Paul & Sabrina's cheap DIY 144v motor controller

[MPaulHolmes]

I think a snubber is a good idea. From that documentation I emailed you, there are a few choices as to how to do it. They suggested those film capacitors. Maybe 1uF. I'd be really interested in hearing how it works. Maybe something like this??:
Digi-Key - 495-3626-ND (Manufacturer - B32614A3105J008)

[jackbauer]

thanks paul. I just ordered this guy:
Arcotronics | Passives | Capacitors | Capacitors, RC Networks | IGBT (Snubbers) C4BS Series |C4BSNBX4150ZA0J
seat of the pants engineering as I don't get on well with maths. I find in general that the theory can't take into account real world conditions and is best used for indication purposes. Have you scoped the b- to m- on your fet based controllers?

[jackbauer]

just a few quick pics. bad quality but should give you an idea. Its a very fast transient. edit: I managed to capture the spike by cranking up the timebase on the scope. Looks to have a period of about 300ns.

[MPaulHolmes]

Nice! I think that snubber will significantly reduce the spike. Joe looked at drain to source and also saw a spike, but it was smaller in magnitude I think. I should try it, but I am supposed to ship out the controller that I have. I still don't own one. hehe.

[jyanof]

jack

here's a picture of my charger drain-source voltage before I minimized the parasitic inductance.



The ringing is much more severe than your results - it's as if you have more damping.

Nevertheless, if you haven't yet shortened the length of wire between cap/igbt/diode, you still have sections of wire where the current is going from output current to zero with every cycle. Large di/dt and any amount of inductance will create voltage spikes.

I recall advice from the members of the evtech list: Minimize the length (and thus inductance) of any wire/bus/trace that has large changes in current (large di/dt). Minimize the area (and thus capacitance) of any part of the circuit that has large changes in voltage (dv/dt).

When I changed the setup, the waveform looked like this:


Actually, that looks more like your output. In these photos, I was using fast turn-on/off times with a low value gate resistor. I think Paul's is set up to have longer turnoff times. Might be another thing to think about.

[jackbauer]

Thanks jyanof. Its all starting to make more sense. hey is that a tektronix scope?

[adamj12b]

Hey everybody,

I have uploaded Version 0.2.0.0 of RDT Explorer to the server. You should be able to click help in the program and then check for updates and use that to update. Let me know how it goes.


You can also get it at the website: www.EVVette.com


We have fixed a bunch of bugs and added some features.

You are now able to connect and disconnect form the controller without an error, and you can also change serial ports from 1 through 4 without an error.

We removed the need to select the AVRboot.exe file for the boot loader. It is not included with the program.

We have added a pause graph and save graph button as well. When you hit save graph, a message will pop up asking where you want to save the image of the graph, when you hit save, thats the image it saves. so its still rolling, hit save quick or you could lose the image that you want, Unless you pause the graph first.

Also, In the bottom on the screen you will see an Amp Hours meter. This is the amount of power you have drained from your batteries so far. Im still working on this, but I believe it is fairly accurate. Maybe somebody could check it for me?

well I think thats it for now. Let me know that you all think.

-Adam

[jackbauer]

just a thought could we have a parameter that would allow the switching frequency to be changed via rtd?

[bennelson]

I just got the new chip and COM cable connector for my controller.

I hope to work on it on Sunday at our EV Club. Hopefully somebody more skilled with electronics than I can give me a hand!

[MPaulHolmes]

Hey Ben! Basically, you have to *somehow* solder on the little 3 pronged thing. It's going to be a tight fit getting a soldering iron in there. You could insert the 3 pronged thing, then heat the metal legs of the 3 prongs, and then melt the solder that way?