Sensorless at standstill, development updates and status

[fechter]

In most cases it should only need to work long enough to get the motor spinning where the BMEF can take over.

[zro-1]

This is really really cool. Its pretty awesome when you realize that for as long as this technology has been around people are still inventing new ways to work with it.

[Arlo1]

Great work lebowski.

[larsb]

I really hope this is possible to realise in high power, then i'll have to learn how to build m'self one of the lebowski controllers

[Lebowski]

I am up to my ears in this stuff now... it seems to work pretty good so far

The amount of calculations though is very large, plus they are all long difficult ones in Octave (the tool I use for simulations), let alone in the assembly that I code in...

[bearing]

Amazing work!

So how does it work with power? Does it take a "break" from driving the motor now and then to run the algorithm, or does it work continuously while powering the motor? (Not that I think it matters much for the user. I am mostly just curious and amazed!)

[zro-1]

...let alone in the assembly that I code in...

Wait. You code directly in assembly? (insert bowing emoji here) That's pretty amazing.

[Lebowski]

Amazing work!

So how does it work with power? Does it take a "break" from driving the motor now and then to run the algorithm, or does it work continuously while powering the motor? (Not that I think it matters much for the user. I am mostly just curious and amazed!)

For now my lips are sealed... am thinking how to turn this idea into cash... considering several options...

[Lebowski]

...let alone in the assembly that I code in...

Wait. You code directly in assembly? (insert bowing emoji here) That's pretty amazing.

I find assembly simpler than C as there are a lot less instructions to learn...

[Lebowski]

Just a small update on this project.

I works. Really well. Can run a motor from standstill as if it had a resolver / hall sensors and at what I call max torque (the point where the stator electromagnets have the same strength as the permanent magnets). But completely sensorless. Just 3 wires to the motor.

I managed to get a company interested enough that they asked me to build a demo. They sent me an 18 V cordless drill with a hall sensored BLDC motor, a big 14cm (almost 6") long building screw and a block of pine wood. Goal was to convert the drill to sensorless and drive the screw in the block of wood, and also out again.

What I liked about this test was that it is a relatively safe indoor way of running a BLDC motor at its maximum performance. The drill had a collar for adjusting how much torque it would deliver before ratcheting (so a mechanical torque limiter). This had to be at max for the screw to go all the way in, meaning the drill and motor had to be run at max intended torque.

Anyway, this was a piece of cake for my tech. 50A amplitude phase current, from standstill after a cold power-up (so no memory about previous rotor position), no problem. True zero speed, motor can stall indefinitely and deliver torque while doing so. Built it with both torque and speed throttle (little switch to choose), and a transition to go from saliency running (so phase obtained from motor inductor differences) to standard sensorless FOC running. This transition was made easy because the saliency running works upto quite high speed, 6 to 12 k-eprm before switching over to standard sensorless FOC. From the drills performance you cannot tell the difference with how it was originally out of the factory.

Processor is a 33EV (16 bits processor, not an ARM or anything like that), running at 70 MIPS. Is busy calculating for about 50% of the time so speed can be lowered. Memory needs, 12k ROM (but included a menu structure), 4k RAM, so very little. Measured error (on the MAC motor) between saliency detected phase and back-emf: around 2 degrees, so really good. Complexity of the algorithm is high, based on the amount of building blocks and calculations it is several times that of (sensorless) FOC.

In the end the company did not like me using expensive ($2 a piece ! when bought in bulk) in the motor line current sensors. I see ways of converting it to low-side shunts (so in the source of the low side FETs) but amount of work is large and it might not work, so risky.

Thinking about what to do now with this tech. I do not plan a controller IC with this as for me it is more of the same, basically lots of not interesting work. Also setup might be too difficult and would ideally require a PC with Labview for drawing performance diagrams. I was thinking about building an ebike with this, but again lots and lots of work with no real return... Am busy trying to get other companies interested, but found the whole process with the first company very stressfull, just not my cup of tea. I am a researcher, not a business person. Coming up with the concept, build a working prototype, but after that I loose interest and want 'to throw it over the wall' so to say (expression we used in Philips meaning giving it over to a product division who then build the consumer version).

Just wanted to let you guys know where I'm at with this...

[whereswally606]

Thanks for the update Lebowski.

I am still here watching your progress. I sold all my scooters (emax's) recently to refocus my efforts on designing and making (3d printing and CNC) in my garage. I still have bobcs prototype on the mti 6pack chip and one of your newer powerboard designs.

At the moment I commute daily using the ebike to a colleagues house before being chauffeured to work (extra 40 mins sleep). Now with 2 babies 26months and 5 months life is hectic and there is little/no rest.

With that said I will convert the Norco DH bike which I run on 72v (macallister packs) to be a Lebowski driven bike. It has a 1kw dd noname brand hub motor but it works great albeit on a noisy square wave cheap (£20) controller. Its also been bullet proof in reliability so it is a great daily rider.

I hope you do find a company which will receive the prototype on the other side of the wall and force the rest of the industry to try to clone it and keep up. Your ideas are too good to simply stay prototypes and one offs forever.

If not I am still looking to help batch produce boards in the future when I've gotten more organised.

[spinningmagnets]

Congratulations, this is wonderful news. Very impressive work.

[izeman]

Cool. Nice to hear about the progress. Sounds really high-tech for me!
On the other hand, and i guess i asked this again: You say that the motor can deliver FULL 100% torque from a standstill - similar to sensored mode. BUT: To me it looks like there is quite little torque from a standstill now (with my sensored MAC), and torque increases with increasing rpm.
Does my imagination play me games?

[bigmoose]

Lebowski great tech! You deserve the :wizzard: label for sure!

I would recommend you form a company. Make your technology the company's IP. Then approach the big guns of TI. This is a chip level solution with associated algorithms. If TI bites, they will buy out your company for the IP. Typical tech takeover/buyout.

Your tech appears so good, so revolutionary, that once it's out there the "big boys" are going to reverse engineer it. A friend of mine who is a patent attorney, and pretty good at it, said "I can bust any patent for around $1M US. ... keep the wraps on this if your intention is to monetize it. Any publication of the techniques can/will void future claims in patents. TI would likely patent it once they own it.

[fechter]

Great news on the design. I know what you're talking about with commerciallizing an invention. The business aspect is not something most engineers are good at. It's even worse in the medical device business to get things implemented and turned into an actual product that people can buy.

At this stage it would be nice to find somebody who is good at the business side and let them run with it. But not run away with it.

[Lebowski]

Lebowski great tech! You deserve the :wizzard: label for sure!

I would recommend you form a company. Make your technology the company's IP. Then approach the big guns of TI. This is a chip level solution with associated algorithms. If TI bites, they will buy out your company for the IP. Typical tech takeover/buyout.

Your tech appears so good, so revolutionary, that once it's out there the "big boys" are going to reverse engineer it. A friend of mine who is a patent attorney, and pretty good at it, said "I can bust any patent for around $1M US. ... keep the wraps on this if your intention is to monetize it. Any publication of the techniques can/will void future claims in patents. TI would likely patent it once they own it.

I thought TI already had this sort of tech as part of their InstaSpin FOC ? Didn't ZombieSS experiment with this ? During this entire project I had something like, if TI can do it then it is physically possible so I should be able to build it too. I never had a look at TI's stuff by the way, build mine from scratch using my own ideas.

Yep, no doubt it will be reverse engineered. This is why I refused the drill company to do any measurements and/or give them a prototype.

I am not a company starter. I cannot really do anything with this tech except build a one-of-a-kind ebike . Want to get rid of it (sell it), maybe get a consultancy job with the buyer...

[csc]

This is solid knowledge. It must find its way and be part of a commercially available controller.

[neptronix]

Amazing. I hope you found an outlet for it's use. Would be a true shame to see this technology rust away in your ebike lab.

If for some reason you redecide on the whole 'not selling controllers' thing, i'd be happy to team up with you and do the customer support/sales/returns/etc side. I have been watching your controller development for a long time and i think it could be huge.

[emmgee]

Don't give up Lebowski, please.... it's a pleasure to follow you over all the years, and I finally had some progress after updating to version 2.A1 (well, it just blew up again recently, but every time I try to learn from my mistakes...).
Just a thought: Maxon Motors in Switzerland is producing tiny and powerful motors e.g. for the Mars-Rovers (I think still with encoders). The motors and controllers cost a fortune because this is the best-available stuff. Maybe Maxon could be interested? Smaller/lighter/more reliable motors without sensors for the next Mars-missions...

[billvon]

I am not a company starter. I cannot really do anything with this tech except build a one-of-a-kind ebike . Want to get rid of it (sell it), maybe get a consultancy job with the buyer...

I'd recommend doing a reference design - a PWB that you can build 20 of, that will also drive a motor. (Pick a motor you like and design for that.) That gets you your controller, and it gives you the ability to easily demo it to other people. Get them to sign a non-disclosure that states they will not reverse engineer it or tell other people how it works. That's your legal protection.

[neptronix]

Ah, another note on top of what everyone else has said.

ebikes.ca has managed to protect their IP yet produce things in China at the same time.
Maybe Justin could be helpful in helping you navigate that maze, or another vendor.

[Lebowski]

Maxon Motors in Switzerland is producing tiny and powerful motors e.g. for the Mars-Rovers (I think still with encoders). The motors and controllers cost a fortune because this is the best-available stuff. Maybe Maxon could be interested? Smaller/lighter/more reliable motors without sensors for the next Mars-missions...

I wrote to Maxon but didn't hear anything. I suspect them of the rather typical Swiss (sorry) attitude of 'how can this guy build that he does not even have a PhD'

[izeman]

'how can this guy build that he does not even have a PhD'

YOU DON'T ???? WHY DIDN'T YOU TELL US BEFORE?
I will go and destroy my controller right away

[Lebowski]

So this is all done sensorless on saliency (did not have the transition to standard sensorless FOC in yet, so it did not go to full speed). It basically runs a sensored FOC but without sensors, the (I believe at this point still 8 bit) phase information comes from the stator inductors having rotor position dependent inducances. The mechanical ratchety torque limiter clutch is on the max value. Note how slow it will run (the drill is in the lowest of its 2 gears), and that it starts from standstill in reverse with the screw all the way in :

DSC02167-800x600.jpg (31.88 KiB) Viewed 1759 times

[kiwifiat]

Congrats, impressive work as usual. I see the automotive EV market as the best place for this new chip soley on the basis that Hall sensors are cheap but resolvers and the associated resolver to digital chips are orders of magnitude more expensive. TI do have a sensorless FOC solution but I can say from first hand experience it was a lot easier to get your brain chip working than the TI development kit a tried about 6 years ago.