GoldenMotor.com Forum
General Category => General Discussions => Topic started by: cadstarsucks on September 01, 2007, 07:36:42 PM
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BEMF is a characteristic of a motor that always exists and is proportional to motor speed. In the case of a Golden HBS-36 is it approximately 0.12V/RPM.
Industrial BDC motor controllers sense motor speed by measuring the BEMF when the switch is off and correct for the drop across the rotor resistance by sensing the motor current.
In the Golden HBS-36 it is the same story accept you are looking at BLDC so the BEMF is three phase AC and the RPM is 3600RPM divided by the number of motor poles.
As an aside, how is the startup from a full stop with a heavy passenger? Is it "rough" (motor cogging)? If so than a better controller could make it smooth. Of course anything costs more - even if there is no excuse other than to line the manufacturers pockets.
When under load the voltage developed across the winding resistance appears in series with the BEMF, hence the ability to add a little extra drive voltage at high loads to compensate.
Dan
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So, If I am correct, the current controller is not exactly what you would prefer as a professional EE. OK , design or redesign a new one/
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How about a layman's explanation of BEMF? I have a good electronics foundation -- Air Force trained for communications maintenance -- but a lot of this theoretical stuff goes right over my head.
Also, if someone (you?!) came up with a good design for the ideal controller and made it open source, couldn't hobbyists like ourselves buy the components and put it together ourselves? Making PCB's isn't that difficult; after that comes the soldering, which is far from rocket science... The thing that is needed is a good design to start from.
(let me know if this is too far off topic. Don't want anyone getting all huffy over that, do we now.) ;)
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First Dave you have to understand what electromotive force is. Think of it this way. when a conductor is in the presence of a magnetic field things do not get interesting until either a current passes through the conductor or the magnet is moved. In the case of the magnet moving a current is induced in the conductor and in the case of a current flowing through the conductor the magnet is moved.
These two inverse relations are a phenomenon we call the electromotive force. And it may help to clarify your understanding to note that "back" EMF is more commonly known as Counter EMF, or CEMF. (...better stop here. Don't want to confuse anyone by getting too technical.) ;)
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How about a layman's explanation of BEMF? I have a good electronics foundation -- Air Force trained for communications maintenance -- but a lot of this theoretical stuff goes right over my head.
Also, if someone (you?!) came up with a good design for the ideal controller and made it open source, couldn't hobbyists like ourselves buy the components and put it together ourselves? Making PCB's isn't that difficult; after that comes the soldering, which is far from rocket science... The thing that is needed is a good design to start from.
(let me know if this is too far off topic. Don't want anyone getting all huffy over that, do we now.) ;)
LOL I would unfortunately I would need permission as what I consider the best technique is not:
http://www.tinaja.com/magsn01.asp
It ends with a 3 phase power bridge such as what is in a every controller. But it starts with a string of numbers in a micro or even just a memory chip... The string of numbers has the side benefits of reducing the harmonics in the motor and making the low speed torque smoother.
The halls tells the micro where in the cycle the motor is to maintain sync and how fast it is going.
The micro controls the bridge.
In the case of a higher rail voltage than the motor rating the micro can apply a lower voltage sine simply by changing to a lower amplitude data stream for lower speeds to maintain the current draw to reasonable levels-20A in the case of an HBS-36.
One thing I have not been able to dredge up for some reason is what frequency these motors are being driven at. :(
BEMF... Back ElectroMotive Force is the opposite of the motor effect - the generator. Just as when current goes through a conductor that is in a magnetic field the conductor is pushed (as in a motor) when a conductor is moved through a magnetic field a voltage is produced that will push current through an external circuit. That voltage is proportional to the rate at which the conductor is passing through magnetic flux and hence proportional to RPM in the motor or generator. A car regulator regulates by reducing the field current in the alternator which reduces the flux which reduces the output voltage at a given motor RPM.
Dan
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First Dave you have to understand what electromotive force is. Think of it this way. when a conductor is in the presence of a magnetic field things do not get interesting until either a current passes through the conductor or the magnet is moved. In the case of the magnet moving a current is induced in the conductor and in the case of a current flowing through the conductor the magnet is moved.
These two inverse relations are a phenomenon we call the electromotive force. (...better stop here. Don't want to confuse anyone by getting too technical.) ;)
Wait a minute. You admit that a motor and a generator are equal but opposite effects, and I presume you would admit that when you draw current from a generator you drop voltage on it's internal resistance...but you won't admit that there is a drop between the "motor" and it's internal resistance?!?
Dan
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Its not a matter of "admission." You seem to have a mind set, possibly from another forum or from your work or home environment, that there is some kind of automatic and competitive ying/yang here, when there is not. This forum is not intended to be confrontational but rather cooperative. We are not here on the basis of controversy but rather we are here on the basis of assistance and cooperation. In that regard this is all I can say to assist you in adapting your attitude to the intent and rightful purpose of this forum. Please keep this in mind if the intent of your remarks is to merit response from me and other owners who are here to give and to get help from each other rather than to argue.
Aside from this I am having difficulty with your purpose here and what you are trying to say. (Dave, on the other hand, understands exactly what it is you are trying to say. ;D)
We know that Counter EMF is proportional to motor speed and can be used to measure RPM but with far more circuit complexity than when using a Hall sensor.
As for internal resistance I am not sure exactly to what you are referring to although you may be referring to inherent capacitance or the charge stored as an induction current in the motor winding when power is removed, which requires induction dumping before Counter EMF is stable in proportion to RPM.
Under no load conditions inherent capacitance or the charge stored as an induction current in the motor winding is small and dumping occurs on the order of milliseconds.
Under load, however, the current through the windings is much greater than under no load condition and a much larger inherent capacitance or charge stored as an induction current in the motor windings is developed which takes much longer to dump before Counter EMF becomes stable, with the initial spike also going deeper into the negative region.
But again I am not really sure if this is what you are referring to by internal resistance and even so what point you would be trying to make or what question you are trying to ask.
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... Aside from this I, like Dave, am having difficulty with your purpose here and what you are trying to say.
... But again I am not really sure if this is what you are refering to by internal resistance and even so what point you would be trying to make or what question you are trying to ask.
Hold up there pardner; I have no difficulty with Dan's "purpose here". I'm just trying to better understand how these things work from someone who has a solid understanding of how they work. You speak for yourself. Please don't lump me in with your issues.
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Well thanks there Dave. You finally told us what your purpose for being here is. Thanks for letting me know my inclusion accomplished something. For all we knew your purpose in posting hear was to promote Crystalytes or LaFrees. ;D
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Well thanks there Dave. You finally told us what your purpose for being here is. Thanks for letting me know my inclusion accomplished something. For all we knew your purpose in posting hear was to promote Crystalytes or LaFrees. ;D
The only thing you've accomplished is solidifying your position as Official Golden Motor Troll.
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Sorry you feel that way Dave, but I was here long before you which makes you the troll, now doesn't it? :(
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Its not a matter of "admission." You seem to have a mind set, possibly from another forum or from your work or home environment, that there is some kind of automatic and competitive ying/yang here, when there is not. This forum is not intended to be confrontational but rather cooperative. We are not here on the basis of controversy but rather we are here on the basis of assistance and cooperation. In that regard this is all I can say to assist you in adapting your attitude to the intent and rightful purpose of this forum. Please keep this in mind if the intent of your remarks is to merit response from me and other owners who are here to give and to get help from each other rather than to argue.
Actually I like to but but get very frustrated when misunderstanding is the rule of the day.
Aside from this I am having difficulty with your purpose here and what you are trying to say. (Dave, on the other hand, understands exactly what it is you are trying to say. ;D)
We know that Counter EMF is proportional to motor speed and can be used to measure RPM but with far more circuit complexity than when using a Hall sensor.
As for internal resistance I am not sure exactly to what you are referring to although you may be referring to inherent capacitance or the charge stored as an induction current in the motor winding when power is removed, which requires induction dumping before Counter EMF is stable in proportion to RPM.
Sorry I used the wrong term, my bad. Counter EMF is there regardless of if you can see it or not. It is the motor voltage exclusive of losses and in an electronic simulation would be electrical energy converted into mechanical energy which would then be subject to friction, rolling and wind resistance losses.
Under no load conditions inherent capacitance or the charge stored as an induction current in the motor winding is small and dumping occurs on the order of milliseconds.
Under load, however, the current through the windings is much greater than under no load condition and a much larger inherent capacitance or charge stored as an induction current in the motor windings is developed which takes much longer to dump before Counter EMF becomes stable, with the initial spike also going deeper into the negative region.
But again I am not really sure if this is what you are referring to by internal resistance and even so what point you would be trying to make or what question you are trying to ask.
What I am saying is that CEMF is always there and is always stable with motor RPM, even if you can not see or use it. It is the CEMF that sets no load speed in a BDC motor and the winding resistance that lowers the speed with load. The motor accelerates until the CEMF equals the applied voltage minus the current times the winding resistance at which time the system stabilizes.
In a pure electronics simulation the motor is represented by a battery whose voltage is directly proportional to motor speed in series with the winding resistance, inductance and capacitance. The motor speed in turn would be effected by the mechanical, feedback and control systems which makes for some very messy and often undefined math. (you can make some measurements and assumptions but over the life of the system, component wear changes things)
Dan
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What I am saying is that CEMF is always there and is always stable with motor RPM, even if you can not see or use it.
Granted... is aways there... but not granted that it is always stable but rather that upon removing applied power to the motor there is a spike in the negative direction and a quick return to a stable CEMF under no load condition and a more pronouced negative spike and longer time for retun to stable CEMF under a condition of load.
It is the CEMF that sets no load speed in a BDC motor and the winding resistance that lowers the speed with load.
Surely your reference to "winding resistence" then means "inherent capacitance or the charge stored as an induction current in the motor winding." Please correct me if this interpretaion of what you mean is incorrect.
The motor accelerates until the CEMF equals the applied voltage minus the current times the winding resistance at which time the system stabilizes.
Humm... CEMF=Va-I(?) If indeed you mean "inherent capacitance or the charge stored as an induction current in the motor winding" then this can actually be determined by running the motor under load then switching if off and measureing the amount and time of recovery of the induction dump between the initial dump spike and stable CEMF voltage.
In a pure electronics simulation the motor is represented by a battery whose voltage is directly proportional to motor speed in series with the winding resistance, inductance and capacitance. The motor speed in turn would be effected by the mechanical, feedback and control systems which makes for some very messy and often undefined math. (you can make some measurements and assumptions but over the life of the system, component wear changes things)
An ideal battery (zero internal resistance) of 36 volts, which is supplying power to an external load resistance of 2.592 ohms will produce a current of 13.89 amps and a power of 500 watts. If the battery has an internal resistance of .01 ohms then with this load the terminal voltage of the battery will drop to 35.86 volts. The output current will drop to 13.84 amps and the output power will be 496.16 watts.
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An ideal battery (zero internal resistance) of 36 volts, which is supplying power to an external load resistance of 2.592 ohms will produce a current of 13.89 = A and a power of 500 watts. If the battery has an internal resistance of .01 ohms then with this load the terminal voltage of the battery will drop to 35.86 volts. The output current will drop to 13.84 amps and the output power will be 496.16 watts.
Well skipping to the end of your verbose and erroneous post ... V=IR, it does not matter if it is the internal RESISTANCE of a battery or a motor.
Therefore if the speed of the HBS-36 motor drops from 308RPM to 216RPM we get that it's internal resistance is (36V (the curve test voltage) x (1-216RPM/308RPM)) (the voltage across internal resistance) / 20.5A (the full load test current) = 0.5 ohms
As a proof you go back the other way - P=I²R ... 20.5A²0.5=210W which coincidentally is just about the difference between the curve input power of 730W minus the curve output power of 509W. Where then is MY error?
Dan
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Confrontational again. That is your error.
If the battery pack has an internal resistance of .5 ohms then with the external load of 2.592 ohms the terminal voltage of the battery will drop to 30.18 volts. The output current will drop to 11.64 amps and the output power will be 351.37 watts. Measuring the internal resistance of a battery by applying an external load and then measuring the voltage drop is how you determine whether your battery has failed which simply measuring voltage across the terminals in a no load situation does not reveal. Also voltage measurements must be taken over time since a bad cell or other anomaly may take some time to show.
Another issue...
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As a proof you go back the other way -
One never tries to prove the validity of a method or formula by going "back the other way." Going back the other way is reserved to check arithmetic only and not the validity of the formula or method.
Also, you have provided any proof to contradict anything I've said.
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Confrontational again. That is your error.
how are facts confrontational?
Dan
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I'm waiting for the fact part. The rest is confrontational.
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Sorry you feel that way Dave, but I was here long before you which makes you the troll, now doesn't it? :(
No. Where is it written that longevity excludes one from making an ass or nuisance of himself?
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Its the other way around Dave. You come to a party and pick a fight with someone who is already there tending to whatever task they have found available or were assigned, then you are the trouble maker and not the other way around. You do not go to the Auto Tag Department and try to break in line. Its a no, no.
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I'm waiting for the fact part. The rest is confrontational.
And how is ignoring the facts in a post not? I'll repeat them shall I?
V=IR, it does not matter if it is the internal RESISTANCE of a battery or a motor.
Therefore if the speed of the HBS-36 motor drops from 308RPM to 216RPM we get that it's internal resistance is (36V (the curve test voltage) x (1-216RPM/308RPM)) (the voltage across internal resistance) / 20.5A (the full load test current) = 0.5 ohms
As a proof you go back the other way - P=I²R ... 20.5A²0.5=210W which coincidentally is just about the difference between the curve input power of 730W minus the curve output power of 509W.
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Its the other way around Dave. You come to a party and pick a fight with someone who is already there tending to whatever task they have found available or were assigned, then you are the trouble maker and not the other way around. You do not go to the Auto Tag Department and try to break in line. Its a no, no.
That is not true...the trouble maker is the one who picks the fight no matter which one was there first.
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Its the other way around Dave. You come to a party and pick a fight with someone who is already there tending to whatever task they have found available or were assigned, then you are the trouble maker and not the other way around. You do not go to the Auto Tag Department and try to break in line. Its a no, no.
That is not true...the trouble maker is the one who picks the fight no matter which one was there first.
In that light then I did not pick the fight. What's more...
V=IR, it does not matter if it is the internal RESISTANCE of a battery or a motor.
If this is true then what is your point? I've not stated otherwise although I might disagree.
Therefore if the speed of the HBS-36 motor drops from 308RPM to 216RPM we get that it's internal resistance is (36V (the curve test voltage) x (1-216RPM/308RPM)) (the voltage across internal resistance) / 20.5A (the full load test current) = 0.5 ohms
As a proof you go back the other way - P=I²R ... 20.5A²0.5=210W which coincidentally is just about the difference between the curve input power of 730W minus the curve output power of 509W.
You have made the assumption that 1.) the above is fact and 2.) that I dispute it. One does not beget the other without becoming a logical fallacy. However, you have ignored this and proceeded to be confrontational anyway.
Am I to conclude then that your purpose for being here is to be controversial and nothing else?
Let me guess.
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Its the other way around Dave. You come to a party and pick a fight with someone who is already there tending to whatever task they have found available or were assigned, then you are the trouble maker and not the other way around. You do not go to the Auto Tag Department and try to break in line. Its a no, no.
That is not true...the trouble maker is the one who picks the fight no matter which one was there first.
Exactly. I didn't come here to pick a fight, nor am I the one who picked this fight. Seems that whenever there is an argument or confrontation Patrick is in the thick of it. No coincidence that.
I suggest we ignore him. For normal people, that's enough to make them go away, but unfortunately he thinks he owns the place so I doubt he will. Doesn't hurt to hope though.
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I suggest you find someone else to pick on as well.
On second thought while you are picking on me maybe I can keep you busy enough where you are not picking on someone else.
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I suggest you find someone else to pick on as well.
Pick on you? That's amusing. I only try to teach and help. You have misunderstandings that you propagate as fact and then have the nerve to be offended when someone knowledgeable comes in and points out the truth of the matter.
Son, had I wanted to pick on you, you would have crawled under a rock crying for mommy. You are way out of your league.
You never did answer as to what your degree was, you only made some mention of a college physics course. Shall we then assume you are a college drop out? And how, pray tell, does that qualify you to make any claims at all?
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Exactly. I didn't come here to pick a fight, nor am I the one who picked this fight. Seems that whenever there is an argument or confrontation Patrick is in the thick of it. No coincidence that.
I suggest we ignore him. For normal people, that's enough to make them go away, but unfortunately he thinks he owns the place so I doubt he will. Doesn't hurt to hope though.
True but then he gets to do more damage to those who come to try and learn.
Dan
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Why do you keep double posting?
Aside from that, even Dave says that you taught him nothing...
How about a layman's explanation of BEMF? I have a good electronics foundation -- Air Force trained for communications maintenance -- but a lot of this theoretical stuff goes right over my head.
Also, if someone (you?!) came up with a good design for the ideal controller and made it open source, couldn't hobbyists like ourselves buy the components and put it together ourselves? Making PCB's isn't that difficult; after that comes the soldering, which is far from rocket science... The thing that is needed is a good design to start from.
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.
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Aside from that, even Dave says that you taught him nothing...
I thought I told you to speak for yourself.
And don't kid yourself bro, your league is way to low for me.
Guess that's why you keep your contact info to the bare minimum on this board. Afraid of pissing someone off and having them track you down. Note that both Dan and I have a bit more info attached to our profiles on this forum. You on the other hand have nothing, and you still spam others in a vain attempt to sell something. As if I would buy something from someone I know nothing about and is not forthcoming with anything more than a verizon.net email address.
I suggest we take this offline. Check your private messages. Or drop me a line by email.
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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.
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Therefore if the speed of the HBS-36 motor drops from 308RPM to 216RPM we get that it's internal resistance is (36V (the curve test voltage) x (1-216RPM/308RPM)) (the voltage across internal resistance) / 20.5A (the full load test current) = 0.5 ohms
As a proof you go back the other way - P=I²R ... 20.5A²0.5=210W which coincidentally is just about the difference between the curve input power of 730W minus the curve output power of 509W.
You have made the assumption that 1.) the above is fact and 2.) that I dispute it. One does not beget the other without becoming a logical fallacy. However, you have ignored this and proceeded to be confrontational anyway.
Am I to conclude then that your purpose for being here is to be controversial and nothing else?
Let me guess.
Interesting...I missed this one.
Actually it IS fact, direct from rudimentary electronics and the performance curve on the Golden site.
Your statements that, in effect, all power supplied to the motor heats it up does indeed dispute it.
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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.
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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
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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?
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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.
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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" (http://dictionary.reference.com/browse/vein). As opposed to "vain" (http://dictionary.reference.com/browse/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.
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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?
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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.
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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.
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Other way around Dave. I was here first, you came alomg and then for some reason (or maybe none) tried to start a scrap.
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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
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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.
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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
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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 (http://goldenmotor.com/SMF/index.php?topic=3.msg982#msg982)
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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
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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
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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
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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.
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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
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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 (http://goldenmotor.com/SMF/index.php?topic=90.msg786#msg786)) 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.
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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 (http://goldenmotor.com/SMF/index.php?topic=136.0) for you so that I might fully address the comment you have just made.
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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)
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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
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Perhaps then you might want to explain to al how to measure motor capacity.
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Perhaps then you might want to explain to al how to measure motor capacity.
Perhaps Al should learn to better phrase his questions
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I understand him fine and even prepared the way for you to help him with your expert 3 phase rectifier knowledge...
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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?
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Topic Cop would not be a good job for you... determining motor capacity is a Motor BEMF real world application.
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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?
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The name of the Chief of Police in Sue Falls, SD.
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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
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Spelling errors are a big thing for you, aren't they David, now part of your MO.
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I understand him fine and even prepared the way for you to help him with your expert 3 phase rectifier knowledge...
Actually it seemed to me that he, unlike you, had a fair grasp of things and had you mouth been shut perhaps I could have gotten back to Offgrid... But that still does not explain who Al is and why he can not ask his own questions.
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Spelling errors are a big thing for you, aren't they David, now part of your MO.
Just call me the Dictionary Bandit.
This is some great entertainment! Thanks for keeping us rolling, Pat. I'm still waiting for that phone call.
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Spelling errors are a big thing for you, aren't they David, now part of your MO.
Just call me the Dictionary Bandit.
This is some great entertainment! Thanks for keeping us rolling, Pat. I'm still waiting for that phone call.
It is interesting when he pointed me to the link, which would have been more obvious than simply "al" that the link actually was and looked for all the world like a typo of "all" pointing to a topic I had never looked at, and I answered Al that magically his message here disappeared.
Dan