Paul & Sabrina's cheap DIY 144v motor controller

[isaac_alaska]

thanks for all the help! i just got a pair of SBE ring capacitors (they sent me two ) to mate up to my IGBT's for the power section.

haha i was just looking and and trying to figure out "how does this thing know when the capacitors are done charging, if it only has a connection to "B+ caps" and no B- connection....and then i realized it was too early in the morning for me to think and that paul's last post explains everything wonderfully!

Does the control board determine when to close the contactor by looking at how the current through the pre charge resistor changes? or does it just have a timer or something to close it after a certain time? I'm guessing the former..or it wouldn't be able to detect shorted mosfets?

hopefully by the end of today i'll have it programmed! i'm installing software right now.

[adamj12b]

Originally Posted by isaac_alaska

thanks for all the help! i just got a pair of SBE ring capacitors (they sent me two ) to mate up to my IGBT's for the power section.

How did you get 2 of these caps? Do you plan to use both in 1 controller? With 2, you can easily build a 2000A continuous controller.

Now im jealous!

On a side note, My new logic board design is almost done. I will share when I get the layout finished.

-Adam

[isaac_alaska]

I emailed SBE and told them i was building an experimental controller, based on Paul's open source work. I told them it was for a research project/ competition (we're building it to compete in the SAE clean snowmobile competition) and asked if they had any available. They said they would be happy to send me two of them!

they're huge, but with the plastic case, they are lighter than i thought they would be. I'm only going to use one of them in the controller, designing a controller for the WarP7 that can handle even a thousand amps is mostly overkill.

looking forward to seeing your new logic board!

If i can figure out the software, it would be nice to use the extra pins on the microcontroller for accepting speed data from the motor. I haven't looked into it at all yet though so i'm not sure if i can use the speedometer output that's built into the machine or if i need a different speed sender. If i can get speed input working and work my way through the software, i think it would be possible to use the last pin to output data to a display, and calculate wH/mile. Or has someone already done this? would be pretty handy for seeing instantly how different throttle inputs (or snow conditions) affect energy use.

[Nevyn]

Awww, I envy you! Keeping it as a spare, eh?

[isaac_alaska]

At least until i make sure the controller works and i don't blow it up would definitely be nice to use it in something though...maybe i'll double it up later like adam suggested and build a 2ka monster! i'm still working on the buss plates for it, i have a preliminary sketch in solid works but haven't started cutting them out yet. i'm hoping i'll be able to bend them on the brake without too much trouble.

[adamj12b]

Originally Posted by isaac_alaska

At least until i make sure the controller works and i don't blow it up would definitely be nice to use it in something though...maybe i'll double it up later like adam suggested and build a 2ka monster! i'm still working on the buss plates for it, i have a preliminary sketch in solid works but haven't started cutting them out yet. i'm hoping i'll be able to bend them on the brake without too much trouble.

What igbt's are you using?

-Adam

[isaac_alaska]

cm400dy-12H by mitsubishi. rated at 400 amps each at 600 volts, i believe. i'm using four of them. just a tiny bit wider than the capacitor, and it will load the igbt driver evenly, two per channel. (using the dual channel VLA-500 and driver board that i got from mrbigh)

[adamj12b]

Originally Posted by isaac_alaska

cm400dy-12H by mitsubishi. rated at 400 amps each at 600 volts, i believe. i'm using four of them. just a tiny bit wider than the capacitor, and it will load the igbt driver evenly, two per channel. (using the dual channel VLA-500 and driver board that i got from mrbigh)

Ah. I have a many of the CM400DU-12F from Powerx. They are actually made by Mitsubishi. I have a design already for the plates that holds 3 of the igbt's. I posted pics a little ways back.

As for the drivers. I have never done the math for 4 modules, but 1 driver can easily do 3 modules.

-Adam

[isaac_alaska]

Do u have any plates built? I could modify my design and use 3 instead of 4. I think 1200 amp rating is sufficient, even with derating

[MPaulHolmes]

Hello Isaac! The precharge method that I ended up using is to wait until {Dvoltage/Dtime = 0} && {voltage >= 24v}. Basically, once the change in voltage was zero, since I was checking it every 0.1 seconds or so, and the overall voltage was nonzero, the caps must be full. If the mosfets were shorted, the voltage on the caps would have been almost zero, so the ">= 24v" woudl never have happened.