|
Hmm. That's strange. | by Longfist | 2014-12-31 07:35:09 |
| Okay, we're in CRUNCH TIME now! |
by Longfist |
2015-01-08 19:48:48 |
So I find that the responsibility for final design has fallen pretty much in my lap. Okay, I can deal with that; I guess I pretty much expected it. BUT I still haven't figured out how to rig overvoltage protection on the output/driver side of this project. The controller (Arduino) side is easily handled by a DC-to-DC converter 50V down to 15VDC at 3 or so amps: the 7809 further steps that down to 9VDC at 1A, which is exactly in the midrange of the Arduino Uno's acceptable input voltage requirement. But the problem lies in converting the upwards of 50 VDC down to 36VDC at 22.2 A - everything I encounter wants to provide me with 3 or so amps at best! This won't turn the motor! Aaaiiiieee! <* pulls nonexistent hair out *>
Let me show you what I'm talking about: sometimes a picture is worth a thousand soundbytes:
36-50 VDC -----> ---+---> [OVERVOLTAGE PROTECTION to 36VDC *only*] ----+
(Battery) | |
| |
[OVERVOLTAGE] |
[PROTECTION ] |
[TO 15VDC ] |
| |
| |
[7809 VREG] |
| |
+-----------> [ARDUINO UNO] -----------> [DRIVER STAGE MOSFETS]
|
|
[BLDC 3-Phase Motor] <--------+
[36V @ 800W (or 22.2A)]
The Driver Stage needs to see only 36VDC at 22.2A (max) to drive the motor. The battery pack puts out something on the order of 48VDC regardless of the school instructor's insistence that it only provides 36V - the voltmeter doesn't lie. So I need to institute some serious Overvoltage Protection or risk burning up the motor. Again. (The prior controller didn't have any Overvoltage Protection and resulted in overheating the motor almost to failure. This cannot be allowed to happen again.)
If anybody has any ideas on how I might - right now - construct the required hardware to accomplish this feat, please let me know soonest! We're in desperation mode here: I've got a lot of finger-pointing but nobody - including our "Power Systems Specialist" here in Mechatronics Engineering - has a good, solid approach for this. Test Track day is the 23rd of this month: I have next to no time to build, program, and test this monster. I can get away with purchasing some of the modules short of buying an actual motor control system: *that's* forbidden for EVs in the Shell Eco-Marathon. Sticky problem. I aim to resolve it, somehow.
So if you have any ideas, or know someone else who does, feel free to message me here or eMail me at [myNickHere@theGoogle.Thing] and I'll do my best to comprehend it and apply it in extremely short order! I may need a little coaching as it's been 15+ years since I had to do any power supply designs like this: most of the time the power is already conditioned and supplied, they just want components strung out in such a way as to make something interesting happen, or keep something undesirable *from* happening. This is not exactly what I bargained for, but I figure I can get by with a little (or a lot of) help from my friends...
Thanks A LOT in advance!
- An anxious LongFist |
|
[ Reply ] |
|
I just dove the web for things that do almost what | by wwill | 2015-01-08 20:45:09 |
|
If it weren't for lack of a hole in the middle, | by LongFist | 2015-01-09 04:59:35 |
|
2N3055s are 15A power transistors. What if we | by LongFist | 2015-01-09 06:56:23 |
|
You WANT the parallel! | by ideur | 2015-01-10 10:12:37 |
|
A hint: | by ideur | 2015-01-11 02:49:40 |
|
Buck converter will do, switching regulator at | by wwill | 2015-01-11 10:46:56 |
|
Battery overcharge isn't so much a problem. | by LongFist | 2015-01-12 13:11:51 |
|
The VR chip or Zener holds the voltage and causes | by wwill | 2015-01-13 09:18:11 |
|
In re the three links. Number one looks good, | by wwill | 2015-01-13 09:26:51 |
|
Working on it. | by LongFist | 2015-01-14 13:08:08 |
|
Did you measure the battery under load? | by ideur | 2015-01-11 03:06:49 |
|
For what? Not sure where you're going, here... | by LongFist | 2015-01-12 13:23:09 |
|
Just wondering why a 36V battery should have 48V | by ideur | 2015-01-12 20:44:25 |
|
Aaaaand *NOW* you see what's so special | by Longfist | 2015-01-13 04:02:37 |
