Thud Does A 6FET ecrazy man mod......

[Thud]

Many thanks Amberwolf,
For taking the time to check out my work.
I am thinking It will be a very tough little controller when I am finished.

Here is a link that takes us through the discovery & trouble shooting of these small controller "cutting out" issuses:
viewtopic.php?f=2&t=16910
I have yet to form an opinion on the reason this circut is so touchy on these models, It is a great saftey feature if that was the intent.

I know that these guys were haveing the same issues also:
viewtopic.php?f=2&t=12616

I am certain the low resistance & high rpm of the smaller motors (non hub) mandate the higer efficancy MosFETS
to get to survival levels of performance. I am just learing enough to realize we need some real power handling units & soon. (I hope the real engineers are making progress on the open source 300 amp units soon )

Oh, my towels are 100%cotton & the humidity in west Michigan rarly drops below 80% (be in the 90's soon enough)
not quite Costa Rico but never dry. I worry more about doing something really dumb like setting the board down on a screw driver or a lead triming.

My only real question's remaining are on programing settings.
Once I modify the shunt (solderd 1/2 shut) to lower the resitance, (thus matching the ratings of a 12 FET controller) I am wondering if the values will be askew enough to make havok on the LVC programed settings. Logic tels me that it should be fairly close. (howerver I failed LOGIC in High school )It should be easy to test though. Once that is determined this should become a really nice controller for a comuter. (even better for the hub crowd)

#1crucher,
If I understand correctly, the Main function of Low Voltage Cut off limits are to protect the MCU unit from an under voltage event. I don't think controller builders give a hoot about the batteies & their life.
(thats fetchers & GGoodrums BMS Job )
Fire works happen if the MCU shuts down in mid signal & leaves a couple FET's turned on at the wrong time.
The R1 resistor will be sized based on pack voltage to keep the 12v regulater from over working (with these mods the controller could be pushed to 100v potentialy)

[amberwolf]

Here is a link that takes us through the discovery & trouble shooting of these small controller "cutting out" issuses:
http://endless-sphere.com/forums/viewto ... =2&t=16910
I have yet to form an opinion on the reason this circut is so touchy on these models, It is a great saftey feature if that was the intent.

I know that these guys were haveing the same issues also:
http://endless-sphere.com/forums/viewto ... =2&t=12616

I'll have to look thru that again and see.

Once I modify the shunt (solderd 1/2 shut) to lower the resitance, (thus matching the ratings of a 12 FET controller) I am wondering if the values will be askew enough to make havok on the LVC programed settings.

AFAIK, the LVC has nothing to do with the shunt. The LVC is simply measuring incoming battery voltage, to see if it should shut down the controller. If the LVC is programmable on that one, then you just set it to whatever your battery LVC should be (or higher if you want some "wiggle room" before total cutout, so that it will start cutting out at high power demands first, but still let you limp a bit afterward without risk to the batteries).

Now, if the current being pulled is higher than your pack can put out without sag, then lowering shunt resistance to increase current capability is likely to cause issues with LVC activating as the pack drops in voltage.

[gwhy!]

Thud,
When programming a 6 fet with 12 fet settings the only difference that I have seen is with the limiting the initial phase current ( if this is what it is ) my guess is that if you are using the standard fets in these controllers ( I think they are 75A constant and around 200A peak ) the programable settings setup a time constant that will allow the max phase current for a set time, if this phase current do not come down within this time constant then the controller shuts down. So it would not be wise to use 12fet settings on a 6fet if the fets have not been upgraded, but with upgraded fets ( im using 120A constant and 800A peak ) it will be safe to increase this time constant which in turn will allow the higher phase current to be passed for a longer period. This is my understanding of the circuit. I am currently running my 6 fet with 18fet settings This has not effected the lvc of the controller that Im aware of ( as its set to the lowest as I use another form of battery monitoring ) but its still there to help protect the controller form something major happening should the voltage disappear from the senistive part of the controller to cause a major blow out. Hope this helps.

edit:
Opps , I have just re-read my post and I have some of things not quite right. The time constant is fixed with component values and selecting a different programming setup changes a length of time "window" at the chip. Also the max pulsed current not the peak current.

[Thud]

Thanks for the input gwhy,

I don't know why I assumed the #s in parameter designer reflected actual ampers draw....but that makes more sence given the way the Block time settings function.(I am going to re-read a couple threads now)

Upgraded the FETs to irfb4110's.
caps low ESR 100v capable.....

The plan is to finish the modified box to house it in & get some real live testing done with the bike this weekend.
Need to be carfull, so I can race it next Sat. & see how it does against the gassers.

I will be starting wth some conservitive settings & only push it to where I feel its competitive. I hope that happens before it blows up.(I have Lyen's 72v 18 fet on the way for back up )

I am using an turnigy 80/85-170 & hope it matches the perfomance of your scooter project.
Are you using your 12fet on the scooter? (please tell me it was the 6 fet model )
Thanks again. T

[mwkeefer]

Thud,

Great work so far... I read your thread and just figured id make a suggestion, I don't see any comment about programming for > 100% speed on any of your % settings... I think once you have upgraded (done) to the IRFB4110s you would see a real difference in accelleration and maybe even top end by tweaking that....

I could be wrong but observation has convinced me that because the 4110s are so much more efficient that they will in effect switch faster than the stock fets...

Another point... when using infineons (only 846 so far, sorry will check the 116 soon) to drive RC motors which I have adapted with Halls... setting phase current to approx 1.25 X that of primary current yeilded the fastest no-load RPMs (combined with 115% speed setting)... 1:1 acheived the same no-load RPM but 1.25 was as far as I could tweak the difference before the noload top RPM went down...

Hope it helps!

-Mike

[gwhy!]

Thanks for the input gwhy,

I don't know why I assumed the #s in parameter designer reflected actual ampers draw....but that makes more sence given the way the Block time settings function.(I am going to re-read a couple threads now)

Upgraded the FETs to irfb4110's.
caps low ESR 100v capable.....

The plan is to finish the modified box to house it in & get some real live testing done with the bike this weekend.
Need to be carfull, so I can race it next Sat. & see how it does against the gassers.

I will be starting wth some conservitive settings & only push it to where I feel its competitive. I hope that happens before it blows up.(I have Lyen's 72v 18 fet on the way for back up )

I am using an turnigy 80/85-170 & hope it matches the perfomance of your scooter project.
Are you using your 12fet on the scooter? (please tell me it was the 6 fet model )
Thanks again. T

Sorry Thud, it was a 12fet running the scoot but on a positive note it is running the stock fets (75A) the current limit on my 12 fet is set to 70A, because of the stock fets (rds) the controller gets rather toasty quite quickly so needs to be nursed. If I was to uprade the fets ( to the same thats what I have put into my 6fet controllers ) and rehouse/better cooling I am confident that I can push 130A constant through the 12fet ( maybe more ), As my 6 fet stands I know it will push 70A constant all day long with the mods that I have made. I think that it is the potentional massive phase current ( not just the heat ) that can kill all the types of controllers ( sensorless/sensored) and as we know the phase current will be at its max upto the maybe the first 1krpm of the motor so this is the danger zone.

[liteCycles]

Another point... when using infineons (only 846 so far, sorry will check the 116 soon) to drive RC motors which I have adapted with Halls... setting phase current to approx 1.25 X that of primary current yeilded the fastest no-load RPMs (combined with 115% speed setting)... 1:1 acheived the same no-load RPM but 1.25 was as far as I could tweak the difference before the noload top RPM went down...

Mike,

Hey, do you know what no-load RPM you hit at the 1.25 setting? And how the no-load amp draw compares to sensorless controller?

I heard Thud posted a youtube vid with some info related to this but I haven't been able to locate it.

[mwkeefer]

I do have the stats from the experiments but they are at my main office, top of head I really don't remember but I do know my no load current is lower than most since my RC motors were converted to wye which really drops the noload current.

I will search for the documents when I get in on tuesday and post the results here...

-Mike

[Thud]

Mike,
Thanks for the tips, I am having fun figuring all this stuff out.
(modding meanwells last night & this mornig)

Here is the thread with the video'a posted:
viewtopic.php?f=28&t=18578&start=30

the video really only quells the 6000 rpm myth currently circulating.
higher poll count hub motors may be more limited.
bottom of page i get 11,300 rpm's on a 116 6FEt

My best settings so far are right where you guys are suggesting. Way to little data logging for me to offer any recomdations yet.
Mwkeefer is the source there.

[Ypedal]

Thanks Thud !!.. i can swing a hammer but the soldering iron i have not yet mastered lol.. the more pictures i see the better i feel about trying it.

[Thud]

MWkeefer,
Thanks again, I modded onother 6fet this afternoon & tried your settings. It seems to hold true on the 116 chip also. I am getting 8650rpms with no load at 46v
Thats about 300rpm improvment. My no load current on the 80/85-170 is right at 7 amps.
I have added monster heat sinks to these baby controllers. Should help if I get into a thermal situation.


this is all bolted to the outer case after lapping & adding artic ice hea sinking compound. (stuffs kinda pricy)

here is the 1st one with 10gage wires & a monster heat sink bolted right on the fet's

been a long weekend of modding controllers & meanwell's. Nice now every thing is working

[Jeremy Harris]

Looks good, but I'm afraid that I doubt if those big heatsinks will really make a significant difference. When you look at the thermal resistance across the whole system, from FET junction through to the air around the controller, the big issue under extreme conditions is right at the FET. The standard case is probably OK if you can get a really good thermal junction between the FETs and the heatsink bar (i.e. chuck away the really crap silicone rubber insulator and use either thin Kapton or mica).

Jeremy

[amberwolf]

If it helps any, I don't see enough of a thermal difference between cheap white heatsink paste and expensive SuperChillAbsolutZeroBrand to be worth the money. The only differences that have mattered were the ability to remain creamy and not dry into a paste that shrinks away from mated surfaces, leaving airgaps.

If the heatsinks are well-lapped and have a flat-fit already, then it *really* doesn't matter, as long as all the compound is applied only to the scratches in the surfaces, and not a whole layer between them (since bare metal to metal will always be better than metal to any compound to metal).

[Thud]

Thanks for the input Guys,
I have a roll of kapton inbound.
(you have to admit, the monster heatsink look industrial)

[Jeremy Harris]

Thanks for the input Guys,
I have a roll of kapton inbound.
(you have to admit, the monster heatsink look industrial)

It does that, it looks pretty mean and it may help out a with overheating a little bit. It'd be nice to find a big finned case that is easy to use, rather than the extrusion with end caps that they come with as standard.

I've not used any of the alloy boxes that these controllers come in (in fact, I just bought a batch of bare boards from Keywin last time) as it's hard to get big cables, bigger capacitors etc inside the small case. My controllers are built into big, sealed, diecast alloy boxes, with neoprene gaskets on the lid to keep water out. This makes it much easier to work on the controller and gives a bit more space around the components, as the wires aren't all bunched up inside.

Jeremy

[gwhy!]

I thought I will post up a picy of my modded 6 fet, It also really helps where mine is located on the bike you get a very good air flow over the heatsink from the tyre.

6fet re-housed controller.jpg (34.36 KiB) Viewed 304 times

[mwkeefer]

Thud,

These turned out well... I see you equipped your race ride with one.

That increased RPM of 300... it should have been higher, but really it depends on the sag your seeing off your pack... with 3P I doubt you will see much if any sag no load.. there I wonder what was your battery voltage at that maximum no load speed?

My experience has given me on order of 3x that RPM increase no load so about 900 on a 230kv motor at a given voltage... obviously each motor has their sweet spot for maximum efficiency which unless I've misinterpreted a bunch of stuff, changes at each voltage potential.

I will be setting up halls on a Turnigy Aerodrive XP 170kv shortly (within a week or so) and will report back the optimal settings I can acheive there... it should be more akin to your setup if I recall from earlier and other threads.

-Mike

[Thud]

Mike,
I was only running a single 12cell pack & the voltage was down to 44v near the end of my tinkering this weekend.
The bike will be 3p for certain. & I really need to keep a better Log of all my program settings.
Baby steps.
Well be seeing if 6 FET's can handle the abuse from the smallest of the "big" Turnigy's.

[FastDemise]

I'll give this thread a bump since it has good information. I'm curious what's the most power that has been pushed through a 6fet. I'm running mine stock with no internal mods minus some thicker power and phase wires. I sealed up the controller and filled it with mineral oil on 18s Lipo @ 50amps. The controller barely gets warm even after 8-10miles of full throttle on my 9C 2808. So 66.6V * 50A = 3.33kW peak. Just wanna ask if anyone has pushed more so I can feel confident pushing up the amps to 60amps or greater.