Accurate Measurements on pulsed system's harder than you think.

[e2matrix]

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]

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.

Mags

[tinman]

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]

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.

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.

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.

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]

   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.

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