Paul & Sabrina's cheap DIY 144v motor controller

[Christ]

Paul - I think you need to see something my friend Ville created. (I dont know him personally, but he's a "friend" b/c we share interests... he's an interest friend.) Anyway - check this out. It might help you with cooling ideas that are more electro-friendly.

100% passively cooled system enclosure by MetkuMods - Because you love your hardware!

[bennelson]

So this




is what the O.S.E.V.M.C. is going to look like!

[Christ]

Lol - it's to give an idea of how one might utilize more passive cooling.

Also - check the same site for an older article on "lapping" CPU's and heat sinks. Given that your controller is going to be hand built, a good way of lessening CPU temps in computers is to "lap" the CPU's IHS surface. (Integrated heat spreader). up to 5*C drops at load can be seen, with only the CPU being done.

Using the same method on the sink itself can produce even better numbers.

Like I said - being hand built, this might be the type of attention to detail that you can put into each model?

[Dangerous Dan]

There are three reasons why Mineral Oil is not good to use. I've worked in a laboratory for many years and I've seen this:
1. A very small amount of mineral goes a long way and is hard to clean up.
2. It loosens soldered connections.
3. Over time, it darkens to a deep brown and begins to form a tacky solid. When it is solid, you have to chisel it loose.
We've stopped all use of this liquid. Its alternative is very expensive.

[MPaulHolmes]

Thanks, Christ! I wish I could hear a computer boot up without any sound.

Dan, I was going to ask the EVTech list about that. Thank you!

A few things came today!

I ordered a copper block for the heat spreader today! C100 copper too! 99.9% pure. It is VERY efficient at sucking heat away from those mosfets and diodes. Almost 2 times better than Aluminum. I also ordered the copper bus bars. Well, a single 45.5"x0.75"x0.25" C100 copper flat bar! It will be cut into 3 pieces, and will become B+, B-, and M-. The only tools required for that is a hacksaw and a drill! Officially Home-made certified!

The electrical insulator for the mosfets/diodes came (free from Rod Hower), the LM317's (which will allow me to change the throttle to a 2 lead one instead of 3 lead, so we can use the standard PB-6 without modifying it. Also, I got a really really good price on 12"x8" 3 ounce copper PCB for the power section of the controller. There is enough for 50 controllers, and it was SUPER CHEAP! If I would have bought them individually, it would have been $30 each, and it would have only been 1 ounce copper! I got 25 of them, and each one can be cut in half to become 8"x6", just enough to fit everything in the power board section! Instead of $30 each, they were $40 for all of them! haha! I love Ebay.

I also got an awesome heatsink in the mail that was the perfect size for the prototype controller! I wonder where that came from? We should ask Ben that question! haha!

[MazdaMatt]

ebay is definately the place to be for electronics, but you CAN sometimes get screwed. There are actually companies in China that specialize in taking old used components from the scrap heaps, shaving off the tops and printing on new labels as a fake knockoff of a more expensive part. I spoke with some salesmen from our electronics supplier that were at a hong kong trade show and one of these companies had a booth. They were advertising that they can knock off the labels of all the other suppliers at the trade show. Classy, eh?

[bennelson]

Hey Paul,

I actually laughed out load when I saw the matching photograph of your thumbs-up with the heat sink.

I was feeling bad that I spent good money on it a while back, and ended up not using it.

And the fact that it just happens to be the EXACT dimensions for the project?

I would say that has to be fate, or at least good Karma.

It's the least that I can do considering all the people who helped chip in to pay for my speeding ticket...

Keep up the good work Paul.

[MPaulHolmes]

The Brass bolts came today! They are normally about $1.65 each, but I got them for like $0.20 each on ebay. There was only one person selling them, too (on all of Ebay)! I have enough for about 10 controllers.

The shiny ones in my hand are a small sample of the ones that I soaked in lemon juice for a while, and then wiped down. The ugly ones in the box are some of the ones that I haven't soaked yet. They will be used to conduct the current from the capacitors to the other side of the power board.

[motor_control]

Originally Posted by MPaulHolmes

You get waste heat of:
500 amp*1 volt = 500 Watt.
If you are sneaky, and use Synchronous Rectification instead, optimistically, the waste heat will be:
0.009Ohm/10*500amp*500amp = 225 Watt.

You save only 275 w but whole consumption is 500*120 = 60 000 w

100 * 275 / 60 000 = 0.46 %

[motor_control]

I think you need harware overcurrent protection. See IR2127 (your mosfet driver will be buffer) like protector. See page 6 in AN-1014 on International Rectifier Home Page - Flash Detection



NO frying MOSFET at all !