Go Back   EcoModder Forum > EcoModding > Fossil Fuel Free
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 10-27-2011, 10:06 AM   #611 (permalink)
EcoModding Lurker
 
Join Date: Aug 2011
Location: Michigan
Posts: 32
Thanks: 3
Thanked 27 Times in 10 Posts
That curved bar idea is pretty slick! If I end up needing more capacitance I might have to go that route.

I'm going to try to do some more testing of my controller with the large film cap installed and see if the new (hopeful) lack of parasitic inductance on the input helps to keep the spikes and nastiness to a minimum.

Another thing I found is that I might have a bit too small of a gate resistor. I'm using 3 ohm resistors on 200A IGBTs. It seems like maybe that's a little on the small side. As such my di/dt is kind of fast and that doesn't help either. I'm thinking it might be safer to go with 4-6 ohm resistors. Any suggestions there?

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 10-27-2011, 10:22 AM   #612 (permalink)
nlc
EcoModding Lurker
 
Join Date: Jul 2011
Location: France
Posts: 90
Thanks: 3
Thanked 61 Times in 28 Posts
Quote:
Originally Posted by CollinK View Post
Another thing I found is that I might have a bit too small of a gate resistor. I'm using 3 ohm resistors on 200A IGBTs. It seems like maybe that's a little on the small side. As such my di/dt is kind of fast and that doesn't help either. I'm thinking it might be safer to go with 4-6 ohm resistors. Any suggestions there?
The only way to answer your question is to look the gate signal with scope to see what happen exactly.
If your gate resistor is too small, igbt turn OFF can be too fast and provoke spike, but also igbt turn ON can be too fast and you will have a high current spike (and then voltage spike and ringing) because of the reverse recovery time of the opposed igbt's diode.
On the other hand if you put a higher gate resistor, you can easily reach autoconduction threshold when the opposite igbt turn ON, because of the high dv/dt on the turned OFF igbt.

The only way to adjust the gate resistor is to carefully look the gate signal, to see the turn ON time, and verify that the gate voltage don't reach the commutation threshold when the opposite igbt turn ON. When igbt are not controlled with negative gate voltage the 4-5V threshold can be reached easily with high voltage bus (and thus hight dv/dt), even with pretty low gate resistor.
With high voltage Vbus it's often mandatory to have different value of turn on and turn off gate resistor with the help of a schottky diode if you don't use negative voltage for igbt turn off.
  Reply With Quote
Old 10-27-2011, 10:38 AM   #613 (permalink)
EcoModding Lurker
 
Join Date: Aug 2011
Location: Michigan
Posts: 32
Thanks: 3
Thanked 27 Times in 10 Posts
Thanks, that sounds like a plan. I'll stay with the 3 ohm resistors for now and scope the controller while carefully running a small motor.
  Reply With Quote
Old 10-27-2011, 11:28 AM   #614 (permalink)
nlc
EcoModding Lurker
 
Join Date: Jul 2011
Location: France
Posts: 90
Thanks: 3
Thanked 61 Times in 28 Posts
Habitually it's also very useful to gradually increase bus voltage instead to directly test with full bus voltage. For example for the 72V/100A controller I work on (the one of my previous videos), I began with 24V, then 48V, then 60V, then 72V.
And at 48V I seen that my turn OFF rgate value was too high and I was at the limit of autoconduction. If I tried directly from 72V, I don't want to imagine the result that I had )))))
  Reply With Quote
Old 10-27-2011, 11:46 AM   #615 (permalink)
EcoModding Lurker
 
Join Date: Aug 2011
Location: Michigan
Posts: 32
Thanks: 3
Thanked 27 Times in 10 Posts
Yes, that's a good idea. I have sort of been doing that. I tested first with about 80v worth of cells (shooting for 330v at the end) and then added a few batteries and got up to around 100V. Once that testing went ok I went right up to rectified 230VAC (the caps charged up to about 339V). Maybe that was too big of a jump. Also, trying to run on rectified AC causes issues with the sagging voltage from the mains so I wasn't helping myself there either. So, maybe I should stick with batteries and just gather up more of them and add them a few at a time until I get up to a reasonable voltage.
  Reply With Quote
Old 10-27-2011, 09:18 PM   #616 (permalink)
AC-DC enthusiast
 
mrbigh's Avatar
 
Join Date: Nov 2009
Location: Long Island, NY
Posts: 282

Dual-PWR PHEV - '04 Toyota Prius

Kopper - '79 Bradley Bradley GT-II
Thanks: 122
Thanked 53 Times in 36 Posts
Quote:
Originally Posted by adamj12b View Post
Looks great MrBigh!

How did you end up bending those curves on the bus bars?

-Adam
I used an acetylene torch to soften the copper bar and then did the bends on a jig.
Then, I welded the two different planes with the same oxi-acetylene.
__________________
. .. .. . .......
Prius Absolutum Dominium . ..........KOPPER
PHEV conversion since Dec 2006.. . .... .Future EV
. . . . . . . .CALCars # 27. . . . . . . . . . ..on the works now !!
. . . . . . . . . . . . . . . . .. . ........
  Reply With Quote
The Following User Says Thank You to mrbigh For This Useful Post:
LouMan (10-28-2011)
Old 10-27-2011, 09:25 PM   #617 (permalink)
AC-DC enthusiast
 
mrbigh's Avatar
 
Join Date: Nov 2009
Location: Long Island, NY
Posts: 282

Dual-PWR PHEV - '04 Toyota Prius

Kopper - '79 Bradley Bradley GT-II
Thanks: 122
Thanked 53 Times in 36 Posts
Quote:
Originally Posted by CollinK View Post
Thanks, that sounds like a plan. I'll stay with the 3 ohm resistors for now and scope the controller while carefully running a small motor.
I'm using 4.7 Ohms 2Watts........driving 600Amps x 144VDC rail, but still in "testing mode" with out any issues with a work bench transmition/motor assy.
__________________
. .. .. . .......
Prius Absolutum Dominium . ..........KOPPER
PHEV conversion since Dec 2006.. . .... .Future EV
. . . . . . . .CALCars # 27. . . . . . . . . . ..on the works now !!
. . . . . . . . . . . . . . . . .. . ........
  Reply With Quote
Old 10-27-2011, 09:30 PM   #618 (permalink)
AC-DC enthusiast
 
mrbigh's Avatar
 
Join Date: Nov 2009
Location: Long Island, NY
Posts: 282

Dual-PWR PHEV - '04 Toyota Prius

Kopper - '79 Bradley Bradley GT-II
Thanks: 122
Thanked 53 Times in 36 Posts
Quote:
Originally Posted by etischer View Post
Make sure your bus bars don't rub through the vinyl insulation on your capacitors! You might also verify the vinyl insulation is rated for your bus voltage.
Tanks for the advice; actually I have some rubber insulation in the buss bars facing the elcos to avoid vibration "peeling" of the caps insulation.
__________________
. .. .. . .......
Prius Absolutum Dominium . ..........KOPPER
PHEV conversion since Dec 2006.. . .... .Future EV
. . . . . . . .CALCars # 27. . . . . . . . . . ..on the works now !!
. . . . . . . . . . . . . . . . .. . ........
  Reply With Quote
The Following 2 Users Say Thank You to mrbigh For This Useful Post:
LouMan (10-28-2011), MPaulHolmes (10-27-2011)
Old 11-03-2011, 10:27 PM   #619 (permalink)
EcoModding Lurker
 
Join Date: Aug 2011
Location: Michigan
Posts: 32
Thanks: 3
Thanked 27 Times in 10 Posts
I have been working on the controller but recently most of my time has been spent elsewhere. Though, if you check the source repo you'll see that I have been making semi-regular updates to that.

Today I started compiling wiki pages which detail the trials and tribulations of making your own controller. The goal is to gather all the relevant info a person might need when designing or modifying a controller. You know, all of the stuff I wish someone had said to me before I blew up some IGBTs and ruined drivers.

It would be cool if any knowledgeable people could either sign up to be a member of the project and add to the wiki themselves or post what info they think should be included. As I can I'll edit the wiki to include more and more formulas and information. If, Heaven forbid, I got some detail wrong, then please tell me that too!

revolt-ac-controller - Open ReVolt AC Motor Controller Firmware - Google Project Hosting

As a side note, I do plan to actually do more testing soon and scope the controller and do more videos and all that jazz. Hopefully that all will happen within a week or so.
  Reply With Quote
The Following 3 Users Say Thank You to CollinK For This Useful Post:
gtx90 (11-22-2011), MPaulHolmes (11-03-2011), sawickm (11-04-2011)
Old 11-03-2011, 11:39 PM   #620 (permalink)
EcoModding Lurker
 
Join Date: Mar 2009
Location: Florida
Posts: 37
Thanks: 0
Thanked 2 Times in 2 Posts
Paul,

About midway through this thread you were working on an AC controller that used mosfets in the power section. I haven't been able to find anything on the wiki in regards to a mosfet based power section. Do you have any of these boards for sale or do you happen to have the PCB files/schematics? I already have the mosfets and capacitors.

Thanks...
Rick

  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Paul & Sabrina's cheap DIY 144v motor controller MPaulHolmes Open ReVolt: open source DC motor controller 7350 07-28-2021 06:32 AM
Paul & Sabrina's Cheap EV Conversion MPaulHolmes Fossil Fuel Free 542 11-12-2016 10:09 PM
Contest! Name Paul & Sabrina's controller MetroMPG Forum News & Feedback 120 10-22-2011 02:59 PM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2022, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com