motors.
Motors play a huge role in our lives. From taking us where
we need to go, to grinding up coffee beans in the morning,
there are many kinds of motors and they all serve different
purposes. But what differentiates motors from other
motors? And how do these motors function?
What will be covered
• brief history of the electric motor
• explanation of electromagnetism
• construction of a motor
• comparison of several types of motors and their
advantages
• conclusion
History of Electric Motors
• First electric motor
created by Faraday in
early 1800's
• Consisted of wire hanging
down into a cup of
Mercury with a magnet in
the middle
• When a current passed
through the magnet, the
wire began to revolve
around it.
Farraday's First Motor
http://www.sparkmuseum.com/MOTORS.HTM
History of the Electric Motor
• It wasn't until about ten years
later that motors took on a
more practical format.
• Rev. William Ritchie began
experimenting on a motor with
coils.
• This, in function, is similar to
modern motors
http://www.sparkmuseum.com/MOTORS.HTM
Electro-Magnets
• Electro-Magnets consist of a electrified metal coil
wrapped around a semi-magnetic metal.
• The electrified wire creates a magnetic field that
amplifies the field of the object, thus creating a powerful
magnet.
• However, this magnet can be powered off if the need
arise, which is more convenient than a permanent
magnet.
• The Magnetic field of an electro-magnet is not
omnidirectional like that of a rare earth magnet, it is in
one direction and also rotational.
http://electronics.howstuffworks.com/motor1.htm
Anatomy of an Electric Motor
• motors consist of a series of
electromagnetic coils which are fired in a
sequence to drive a central shaft, or rotor
• the rotor is surrounded by magnets. this
provides an opposing force for the rotor to
“push off of” - stator
• motors need a way for the coils to push and
pull at different times, not just push
constantly. this is accomplished by a
commutor
animation
Types of Electric Motors
Brushed Motors
• use small brushes to switch current
back and forth
Brushless Motors
• uses sensors and electronics to switch
current back and forth
Brushed Motors
Brushless Motors
• Brushless Motors use a cylinder of
magnets surrounded by a ring of coils.
• The coils are charged, which spins the
magnet.
• This is basically the inverse of a
brushed motor
• It also cause little to no friction as no
contact is made between surfaces.
• This setup is superior in high-speed
applications or at highly variable
speeds
Brushless Motors
• Brushless Motors use a cylinder of magnets surrounded
by a ring of coils.
• It also cause little to no friction as no commutator is
required
• This setup is superior in high-speed applications or at
highly variable speeds
• Requires an electronic
control, which can easily
double its price
Brushless Motors (cont.)
• Brushless Motors use a cylinder of
magnets surrounded by a ring of coils.
• The coils are charged, which spins the
magnet.
• This is basically the inverse of a
brushed motor
• It also cause little to no friction as no
contact is made between surfaces.
• This setup is superior in high-speed
applications or at highly variable
speeds
Conclusion
Pros
Very Good for high-torque situations.
Brushed
Powerful
Tough and reliable
Cons
not very fast
heavy/bulky
could possibly have "too much"
torque and break parts or strip gears
Sensitive to excessive vibration
Brushless
High-Speed
waterproof
versatile
Expensive (requires separate speed
control)
will stall if to much torque is put on it
"Smart"
Works Cited
• http://www.sparkmuseum.com/MOTORS.HTM
• http://electronics.howstuffworks.com/motor1.htm
• http://www.animations.physics.unsw.edu.au/jw/electricmotors.html
• http://www.walter-fendt.de/ph14e/electricmotor.htm