Motor BEMF

[myelectricbike]

I suggest a Googling for good tutorials on BLDC motors which include Hall effect sensor and CEMF switching methods or look for separate tutorials. They are not that complicated to understand but as a very good learning aid you might want to also write a BLDC simulator program while you are learning to secure an in depth understanding of BLDC motor operation.

[cadstarsucks]

Ah yes... it would be natural that the controller's logic is treated as proprietary, and asking you as an evaluator/reviewer to essentially reverse engineer their algorithms would not be appropriate.

The "simple" algorithm you describe certainly makes sense, especially if you throw in some various fudge factors for responses, etc.

I'm not clear on what the hall-effect transistor is there to measure if it isn't the current flow through the motor/generator....

I am not as interested in reverse-engineering their controller as I am in understanding the performance characteristics of their motor to evaluate the "theoretical" and "practical" limits of it's utility as a motor-generator.

Naturally, their regenerative controller is going to be tuned for expected use as in regenerative braking and in increasing distance in a bicycle application...  and my interest is somewhat different... 

I guess I could just buy one and start monkeying with it on one of my bikes (a convenient test-stand when not riding it) and then re-build a windmill around it when I'm ready (or not).

- OffGrid

Hello Offgrid 

Actually the brushless motors *are* permanent magnet 3 phase generators.  As you well know the functions are the exact opposite even though some structures do not operate well in both modes.  The brushed direct current motor does not operate as well as a generator as it does a motor but the brushless does.

Looking at the performance curves it can be determined that the output of the HBS-36 would be 36V 20A @ 300RPM with an aggregate armature resistance of 0.5 ohms.

Your best bet for a thumb drive interface is http://www.mouser.com/search/ProductDetail.aspx?R=VDIP2virtualkey62130000virtualkey895-VDIP2

You can tie that to a PC or a micro and talk to a thumb.  We currently mount the chip directly on a PCB to avoid monkeying around with all the USB protocall crap.

Dan

[Dave]

If you had reviewed the posts from the beginning as you claim then you would have found that Dave requested purchase information which I provided him both as a post to the forum and by email.

Both of you really need to get a life, instead of remaining preoccupied with mine.

Wrong as usual. I was looking to buy from Golden, wondering what the process was (read that original post) so I went to the "owners forum" & asked the question, just guessing that others who had already been down that road would have some advice for how best to accomplish it. Suddenly I get spammed by you wanting me to bypass Golden & send you money for goods that were supposedly in a container enroute to you. It was actually several days before I figured out that the spammer behind the ebike@verizon.net address and the user myelectricbike on this forum was the same person ([ur=http://goldenmotor.com/SMF/index.php?topic=90.msg807#msg807l]link to that comment[/url]). (Nobody ever accused me of being Magnum PI. )

Again, I wonder if Philip is aware that you're trying to dig into his sales using the forum that he's hosting.

Preoccupied with your life? Please. The world doesn't revolve around you, Patrick. Nor does this forum.

Now, back to the topic at hand, which was indeed started by cadstarsucks, and was becoming very informative before being hijacked (for some unknown reason) by myelectricbike, who finds it necessary to expound on every topic, whether he has anything worthwhile to say or not.

[myelectricbike]

I agree that this is not the place for you to start a new topic or to hijack a topic started by someone else, so in that vein I will start a new topic for you so that I might fully address the comment you have just made.

[OffGrid]

Dan -

>Actually the brushless motors *are* permanent magnet 3 phase generators.

  Thanks for the clarification... that was essentially what I was asking I guess...
  In particular, if these specific brushless motors were *designed* to be generators
  originally (is that why they happen to be 3 phase or is there a more obvious answer?)
  then all the more likely they will be high-functioning in that regard.

As for "controlling" the output... I assume that the motor's "power curve" is approximately the same in both directions (motor/generator)it's divergence from a simple linear response indicating (mostly?) losses through hysteresis and friction?     Where does one find the "performance curves" for these motors?  I didn't find them (easily) on the website.

Windmills generally need to get up to some minimum speed before you can get any useful work out of them, so a controller would want to "acknowledge that" in it's design... also, at high wind speeds keeping the windmill from tearing itself apart often involves loading it up as much as possible and then the amount of power generated usually overwhelms any battery storage system.  Resistive elements are often shunted in (heating a living space or domestic hot water) to make the difference. 

Windmills also sometimes have governers which feather the props or turn slightly (or completely) out of the wind to avoid "racing".

My guess is that I can use a simple "piecewise linear" control system.  Naturally, in this day and age, a digital system at a high sample rate is probably appropriate.

Below X EMF/RPM (unloaded voltage) no load.
Above X EMF/RPM, load proportional to the EMF to maintain constant voltage.
Above Y EMF/RPM, shunt excess current (doesn't matter to the generator though)
Above Z EMF/RPM, do something mechanical to save the windmill/generator from self-destruct.

Thanks for the link to the USB interface... etc.

- OffGrid but OnTopic (sortof)

[cadstarsucks]

Now, back to the topic at hand, which was indeed started by cadstarsucks, and was becoming very informative before being hijacked (for some unknown reason) by myelectricbike, who finds it necessary to expound on every topic, whether he has anything worthwhile to say or not.

Apparently since I started this one I get to decide what is on topic and what isn't, much to 'lectricsnipe's dismay.  Since my purpose is to help and perhaps educate a bit, and maybe learn a couple things along the way, feel free to query me.   

Dan

[myelectricbike]

Perhaps then you might want to explain to al how to measure motor capacity.

[cadstarsucks]

Perhaps then you might want to explain to al how to measure motor capacity.

Perhaps Al should learn to better phrase his questions

[myelectricbike]

I understand him fine and even prepared the way for you to help him with your expert 3 phase rectifier knowledge...

[Dave]

I understand him fine and even prepared the way for you to help him with your expert 3 phase rectifier knowledge...

Come on, Pat; where's the Topic Cop?

[myelectricbike]

Topic Cop would not be a good job for you... determining motor capacity is a Motor BEMF real world application.

[Dave]

Topic Cop would not be a good job for you... determining motor capacity is a Motor BEMF real world application.

The point, Einstein, is that you're veering off topic, and since you are the self-appointed conversation-keeper-on-topic, that's your job.

Anything else you'd like me spell out for you?

[myelectricbike]

The name of the Chief of Police in Sue Falls, SD.

[Dave]

The name of the Chief of Police in Sue Falls, SD.

Name is Doug Barthel. You can find it (just as I did) through Google. Oh, but wait; you'd first have to spell it correctly. Sioux Falls.

http://www.siouxfalls.org/police.aspx

[myelectricbike]

Spelling errors are a big thing for you, aren't they David, now part of your MO.