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Author Topic: Muller Dynamo  (Read 4322139 times)

gyulasun

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Re: Muller Dynamo
« Reply #5670 on: February 26, 2012, 03:15:07 PM »
Hi all
I wanted to see how to collect the backemf/recoil with a bidirectional mosfet circuit that also has pulswidth control to it too, this circuit using two pairs of bidirectional mosfets, and one pair is normallyOFF switchesON and the other is normallyON switchesOFF and each pair has its own halleffect, so the pulse widht is adjsuted by distance between halleffects...
Anyways I was wondering how to take the  backemf/recoil out when using this circuit - there being 4 seperate mosfets in it.... and turns out the only way to collect it, is through the mosfet "C" as shown in this drawing....logically you would think mosfet "D" being the last in line would be the one to "tap" but that one puts out nothing, and the diode and cap need to connect to mosfet "C" then the cap fills up super fast and the "fzzzzzt" sound from the motor coil dissapears too.

Hi Doug,

You show an interesting schematic.  Lets consider MOSFET A&B as a single switch and also MOSFET C&D as another single switch: it is sure that in order to connect the 12V battery to the motor coil, both switches should be closed and then to break the motor coil current one of switches must open, i.e. the switch MOSFET C&D must be opened once you connected the recovery diode and the puffer cap into the C&D switch.  In this moment the MOSFET A&B switch must still remain closed, otherwise the backemf cannot get to the recovery diode in this schematic and also it is interesting that you drive the backemf current through the 12V battery too while some part of it goes to the recovery capacitor too. (One should ponder on the polarities of the battery and that of the backemf if the driving-through of the backemf current gives any advantage or not...)
Now the question is how the circuit is still closed when MOSFET switch C&D should be open during the backemf collection?  Well, it is the built-in body diode in MOSFET D (between its drain and source pins) which closes the circuit and makes the backemf capture possible at all in this schematic and you found it as the only way, which is correct of course.  The body diode of MOSFET D represents a forward diode for the backemf voltage (hence current) coming from the coil via the closed MOSFET A&B because the blue wire of motor coil will become positive polarity (due to the backemf) the moment the 12V battery voltage is switched OFF.

rgds,  Gyula

konehead

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Re: Muller Dynamo
« Reply #5671 on: February 26, 2012, 06:34:43 PM »
Hi Gyula
I didnt realize that the backemf is going back through the 12V battery too, besides filling up the capapcitor in  that circuit - can you explain this again? Is it from mosfets Aand B??
Is it reason of mosfets being bidirectional  instead of two single mosfets to do the pulse width contorl?
I would rather put all the backemf power go into the cpa if possible since I dont thing the backemf spikes going back to battery si going to really help charge it up very well - maybe desulphate or raise volts is all .... so if it can fill cap a little faster that would be better - maybe solutions like diode somewhere?

gyulasun

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Re: Muller Dynamo
« Reply #5672 on: February 26, 2012, 09:58:02 PM »
Hi Gyula
I didnt realize that the backemf is going back through the 12V battery too, besides filling up the capapcitor in  that circuit - can you explain this again? Is it from mosfets Aand B??
Is it reason of mosfets being bidirectional  instead of two single mosfets to do the pulse width contorl?
I would rather put all the backemf power go into the cpa if possible since I dont thing the backemf spikes going back to battery si going to really help charge it up very well - maybe desulphate or raise volts is all .... so if it can fill cap a little faster that would be better - maybe solutions like diode somewhere?

Hi Doug,

I edited your schematic drawing to show the relevant circuit.  So it can be seen the 12V battery is in series with the motor coil, whatever direction you consider the current flow, meaning both the emf and the backemf current directions.  And when the motor coil current is switched OFF, the coil will behave as a second 'battery' in series with the 12V battery as if you had connected a second source polarity-wise correctly in series with it (the two sources add like two 'batteries' in series, + - + -),  this means the current driven by this second source i.e. the backemf current goes through also via the 12V battery when it also charges up the recovery capacitor and this charging current lasts till the backemf (voltage-wise) reduces to the 12V level .
I indicated in blue arrow the backemf (voltage) direction and in red arrow the normal 12V emf.   I am uncertain if the backemf current has a real charging effect for the 12V battery, (remember: the coil current does not change direction when you switch it OFF, only its amplitude start decreasing towards zero),  it would be good to see the current waveforms by a scope across a series 1 Ohm or 0.1 Ohm 'shunt' resistor to study the ON-OFF process.

The 'classical' backemf capture in your original schematic would include a diode bridge placed directly across the motor coil with its AC input side and the recovery capacitor would be connected to its DC output.  This way the two bidirectional switches would clearly serve as a variable duty cycle ON-OFF switch (but the 12V emf would be also as an input to the recovery cap, so you would not want to discharge it lower than 10-12V when utilizing the captured energy from it.  And if you do not wish the 12V input would be also pumped into the recovery capacitor at the motor coil switch-on time, then you may wish to use a single recovery diode with a capacitor as you drew the steering diode above but not at the MOSFET C drain of course but at the blue motor coil wire and the capacitor negative point would be connected to the red motor coil wire.

To answer your direct questions: yes, backemf current has a low resistance path via MOSFET switch A&B, of course this switch must be kept ON during the capture process;  and no it is not a reason the MOSFET switches are bidirectional when they control pulse width (the bidirectional MOSFET switch 'only' improves upon the single MOSFET switch by mutually 'neutralizing' the body diodes in the two MOSFETs, the two diodes connected oppositely facing each other,  in a single MOSFET switch the body diode is perpetually included between the drain and source legs, this way the diode is in parallel with the two points to be closed or opened and this maybe a big problem when the current direction changes in the switched circuit).

rgds,  Gyula

crazycut06

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Re: Muller Dynamo
« Reply #5673 on: February 27, 2012, 12:29:58 AM »
Here it is the other cool effect of the coil. With a small drop in rpm ( less than 30rpms) the coil rises the voltage on the light bulb from 0.92 to 1.26 and stays there.
http://www.youtube.com/watch?v=AH7YQ_gOWAY&feature=youtu.be


Hi Marius,
    Have you tried using a short ferrite core, and what would the effect be? also try shorting the output coil see what will happen.


keep it up!

konehead

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Re: Muller Dynamo
« Reply #5674 on: February 27, 2012, 09:05:13 AM »
Hi Gyula
Thanks alot for all t hat and the drawing let me read througit 4 or 4 times until it all sinks in and I willget back to you on it.
 
 

konehead

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Re: Muller Dynamo
« Reply #5675 on: February 28, 2012, 08:51:15 PM »
Hi Gyula
OK pretty much understand what you are saying now - the first pair of bidirecitonal diodes, when they turn off, send a back spike into the battery, and this can be gathered,  by having cap with its neg on the positive-rail....and then steering diode from drain to pos lead of this cap.
I dont know if this backspike will amount to much, since that mosfet-pair (AB)
is still ON when the other mosfet (CD) pair acutlly shuts off the circuit so I assume the "brunt" of the backemf/recoil exits through the mosfet C but I dont know that is just assumption...
I didnt try the other diode on cap over AB out like that,  out so thanks for the tip - I thought here must be some other way for backemf/recoil to "sneak" out of there - as you say the classical way is put AC legs of FWBR across the whole mess of mosfets and this should catch everything going which way...
having single diodes is better I think since then making it work in "diode plug" manner is possible plus less resistance/loss (perhaps) using single diodes also I bet the circuit is heavily biased backemf-wise on mosfet CD side of it, rather than mosfet AB side, so perhaps different caps and different diodes will work better for one side as compared to other side.
this might work out for bettew way to take out power from coil-shorting at peaks too with genrtor coils, since I use FWBR in  that, but maybe singel diodes situated like thiswould work better for that...
 

gyulasun

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Re: Muller Dynamo
« Reply #5676 on: February 29, 2012, 12:53:39 AM »
Hi Doug,
 
 I have made another schematics from your original schematic to make it clearer for everyone.  Consider the first circuit on the left.  The two switches (each is a bidirectional MOSFET pair) are in series with each other so they both must be ON whenever you wish for any emf current flow in the motor coil i.e. you wish to use the coil as an electromagnet.  This is how you drew your circuit in your original backemfdirectional.jpg picture, which I simplified as you can see on the left, ok? (without the bemf recovery) 
 IF you disagree with this simplification, please tell.
 Now if you wish to switch the current OFF in the coil at a certain moment (duty cycle point of view) and capture the bemf  i.e. the collapsing energy of the motor coil,  you have to switch OFF the second series switch (consisting of MOSFET C&D) because you assigned Hall B to control duty cycle and Hall B drives MOSFET switch C&D.
 BUT the moment you place the recovery diode to the drain electrode of MOSFET C (and it is exactly the connecting wire between the two switch symbols in my simplified drawing) and you connect recovery capacitor negative to the common source electrodes of MOSFETs C&D as you showed in your original drawing,  THEN you have to keep MOSFET switch A&B still ON while you switched C&D OFF to insure closed current path for the energy flow coming from the blue wire of the coil due to the collapsing field because  the voltage spike developes across the coil at switch OFF of course (I indicated its polarity in my yesterday drawing wrt the emf polarity) and the circuit from bemf point of view is closing via the 12V battery and drain-source body diode of the MOSFET D and meeting on the common source with recovery cap negative pole.  IS this ok?  Because this is how your original circuit works.
 
 Now to reflect on your present post, I refer to my second drawing where I meant the recovery diode + capacitor yesterday and you got it correctly.  And the amount of the backspike can be high if you interrupt the motor coil current fast (and you do it fast by the 4421-22 chips)  no need to worry about the still ON A&B switch because the C&D switch in series with it is already an open circuit (this latter is which interrupted the motor coil current) so no any current can develop via C and/or D.
 
 IF you were to use diode bridge across the motor coil then it would be worth thinking on whether the induced voltage by the approaching and leaving rotor magnets (which induction is interrupted by the ON time of the motor coil of course) could give any extra into the recovery capacitor,  I forgot to mention this yesterday.  This should be tested if induction really can give useful extra, justifying the bridge usage.
 I do not see as you say "the circuit is heavily biased backemf-wise on mosfet CD side of it, rather than mosfet AB side, so perhaps different caps and different diodes will work better for one side as compared to other side"  because everything is in series from the motor coil point of view: the 12V battery, MOSFET D&C, MOSFET B&A (and the source of the voltage spike is the motor coil);  the 12V battery is a short circuit from AC (and DC) point of view, and D&C is OFF and B&A is ON.
Hope this helps those who may still have had some problem with my earlier post.

 rgds,  Gyula
 

konehead

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Re: Muller Dynamo
« Reply #5677 on: February 29, 2012, 09:36:38 AM »
Hi Gyula
I'm a little bit confused now - the simplified circuit you show now has only one cap, and over on the "other side' of the circuit - it is what I didnt have in my original circuit - which is that diode and cap off the pos feed to coil (high side recovery circuit you could call it?)
So are you saying that this is "better" than the low-side recovery circuit, which I showed in my orignal circuit (with diode and cap coming off the C mosfet)
Or is it better to have BOTH what I had before, plus this cap and diode too??? Thats what I thought you were saying in your drawing before this one...
anyways I will have to try both ways - and see if they both will work at same time - -  is that what you are thinking? 
So for that pulse-width adjsut circuit with the two pairs of mosfets in series, there should be two caps and two diodes total - one diode and cap coming off the ground (low) side, and one diode and cap coming off the pos side as shown in this new simplofoed drawing?

gyulasun

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Re: Muller Dynamo
« Reply #5678 on: February 29, 2012, 09:58:09 AM »
Hi Doug,

Sorry for this, I did not mean using recovery circuit at two places,  only I meant across the motor coil.

When you use recovery diode + cap across MOSFET C as you showed originally then the current from the spike is directed through the 12V battery too and when the recovery circuit is across the coil only, this current goes directly into the recovery cap only.

I cannot tell you which method is better, it should be tested, I only analyzed your original circuit. 

I do not see much sense in using a diode + a cap across BOTH MOSFET pairs, if the the 'lower side' recovery turns out to be better vs the-across-the coil-recovery then the circuit you originally showed is ok,  because MOSFET switch A&B should be kept closed while you open MOSFET C@D  and by the time the collapse rings down and you open switch A&B there is no current in motor coil to interrupt.

rgds,  Gyula

Scorch

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Re: Muller Dynamo
« Reply #5679 on: March 01, 2012, 10:21:35 PM »
So... I'm still waiting for parts and building this Muller dynamo thing to include bifilar coils and mechanical switching and I am just wondering-

Has anybody considered all the different possibilities that can be done with all these outputs?

For example; might it be possible to configure this dynamo in a "progressive" mode?
In other words, as each coil 'fires' the resulting generator output, or the BEMF energy, be fed to the next coil in line so it's already being 'charged' as the magnet approaches?

Or how about a 'cumulative' mode where BEMF energy is, somehow, collected from EVERY coil and stored in capacitor?

Or how about a combination series/parallel mode with some coils in series then sets of series coils wired in parallel?

Can one simply short one side of the bifilar to get a strong BEMF back out?
And would this require additional switching?

With 18 coils, each having 2 'input/output', and 72 wires to play with, which may be configured in MANY different ways in relation to each other, I am surprised some of these other configurations have not yet been attempted here. . .

Start with step one: First coil, or coil pair, to spin the rotor.
Step two: What should be done with the BEMF energy OUT from the first coil or coil pair?
Should it go to the next coil in line? A capacitor? Additional switching? Should other coils operate independently? Or another combination of things?
How many combinations might be accomplished with 72 wires and lots of BEMF potentialities?

And one thing I THINK I know about this device; it should be built as a complete unit to take full advantage of the off-set between 8 magnets and 9 poles.
If all your poles are not in place; will you obtain the same cogless effect?
And if all coils are not configured to operate in unison, or are complimentary to each other, what would this accomplish?

}:>

mariuscivic

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Re: Muller Dynamo
« Reply #5680 on: March 02, 2012, 12:10:29 AM »
Hi Scorch

I have tried to use all the 9 pairs of coils as driver coils and to colect the bmf from all. With the first 5 pairs of coils everything was ok ; the imput was not so high and the 47000uF cap was filling fast. When finally made the connection to the rest of the coils, everything went crazy , the halls were on too much time; when touching the negative, rpm begun to rise, and there was not a fixed rpm; i stayed 2 weeks trying to find out whats going on but nothing. I have change 2 times the cables; lots oh halls and i couldn't get it to spin normaly without any strange effect. In the end  i begun to take out the coils one pair at the time. After removing coil paires 9 8 7 6 everything went back to normal.

I saw some video and info about the orbo steorn. Made a little replica of the driving coil wich is a toroid filled with turns. Didn't came out so efficient but the principle is working.
We know that the orbo driving coil is not kicking the magnet when current is sent to the toroid. The magnet from the rotor is atracted by the toroid and when it's energysed the toroid is not atracted any more by the magnet and this is giving free spin to the rotor.
The thing that i observed is that the input power stays allmost the same at high and low rpm.( just like in romero's video.)

Now the big question: is it possible that romero used this principle?

Let's imagine that the driving coil is not kicking the rotor magnets but  it is shielding the rotor magnet and the backing magnet. Then after TDC the coil is not energysed anymore  and the magnetic field from the rotor magnet and backing magnet are in repulsion. We all know how strong are these magnets; this would have a huge torque.


 
 
 

gyulasun

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Re: Muller Dynamo
« Reply #5681 on: March 02, 2012, 12:44:41 AM »
Hi Scorch

I have tried to use all the 9 pairs of coils as driver coils and to colect the bmf from all. With the first 5 pairs of coils everything was ok ; the imput was not so high and the 47000uF cap was filling fast. When finally made the connection to the rest of the coils, everything went crazy , the halls were on too much time; when touching the negative, rpm begun to rise, and there was not a fixed rpm; i stayed 2 weeks trying to find out whats going on but nothing. I have change 2 times the cables; lots oh halls and i couldn't get it to spin normaly without any strange effect. In the end  i begun to take out the coils one pair at the time. After removing coil paires 9 8 7 6 everything went back to normal.
....

Hi Marius,

MAybe your rotor disk diameter is too small for the many and strong magnets, there must be some narrow relationship in diameter vs number of magnet and their strength,  otherwise the fields can get interfere negatively

I am not sure the Orbo principle has ever been shown to be giving more output than input? BUT you think combining it with this Muller-Romero setup as you wrote in the last sentence, it sounds interesting.

Gyula

mariuscivic

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Re: Muller Dynamo
« Reply #5682 on: March 02, 2012, 01:05:39 AM »
Hi Gyula

Just make a small test: take a bifilar coil and connect is in series canceling. Then use it as driving coil. The rotor will not spin. Leave it connected and turn the rotor by hand as fast as you can. You will see that the input curent will be allmost the same.  This is what i found interesting here. Just like the orbo.

Scorch

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Re: Muller Dynamo
« Reply #5683 on: March 02, 2012, 01:54:31 AM »
What I think I know about mechanical engine ignition timing systems is that, in addition to a vacuum advance of timing to compensate for acceleration, there is also a centrifugal advance of the timing to compensate for both electricity, and magnetic, 'lag' inside the wiring, and coil, during higher RPM and switching frequencies which can have a dramatic effect on the delivery of the current to the coil as well as the collapse of the magnetic field at the proper time.

And there are typically THREE different adjustments that can be made to these systems. #1 Point Gap. #2 Dwell (on time) #3 Spring tension on the centrifugal advance plate below the switch (points).

See:
http://en.wikipedia.org/wiki/Ignition_timing

And if you are using a fixed position hall sensor you may run into problems when RPM changes requiring more sophisticated logic to compensate.

But today's electronic ignition systems do it all automatically and one of these systems may actually be the answer these problems and they are very commonplace; even in small engines like lawnmowers and chain saws.

See history:
http://en.wikipedia.org/wiki/Ignition_system

It all about obtaining the collapse of the magnetic field EXACTLY when you want it but RPM effects the timing of the switching which is probably why "everything went crazy".

If you have a rotor that has 8 magnets then a common electronic ignition system for any 8 cylinder engine should suffice.
Either salvaged or new such as this kit that includes the 8 position rotor and switching.
See:
http://www.hot-spark.com/

BUT, be aware, most of these retro-fit kits are designed to be installed into a distributor that already has the centrifugal advance built below the cam/rotor.

And, as near as I can tell, even the latest, greatest, technology and billet distributors STILL use an RPM sensitive, mechanical, centrifugal advance mechanism.
See:
http://www.pertronix.com
(includes videos and documents)
Detail of centrifugal adjustments-
www.pertronix.com/support/manuals/pdf/billet.pdf

It's amazing how much technology goes into the simple goal of generating a BEMF spark at exactly the right time at any particular rpm!

And what I want to know is THIS:

Is it absolutely necessary that my Muller Dynamo rotor shaft has to be non-ferrous?
Or can I simply cannibalize an old automotive distributor, complete with bearings, shaft, switching, and timing already built in; and simply build my dynamo around THAT?

}:>





Hi Scorch

I have tried to use all the 9 pairs of coils as driver coils and to colect the bmf from all. With the first 5 pairs of coils everything was ok ; the imput was not so high and the 47000uF cap was filling fast. When finally made the connection to the rest of the coils, everything went crazy , the halls were on too much time; when touching the negative, rpm begun to rise, and there was not a fixed rpm; i stayed 2 weeks trying to find out whats going on but nothing.


gyulasun

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Re: Muller Dynamo
« Reply #5684 on: March 02, 2012, 11:41:56 PM »
Hi Gyula

Just make a small test: take a bifilar coil and connect is in series canceling. Then use it as driving coil. The rotor will not spin. Leave it connected and turn the rotor by hand as fast as you can. You will see that the input curent will be allmost the same.  This is what i found interesting here. Just like the orbo.

Hi Marius,

And what are your thoughts on utilizing the lack of induction in the bifilar coil from the rotor magnets?

Thanks,  Gyula