Download Electric Motors - MSU College of Engineering

• Conversion of energy from
one form to another
• Creating useful energy for
a certain task
• Can use any type of
energy
• Mechanical to
electrical, vise versa
• Actuators, controllers,
sensors
• Each can be
mechanical or
electrical
• Scale can vary greatly
Transducers – changing one form of energy to another
Piezoelectric
Microphone
Ultrasound
Motors/Generators
Switches
Solenoids
Relays
EAPs
• The portmanteau
"Mechatronics" was first
coined by Mr. Tetsuro
Mori, a senior engineer of
the Japanese company
Yaskawa, in 1969.
• Mechatronics may
alternatively be referred to
as "electromechanical
systems" or less often as
"control and automation
engineering".
The integrated design of products and processes that include
mechanical and electrical components under intelligent
control.
– Underlying products are physical in nature:
Electromechanical
Hydraulic
Magnetic, etc
– Sensors and Actuators are used to interface with these products.
– There is "intelligence" through imbedded computing capability. All
these processes are highly integrated into sophisticated products
and processes.
• Logic-level outputs can’t drive a
motor directly.
• Solution: Relays
– Relays allow one circuit to switch a
second circuit
– isolates circuit from potentially
dangerous voltages
• Main types of relays
– Reed Relay
– General Purpose Relay
– Solid State Relay
– Transistor
• Advantages
– Little power to energize
– Relatively quiet
• Disadvantages
– Can’t control large loads
– Contacts can weld together
• Advantages
– Can handle very large loads
– Control multiple contacts
• Disadvantages
– Physically large
– Mechanical failure
• Advantages
– Fast switching
– Silent
• Disadvantages
– Higher cost
– Heat production
• Advantages
– Fast switching
– Silent
• Disadvantages
– DC only
– Small currents
Q1 Q2 Q3 Q4 Function
-----------------------------------1 0 0 1 Forward
0 1 1 0 Reverse
1 1 0 0 Brake
0 0 1 1 Brake
1 0 1 0 Burn motor
0 1 0 1 Burn motor
• Mechanical
– Converts rotary motion of a knob or handle into linear
displacement via screw or gears
– Rotation of the jack handle is converted mechanically
into the linear motion of the jack head
• Pneumatic / Hydraulic
– Typically involves a hollow cylinder having a piston inserted in it
– The two sides of the piston are alternately pressurized/depressurized to achieve controlled linear displacement of the
actuator arm
• Lead Screw
– Converts rotary motion via
motor into linear
displacement. A lead screw
with helical threads machined
on its circumference rotates,
while a nut with
corresponding helical threads
moves the actuator linearly
• Rapidly switching
magnetic fields to
generate motion
• F = qv × B
• Low acceleration
or high
acceleration
versions are used
Why?
• Chip Substrate Collapse
• Melting
• Fire
Why not Fuses?
• Fuses: Inexpensive
• Fuses: More Reliable
• CBs: Can be Reset
Automatically operated electrical switch
designed to protect an electrical circuit
from damaged caused by overload or a
short circuit.
Features vary based largely on voltage
class, current rating, and the type of circuit
breaker.
Common Features:
1. Electromagnet or Bi-metallic strip
used to detect and act upon a fault
2. Control the arc
3. Reclose the contacts
• Low current and/or voltage circuit breaker:
Detection occurs within the breaker
enclosure
• High current and/or voltage circuit breaker:
– Usually utilize a pilot device to sense a fault
current and to operate the trip opening
mechanism. Trip solenoid usually operated
by a separate battery.
Magnetic:
Field proportional to current in coil
Tuned mechanical trigger
Contacts are pulled apart in response to Magnetic force
Thermal:
Material bends or expands with dissipated heat
Contacts pulled apart when spring-loaded trigger is released
http://www.zlan.com/brk_info.htm
Electronically-controlled:
Controller reads current value from sensors
Detects when current rises above a threshold
Signals actuators to break contacts
- - In high-power apps, sensors may need to be separated…
• Arc must be contained, cooled, and extinguished
in a controlled way
• Vacuum, air, insulating gas, or oil are used as
the medium in which the arc forms
• Techniques to extinguish the arc:
•Lengthening of the arc
•Intensive cooling (in jet chambers)
•Division into partial arcs
•Zero point quenching
•Connecting capacitors in parallel with
contacts in DC circuits
Here is why
Even a small spark can ruin
some equipment
- Uses electrical energy to produce mechanical work
- Commonly used in refrigerators, washing machines,
fans, pumps, and computer equipment
Advantages
- No fossil fuels
- Noise reduction
- Wide range of sizes
- Fewer components
Disadvantages
- Less powerful
- Battery limitations
Types
AC Induction
AC Synchronous
Stepper DC
Brush DC
Brushless DC
- Transforms mechanical energy into electrical energy
- Sources of mechanical energy include
-
Combustion Engines
Compressed Gas
Steam/Gas Turbines
Solar and Wind
• DC motors use have a locked ratio. Speed
is more exact.
• AC motors make more power per weight
and dominate the market mostly because
of power distribution.
• Power distribution is easier for AC
because of the transformer.
Sinusoidal windings and power translation