Maybe possible idea for duplicating effect of Holcomb and others

[citfta]

Hello everyone.  A big thanks to all for all the positive comments and so far not one single negative comment.  Wow that is a first for me.


Well I do have a few more things to share with you.  I have done some more testing using my original test setup with 2 alternators and the scooter motor.  So I'll share the results of that first and then have some more to share about the videos that UFO gave us links to.


I decided I wanted a little better data so I put some meters on my system.  I had a DVM set for AC volts on the slip ring circuit of the output alternator and a DVM set for AC volts on one of the 3 phases.  I still used the scooter motor being driven with about 18 volts DC and still had about 3 amps DC going to the slip rings of the first alternator.  When I locked the rotor I used a pair of long nosed vise grip pliers.  This allowed me to make some very fine adjustments of the position of the rotor in relation to the stator coils.  As I suspected there is a sweet spot that will give you the most output for the least input.  When adjusted for that spot and with the 120 night light as my load I got 31.2 volts coming out on the slip ring while the AC voltage on one of the 3 phases rose to 4.39 volts AC.


If I kept everything else the same and just disconnected the load so I had an open slip ring circuit my phase voltage only rose to 4.40 volts AC while my slip ring voltage rose to 32.5 volts AC.  If I shorted the output my phase voltage still stayed the same as 4.40 VAC.


If I let the rotor turn freely my phase voltage dropped to 4.04 VAC while my system when loaded with the bulb dropped to 28.2 VAC.  If I shorted out the slip ring my phase voltage dropped to 3.84 VAC and if I left the slip ring circuit open  my phase voltage rose to 4.06 VAC and my output voltage was 29.2 VAC.  So the system definitely works better with the rotor locked and adjusted for best induction from the  rotating magnetic field.


I did one more thing before dismantling that system.  I turned the slip ring current on the driving alternator up to several more amps to see what would happen.  I only ran it like that for a short time because of the heavy load on the scooter motor.  When I did that with the second alternator free to turn it took off like a regular motor and reached a pretty high speed very quickly.  I took a quick glance at the meters and the scope and there was barely any voltage being generated in the slip ring circuit.  I think this proves the induction into the slip ring circuit is coming from the moving magnetic field because when the rotor got up to close to the same speed as the moving magnetic field almost all induction stopped.  A quick glance showed less than a volt being generated as compared to 30 volts or so when locked even though the 3 phase field was much stronger.


Okay,  time for part two.  After watching the videos UFO posted links to I decided to set up the same demo as in the first video.  If you want you can watch it first and then read my comments.


https://rumble.com/v1hh4ux-driving-an-alternator-with-rc-speed-controller.html


If you watched the video you saw that the signal from the little RC ESC is actually a bunch of PWM pulses.  With the rotor sitting still no matter what speed I set the ESC to I could not get any generation in the slip ring circuit above a few millivolts.  So next I did connect a supply to the slip ring of the single alternator and that is what you see in the video.  As I said in the video I am really curious what kind of signal he is generating with his 3 mosfet circuit in the second video.  I am not sure just what is generating a signal to cause the mosfets to switch.  I haven't taken time yet to actually watch the video carefully and draw out that circuit.  I could see he is using the center connection from the Y configuration the alternator is wired for.  Both of my alternators are wired like that also.


The Y configuration is commonly used in industry.  From the center connection to any other leg you get about 120 volts.  And from any one leg to another you get about 208 volts.  So with a breaker panel being fed with 3 phase Y power it is easy to get just what you need by just making the right connections in the panel.  But I am not sure how his mosfet circuit works using the center connection. I am thinking that somehow as each phase powers off it triggers the next phase to power on.  However it works it seems to work well so I guess I need to build it and see for myself how it works.


If it in fact actually is turning each phase on and off fully without the PWM of the ESC then I think it is possible it will produce a nice high speed rotating magnetic field that could induce a good signal into a locked rotor.  I am not convinced yet that there is a need to make any changes to the rotor coil.  I think my own testing has proven the alternating claws of the rotor are perfectly capable of inducing a changing magnetic field across the coil.  But further testing is of course needed. 


I don't know how soon I can get around to building the MOSFET controller.  I am pretty sure I have all the parts but I am going to be pretty busy with other things for the next couple of weeks.  Hopefully what I have shown will encourage some of you to see what you can do with something like an alternator.  I will be looking in from time to time.  Looking forward to seeing what UFO can do with his project.


Take care guys and gals too if there are any,
Carroll

[Feb2006]

An ESC is sensing the back emf to get the timing right ,that's what probably makes it not working.
You need an ESC that does not sense the rotor position and tries to adjust.
An open source one that you can program yourself.

[citfta]

I don't understand your comment.  Makes what not working?  The ESC I used drove the alternator just fine.




Edit: Did you watch the video?

[Feb2006]

"With the rotor sitting still no matter what speed I set the ESC to I could not get any generation in the slip ring circuit above a few millivolts. "
In motor mod is working not in generator mod.
In motor mod you get back emf and right rotor timing.
An ESC is made for driving motors.

[citfta]

I think you need to watch all the videos from the beginning so you will understand what we are experimenting with.  We are doing basic research on the idea of making a virtual moving magnetic field and the effect it might have on generating power.  The ESC I used uses PWM to generate a sort of sine wave.  Because the PWM pulses are so short they don't have time to generate a field into the slip ring coil because the impedance of the slip ring coil is too high for that short of a pulse.  An ESC such as the one in the second video UFO linked to probably has a simple on and off pulse without the PWM.  If that is the case then it should be able to generate a moving magnetic field like we are looking for.


I hope this helps you understand what we are doing.
Carroll