Doc EXTREME 36 FETS controller

Doctorbass

100 GW
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Apr 8, 2007
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======= DOC'S 36 FETS CONTROLLER ========

NO MORE FEAR ABOUT EBIKE CURRENT LIMIT !!!! :twisted:

I waited few month to finally get one of these boards and finally that happened. :mrgreen:

This thread is to show how i build mine and maybe to give some inspiration for anyone that would like to make one. And also to share any future mod or idea.

I remember few month ago when steveo talked to me about that 36 fets coming... we kept the secret for few weeks and then fianlly he posted some info on that.

Today it's possible to get some from Lyen, Marko or Steveo( i think) or directly from Keywin.

The only problem is that if you order directly the complete controller, you'll get a 75V fets version with poor mosfets... I mean worst performances than the 18 fets 4110 controller...

And If you order only the board and want max performances out of that 36 fets PCB by.. ex using the 4110 fets for 100V 300A or the 4115 fets for 150V 150A, you'll not have the case, the 2 aluminums bar and wiring and fets. From now yuo only have two choices:

1- Getting a complete 36 fets controller for around 350$ with lower performances than the actual 18 fets

2- getting the 36 fets board version with capacitors only and buy everythink else.

Fortunately you can buy the board for around 75$, the fets for around 100$, the better capacitors for around 15$ the best case you can get that will fit with minor modification for around 60$ and two aluminum bar to hold the fets for around 30$

all that for a total of 280$ only!! and few hours of great work :wink:


Ok.. now What does that mean a 36 fets controller :?: :wink:

More current limit than the actual X5 legend can hold !!!

Since we can get burst of 20kW with a 18 fets.. do the math!!!

With my 18 fets i can get CONTINUOUS ACCELERATION on a 5303 with around 8-10kW of power..

WANT TO USE A 5302 or 5303 on a 26" wheel AND 250A limit WITHOUT ANY PROBLEM??

NOW IMAGINE 16-20KW continuous acceleration!

I'll use the rest of this thread to post pictures and important things about that controller.

Doc
 
CASE

The first problem to solve was finding the right case for the pcb.

After examinating a little bit the board it is evident that the pcb is too wide and that it is waste of space. that too wide pcb would force us to find really large case and WE DONT NEED THIS :wink:

So the first thing i did was to measure and cut to keep only the usefull width of the PCB.

Then finding the right case that is easy to find and no need for custom made.

And... finally i found it!.. it's Hammond extruded aluminum case that just fit nearly perfect with or need !

PCB dimensions
There was a little but solvable problem about the width of the case. The max width of that Hammond case serie was to allow 100mm pcb. and if cutting only the empty portion of the pcb, that still dont fit. Since i will add strong big cooper bar to the high and low side supply, the pcb trace no more need to be so wide on the high side.. so i can cut it! :wink:

That's what i did to free some width on the pcb.

Then... it slide perfectly into the new case!!!


CAPACITOR

Another little problem here but again that can be corrected easy and btw amelioration the performances of the controller is to replace the actual capacitors.

The original 470uF 200V caps that Lyen sent me are good for low current and high voltage setup.. but not for ultra high current!!

and... their height was too high to fit into the case and also allowing some room under the pcb to install the copper bus bar on the high and low side.

I found a great solution: downsizing the capacitors and choosing lower voltage tolerance since 100V caps have prooven to work great with 24s lipo setup ( 100.8V)

My final choice was the 680uF 100V nippon chemicon low ESR capacitors bought at digikey and shipped in 1 day!

18mm x 35.5mm.... that's exactly 4.5mm lower height and that is exactly what we need !

at 2$ each shipped that's 14$

100V
680uF
27miliohm ESR !!!!
2.5A ripple current.

Here is some pics:
 

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Some comparaison between the 18 fets, 24 fets and my 36 fets(middle)
 

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Drool. :D
 
Doc,

Don't plan on getting too crazy with the current on a low turn count motor. There's more to it than just the FET count. eg My 24 fet controller with 4110's gets pretty hot at only 120A and 74V with my low turn count motors, and that wasn't even going up a hill. That was in normal type riding. It still gets hot at even 75A with much partial throttle use. On the highway it's a different story, because at WOT where the motor can get up to high enough RPM for the controller to get out of current limiting then the controller stays absolutely cool to the touch. I think there's a piece of the puzzle missing that we didn't fully flesh out in the discussion about phase current multiplication, and that missing piece is probably responsible for the repeated blown FETs on your 18fet controller with the X5303.

John
 
Yes John..

It might not work perfect as i expect... but someone need to try it to get the truth!!!

I'm willing to pay few hundred's $ to discover that.

That 36 Fets controller will certainly give me better results than my 18 Fets!!

Steveo said it is the High side that heat more and in my case desing i'll not only have the top of the moset aluminum bar that touch anc conduct the heat to the case BT I'LL HAVE ALSO THE SIDE SURFACE.. and i think that will improobe the max current tolerance.

Arlo is making copper tubing on his 24 fets... it's something nobody ever tried and he want accept being the Guinea pig and i think it's great because that show we still have members that do their own R&D to help having better performances and share the way and results to the crowd. as i know nobody ever used a 36 fets on the ebike power range we have.... I wanna be the first !! :twisted:

I still have 3 x X5 motor for that :twisted: :mrgreen:

Doc
 
Now let measure the dimensions to make the aluminum bar for the 2 row of 18 mosfets and also the room for the bus bar under the pcb..

The copper rod i will install in the pcb are recovered from 220V 6 AWG cable ground i had surplus from our hot tub installation.
4.11mm is 6 AWG

Doc
 

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Close up shots of the gate drive circuit area with part numbers?
 
liveforphysics said:
Close up shots of the gate drive circuit area with part numbers?


No prob.. i'll take pics in the next minutes..

I can say it is using the old good 2n5551 ( to-92 case) just like in the old analog C-Lyte controller...





5 minutes later.....

p-n :

High side:
T4 diode
HY2D transistor
2n 5551 Transistor

Low side:
same as high side but with
M7 Diode
Y1 transistor

Doc
 

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Doc, I am really really interested in following this... Please please let me know what you use for the aluminium bar! Keywin was trying to source some for me, but said after a while of trying that he just couldn't get them (the original ones).

My plan for my boards, was to use a ABS project box enclosure for the controller. It would provide 0 radiant cooling through the case, however, it allows me to fit pretty much whatever I want inside it. The original plan was to mount a crap load if small heatsinks to the aluminium bar, covering all surfaces. I would then create a duct around the fets, and holes in each end of the case. A fan would then blow air right over the fets, and the mass of heatsinks, and then right out the other side of the case.

I also don't have to worry at all about fitting large caps in the case, or whatever I wish to do.

Water cooling looks amazing, and if I get these working properly with air, I may then move to water later. But I don't want to add that complexity to the initial build. I'd rather get the controllers done and working quicker.

P.S. I am planning on running the two I bought on 4115's for 36s lipo. Jay64, who is building a couple with me, is gonna build a 4110, and a 4115 controller.
 
If it were me, then I'd just buy some copper bar (maybe 3/16" thick and around 3/4" wide, around the size of lightning conductor strip) and use this to mount the FETs. I'd solder a length of 1/4" copper pipe along the back of each bar and hook it up to a PC liquid cooling set up. The case wouldn't matter then, as the FET cooling would be taken care of by the liquid cooling system.

Mind you, I'm far from convinced that a big multi-FET controller is the way to go; I think that it's extremely unlikely that the FETs will current share effectively, so the cumulative current handling capability of a 36 FET controller is likely to be a lot less than might be expected from having 6 FETs per switch.

Jeremy
 
Jeremy Harris said:
If it were me, then I'd just buy some copper bar (maybe 3/16" thick and around 3/4" wide, around the size of lightning conductor strip) and use this to mount the FETs. I'd solder a length of 1/4" copper pipe along the back of each bar and hook it up to a PC liquid cooling set up. The case wouldn't matter then, as the FET cooling would be taken care of by the liquid cooling system.

Mind you, I'm far from convinced that a big multi-FET controller is the way to go; I think that it's extremely unlikely that the FETs will current share effectively, so the cumulative current handling capability of a 36 FET controller is likely to be a lot less than might be expected from having 6 FETs per switch.

Jeremy


Jeremy, I totally agree with you. Multi fet apprae risky and the current share might not be perfect so the risk of overloading one of the 6 fet set might happen as well.

I agree on that but i want to confirm. Theory is one thing.. Pratic is another and i want to be the guinea pig for that.

Something that is REALY interesting is that the High side and low side are TOTALLY independent.. I mean.. one of the two bar could be the positive side and the other could be the negative. (These fet are mounted in two row.. on the 24 and 36 fets only)

If we could connect directly the to-220 fets tab( center pin 2) to these copper bar without the insulator and just insulating the copper bar to the case the heat transfer and heat share between each mosfet wold be better.

so by that way the positive and negative that supply each fet could be connected thru the heat sink bar
:wink:

Doc
 

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Hi Doc,

Wow amazing works how i can expect following you now with this controller i was not able to do it with your 18 Mosfets :lol: . This controller will be great and you will have a allot of fun no doubt. :wink:

Good day!
Black Arrow
 
36 Fets?!?! When will the insanity end?

Love it. Doc. Keep up the good work:D

BTW, did you get this straight from Keywin?
 
Doctorbass said:
If i decide to go with aluminum bar, i might go with these "L" shaped bar from McMaster carr;

Part Number: 8982K314

http://www.mcmaster.com/#aluminum-bars/=90qq0d

unpolishedmillroundlegangle.gif


Or another idea that bison_69 designed for me is this one:

I like the idea very much ; but , maybe its better to exclude water tank out of the kit and make more copper on the upper part of fets....so you have enough liquid running around ?
 
grindz145 said:
36 Fets?!?! When will the insanity end?

Love it. Doc. Keep up the good work:D

BTW, did you get this straight from Keywin?

I got the pcb from Lyen. (very fast shipping and great packing as usuall ):wink:

Doc
 
Okay let me get this straight... if we keep the alu bars isolated from each other we don't have to use kapton tape between the fets and the alu bar?

Please tell me that's true!!
 
tostino said:
Okay let me get this straight... if we keep the alu bars isolated from each other we don't have to use kapton tape between the fets and the alu bar?

Please tell me that's true!!

Possibly... not sure..

Well.. using one bar for the positive rail could work.. since the pin 2 of each fets are conducting current exactly like the back of the mosfet and the entire conductive part.

The problem is conducting heat and current.. and the heat sink compound is not conductive material and would insulate... just the screw that fix hold the mosfet to the bar could really conduct...

but for the goal of not using any insulator between the 2 bars and the mosfets to better conduct heat and just put heatsink compound it would work... but you MUS ensure that none of these 2 bar are conudcting with the case!!

Doc
 
Doctorbass said:
tostino said:
Okay let me get this straight... if we keep the alu bars isolated from each other we don't have to use kapton tape between the fets and the alu bar?

Please tell me that's true!!

Possibly... not sure..

Well.. using one bar for the positive rail could work.. since the pin 2 of each fets are conducting current exactly like the back of the mosfet and the entire conductive part.

The problem is conducting heat and current.. and the heat sink compound is not conductive material and would insulate... just the screw that fix hold the mosfet to the bar could really conduct...

but for the goal of not using any insulator between the 2 bars and the mosfets to better conduct heat and just put heatsink compound it would work... but you MUS ensure that none of these 2 bar are conudcting with the case!!

Doc


Keep in mind it can only work for the high side FETs. If the drain tabs are all connected together on the low side FETs, it's 100% fail.
 
Yeah, thermal reasons are why I want to do it without an insulating material. That will probably have the biggest impact of all on current handling of these controllers.

My cases are plastic, so there is nothing for them to conduct with! This is amazing.
 
liveforphysics said:
Doctorbass said:
tostino said:
Okay let me get this straight... if we keep the alu bars isolated from each other we don't have to use kapton tape between the fets and the alu bar?

Please tell me that's true!!

Possibly... not sure..

Well.. using one bar for the positive rail could work.. since the pin 2 of each fets are conducting current exactly like the back of the mosfet and the entire conductive part.

The problem is conducting heat and current.. and the heat sink compound is not conductive material and would insulate... just the screw that fix hold the mosfet to the bar could really conduct...

but for the goal of not using any insulator between the 2 bars and the mosfets to better conduct heat and just put heatsink compound it would work... but you MUS ensure that none of these 2 bar are conudcting with the case!!

Doc


Keep in mind it can only work for the high side FETs. If the drain tabs are all connected together on the low side FETs, it's 100% fail.

Yes, Thanks for the remark Luke, I know that.

I also know that it's the Hi side that generate more heat so puting directly the mosfet to it without insulator would be just better... the low side can still survive by leaving them with standard insulator method.

Doc
 
Luke, Any idea on leaving longer legs on the fets to increase a little bit their resistance and better match them in parallel??

I mean alot of high power amplifier are using low ohm resistor between the rail and collector and emitter to compensate for the gain difference and make a better equilibrium on the current share...

Could leaving the fet leg like 2-3mm longer could help that... or cold it also decrease performance on another way by doing that... any pros and con ??

Doc
 
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