View Single Post
Old 11-01-2012, 01:26 PM   #5902 (permalink)
MPaulHolmes
PaulH
 
MPaulHolmes's Avatar
 
Join Date: Feb 2008
Location: Maricopa, AZ (sort of. Actually outside of town)
Posts: 3,832

Michael's Electric Beetle - '71 Volkswagen Superbeetle 500000
Thanks: 1,368
Thanked 1,119 Times in 734 Posts
Hi James, sure you could post stuff here. I have used IC sockets before, but some people had trouble with bad connections after close to a year. I think maybe corrosion was an issue. Mounting the mosfets' backs directly to metal would improve their ability to remove heat, but it makes the heat spreader a part of the circuit. Also, there can be issues with the heat spreader switching from high to low voltage really fast. But it's definitely worth pursuing. LEDs are a good idea. That could show that everything is working as it should, but it would also increase the current usage by another 100mA or something. I think the ads are so the site can make a little money. It's a lot of work to keep it running.

Hi Joe! I'm going to check with scope probes removed when I get home. For a given M- current, the spike actually decreased as voltage went up (well, at 36v the spike was less). Maybe that's because the mosfet was actually passing less current, even though M- current was the same as at 24v? I'm going to run the voltage up to 150 or 160 and test it at lower currents and see how things look. I don't have enough resistance wire for high voltage high amp tests. If I cranked it up to 150v with the currrent setup, it would be 1000 amps at 100% duty, which is great, but I'm testing 2 mosfets and 2 diodes. haha. I'd be blasted to another dimension. Maybe I could have throttle range from 0 - 10%? Sounds scary, but I might do that.

Hmm... What's the affect of, say, 100kw of power being dissipated into a bunch of water? Dang! 1000 liter of water that starts at 20 degC and ends at 90 degC can take 81.7kW for a full hour! then you can take a nice warm bath, and also cook some oatmeal with the water once the testing is done.
__________________
kits and boards

Last edited by MPaulHolmes; 11-01-2012 at 01:34 PM..
  Reply With Quote