Paul & Sabrina's cheap DIY 144v motor controller

[xtian999]

I only see a few wires from the power stage to the control stage, and they are 5v and grounds. A few more inches and a plug won't kill the system, will it?

[xtian999]

You mean the others who failed to think outside the box? Lol.
I can overcome losses with better materials. What I cannot overcome is a burnt out, soldered in capacitor on the side of the road. If I can use screw mount caps and modular control units, I can get home without a tow truck. That is a gain worth asking about.

[Tweety]

Originally Posted by xtian999

I only see a few wires from the power stage to the control stage, and they are 5v and grounds. A few more inches and a plug won't kill the system, will it?

Those wires carry the PWM signal controlling the powerstage... And yes they are 5V... Basicly if you make them longer, you create delays, same goes for adding resistance (a connector does this), delays and signal losses... In a 5V system with PWM signals small differences like this makes huge changes to reliability and predictability of the system...

Ideally all those cables should have the exact same electric charcteristics ie same length, resistance and so on... The larger the variance the more potential for problems... If you add an inch or two of flexible wire insted of the resistors leg, it's fine as long as you do it uniformly... If you add a foot or two of wire and two connectors it's likely to cause problems... YMMV...

The question however is WHY you wan't to move it out? It's designed in such a way that it should withstand several magnitudes worse EM environoment... (I do radiocircuits for a living, I can look at it and tell you it's not going to cause problems in that way...) The box on the controller keeps other things from being mucked up... So why mess with something that works? Especially in a way that more than likely will introduce a problem that wasn't there in the first place?

The wires being flexible like you suggested so that you can move them without damaging them is a good simple idea that improves things... Go with that...

Screw mounting the parts is a bad idea... You will decrease the efficiancy of the controller by measurable amounts... Ie you will essentially need to add an extra battery or so for the same range... (slightly exaggerated probably, but you get the idea...) And really honestly, do you think you will do roadside repairs to a motor controller even if it's "modular" ? I honestly don't...

Besides Ben blowing up the controller seems to be a isolated event... So far I'd say the design has proven to be very reliable and robust for it's humble beginnings... I'd say most companies developing stuff like this has more teething problems than this project has had...

[bennelson]

Oh sure, talk about Ben blowing things up again.....

Actually, that was sort of almost on purpose. It was the very first design, and we knew there would be some issues with it. So, the idea there was to test the controller until destruction, and then fix whatever the problem was.

Since that correction and rebuild, running on the same original controller, it has worked FANTASTIC!!!!

Paul, was my controller the very first one? It is still the one you originally tested in your car at 72V isn't it?


PS: I did see a guy's home-built controller which looked all crazy because it had wires going everywhere. I asked why, and he told me that it was so there was all the exact same distance between all the parts for the signals to stay dead-on

[MPaulHolmes]

Ben, your controller was the very very very very very first one. Well, there were those practice weenie ones, and the one that was 5v 0.001amp that drove the LED. hehe.

[Tweety]

Hey... For once it's not me blowing stuff up, so I just have to tell it...

And yeah, I know that was kind of an expected failure... Can't fix what isn't broken eh?

And like I said... I imagine most companies would be damned proud to have the failure rate of these controllers... I can tell you in some production lines they plan for 20-30% failure rate on the prototype runs... And as high as 10% on first production run isn't unheard of...

[MPaulHolmes]

Every time I get an email or see a post from Joe, or Ben, or you name it! My heart sinks, because I figured its one of those "the controller blew up" letters. haha.

By the way, I'm working on the layout for a synchronous rectification controller right now. I'm using PCB artist, which is free, but pretty easy to use.

[E Vdubya]

All

I'd say this design is quite robust. Leave it to me to put a component in backwards (Q2) and then have B+ and B- reversed and still not blow it up. I'm sure if my traction pack was more than 12v it could/would have been worse.

It really does work doesn't it Paul? Also I left you a little something in the collection plate last week. Keep up the good work.

John

[MPaulHolmes]

It works perfectly! Sorry I've been hogging it for a while. I've been driving it around and trying out some new software. I can mail it back any time you are ready though. Your soldering is very very professional. When I took it apart, and saw your work and decided that it was going to be something simple that was wrong. Certainly not the soldering or anything more fundamental. That's when I noticed your permanent marker writing for B+ and B-! ya!

[E Vdubya]

Paul

You can hang on to it for now. I won't be needing it for at least a month or more.

The software you're testing...does it have the over rev protection?