Paul & Sabrina's cheap DIY 144v motor controller

[MPaulHolmes]

No this one is just 15v, 0v to 15v. No splitting for negative voltage. But some people suggested that it might be that I needed a snubber. I added a 0.01uF cap and 4.7Ohm resistor, and now the spikes are much smaller. I believe there's a good chance that the previous failures were due to no snubber, and maybe bad soldering technique before. The ringing that was from drain to source during turn-on was making its way to gate to source, and high current probably caused voltages that kept trying to go well over the 30v limit. The TVS diode probably got overworked and blew. I think it will actually work this time!

Next, I'm going to use the same snubber, but at 24v, and see what affect increased voltage has the spikes. The snubber resistor will have to dissipate more power, and the mosfet's output capacitance (I think they call it coss) drops the higher the voltage... It will be interesting to see how it goes. Then I'll install some mica capacitors (470pF) and try it out at maybe 144v. You have to use much smaller capacitance at that voltage since the power requirement of the resistor goes through the roof.

[dave koller]

You did try a gate ferrite up as close to the gate input as you can get...
It has always worked for me on robots.

[MPaulHolmes]

Oops, no I never did try that.

[64jeep]

Hey, first post on here. I'm building my control board and came across a discrepancy in the BOM. Looking at the Rev 2C BOM, capacitors C23 and C24 are described as 20 pf. If you look up the part number on Mouser it's a 15 pf.

ww.mouser.com/ProductDetail/Murata/RPE5C1H150J2P1Z03B/?qs=%2fha2pyFadugkewjtNwIYPBNjI2oyGwEUpOZcNUad1wjL 1UAqawPWvg%3d%3d

Doh, I'm so new they don't even let me post links! So you'll just have to take my word for it or add an extra w to the front of that link...

I'm still about 300 pages back reading this thread, but post 1287 mentions a change from 15 to 20 pf. Just wondering which it's supposed to be and hoping someone can correct the BOM.

Thanks!

[MPaulHolmes]

That's interesting. I know that 15pf and 20pf work fine though. I think 20pF is what I usually order for a kit.

[MPaulHolmes]

Here's a test at 12v, 24v, and 36v, up to around 8 amps or so. It has a snubber of 0.01uF and 4.7Ohm from drain to source. I'll have to use a smaller capacitor for higher voltages, since the power requirement of the resistor goes up with the square of the voltage. At least I think it does. I forgot. haha.

http://www.youtube.com/watch?v=7cqkWRkrP9k

[isaac_alaska]

For a sin wave centered around 0V, power is ((Vpeak)^2)/(2*R)
and for a square wave centered around 0V the power is ((Vpeak)^2)/(R)

[blacksun1989]

Sorry for not replying for so long. So i posted a few weeks ago that my controller wont work. So Paul wanted to know if the controller has 12v at j1. And yes it das 12v.

So My dad thought that i may had damaged a piece while i soldered it together so he started building up a new one. But here we have the same Problem. The yellow Led blinks. So we thought it is maybe the HAS 300-S so we bought a replacement. But with that new one still no change. So my dad played around with it and he removed the HAS 300-s. And did put 2 Resistors on the cable. In this case when you start the controller the yellow led is on all the time. But when you turn up the throttle it starts blinking again and if you go down with it it's on all the time again. And when you start the controller with a turned up potentiometer the controller blinks all the time. So we really dont know what to do anymore. I hope someone has an idea! Thanks!

[MPaulHolmes]

OK this is very close to working... When you give it throttle with the 2 resistors in place of the current sensor, it starts to blink fast because it gets a fault of 100% duty, but zero current feedback. It's just a safety feature, so it's working like it should.

So, is it possible that the current sensor cable is wired wrong? Lem sensors are very reliable. Both not working is very unlikely.

See page 3 here:
http://www.lem.com/docs/products/hass_e_rev14.pdf

Pin 1 (inner most pin) is Vref, which shoudl be around 2.5v all the time.
Pin 2 is Vout
Pin 3 0v
Pin 4 is +5v.

There HAS to be a wiring issue. I can't think of any other reason why a resistor divider would make it work. There's no way 2 lems were broken.

[isaac_alaska]

haha paul i think you mean there HASS to be a wiring issue