Xlyte Controller Repair with Words and Pictures!!

[knoxie]

Hello


This controller had failed possibly because of the high voltage (80V) that I was running or maybe a bad fet, I am not 100 percent, I can upgrade the fets in this controller so that they can run at 100V 140A!! crazy!! or what?

This fet failure had also blown a number of surface mounted resistors and their associated gate transistors, I diagnosed most of these failures simply with a DVM set to ohms and measured the values and compared them to the healthy areas of the circuit.

I chased my tail a little as I was in a hurry and changed components then powered it up only to blow them again!! it pays to take time and check all of them before you do anything, the gate resistors go easily as do the high side drive transistors. I also replaced the Ir1201 chip downstream of these just incase.

I am happy now that this controller is back on song, I think I will take Bob Mcree's advice and fit the higher rated fets next time though, I will do this on another controller I also like Richard Fechters idea of making it an adjustable controller with a knob on the outside!! very cool.

Major thanks to Richard Fechter for this though he helped me al the way through, I was determined to fix it and now I know so much more about them and how they work that I don't worry if another controller fails as I know I can fix it.

The controllers are relatively cheap to fix and other than the fets the components are very cheap, I got in a stock of SMD resistors and good qtys of transistors as its all so cheap esp. when you buy in qty.

I hope this may help others diagnose and fix any faulty controllers that they have, I believe Richard Fechter is also going to publish some pictures and drawings of what he has found also.

The BMX is back on the road!!

All the best

Knoxie

[knoxie]

Hello

It seemed to clip some of my comments in the pictures, apologies about that, there are a couple more pictures here as I can only attach 10 per thread.

Cheers

Knoxie

[xyster]

Wow that's great. I read that Bob McCree is doing this as a hobby. The technical end is no problem, but I lack the fine hand dexterity to work on tightly packed circuit boards. Some future time it'd be nice to be able to send my controller to one of you guys (along with some thank you and parts money) for a FET/current limit upgrade.

[knoxie]

Hi Xyster

Yes of course I know that Richard or Bob would do this for you for sure, Bob has already offered this over on PA so anyone with a blown controller or anyone who wants their controller upgrading can get it done. Its early days yet for this but I think Richard is having great results with his controller, most Power Assist users wont need the extra amps nor will they have the batteries to go with it, however the higher rated fets have lower on resistance than the fets used in these controllers and as so will run cooler and more reliably at the same voltage.

If the adjustable current limit can be added as a knob or pot on the outside this would make this a truly remarkable and very versatile controller, I am not sure but it may be a good Idea to put bigger caps in for 140A use to get the real low down amps though? they could be fitted in the case somewhere I am sure.

I would be happy to look at any controllers in the UK to fix or beef up.

Have a good day all!!

Knoxie

[patrick_mahoney]

Thanks for the post. Very nicely and cleanly repaired. I have a dead controller that I haven't looked at. This thread is inspiration.

[knightmb]

Hello


PLEASE READ THE PHOTO THREADS FROM THE BOTTOM UP!

Sorry about that the board formatted them that way.

I changed around the order for you so that it reads top to bottom

I've also fixed up the comment field in the database to allow longer comments. It was originally set for only 255 characters, should be able to do about 25,000 characters now (hopefully you won't need more than that )

You should be able to edit your post and update the comment fields so they have everything you wanted to put in there now.

As for picture order, it got me to the first time, especially attaching multiple pictures. Basically, think of it like Tetris, those attachments that go first land at the bottom and everything else stacks on top. I do wish for a nice "move attachment order" button, but for now this is what we have.

[Mathurin]

Dude, nice writeup.

From what I take of it, too small a cap will tend to heat up.


What's this you say about using some silicon sleeving to insulate the
tab of the fet from the heatsink instead of the stock liner?

[Lessss]

Bob over in PA????? Power assist? Pensylvania?

[knoxie]

Thanks for the post. Very nicely and cleanly repaired. I have a dead controller that I haven't looked at. This thread is inspiration.

Hi

Yes go for it!! let me know how you get on!!

Cheers

Knoxie

[knoxie]

Dude, nice writeup.

From what I take of it, too small a cap will tend to heat up.


What's this you say about using some silicon sleeving to insulate the
tab of the fet from the heatsink instead of the stock liner?

Hi

No its not heat its just the std caps may not be enough if you want to run 100A out of it thats all, the liners are little pieces of plastic they fit to insulate the screw from the tab and the heatsink, I found on some of them that undoing them had caused the thread to cut through the side which may lead to the tab shorting out to the case when the contoller gets hot.

Not good so I snipped up some small silicon tubing and replaced all of them should be good as long as the controller doesnt start shooting flames!!

Cheers

Knoxie

[knoxie]

Bob over in PA????? Power assist? Pensylvania?

Sorry

Bob Mcree from Power Assist!! he lives in california!

http://www.bobmcree.com

Cheers

Paul

[knoxie]

Thanks Kinght

Yes I was rushing to post as I was at work and didnt want boss man trouble so didnt want to go back and post in the other order, thanks for doing this for me!! and also for fixing the other things as well, this forum is becoming a really cool place to hang out and If we all start to contribute people will start to flock here.

I like this software a lot as I use another forum with it regularly however you can tweak them to suit hence me getting the pics in the wrong order.

Thanks for all your hard work

Knoxie

Hello


PLEASE READ THE PHOTO THREADS FROM THE BOTTOM UP!

Sorry about that the board formatted them that way.

I changed around the order for you so that it reads top to bottom

I've also fixed up the comment field in the database to allow longer comments. It was originally set for only 255 characters, should be able to do about 25,000 characters now (hopefully you won't need more than that )

You should be able to edit your post and update the comment fields so they have everything you wanted to put in there now.

As for picture order, it got me to the first time, especially attaching multiple pictures. Basically, think of it like Tetris, those attachments that go first land at the bottom and everything else stacks on top. I do wish for a nice "move attachment order" button, but for now this is what we have.

[fechter]

I have quite a bit of technical information on Knoxie's controller. It is one of the more popular and common brushless controllers. It uses a shunt based current limiting circuit. The current is measured by the shunt, which is just a bunch of wire, though perhaps a special wire. By soldering a pair of the shunt wires together, the current limit went from 35 amps to around 60 amps.

Don't do that with the stock FETs!

They can barely handle 35 amps.

[knoxie]

Hi Richard

Thanks again for your help on this one as I would have struggled without your input, nice clear shot of the busbar as well. I have not linked mine however I am really interested in making one of the these controllers current adjustable that would be so useful.

Hopefully posting in this way people will experiment a little themselves and fix / adapt and modify these controllers as they are good but they are not perfect of course and so much can be done to improve them, they are a great building block for a very powerful and robust system.

Thanks!!

Paul

[fechter]

Here's how to make the controller current limit adjustable. This setup should adjust the current from whatever the max was stock, to near zero.

If you want a higher current, it's best to beef up the shunt first, to get a higher max, then use this mod to lower the current limit.

You can mount the adjustment pot anywhere. On mine, I'm going to drill a hole in the end plate of the controller and install it with a small knob. Just like a volume control.

[fechter]

You can tack solder the wires right onto the chip legs. The B- connection is a solder pad on the board.

[knoxie]

Hi Richard

Wow!! that's great such a clear thread and nice and easy to do as well I would like to calibrate the Knob as well this may be a little tricky, can you think of a way? be nice to mark on a label the max amps.

Its also great to have this on the bars so you can limit the current on a long ride so you can limit it to something reasonable and then not have to concentrate to have to hold the throttle half open which can make your wrist ache a lot!!

Thanks Richard this is brilliant, please show more pictures when you have your mod in place. Brilliant!!

Knoxie

[bobmcree]

thanks to fechter for the details on the current limit section. i have never had problems with that part of the circuit, so i have not needed to draw a schematic of it yet. i have increased the shunt conductors to raise the I limit on mine, but having it adjustable would be nice, especially if someone else rides my bike. full throttle at low speed now will push 3 kW, and most of it just goes to waste. i use the drainbrain and watch the current, so it is ok for me to have a 50A limit, but not everybody knows about throttle control, and it is a bit difficult to finesse that last few degrees of throttle control needed to keep the current down. i think i will try using a voltage controlled fet instead of a pot and then i can adjust the current remotely without injecting noise into the current comparator section.

if paul has not mentioned the part, the IRFB4310 can be substituted for the IRFB4710 used in the 72v controllers. the 4310 has half the on-resistance of the 4710 and only 10% more gate capacitance, so the driver will handle them no problem. it would be nice if the 4110 would work, as it is the 100v fet with the lowest Rds-on, but the gate charge is pretty high, and i am not sure the ir2101 driver could handle it.

in a 20A controller they just use 6 fets and they are driven directly by the ir2101 driver chips. you could drop in a set of 4310's and add another piece of bus wire to the shunt making one of these a 35A controller. just please don't come crying to me when your motor fries if you are not cautious

in the 35/40A controllers they use pairs of the same fets and the low side pair is driven directly by the 2101 through a pair of 10 ohm smt resistors. the high side pair, which handles the pwm, has a complementary transistor pair added to the output to boost the drive current. you can replace all 12 of these fets with the 4310 and if you beef up the high current paths it could be a 100A controller. i set mine at 50 because there is an advantage to limiting the current to a reasonable level. in addition to being easier on the batteries, very high currents can actually damage the magnets in the motor, resulting in permanent loss of power.

one thing i have noticed in doing the repairs is that the 10 ohm gate resistors tend to get overheated and change value. i replace them with a stacked pair of 20 ohm 0805 thin film resistors to prevent this.

the IRFB4310 is about $2.50 for qty 25 pcs from irtronix. this is a very good price. for those looking for somebody else to repair their controller or to upgrade it to higher current, contact me off list. i am doing it because retirement is just not keeping me busy enough, and because there seems to be a need. it takes me back to my early days fixing tv's back when you actually fixed them and didnt just toss them in the trash.

[knoxie]

Hi Bob

Thanks big time for your input and the clarification of the fets and the controller current limit, this is just what these forums are for isnt it!! I love it.

There seems to be quite a bit of interest from people in getting their controllers modified to do this and also beefed up as well, most seem to be state side and many are in your areas it seems so maybe you and Richard can share the load and modify and repair and sell a few maybe?

I think a lot of people would want this feature on their controllers, its a shame for the TF guys as none of this can help them, I wish we could come up with a way of beefing the 750s for them as I think the 1KW TF is a good ride as std.

Thanks again big time for the input.

Cheers

Paul

[Stevil_Knevil]

Hi Y'all,

Happy to see that everyone is still pushing the manufacturers' rated output.

This thread is priceless! I had just begun dipping my brain into Fechters' posts on modifying these controllers over at the old V is for Virus forums.. then poof! They were no more. Real pisser, because I was getting ready to crossover from brushed to brush-less tek.

I'm learning tons here (thanks Knoxie, Rich and all), and I don't mean to derail this discussion, but I have a quick question. Has anyone here experimented with getting brake regeneration from these controllers?


Ridefastakechances; ) -S

[knoxie]

Yo Stevil

Great to see you on here!! I used to read your posts regular on the old VV forum great to see ya!!

I haven't done anything on the regen side, others may be able to comment though, nice to see you are still tinkering!!

Cheers

Knoxie

[fechter]

it would be nice if the 4110 would work, as it is the 100v fet with the lowest Rds-on, but the gate charge is pretty high, and i am not sure the ir2101 driver could handle it.

Bob, I already built one with 4110's
The gate capacitance is a bit higher, but when I run it, the gate waveforms look nice and square, so apparently the drivers are up to it.
The low side switches are only switching at the commutation frequency, so switching speed is not really an issue for those anyway. The high side drive is boosted by a pair of transistors, so the IR2101 isn't handling much current.

The on resistance is less than half of the stock FETs.

The first one I did used IRFB3808's, (75v rating) and that's the one I'm running right now. The current limit is 90 amps, but with my present gearing I only see that much on takeoff for a second. Climbing a 18% grade at full throttle will draw around 60 amps. [/quote]

[fechter]

'm learning tons here (thanks Knoxie, Rich and all), and I don't mean to derail this discussion, but I have a quick question. Has anyone here experimented with getting brake regeneration from these controllers?

All the silicon you need for regen is there, just no logic. The commutator chip does not have a brake function. I think you would need to figure out a way to make all the low side switches come on at the same time and PWM that signal. I think it could be done.

I've also thought about using the logic from a RC model controller to drive the power stage. Some of these have braking. Sensorless would make switching motors much easier (no pesky hall sensors!).

[fechter]

Here's one of the controllers I started out with. It was free!
It blew the two FETs that are obvious, 4 gate resistors, one high side driver transistor, and one IR2101.

[fechter]

Here's a general layout of the board: