Ohio race bike.....controllers...I hate them all!

[gwhy!]

Now for my mate GWhy, i have an answer to your question i.e-->

Hi Kim, Im not sure why you think you need a controller the size of a house brick :? , the little 6 fet controllers are not really any bigger than the CC rc controller cos you need to add a BEC and throttle interface so it comes out the same size and my little 6 fet can push 5kw no problems on 44v and in theory i can up that voltage upto 70v which would be 8kw +.

Well GWhy Thudsters blown 6fet controllers enough evidence for you that 6fet controllers don't work with the big Turnigy
outrunners? Edward Lyen has told me more than several times now in MSN chat to not bother with a 6fet Infineon
they wont work with the 800-100Turnigys...Lyen has told me 12fet minimum for the Turnigy if you want to run it
hard, i.e controller the size of a house brick as i originally stated months ago. ...Unfortunately Thudster
has found this out the hard/expensive way. Pitty you couldnt get the HV160 working on the BMX Thud hanging to see that tear up the dirt!

KiM

Well What can I say AJ , I more than happy with my 6 fets what I am running. I will say though I have not pushed my massive turnigy to hard with a 6fet ONLY upto 5kw this was on the scooter project Im playing with :wink: but now I am using a 12fet with stock fets and it needs to be nursed and watched over ( this is not a real test though as there is no real load on the motor until it gets up 1krpm ). On my e-bike the 6 fet is still going strong and able to do 5kw bursts but this is on a smaller 3250w motor without braking a sweat. I really think the secret in reliablility is the fets that are used and cooling and not whether its a 6,9,12 or 18fet controller and noting to do with the controller itself they are basically the same lv/driver circuit. If Lyen has a reason for believing that a 6 fet is no good for the larger motors then he should post these reasons on this forum to save a lot of peoples grieve ( I have my own reasons why Lyen may say this ).

I wish they would hold something like this is the uk.

Plus one on that.

Though I would prefer to be racing on a hard surface rather than dirt. Maybe a kart track.
I do actually have access to a site in Somerset where we could do something. Its got a moto-cross course with serious jumps on it; we might be able to use that, or we could set up something around it.

Well done, Thud, BM, etc.

Nick

Anything would be good, I will be up for mx, or hard flat surface or even a bmx track maybe something could be sorted out for next summer if there was enough interest from riders within uk. I would be more than willing to help organize it if you have access to some land that we can use, ( somerset is on my door step :wink: ).

 

[grindz145]

Thanks for the pictures and videos! Too bad about the rain and dead controllers, but it looks like that didn't stop you from having a great time anyway

 

[Tiberius]

Anything would be good, I will be up for mx, or hard flat surface or even a bmx track maybe something could be sorted out for next summer if there was enough interest from riders within uk. I would be more than willing to help organize it if you have access to some land that we can use, ( somerset is on my door step :wink: ).

PM sent.

Nick

 

[dontsendbubbamail]

Thud,

Can you give us a postmortem on the 6 fets?

Bubba

 

[Thud]

Postmortem:

Looks Like I blew a single FET in all 3 units.....weird that it was the same position on all three boards phase "c" the last transistor in the bank. That has to be a sign for something....anyone care to speculate.....mabye educate?

I am making up another hall sensor mount for a 63mm motor (either souping up the bmx or it will end up on the tidalforce long tail) hopefully I can get at least one of these back in service soon.

 

[bigmoose]

Thud, was it the top fet or bottom one? That is the fet that connects the phase to the positive rail (top) or ground (bottom)? I should have looked closer or taken a pix of the layout of the board when you had one of the controllers open Saturday.

 

[Thud]

Hey bigmoose,
Looks like the bottom one (neg trace). here is a photo but you really cant see anything:

far right fet was the shorted one.

and the bottom view: the neg side is nearest the edge of the board.

the good news is I have one of the baby controllers working like new & am following scientific metheod to see what perfomance envelope can truly be expected. (i had the phase current to high to start with....no time to experiment proper with the dead line(excuses, excuses)

so far it seems my starting tourque is pretty low. I am assuming my motor is just to big for this tiny controller. I can crank up the phase amps in parameter designer & it improves...but the fet's start to heat up quickly. I need to try a smaller motor & see if the tourque is more in proportion.
or try the 18FET on this motor & see what happens.

Thanks for looking, & any insights are welcomed.

 

[gwhy!]

Hi Thud,
When I very first upgraded my first 6 fet I to also blew the same fet as you have and for no apparent reason ( just plugged in the battery tried the throttle and nothing ) I have no idea what caused this and I just put it down to a dodgy Fet as it has been fine ever since, but maybe its is something to do with that part of the board. Just thought I would also mention that I am not using 4110's I am using IRFB3077PBF these are higher current, lower Rds but lower voltage.

 

[amberwolf]

Could there be a trace there that is too close to the edge, and is shorting against the case?

Or could the wire bundle be pushing down on that end of the board and forcing a slightly-too-long clipped FET lead to touch the case only at the corner/end?

 

[Thud]

I looked it over pretty closely, & I dont see any clearance issues. I will double check though to be certain.

I have plans to finish your Jack shaft this week Amberwolf....watch your pm box 8)

 

[johnrobholmes]

Could be some board inductance causing more ripple over there. Hard to say without watching it under a scope with a load on it.

 

[bigmoose]

Ok... I am interested in what other experts would say, so feel free to opine and agree/disagree with my opinion.

The fact that it was the bottom FET that failed, tells me a lot. Now, I don't have the controller in hand with my scope and test tools, so this is a bit of conjecture.

The usual practice is to switch the phase leg onto the bus with the top fet to the rail, so it turns on and stays on. Phase current is measured and the bottom FET is PWM'd to keep the currents in check. Now with the large outrunners the inductance is very low, so the current builds "quickly" according to dI=Veffective * dt/L So dI can get very very large in a short time. If the controller is designed with a fixed cycle time in the do loop and L gets too small, the physical currents can outrun the controllers timing to control them.

That is we have a loop that executes over a microsecond to measure current with ADC, calculate stuff, then keep lower FET on or turn off lower FET that works with a range of L values. Now if we cut L by a factor of 10 or 50 but don't speed up the execution time in the loop; we get internal punch thru on the FET or a lead bond failure. If your FETs failed open, perhaps it was a lead bond failure to the die. It would be interesting to decap a blown FET for inspection.

For very, very low inductance motors, the current cutback must be interrupt driven and not a polled function in the control loop of the micro.

Just some BigMoose Musings(tm)

 

[gwhy!]

I know my failed fet problem may be completely unrelated to Thuds but I thought I would also mention the fet that failed for me was short. Did Thuds fail open

 

[Jeremy Harris]

Ok... I am interested in what other experts would say, so feel free to opine and agree/disagree with my opinion.

The fact that it was the bottom FET that failed, tells me a lot. Now, I don't have the controller in hand with my scope and test tools, so this is a bit of conjecture.

The usual practice is to switch the phase leg onto the bus with the top fet to the rail, so it turns on and stays on. Phase current is measured and the bottom FET is PWM'd to keep the currents in check. Now with the large outrunners the inductance is very low, so the current builds "quickly" according to dI=Veffective * dt/L So dI can get very very large in a short time. If the controller is designed with a fixed cycle time in the do loop and L gets too small, the physical currents can outrun the controllers timing to control them.

That is we have a loop that executes over a microsecond to measure current with ADC, calculate stuff, then keep lower FET on or turn off lower FET that works with a range of L values. Now if we cut L by a factor of 10 or 50 but don't speed up the execution time in the loop; we get internal punch thru on the FET or a lead bond failure. If your FETs failed open, perhaps it was a lead bond failure to the die. It would be interesting to decap a blown FET for inspection.

For very, very low inductance motors, the current cutback must be interrupt driven and not a polled function in the control loop of the micro.

Just some BigMoose Musings(tm)

From what we've worked out between us, the secondary current limit is interrupt driven. These controllers have two current limit circuits, one adjustable in software, that uses an ADC to measure current via the voltage across the shunt, and a second circuit that kicks in to limit current spikes by a direct logic level trigger to a ucontroller pin activated by the voltage across the shunt.

I believe that this secondary current limit is intended to trap just the sort of potential problem you describe, BigMoose, so my guess is that it's either still not fast enough to kill quick spikes, or the FET failure was from some other cause. There's a bit more on our digging around to see how this part of the controller works on this thread: http://endless-sphere.com/forums/viewtopic.php?f=2&t=16910&start=30#p252823

Jeremy

 

[bigmoose]

Thanks Jeremy, I was hoping you would have a few words to say! I'll start reading the thread you pointed to.

 

[Thud]

The 3 blown fet were all closed in this case also. (too easy to find)

I have a used 12fet controller that is DOA & cant find a "shorted" fet in the bank. I need to pull them to test out of circit. (unless there is a fool proof way with a cheap meter & high hopes)

Jerremy said:

so my guess is that it's either still not fast enough to kill quick spikes,

hmmnn, We are soldering the shunts down on these lil units & programming using other board designations to bypass that (maybe not) too sensitve 2nd current sampling/interupt circut.

I will keep testing but conjure at the moment, the "Big" turnigy is too much these 6fet controllers.
(Is there a frock motor in thuds future?????)

gwhy has higher amp rated FET's in his unit....and also runs a smaller motor.
Panacea seems a bit further up the road for me. :lol:
I will set up some halls on a 63mm motor I have & compair the performance.

Thanks again for looking this over Jerremy & Moose. Your opinions are always "value added" in any thread.
Thud.

 

[AussieJester]

(Is there a frock motor in thuds future?????)

We will be having some serious words if there is Thudster :lol:
Anyone else thinking.... "intervention" ?

KiM

 

[Thud]

I Knew that'd get a rise outa you AJ LOL!!!
mission acomplised!

 

[John in CR]

Thud,

I think you'll need at least one hubbie to ensure victory next year. A guaranteed to work small hubbie on the front and a dirt rooster tail throwing RC motor on the rear, could be the ideal approach. Plus it would bring balance to the force. It would be a shame for the 2wd to show up and beat the pants off everyone not have you on it.

John

 

[AussieJester]

I Knew that'd get a rise outa you AJ LOL!!!
mission acomplised!

We can't have a high ranking member of the M.E.N.S organisation defecting to 'the enemy' all hints of defection must be acted upon
post hast :lol:

KiM

 

[liveforphysics]

Thudster! Nooooooooooooooooooooooooooooooo!!!!!!!!!!!!

Use the 18fet controller! Quick! I know it's bulky, but it handles the big HXT motors pretty well. It's at least the best option we've got until Moose/Me/Methy and/or Jeremey finish up some indestructo BLDC controllers.

 

[bigmoose]

Thudster! Nooooooooooooooooooooooooooooooo!!!!!!!!!!!!
Use the 18fet controller! Quick! I know it's bulky, ...

Luke and Thud, I was going to post that same comment last night. Thud your RC driven bikes are a work of art! I will never forget the wheelies in the rain! I was going to suggest that Luke could get you a modified Methods controller somehow... Your 99% there, there is room under your battery box, I'm with AJ on this one! What's he call them "frock motors" Noooooooooooooo

You & AJ could even start a tag line like: "real men use sprock-ets..." Lord knows you have the biggest one around!

 

[Thud]

lol.bigmoose,
They say size doesn't matter!...I have allways had my suspicions,(or is that "feelings of inadiquecy"?) who are "they" anyway. :lol:
I have an 18fet loaded with 4110's procured from Mr. Lyen. I need to drop it to 48ish volts as I don't have the gearing for 11k rpms. (although it would be fun with 60+ mph in theroy)

Fear not fellow M.E.N.S,
as I have no closet frock motor tendancy's (not that there is anything wrong with that :lol: ) however, being a confident hetrosexual, I feel the "MY Little Pony" stickers are a totaly acceptable decoration for an e-bike. I am contemplating handlebar streamers on my 1000watt racer...I know the drag is horrible, but they could be Jettisoned to tangle in a competitors frock.

 

[spinningmagnets]

Make them sticky, so that when they are jettisoned they stick to your competitors face-shield!

 

[AussieJester]

I am contemplating handlebar streamers on my 1000watt racer...I know the drag is horrible, but they could be Jettisoned to tangle in a competitors frock.

hehehe put some "spokey-dokeys'" on the wheels too Thudster perhaps a playing card pegged to the chain
stays fluttering in the spokes also for some increased sound effects ... FYI:- My Little Pony Stickers according to the
:man" in the know i.e HiGHSiDE Hyena are so yesterday, with Barbie Stciker Packs replacing the My Little Pony packs handed out to new F.A.G.S members :lol:

KiM