25 August 2012

A lot of people wonder how alternating current (AC) induction motors work. In fact, I myself wondered exactly how they worked for a long time.

You see, I’m an electrical engineer, so I should know these things from my university education.

Unfortunately, in this age of digital everything, power electronics tends to get the shaft in favor of microprocessor design, digital signal processing, and so on. Digital is where the bucks are, you see…

And so, for the longest time, I never actually fully understood how AC induction motors work. DC motors are easy enough to understand, but the AC versions are a bit more complicated. That Tesla was a smart dude (the man, not the car company).

Enter a series of YouTube videos that explain AC motors so well, even a monkey with half a brain could understand it!

The following is a series of copyrighted video lectures from 2010 by Dr. Luis R. Linares of the University of British Columbia.

The first two videos give some physics background and other basic concepts, and the second two videos get into the good stuff.

The only things you really need to grok to start off are:

  1. The concept of a bar magnet, with N and S poles
  2. The fact that when you pass an electric current through a coil of wire, you get an electromagnet that acts like a bar magnet
  3. Alternating current changes direction 50 or 60 times a second, so AC going through an electromagnet causes the poles to “flip” 50 or 60 times a second

That’s it. Dr. Linares’ explanations are of course glorious, so don’t worry if you don’t understand something above. The total length of all four videos below is about 32 minutes, so grab a tasty beverage and get watchin’!

If the YouTube vids above don’t work, you can download the video files in MP4 format below:

  1. INDUC 01 – The Induction Motor, Physics Background 01 (9.5 MB)
  2. INDUC 02 – The Induction Motor, Physics Background 02 (7.8 MB)
  3. INDUC 03 – The Induction Motor, Rotating Magnetic Field (35.4 MB)
  4. INDUC 04 – Induction Motor, Stator Coils (13.6 MB)

Thanks to Dr. L for THE BEST explanation of AC induction motors that I’ve ever found!

AC Induction Motors: How do they work?
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