# IGBT Tutorial for dummies dc motor controller basic Video



## subcooledheatpump (Mar 5, 2012)

you're going to embarrass me posting that here, lol


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## locoo (May 6, 2010)

I dont think it will it is a great video .

Pleas coment and tell what a great video is .

Ringing i didnt know what that is until now.

Tnx


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## PStechPaul (May 1, 2012)

It is a pretty good video. I added some comments on your YouTube channel. Is that a PM brushed DC motor or series wound DC? And it would be interesting to see how it responds to an inertial load (flywheel) under dynamic conditions of acceleration and braking. 

I'd really like to see a video explaining regeneration using series wound DC motors. I did find this, but it does not give much usable info:

http://www.youtube.com/watch?v=FaUp83v0bd8

I found more info on his website:

http://electricmobile.ru/regenarative-braking-on-series-dc-motor/

It has also been discussed in this forum, and here is an interesting read. But I know this is moving off-topic...
http://cafeelectric.com/curtis/regen/index.html


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## subcooledheatpump (Mar 5, 2012)

one of the interesting things I've found with these DC motors (yes they are PM), the back EMF seems to be greatly reduced under load (if you hold the shaft) 

The waveform during turn off can peak to a few volts above the battery voltage if the motor is unloaded. This peak seems to disappear when loaded. 

I also read this happens with AC motors as well, in the thread about DTC and FOC control


I would experiment with series wound or other field wound motors....but I actually don't have any. How does a universal motor compare? I might get one of those if you think people could learn something by seeing one of those on the scope


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## PStechPaul (May 1, 2012)

I purchased a small series wound motor for $8 and they are still available:
http://www.herbach.com/Merchant2/me...AR&Product_Code=TM01MTR4476&Category_Code=MTR

It is 3900 RPM at 12VDC and 4.5 amps full load, with a rated torque of 8 in-lb. This equates to 54 watts or 0.07 HP input, while the torque and RPM equate to 0.5 HP. So it is likely that the speed will drop to 500 RPM or so with that torque. It might be able to produce even higher torque for short bursts. I haven't done anything more than apply voltage and watch it spin.


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## locoo (May 6, 2010)

This is my igbt ruining a 5kw series motor .

Snubber is a standard voltage stabilizing capacitor .

http://www.goodluckbuy.com/2-2uf-275vac-polypropylene-film-capacitor-10-pack.html

I connected three of them in series to try to increase voltage rating.

And still ringing 

http://www.youtube.com/watch?v=AwmWLkRemDs


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## Siwastaja (Aug 1, 2012)

Ringing cannot be completely eliminated (at least without using a very lossy snubber) and it is perfectly acceptable to have some. This is why a controller using 600V IGBTs typically has 400V rating (and those are very carefully designed. In DIY controllers, you should leave more leeway).


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## locoo (May 6, 2010)

My igbt is rating is 1200v so 

Very lossy snubber what does that mean. 

I odder 30uf 800v snubber i will mount one on the switching and one on the freewheeling igbt.

One thing that worries me is look in the movie before the ringing appears when the igbt yust opens there is a BIG spike is that normal can i do some thing about that.

http://www.smalltao.com/product/16294317528/Fixed capacitors Capacitor Film Capacitor


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## subcooledheatpump (Mar 5, 2012)

Yes it is normal for the voltage to spike during turn off, just as Siwastaja said. 

You cannot completely eliminate ringing or the turn off spike unless you slow the switching speed down significantly, which is not recommended, as the IGBT (and/or capacitor) will overheat. 

As long as you don't exceed the IGBTs maximum rating you should be okay. If your spike voltage is 1000 volts and your IGBT is rated for 1200 there should be no problems. 

You will be using a 144 volt battery correct?


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## locoo (May 6, 2010)

Yes i did the tests for my controller on 96v so if the spike was 20v on 36v so i will have estimate 156v on 96 V.


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## PStechPaul (May 1, 2012)

You should use DC coupling so you can see the initial spike. A storage scope would also be a good tool for this. Another thing to consider is that sometimes a scope and the probe will pickup spurious signals from the high current and electromagnetic field. You can see how much by shorting the tip of the probe to its ground clip at the point where you are measuring.


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## locoo (May 6, 2010)

What does dc coupling mean .

Yea that scope i borrowed that scope from work it is a bit to much for me 5000 uk pounds is the cost of it.

I used 36v on the movie so it shoud not produce much of a inducion.?


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## PStechPaul (May 1, 2012)

With DC coupling the trace will have a constant position at zero volts and will move up and down for positive or negative voltage. In your case you would set the vertical position to the lower part of the screen for zero volt position, and when you turn it on it will assume a position at the top of the screen for the full bus voltage. As you apply the throttle it will show negative-going pulses of varying width.

The initial "spike" you observe may just be the scope's AC coupling capacitor charging up.

There is a "soft" button just to the right of the screen which is "coupling" and that should change it to DC.


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## Siwastaja (Aug 1, 2012)

locoo said:


> What does dc coupling mean .


Please use Google to get started! Electronics is fun but you need to spend some time learning the basic stuff.


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## TexasCotton (Sep 18, 2008)

I am new to power electronics. I am curious okay Insulated Gate Biopolar Transitor aka IGBT. I know very little here other than IGBT do switching.High voltage switching However really trying to figure out the application or applications aka inverter example. any1


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