Motor BEMF

[cadstarsucks]

However, I am learning what the risk might be were I not here to keep you busy until I find a more militant, combative type who might enjoy taking my place. And don't kid yourself bro, your league is way to low for me.

You really are quite amusing, do you know that?  My Irish may be below your's but my IQ, knowledge and experience in electronics far exceeds your's.

As to finding someone more militant, there are not many who are as stubborn in their misunderstandings as you are...funny thing about it is that they all seem to be in control of hobbyist forums such as this one.

[mustangman]

  OK, Time Out!! Everyone cool down. Dan, you are an EE professional, I Know it may be hard or near impossible to explain 2-4 years of electrical engineering theory and pratical application to everyone,(I got as far as Amps X Volts = WATTS) please for the sake of everyone explain things in laymans terms then I could follow your train of thought.  Dave, I am sorry you got offended, please take time to reflect on the battle. If it is really that important to win the battle or the war?  Patrick, as the impromptu host, you have to respect their opinions, right or wrong they are still their opinionsand as my grandma said "everyone's got one" .  I enjoy rational discourse and not a bunch of finger pointing. Please, lets keep it friendly and informative for everone. Thanks, mustangman

[myelectricbike]

My intent mustangman, exactly. However, I recently asked for advice from administrators of another forum and they said that sometimes it is just not possible to do anything else but to give them the scrap they are looking for. In that vein I will finish my reply to Mr Electronic engineer...


Mr Electronic Engineer:

Why are you still posting in succession?

...
Your statements that, in effect, all power supplied to the motor heats it up does indeed dispute it.

Interesting, you would quote everything except statements you incorrectly paraphrase that I have stated, but this has been typical of every inflammatory post you have made.

Ever hear of Dan Lafferty, the guy who committed those murders? If you are related, you might want to share that with us now.

[Dave]

My intent mustangman, exactly. However, I recently asked for advice from administrators of another forum and they said that sometimes it just not possible to do anything else but to give them the scrap they are looking for. In that vien I will finish my reply to Mr Electronic engineer...

The word you're looking for is "vein". As opposed to "vain" which doesn't apply in this thread. Or does it, since you refuse to yield when you are obviously outgunned?

Interesting  you would quote everything except where you incorrectly paraphrase what I have stated, but this has been typical of every inflammatory post you have made.

Good grief. Talk about the pot calling the kettle black.

Ever hear of Dan Lafferty, the guy who committed those murders? If you are related, you might want to share that with us now.

Wow. He can Google and make stupid name connections. Now I suppose you'll do my name see what you can dig up. You really are pathetic. I somehow have difficulty finding pity for you.

[Dave]

Sorry, Dave you had your chance with offline communication and then came online and made essentially the same comment in regard to my private contact, making it public for everyone else to read from your twisted and erroneous point of view. You are the one who has proven themselves not to be trustworthy Dave, rather than I. And yes, I've been on the Internet since the early 90's and know well enough to avoid providing personal information to such persons as yourself who have demonstrated or expressed malicious intent that I might run into online.

What in the he11 are you talking about? What did I make public that you wanted kept private? That you spammed me and tried to sell me a motor before I bought one from Golden? Does Philip know that you're trying to undercut his sales by talking down Golden's delivery times? I'm sure you've tried the same with everyone else on this forum that's shared their email address.

You don't really expect people to buy from you without knowing anything more about you than your email address, do you? If you had put any thought to your decade of experience you would know that people aren't going to send anyone $300 without knowing a little more than what you shared with me. There is a difference between sharing personal information and giving me reason to believe that you aren't out to scam me out of my money.

I would be glad to share with the forum the totality of our offline "conversation" that was initiated by an unsolicited message from you offering to sell me something, also known as SPAM. I doubt any reasonable person would find anything there that would be construed as offensive. But then again, I'm not dealing with a reasonable person in you, am I?

[myelectricbike]

Sorry Dave, I don't need Google to find out about you... other than my experience all I need now is a comment from the commissar at MacDill.

[Dave]

Sorry Dave, I don't need Google to find out about you... other than my experience all I need now is a comment from the commissar at MacDill.

And still you fail to answer my questions.

We obviously got off on the wrong foot -- you've had an attitude towards me from the beginning -- but for you to fault me for it... That's rich.

[myelectricbike]

Other way around Dave. I was here first, you came alomg and then for some reason (or maybe none) tried to start a scrap.

[cadstarsucks]

Other way around Dave. I was here first, you came alomg and then for some reason (or maybe none) tried to start a scrap.

Actually 'lectric, you started it.  Having reviewed ALL Dave's posts, there was no friction until you tried to sell him a motor and he refuse to deal with you and the pissing contest began.

Sounds familiar actually...I was happily posting helpful, intelligence conveying posts and you decided you disagreed with my more educated position.

Dan

[myelectricbike]

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.

[OffGrid]

Not to disrupt the streetfight going on here, but I do have some questions about the original topic and it's relevance to my interest in using one of these hub motors as a motor-generator.

I have degrees in Mathematics and Physics and do generally understand the electromagnetic/electrodynamic principles being discussed...  but I have been around long enough to know that such theoretical knowledge misses a lot about the real-world and engineering details of precisely how everything was designed and manufactured.

What I am curious about on this topic is whether anyone here has a sense of how efficient/practical these (hub) motors really are as motor-generators (or generators).  It seems possible that these motors are equally capable generators, but I don't know what the practical issues might be.  Some possibilities spring to mind:

1) Wiring Resistance...  shouldn't matter which way the current is flowing, whether EMF or BEMF is happening. In the frame of reference of the magnets, the wiring and the electrictromagnetic field, these are identical except for sense/direction, right?
2) Permanent magnet mounting... are the magnets mounted in any way such that reversing the direction of the torque is a problem?
3) Bearing stress... seems like it would be hard to make a bearing that is asymmetric in it's performance... but one never knows.
4) Hub mounting... more likely to be asymmetric, but is it?   Not with the spoked wheels I don't imagine.

So the controller seems to be the key... probably...   
I haven't thought through (or done the research) to understand how motors and generators differ from a control standpoint...  except that it seems that instead of voltage regulation based on EMF monitoring, one would be doing "load" regulation based on BEMF monitoring.   

What do the motor controllers measure (directly) to determine input waveform?  BEMF? Or I suppose infer it from the current implied by voltage-drop/resistance?

Voltage Amplitude, Phase, Frequency and Waveform shape seem like the only things to be controlled.

Since MyElectricBike seems to have one of their controllers to test, I wonder if he has or will be instrumenting it both on the bench and under loaded conditions...   

I did see the interesting post on another thread for a DIY interface to a USB Memory Device...  Another posting by MEB seemed to indicate that he might have enough gear/sophistication to document it's specific behavior under a range of conditions.

CadStarSucks seems to be pretty knowledgeable as well... any thoughts? 

- OnTopic

[myelectricbike]

I can give your the results of my emperical test but answers to the rest of your questions will have to wait since the supper bell is about to ring ... yes dear I'm coming...

recharge times

[cadstarsucks]

  OK, Time Out!! Everyone cool down. Dan, you are an EE professional, I Know it may be hard or near impossible to explain 2-4 years of electrical engineering theory and pratical application to everyone,(I got as far as Amps X Volts = WATTS) please for the sake of everyone explain things in laymans terms then I could follow your train of thought.

Thank you for bringing things into focus mustang.  The hardest thing for me might be know what "laymans" terms are...If you like we can go through basic electronics, or just pick a question and beat it to death till everyone who wants to, understands.

As for some of what I was saying, I guess the starting point would be to make sure everyone understands what a series circuit is.

Dan

[myelectricbike]

Offgrid -

In the Golden controller the function has been allocated to proprietary software so an exact  description is not available for now. I can speculate, however.

As you know, CEMF is proportional to actual speed while desired speed is proportional to throttle position. Thus, a comparator is used to make a determination as to the following possible conditions.

1.) desired speed is greater than actual speed
2.) desired speed is equal to actual speed
3.) desired speed is less than actual speed

The next step is to determine the value of the actual speed, which is proportional to EMF. This is done using the Hall sensors rather than measuring the CEMF.

The next step is the logical decision as to whether the RPM and hence the CEMF is great enough to bother using to charge the batteries or capacitors

If so then CEMF is used to charge the capacitors and batteries using PWM so that the process never goes for more than a few microseconds, milliseconds or hundredths of a second before the evaluation sequence is repeated and a regen decision made. 

Other methods and evaluation sequences may be used, some more efficient or complex than others. At this point in time though I think the Golden controller is searching for sophistication as indicated by the new, new regen controller which will offer user adjustable settings for freewheel (neutral) and low and high RPM settings

[OffGrid]

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