Power ratio over one

[handyguy1]

Hay Stefan:
Thank you for the help on posting this and the photos.

On both shots the top line is voltage across a .05-ohm precision current sense resistor, which when divided by .05, the input amperage is obtained. The look is deceiving. When you click on the channel number to the left the waveform increases in height. To put it in perspective you need to right click on the channel number.

The second line is the input voltage taken at the driver coil terminals.

The third line is voltage across a .05-ohm precision current sense resistor, which when divided by .05, the output amperage is obtained

The forth line is output voltage taken from the output coils terminals.

Both charts show the same half cycle. That half cycle shows what I call the payment half. If you post the next waveform you will notice that it is longer, and line three will show a higher voltage (amperage) reading.

If you look at both ends of line 3 in these charts, you will notice the waveforms are taller.

Input- first column is amps, second is voltage, the third is VA, total power is watts
RMS   0.317   0.441   0.14   
Average   0.26   0.417   0.109   
Power Factor      0.777   
Total Power      0.084   

Output-first column is amps, 2nd is volts, 3rd is VA, total power is Watts, 4th is power ratio
RMS   0.024   27.075   0.639   
Average   0.017   25.698   0.441   
Power Factor      0.691   
Total Power      0.305   3.61511

These numbers were obtained from the instantaneous readings exported to excel. As you can see the power ratio is 361% for this half cycle. The power ratio in the second half waveform (not shown in either chart) is even higher!

This test was done with an almost depleted 1.2-volt 500mAh cell.
David Middleton

[handyguy1]

 I should say that this is just one of the three coils!

[hartiberlin]

Okay, I found now the horizontal compression display setup in the Winddaq
software.
Here is the waveform display from a few cycles on autoscale amplitudes:

[hartiberlin]

I wonder,
why the current in the LEDs ( trace 3) is so noisy ?

Maybe you should use there a higher ohm shunt.
As the coils have probably around several hundred Ohm DC resistance
you could take a 10 or 100 Ohm shunt for measuring the current
in the LEDs much better...
Maybe you were already in the error range of your Windaq acquisation
analog to digital converter
hardware as the shunt voltages were too low...
Maybe there is the error coming from...

The current inside the LEDs should really follow the voltage of the coils
and be not so noisy...

Regards, Stefan.

[gyulasun]

I wonder,
why the current in the LEDs ( trace 3) is so noisy ?
.... The current inside the LEDs should really follow the voltage of the coils
and be not so noisy...

Hi Stefan and all,

I think we all know Trace 3 is noisy because the voltage drop across the 0.05 Ohm shunt resistor is only 2 or 3 times higher than the noise level of the data logger David uses.
Any instrument produces such noise when used in its most sensitive measuring range and the only remedy for this situation is to increase somehow the voltage to be measured.  You rightly suggested increasing the value of the shunt resistor, I would use at least 1 Ohm or 5 Ohm shunt (this latter value would improve the situation 100 times). Of course the power wasted in this higher value resistor should be accounted for in the final evaluation of the output power.

rgds,  Gyula