BIONX motor controller revealed

[itselectric]

Inside look of the Motor
you can see the Q.A. year was 2004.




for high resolution pictures, click the link below:
View attachment 5

 

[Doctorbass]

I hope I am not hijacking this posting, it's all related topic. This is only time we have in depth information on Bionx

No prob Ken!.. it's welcome!

Doc

 

[wrobinson0413]

.

 

[Doctorbass]

Hey Doc

What are they using to insulate the PCB board from the hub motor underneath the heat vias for the D2PAKs? All of your pictures haven't shown any insulation at all, unless I missed one.

Great question.

Here is the answer: They installed a white insulator ring disk between the back of the PCB and the metal frame. This disk is made of white flexible material just like the grey one supplied with the infineon controller for the mosget and aluminum bar.

It also have 3 holes spaced from 120 degree to let the screw that fix the board to the metal frame to pass thru it.

Since they have holes from the size of the screw diameter, i also discovered a potential assembling error.

On the second motor i dissassembled ( the 2004 version) the very little disk that come from the 3 holes when they puncture it dont seem to be kept away and i found one of these little waste part of the disk to be right under board.. so the thicknedd of the board is twice at this place but the board only touch the highest part wich is that little disk and leave an air gap that block the heat thansfer at this mosfet location.

So the puncture waste from the 3 perforated disk sometime stay on the insulator disk ring and double the gap...

That unit was'nt damadge but i bet that the first unit i got had the controller board blown duew to something stupid like that...

Doc

 

[wrobinson0413]

.

 

[cferron]

Hey Doc, any idea how the 32km/h limit could be removed from the BionX system?
I have a PL250 and can get to 28 km/h easy without the system assistance. My guess is that if it could be unlock I could go up to 50km/h? I'm I thinking right?

Thanks

Claude

 

[alan]

Hey Doc, any idea how the 32km/h limit could be removed from the BionX system?
I have a PL250 and can get to 28 km/h easy without the system assistance. My guess is that if it could be unlock I could go up to 50km/h? I'm I thinking right?

I don't think you are correct assuming you will get any assist at all much above 32 km/h without increasing the voltage.

A motor has an inherent relationship between voltage and speed described by the constant Kv. For any given voltage, multiply times the Kv and you have the motor's target RPM (speed). If the motor is going slower than that, then the motor will "draw" current, and if faster, the motor will generate current. The greater the difference between the actual speed and the target speed, the more current drawn or generated. In practice, the controller electronics can modulate down the voltage to reduce both the current and/or speed, or to cause the motor to send current back into the battery to charge it. Also, it can cut off the current when the motor is going faster than the voltage times Kv to keep from charging the battery and "braking" the motor in the process.

What I expect is the case with your BionX system is that the 32 km/h limit is just below the V * Kv target speed (to optimize the overall system performance). If you remove the limiter, then you should expect a bit more assist, maybe up to 35 km/h or so. Above that, the system should basically act like it is turned off, until you apply the brake an put the system in regen mode. That means that if you could only pedal to 28 km/h without the BionX assist, then with the BionX assist and it's speed limiter defeated, you will probably only be able to get a bit above 32 km/h.

There is one other difference to consider, however. I was able to do about 18 MPH tops on my bike (flat surface, no wind) before I added my BionX PL350. After adding the BionX, I find myself able to ride 21-22 MPH, even though there is no assistance! The difference is that I am not as physically tired getting my bike up to 20 MPH, and have more energy to pedal above that when I do get up to 20 MPH. I can keep that up for less than a mile, though. For continuous flat riding, my BionX assisted limit is still about 20-21 MPH, and I have to work hard to do that. Upping the assistance level, and riding with an easier pedal effort will only keep me going about 18-19 MPH. Note that this is on a converted mountain bike with fat tires. A faster bike would likely do 20 MPH or a bit more with less pedal effort.

-- Alan

 

[MadRhino]

Hi Doc

This thread died after dismantling and observations. I wonder if you have made any attempt to run a bionx motor at higher voltage, either by modifying the actual bionx controller, or using an external controller.

 

[Doctorbass]

Hi Doc

This thread died after dismantling and observations. I wonder if you have made any attempt to run a bionx motor at higher voltage, either by modifying the actual bionx controller, or using an external controller.

thread in sleep mode YES.

This bionX project is in standby from now..

Doc

 

[Arlo1]

Those Bionx stators are Very nice they look hand wound!

 

[DISH]

Hi Doc

This thread died after dismantling and observations. I wonder if you have made any attempt to run a bionx motor at higher voltage, either by modifying the actual bionx controller, or using an external controller.

I've been running mine (350 watt 36 volt Bionx system) at 64 volts with a $25 sensor-less controller at the 1500 to 1600 watt level for over a year. I'll try to make a very long story short...

I blew the first 350 watt motor in the first month I had it. I was going down hill in excess of 42 MPH when all of a sudden the rear wheel LOCKED!!! Needless to say I left rubber on the road and was lucky I was not hurt. Fortunately this happened on my trike. Had I been on a two wheel bike I don't think this would have turned out well as all. I don't even want to think about what could have happened had this motor been mounted in the front fork of a two wheel bicycle when this happened!!! People around here have been known to go down the side of the same mountain on a road bike doing 65+ MPH so 43 MPH is no big deal around here especially on a trike.

Normally i repair everything myself but since this was under warranty, back to the facotory it went for replacement under warranty.

A couple months later same thing happened. Different hill but approx. the same speed. Somewhere around 42 to 43 MPH. Back to factory. Replaced under warranty. Starting to see the pattern?

The same thing happened a THIRD time but this time the system was out of warranty and it was my baby so I had nothing to loose by opening the motor. I even posted a video on how I did it.

http://www.youtube.com/watch?v=Uy6ua2XoorM

I used nothing special but as others have pointed out you do have to be careful and tap the other side of the motor housing otherwise you may crack it. The Bionx motor is a bit of a pain as there is no way to get at the internal controller without taking all the spokes out and completely tearing the motor apart. Not a design that lends itself to tinkering or modifications!!!

I replaced the MOSFETs. Everything was fine for another six months or so. Then I did it again. Only this time when the wheel locked up smoke came out of the battery pack. At this point I had it with Bionx. I had thought about removing the controller from inside the motor and mounting it OUTSIDE the motor but it was obvious that this system has a design flaw and I was tired of dealing with it.

I opened the motor (hopefully for the LAST TIME!!!), gutted it of all Bionx electronics, brought out wires hooked to the three phase wires, hall sensors, and torque sensor.

Although I have run this motor with the hall sensors hooked up, it runs so well without them hooked up that I no longer bother using them. I have converted three Bionx motors so far. All of them are using either one of these two controllers:

http://www.endless-sphere.com/forums/viewtopic.php?f=4&t=13691

Same controller but later version:
http://www.endless-sphere.com/forums/viewtopic.php?f=4&t=20176

I chose this controller because it was cheap, had regen braking and allowed the option of not having to hook up the hall sensors. This could be an issue if the motor has a bad hall sensor and you don't want to have to deal with replacing it.

Although this is spec'd as a 500 watt 12 MOSFET controller, I've been pumping over 1500 watts into the 350 watt Bionx motor for over a year now with no issue whatsoever!!! (25 amps x 60 volts = 1500 watts and 25 amps x 64 volts = 1600 watts the highest I've dared push this controller so far.) Top speed at 60 volts is close to 40 MPH using a 20x1.75 (46x406) knobby BMX tire. I've pushed this controller to 64 volts hot off the charger but since the internal capacitors are rated at 63 volts there is some risk in doing this. Best to keep it at 60 volts or so if you want to play it safe.

The controller comes from the factory with the internal current limit is set to around 25 amps or so and seems to do what it's supposed to do as far as limiting current is concerned. Since I have more than enough power at this current level I made no attempt to run it any higher. I always peddle when I'm on the bike. The motor is more of an assist for climbing hills with a heavy load but I do occasionally open it up on the open road just for fun and to give my legs a break. I've been known to haul more than a 100 pounds of groceries home at times!!!

I plan on changing the capacitors to 100 volt units so I feel a little more comfortable when the battery is at 64.0 volts hot off the charger. There is no problem running the Bionx motor at this voltage. It shows very little heat running at the 1500 watt level. However, after changing the capacitors the next issue is going to be the MOSFETs in the controller I'm using as they are rated at 75 volts and I already know more than I care to know about the voltage rating of MOSFETs and what can happen when blasting down a hill at high speed!

One other issue to keep in mind when pushing the voltage limit of a controller that has regen braking. If you are right at the voltage limit (in this case 63.0 volts) and you hit the electric brake, your voltage may go UP another volt or so, depending on how stiff your batteries are. So be careful about using regen braking in the first couple of miles until your battery voltage drops to whatever you consider safe. Having a MOSFET go dead short is not only a nuisance, it can be extremely dangerous when the rear wheel locks up. As mentioned before, I don't even want to think about this happening to a front hub motor on a two wheel bike!!!!

I have no idea of what this motor can be pushed to. I live in the foothills of the Allegheny Mountains (3100 foot peaks) so it gets a workout climbing hills but it also gets a workout blasting down those same hills while using regen braking. I used to have to change disc brake pads several times per year. Since going to regen braking I've had the same pads on the bike for over a year now and for me that's 5000+ miles. I've been gas free for the past six years so I depend on this system to get to where ever I have to go...

 

[amberwolf]

Having a MOSFET go dead short is not only a nuisance, it can be extremely dangerous when the rear wheel locks up.

I'm not sure if it would help (brain not awake enough yet to be sure I'm thinking the right way), but what if you put a fuse inline with each phase, so that if the controller did blow, the resulting higher current pulled in the phase would blow the fuse and release the wheel.

It'd still start to lockup, and you might begin to skid, but you'd then regain control as soon as the fuse(s) blew.

I think you could test this using switches on the phases instead of a controller, just coasting down a hill fast enough to be in the range where this would happen, and then flipping the switch to simulate the short, to see whether the fuse then blows or not.

You could also test it on the bench if you had a way to drive the wheel using another motor, via friction drive, like on a test stand.

 

[DISH]

That is an EXCELLENT idea and one that I've thought about more than once. It might take a bit of playing around though to find the correct fuse size as motor winding currents can be quite a bit higher at times than what's being pulled from the battery.

After going through this more than once I had given some thought to some way to be able to disconnect the motor windings from the shorted MOSFETs and fuses was one of them. When the MOSFETs short It's like riding with the rear brake fully engaged and the faster you try to go the more effective the brake becomes due to back EMF from the motor windings feeding the short!

The issue with the Bionx motor is you can't unplug the motor from controller (removing the short) and ride it home and getting to the electronics of the motor means taking the wheel completely apart. So internal fuses would be a pain to get to and mounting them externally I don't think would be possible as there's barely enough room to get the existing cables out of the motor.

Considering all of the above is why I chucked the Bionx electronics and went to an external controller. No more expensive failure prone Bionx electronics, no more 20 MPH speed limit, and now I can use any battery that I want.

I think if I ever got guts enough to try a fork mounted hub motor on a two wheel bike, I'd put the fuses in and test to see that the idea worked before ever riding it. In my opinion the front wheel is no place for a motor, especially after seeing the issues I've had with shorted MOSFETs locking the wheel. Had this happened to me on a two wheel bike with a front mounted hub motor and going at the speeds I was going when it happened, I probably would not be typing this right now.

By they way brushed motors have the exact opposite effect when the controlling transistors short. Instead of locking the wheel they go FULL THROTTLE!!! That happened to me ONCE and I immediately mounted a cutoff switch under the seat!!!

 

[DISH]

I dug through my junk box and come up with a Bionx motor that didn't fair so well. You will see what I mean when you see the photos.

As several have pointed out the Bionx motor is also prone to water damage. There should be a clear piece of tape over the split between the two halves of the motor case. That's all that's keeping the water out of the inside of the motor! And you don't want to know how many people I've seen with these motors that for whatever reason the tape is MISSING!!! If they only ride in dry weather, probably not a problem. But all you need is one ride in wet weather and the problems start.

If the motor you are taking apart is in good physical shape and has never been wet then you should have no problem taking it apart by using the three prong puller and tapping on the opposite side as seen in this video:

http://www.youtube.com/watch?v=Uy6ua2XoorM

and the other video posted previously.

HOWEVER, if like the motor you are about to see, the sealing tape was missing while the motor was used on wet rainy snowy days then you need to be EXTREMELY CAREFUL as to how you go about taking it apart or this may happen:




The electronics looked pretty clean inside this motor:


However, the ends of the pole pieces were rusted to the magnets and some of the magnets came out bonded to the poles pieces. In a few places you can see where pieces of the poles broke off before the rusted bond broke. In that case the magnet was still attached where it was supposed to be but the end of the pole piece was attached to the magnet!!! I didn't know what these pieces were at first. Then I noticed the chunks gone out of the pole pieces!



This particular motor (which the owner told me was a 350 watt 36 volt Li-Mn system) has seven windings and IRF3205 MOSFETS:




An IDENTICAL motor in all respects that I can tell (has the same board, same number of motor windings, 350 watt 36 volt Li-Mn system) has the 1407 MOSFETs:

Or should I say USED TO HAVE 1407 MOSFETs. This is what happened when the owner went down a hill and hit 43 MPH:


As far as I can tell the motor with the cracked housing is completely operational except for the water damage. Had the owner taken the time to seal the split separating the two halves of the motor they might still be using it!

I'm going to glue the magnets back in and see what happens before I gut the thing and connect it to an external controller. There is NO WAY I'm going to ever use the internal controller again. The only way I'd ever use that controller is by mounting it EXTERNAL to the motor and bring out phase, hall and torque sensor wires. Then I could play with it while it's in operation and replacing MOSFETs wouldn't be any big deal.

Whether you decide to use the internal controller or scrap it and go with an external controller it's VERY important that you seal the split running down the center of the motor housing before exposing the motor to the weather. I've had very good luck using a product called Goop. Unlike silicon rubber it's doesn't seem to peel off when exposed to salt and water. Judging by what I've seen of Bionx motors the tape that Bionx used to seal these motors didn't do the job so don't bother trying to put the tape back the way it came from the factory.

 

[DISH]

After sending the previous post I found the photo of the other side of the motor showing the magnets.

The magnets aren't just rusted. The rust was bonding the magnets to the ends of the pole pieces!

And those little green things and other blobs are pieces off the ends of the pole pieces that broke off as the motor halves were separated...

Now you see why the housing broke trying to get this motor apart.

Although it would have made a mess, dumping some penetrating oil down in the crack between the two halves of the motor before and during the opening attempt might have made things come apart a little more gracefully and may have prevented the housing from cracking. Of course it would have made cleanup an even bigger mess especially in preparation for gluing magnets back in.

I don't use anything special when putting these motors back together. I don't have a press nor was one needed. After getting things in reasonable alignment I used a rubber mallet and tapped the two halves together. One of my motors has been taken apart and put back together more than a half dozen times now with no issues. But it's not rusted like the one above and that makes a HUGE difference...

 

[DISH]

Having a MOSFET go dead short is not only a nuisance, it can be extremely dangerous when the rear wheel locks up.

I'm not sure if it would help (brain not awake enough yet to be sure I'm thinking the right way), but what if you put a fuse inline with each phase, so that if the controller did blow, the resulting higher current pulled in the phase would blow the fuse and release the wheel.

Something that's been running around in the back of my mind is re-settable fuses. I've used them for low current stuff (1 to 2 amps) but I know they come in larger sizes. Whether or not the series resistance could be tolerated in this application would have to be determined.

The way they work is they are almost a dead short until a threshold current is reached at which point they become a much higher resistance and begin to heat. The current and heat keep them in a high resistance state. They reset when the current drops to almost zero and the device cools. They then go back to a low resistance state.

The way this would work in a motor if a MOSFET shorted you would get a short braking action (locked wheel) from the motor then the re-settable fuse would go open circuit. You would loose motor power but you would not have the issues of dealing with a locked wheel.

Initially starting from a dead stop with a shorted MOSFET would be a bit difficult but once the fuse heated and went open circuit again you'd be free wheeling once again until you stopped. Not the best situation but at least an accident might have been prevented and you could peddle the bike home.

Something like this might be the way to go when the controller in inside the wheel like the Bionx system. Of course with an external controller you just unplug the controller and ride home...

 

[amberwolf]

Yep. My suggestion was meant for use with the external solution, but would be a good idea (if it works) even with the internal controller, with the fuses inside the motor, because at the least:
A) The wheel lockup wouldn't cause a potentially fatal wreck.
B) You could still ride the bike home, assuming you can pedal it thru the terrain you're in without the assist.

FWIW, I've dealt with total wheel lockup twice, fortunately on a rear wheel in both cases. Once on CrazyBike2, IN TRAFFIC, when the chain (in about half a second) did the following: derailed from the jackshaft chainrings, caught in them, tacoed them, wrapped around them, pulled the rear wheel out of the dropouts, bent it's axle, pulled spokes almost out of the rim, bent the rim, and almost threw me off as it skidded to a halt, just as the motor current blew up the controller.

All with cars coming up behind me scarily fast and nto really going around me nearly far enough, as I tried frantically to drag the 150lb monstrosity out of the left most lane I was in and onto the median (the only place I could go). It took me an HOUR to fix the wheel well enough to be able to even walk the thing home the two and a half miles or so.

On the other hand, I found out that the little powerchair motor could really kick butt with torque, at 36V with 17Ah SLA, with 153A flowing thru it for something like 3500W. :lol:

The other was on DayGlo Avenger, where the pedal chain came off the left side of the cassette due to me forgetting to reset the derailer's low-limit and also not remembering to put the plastic spoke-protection ring in place, so when I downshifted in preparation to braking for a possible stop at a traffic light (still going about 20MPH), the chain skipped over the last gear and into the spokes, instantly jamming the wheel and skidding me to a stop. How I managed to stay upright and on the bike, without skidding out, I don't know, but I did. Took almost 20 minutes to unjam the chain and inspect the spokes for possible imminent failure before I could trust them to ride home on.

 

[liveforphysics]

The picture of Doc's original board has phase current monitoring:

The picture of this other one doesn't.

Also interesting, it looks like they have used both laminations and soft-magnetic material for the stator cores.

 

[grindz145]

It would be fun to to sniff those CAN lines, to see what it will tell you.

 

[DISH]

Hey Doc, any idea how the 32km/h limit could be removed from the BionX system?
I have a PL250 and can get to 28 km/h easy without the system assistance. My guess is that if it could be unlock I could go up to 50km/h? I'm I thinking right?

Thanks

Claude

I can confirm what others have told you.

When I removed the internal controller from my first Bionx motor and connected it to an external NON Bionx controller I used the same 36 volt (42.0 volts hot off the charger) Li-Ion battery. The system performed pretty much the same as it did with the internal controller. I may have picked up 2 MPH or so but the Bionx motor simply would not do any more speed when driven at 36 volts.

I haven't done careful measurements but the speed on a flat road with the system running a bit over 60 volts is close to 40 MPH. More typically 35 to 37 MPH as the battery voltage drops a bit and depending on how much I'm pedaling. At that speed the current drawn by the motor is minimal. I have enough gearing to allow human power at speeds above 40 MPH. (Front chain ring 92 teeth equivalent obtained via step-up idler gear - Back freewheel 11 or 13 teeth depending on bike.) At lower speeds power tops out a bit over 1500 watts and is limited by the controller which is set at 25 amps. (25 amps x 60 volts = 1500 watts).

Even after a long climb up a steep hill in the middle of summer the motor is barely warm. I've also looked at the windings after a year of running it at the 1500 watt level and nothing is discolored so I would say it could probably handle twice this power (3000 watts).

I stopped at 64 volts because the capacitors in the present controller I'm using are rated at 63.0 volts and I'm already pushing my luck a bit when firing the system up hot off the charger (64.0 volts)...

 

[DISH]

The picture of Doc's original board has phase current monitoring:

The picture of this other one doesn't.

Also interesting, it looks like they have used both laminations and soft-magnetic material for the stator cores.

Four of the internal controllers I blew were the newer type with current limiting. I've never had an issue with excessive current. In all cases the MOSFETs exploded while blasting down a hill in excess of 40 MPH. Most likely due to excessive back EMF from the motor.

In my case the MOSFETs always blew by going dead short making it next to impossible to ride the bike back home. It's like trying to ride with the brakes locked on and it's impossible to clear the short by unplugging the controller as it's inside the wheel.

What amberwolf was suggested was the use of fuses that would blow in the event of a shorted MOSFET so at least the bike could be ridden home without fighting a locked rotor. Although that would probably work I'm not sure how it would be implemented as replacing the fuses would require complete dismantling of the motor. I don't think mounting the fuses externally is possible as there isn't enough room to get any more wires out of the motor and the extra resistance of the wire isn't something that is desirable. I'm not sure if resettable fuses would work but at least they could be mounted inside the wheel with the controller.

Considering all of the above is why I gave up on using the internal controller. After blowing the internal controller four times due to excessive voltage while blasting down a hill I gave up, gutted the motor of all Bionx electronics and went with an external controller. Best decision I ever made. It all cases the motor failed with the MOSFETs shorting, exploding the case of the device(s) and resulted in a bike that was next to impossible to pedal home.

I've seen both types of core material. Laminations and powered iron. I haven't compared the two to determine the characteristics.

 

[DISH]

Also interesting, it looks like they have used both laminations and soft-magnetic material for the stator cores.

Did some snooping and found this:

Handbook of small electric motors By William H. Yeadon, Alan W. Yeadon

2.51 Abstract
http://books.google.com/books?id=TsXEHPofiAYC&lpg=SA2-PA51&ots=QNOM9d7n52&dq=powered%20iron%20vs%20laminations%20brushless%20motor&pg=SA2-PA51#v=onepage&q&f=false

"A new soft magnetic material has been developed for ac and dc motor application. The motor components are made by a powder metallurgical process, in contrast to the traditional method of stacking punched laminations. This new material not only offers many manufacturing advantages but exhibits a core loss that is comparable to that of many grades of motor laminations steels at 60 Hz. Because of it's low eddy current loss, the material has excellent high frequency magnetic properties, making it an ideal material for brusheless dc motors operaing in the high frequency range."

Just don't drop it on the floor or let the magnets rust to it....

 

[DISH]

Also interesting, it looks like they have used both laminations and soft-magnetic material for the stator cores.

Did some snooping and found this:
2.51 Abstract
http://books.google.com/books?id=TsXEHPofiAYC&lpg=SA2-PA51&ots=QNOM9d7n52&dq=powered%20iron%20vs%20laminations%20brushless%20motor&pg=SA2-PA51#v=onepage&q&f=false

Double post again. Sorry...

 

[billvon]

Great pictures!

Can you see what bridge driver they used? (It's the small 8 pin IC on the FET side; there should be three of them, one per phase.)

 

[Toorbough ULL-Zeveigh]

silk on docs bord sez july 2008.
whereas the other 1 dates from december 2004.
good that they're larnin.