Paul & Sabrina's cheap DIY 144v motor controller

[drbobwoolery]

Paul, I made one shunt today. The manganin was almost 1 1/4 inches wide by .060, so I made two sets of taps, one at 0.1 milliohm and one a bit short of .2.The current tabs are just the extension of the manganin strap,
If this and an instrumentation amplifier replace the noisy Hall device, some serious reduction of the resistance between the measuring leg and the current connections will be needed. I roughly calculated the total dissipation of this one at 1000 amps to be 500 watts. Over 100 watts at 500 A. Only the area between the sense leads needs to be manganin, so I figured to silver solder copper pieces on each end for the current connections if it is to be a operating component of the controller. This one was planned to give Paul a way to look at battery current in testing. Give feedback; I can do more. Vista Metals was generous and I have the oxyacetylene torch, silver solder, and copper.
bob

[MPaulHolmes]

Thank you Bob! This is going to be perfect! I can view the voltage drop across my volt meter set on the 200mV setting. It is going to be so nice to actually see the real life actual bonafide current!

[MPaulHolmes]

Aluminum doesn't shield from magnetic fields. Maybe the aluminum case isn't stopping the RF interference? I don't know! This is sort of hilarious.

Here's what I don't get. EMI is electro-magnetic interference. Once it's flying through the air, what does the aluminum enclosure block? Can it block only the electrical part? That doesn't make any sense to me at all. electricity and magnitism are 2 aspects of the same phenomenon. How do you stop it?! Maybe the enclosure needs to be steel? I have no idea what I'm talking about!

[MPaulHolmes]

Ben, don't worry about changing the resistor values. I don't think that's it. Your controller looked fine on the oscilloscope before mailing it out. There are several of us working on this problem right as I type! ya!

[jackbauer]

The following takes place between 4pm and 5pm:
We now have an avr programmer!
Now i just need to learn c......................CHLOE! DAMMIT! WHERE ARE YOU?

[jyanof]

Originally Posted by bennelson

Has anyone else run into getting RF noise from their open source controller on the FM band of their radio?

My radio has a "feature" of auto-tuning to the next station if the station you are on doesn't come in anymore. Tonight, I accelerated enough that the radio automatically changed stations on me!

Is there someway to keep static off my radio?

Do I have to wrap tin-foil around my controller? Time to build a Faraday Cage?

Nope, Haven't had any problems with FM radio, though our signals are pretty strong in the valley. Maybe some other part of the traction setup is the cause? Like, maybe running the motor cables as close together so the high currents in opposite directions will cancel most of the noise they emit. Were there problems before? or only with this controller?

[MPaulHolmes]

Fran got the bootloader working, and fixed a bunch of bugs, and added safety features, and all sorts of awesome stuff to the code! He worked on it until 1:15am Croatia time and just emailed it all to me! That man needs to get some sleep!!!!

[drbobwoolery]

Shields and grounds present some major issues; Morrison's Shielding and Grounding is a standard reference, but I can't find my copy. Must clean up the library!

The main impetus for the shunt project was getting you a way to look at the battery and motor waveforms. Ringing on these waveforms is most of your EMI. First get the source minimized, then shield the sensitive stuff from it.

[chapper]

Here's an interesting page on shunt details from DIY Electric Car
Fieldlines.com || Make your electricity from scratch!

[chapper]

correction: The site is Fieldlines, I found the link on DIY Electric Car