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Author Topic: Accurate Measurements on pulsed system's harder than you think.  (Read 83345 times)

e2matrix

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #15 on: December 09, 2015, 06:51:54 PM »
First ,we are using an incandescent bulb-not an LED.

yes,your eyes can be fooled with LED's,but incandescent bulbs do not work that way.
What if we use a solar panel to measure light output--can a solar panel be fooled like your eyes can?
So we shall see.
Why not just get a Lumen meter - for less than $20 and it will be more accurate.   It is said that a light bulb output needs to be nearly double for the human eye to notice a difference.   I use a Lumen meter and have found them to be quite telling where I could not even perceive a difference. 

Magluvin

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #16 on: December 09, 2015, 07:47:02 PM »
This will be a good topic.

Im making some changes to and electric bike hub motor. Its from a Tidalforce M-750.  I have not been able to get much info on the motor architecture till I found this paper this week.  Always searching for info on this as the original company dropped out of the motorized vehicle industry some years ago. So I figured if I keep looking, and there is a lot out there, I might find something.  Was checking through a forum and a guy posted the pdf below.  It is pretty much what I needed to work with.

Im removing the controller board and replacing it with an arduino setup.  The pdf gives me a pretty good idea of what I will be aiming for.

The M-750 is limited to 750w and 20mph.  Cant pedal faster than 20 with the throttle engaged.  But the M-750X is 1kw and 30mph max. From what I have read it is all in the programming. So really, I can get this thing to pull wheelies and do over 30mph, probably for limited amounts of time. Just call above 30 turbo mode.

Im thinking I want to pulse this motor(pwm) but the pdf seems to describe a sine input to the coils. Just went over the pdf 1 time and need to read again. So What IM thinking is the sine is dc biased and sends smooth sine instead of brute pulsing.  So I have to decide. With sine there will be no bemf to capture. Pulsed I can.  But again, that will all be in the programming. ;)

Its a 7 phase motor. the coils are in pairs and in series, so both are operating at the same time. The motor uses optical sensing for timing and the transistors are very low ohm .008ohm. 

Ill be making a topic on the build as I get everything together.  But this topic here will come in handy if I go pulsed mode. ;D

Mags
« Last Edit: December 10, 2015, 02:09:41 AM by Magluvin »

tinman

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #17 on: December 09, 2015, 11:47:41 PM »
Here is the second video showing dissipated power by the incandescent bulb using a solar panel to measure output changes,in stead of our eyes.

https://www.youtube.com/watch?v=lElIrYuKGag

tinman

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #18 on: December 10, 2015, 12:01:27 AM »
Yes, an inductive CVR can lead you up the garden path.
Non-inductive CSRs (CVRs) do not lead up the garden path.
In this video you seem to be using a wirewound CVR that is inductive.

Also, the light bulb has a coiled filament which makes it inductive - maybe that amount of inductance does not matter at these frequencies but it will at higher ones.
I recommend automotive dome light bulbs with straight filament, which are not inductive and are much better candidates for power measurement via optical coupling to the photovoltaic cell.




As can be seen on the scope traces,there is no inductance shown. If inductance was a problem,then channel 1(across the globe) would show it in the form of a reversed voltage polarity-and we do not see that.

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It is hard to follow even that amount of wires from the video ...especially at high zoom.

Sorry about what looks like high zoom,but that is as far as my camera zooms out.

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P.S.
Could you draw a schematic of your setup?  It can be on a sheet of paper or a mouse-scrach in MS-Paint.

Will do tonight when i get home from work.

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Yes, an inductive CVR can lead you up the garden path.
Non-inductive CSRs (CVRs) do not lead up the garden path.

We shall see.


Brad.

tinman

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #19 on: December 10, 2015, 12:04:21 AM »
   It is said that a light bulb output needs to be nearly double for the human eye to notice a difference.   I use a Lumen meter and have found them to be quite telling where I could not even perceive a difference.

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Why not just get a Lumen meter - for less than $20 and it will be more accurate.

I have a lumen meter,and we will get to that. I can only do so much in a given time.
I need to go through each step,so as others that may not have a lumen meter can follow along with a pulse motor they have.


Brad

tinman

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #20 on: December 10, 2015, 05:33:57 AM »
Those that are following this thread, take some time to think about what you see.
It is said and stated by ohms law that the power disipated by any resistor is determined by the current flowing through it, and the value of that resistor. Now think about the incandescent bulb, and what is needed in order for the resistance of that bulb to increase. Then think about what is needed to raise the light output from that globe, and what must increase in order to raise the dissipated power from that bulb.

When you have the answers to the above, ask your self how is it we see the opposite happening on the scope. How dose ohms law explain more power being dissipated across a resistor with less current flowing through it, and less power being dissipated across it with more current flowing through it.

Can we really dissipate more power from a pulsed resistor or resistive load than we could using straight DC.


Brad.

TinselKoala

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #21 on: December 10, 2015, 07:55:09 AM »
I think that when you connect the capacitor to the probe side of the bulb, you have contaminated the reading and are no longer reading simply the voltage drop across the bulb.




tinman

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #22 on: December 10, 2015, 10:24:10 AM »
I think that when you connect the capacitor to the probe side of the bulb, you have contaminated the reading and are no longer reading simply the voltage drop across the bulb.

 :)
And if the bulb was removed TK,and we had just the CVR,would not that contamination you speak of still exist at the probe side of the CVR?,as it is just a resistor like our bulb. We have done nothing more than remove one of the two resistors that are in series,and now the cap is conected to the probe side of the CVR.

What is this contamination?-->how can a voltage be seen across a resistor that dosnt actually represent the true voltage across that resistor?.

I will get deeper into this as we go-->this (what you call) contamination.
But first a few more video's on testing done to find the answer. Next wee will be connecting a DC current source to our bulb,and increasing the voltage until  we get the same power output from our solar panel. We can then see what is truth,and what is not. I will replace the current resistor that is across the solar panel with a higher value one,so as we can get a more accurate voltage reading across that resistor. Then we will run the pulse motor again,and obtain our two reading's and values. then we send a DC current through the light bulb,and keep increasing the voltage until we get the same output from the solar panel.


Brad

TinselKoala

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #23 on: December 10, 2015, 11:06:42 AM »
OK, I've essentially duplicated your results, using a " no-Bedini Atoll " circuit as illustrated below.

I found that the value of the inductor-resistor combination determines whether the bulb gets brighter, or dimmer, when the capacitor cliplead is connected.

The values shown in my circuit image produce _no change_ in the visible bulb brightness when the clip lead is connected, even though the scope shows over twice the power through the CVR-bulb when the cap is connected than when it is not.

A slightly higher resistance produces less brightness when the cap is connected; a slightly lower resistance produces more brightness when the cap is connected.

With 21.3 ohms, it is easy to see that the bulb is less bright when the cap is connected than when it is not.

TinselKoala

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #24 on: December 10, 2015, 12:04:21 PM »
I've made a video showing my results but it will probably be an hour or so before it's ready to view on YouTube.

I don't know if my "contamination" idea is correct or not. It is certainly an interesting effect that TinMan has discovered, and as my testing shows it doesn't depend on a Bedini motor or any pulse motor at all, just a pulsed circuit. I don't know if the inductor is even necessary either.

Ah... where is MarkE when you need him. Sigh. He'd set us straight on this, I'm sure, but alas it is not to be.

tinman

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #25 on: December 10, 2015, 12:40:14 PM »
I've made a video showing my results but it will probably be an hour or so before it's ready to view on YouTube.

I don't know if my "contamination" idea is correct or not. It is certainly an interesting effect that TinMan has discovered, and as my testing shows it doesn't depend on a Bedini motor or any pulse motor at all, just a pulsed circuit. 

Ah... where is MarkE when you need him. Sigh. He'd set us straight on this, I'm sure, but alas it is not to be.

Thank you TK for taking the time to carry out these test.

As i stated at the start of the thread--Yes,it is with pulsed system's,not just the bedini circuit.

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I don't know if the inductor is even necessary either.

During this thread,and after doing some other tests,it will come to the stage where we will find this out--next couple of video i hope i will get to it,but my experimenting time is short during the working week. Feel free to carry on as you will ,and carry out tests as you see fit--oh,and post your results  ;). The ramifications of the pending outcome could be high--as far as accurate measurements of pulsed systems go.


Brad

TinselKoala

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tinman

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #27 on: December 10, 2015, 03:23:04 PM »
http://www.youtube.com/watch?v=Xh16cxceN9w

TK
Try an inductor with a core.
I think the results will be better and more evident.

Brad

tinman

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #28 on: December 10, 2015, 03:23:46 PM »
Here is the pulse motor circuit from video 1 and 2,showing scope probe placement as well.


tinman

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Re: Accurate Measurements on pulsed system's harder than you think.
« Reply #29 on: December 10, 2015, 03:26:54 PM »
Here is video 3-with circuit attached.
I have switched over to pulsing the inductor with my FG,so as to get a cleaner wave form,and also have raised the frequency to 100Hz.

As my scope and FG share a common ground,i had to change the CVR and globe over to the negative side of the circuit.

Next video,we will remove the inductor,and see it we still get the same effect.

https://www.youtube.com/watch?v=bMHk3m6DsFE