Download Electric Motors

Applications
•
•
•
•
•
•
•
•
Fans
Blowers
Machine tools (drill)
Appliances (blender, food processor)
Wristwatches
Disk drives
Pumps
Etc.
How it works
• Simply put, an electric motor converts
electrical energy into mechanical energy
(work)
• They operate through interacting magnetic
fields and current-carrying conductors to
produce a force
• (This might sound familiar)
Parts of a Permanent-magnet motor
•
•
•
•
Battery
Magnet
Brush
Armature
Brushed DC motor
•
•
•
•
Oscillating current in wound rotor
Split-ring commutator
Wound or permanent magnet stator
Limitations
– friction as brushes press against communtator
– sparks can cause shorting through adjacent
sections (limits max speed, as melting of the
commutator may occur)
LHR for the motor principle
• If the thumb points in the direction of the
current flow (real current), fingers are the Bfield, palm is the force
• 𝐹 = 𝐼𝑙𝐵𝑠𝑖𝑛φ
• I is the current in the conductors, [A]
• l is the length of the conductor in the field [m]
• B is the magnetic field, [T]
Time to motor
• Motors are easy to make, so let’s try!
• Check out the following simple designs and try
to identify the parts
• Make sure the force on your coil agrees with
LHR