Electric Motor Design


Uploaded by engineeringdotcom on 28.04.2011

Transcript:
I'm Allison Toepperwein.
And I'm Vince Penman.
In this episode we're going to take a look
at the designs behind electric motors, and how they're used.
An electric motor is a device that turns electrical energy into mechanical energy.
The basic design for the electric motor was invented over 200 years ago.
Although electric motors have thousands of applications, they all work based
on the same concept, electromagnetism.
The basic principle of electromagnetism
states that when you run an electric current through a wire, a magnetic field is generated.
So when you run electricity through a wire, the wire itself becomes an electromagnet.
An electric motor has a stationary part called a stator and a rotating part called a rotor.
The stator generates a magnetic field and the rotor is
an electromagnet that rotates inside this field.
Because opposite poles of a magnet attract and like poles repel, the magnetic south pole
of the rotor will move toward the magnetic north pole of the stator.
By repeatedly switching the direction of the current in the rotor's electromagnet,
the poles keep flipping sides and this rotational motion continues.
The output shaft of the motor is attached to the rotor and the rotational motion drives
the device attached to the motor.
And so ends the sexiest description of electromagnetic theory in the history of the world.
You're welcome.
Sometimes you want an electric motor to run at different speeds depending
on the application you're using it for.
Engineers use units called variable speed drives to control the speed
of an electric motor by controlling the voltage or frequency of the electricity used to run the motor.
The use of drives allows for smoother operation, acceleration control, accurate positioning
and torque control in electric motors.
It's variable speed drives that allow us to have 12 speed blenders
instead of just one speed blenders.
That means we can get our smoothies in 12 deliciously distinct consistencies.
These drives also control the speed of fans, pumps, and blowers.
While the basic principles of drives and motors are the same,
the vast number of applications presents engineers with lots of different design challenges.
At companies like Buehler Motor, Heinzmann and WEG in Germany engineers and designers use software
modeling tools like PTC's Creo Direct modeling solutions
to design electric motors and drives for a wide variety of consumer products
and industrial applications.
WEG designs motors with specific dimensions designed
for a circular saws, motors designed so they won't corrode in high humidity environments,
like cooling towers, and even poultry fan motors with totally enclosed
designs so they can be used in agricultural environments
without getting clogged with airborne debris.
The Heinzmann company manufactures a range of drives for fuel injection systems
and control systems on diesel electric locomotives.
Electric motors and drives also have a variety of applications in the transportation industry.
As concerns about climate change associated with the emission of greenhouse gases grow,
some jurisdictions, like California, are mandating that a certain number of vehicles automakers produce
must be zero emission vehicles.
While cars that run on electric motors are currently available, they have
to overcome some challenges that are impeding their adoption.
The current battery technology is expensive and isn't quite at the level required
to make long distance travel practical in an electric car.
Also, the lack of charging stations for electric cars is a practical concern.
For over 100 years electric motors have been used to power trains,
subways, cable cars and electric buses.
Power is transferred to some electric trains and road vehicles by overhead cables.
Some electric trains and most subway systems are powered by an electrified third rail.
In the US certain rail corridors in the North East have been electrified. In Europe and in Japan
most of the high speed trains like France's TGV and Japan's Shinkansen run on electric motors.
You can try Creo Direct Modeling Solutions, the same software that engineers use
at Buehler Motors, Heinzmann and WEG with a free for lifetime version from PTC.
Just go to ptc.com/go/modelingpe.
That's it for the Product Design Show this week.
Maybe next week I'll talk about more exciting engineering theory, like eddie currents.
If you like the show, please give us a Like on Facebook, subscribe
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We'll see you next week when we delve into the engineering of toys.