Sharing ideas on how to make a more efficent motor using Flyback (MODERATED)

[verpies]

All right, so the mean power during the pulse is 4.478W
The scope shows 447.8mW mean power, but this is 10x too low because the current vertical scale is set to 50mA/div, while in fact 500mA flows through the 0.1Ω CSR when the scope trace is deflected 1 division ( IMPORTANT: please confirm this ).

So, if we multiply 4.478W * 4ms (the width of the ON-period), we obtain the input energy for 1 ON-pulse equal to 17.91mJ.

Let's see how that compares to the triangular/sawtooth method:
I estimate the interpolated peak current (blue Ch2) as approximately 650mA, so the input energy for 1 ON-pulse equals 12.4V * 650mA * 4ms * ½ = 16.12mJ

Both methods are pretty much in agreement.

P.S.
When setting up the Math trace to multiply 2 channels, make sure that the vertical scale/amplitude of these channels is set as high as possible, as it avoids inaccuracies due to multiplying two quantization errors introduced by the ADCs, which leads to large round-off errors.

[partzman]

I think so as i  do not see much difference when running or stopped, see this post:
http://overunity.com/16167/sharing-ideas-on-how-to-make-a-more-efficent-motor-using-flyback-moderated/msg468976/#msg468976


Ok,   no no posibility to measure power between the cursors, so i manipulated the display to show only the "on" time, see screenshot 1 below.
Its negative as the purple trace is on the negative part, so i inverted the purple trace in screenshot 2

Both situations are when running at 40Hz @ 18% duty cycle  (12V)
Remember, i use here the 0.1 Ohm csr

Thanks,  regards Itsu

Itsu,

Just browsing and ran across this thread and would like to make a comment in regards to your TDS3054 scope.  I'm sure you are aware of this but the scope is capable of vertical or horizontal cursor measurements of any of it's functions. To access, press the front panel "Quick Menu" and then select desired cursor function in the "Cursor" screen menu.

If you are using the "sample" acquisition mode and are concerned about enough samples on the screen, select an "average" acquisition and set for "8" which I have found found to be more than adequate. You can now accurately measure one complete cycle of the periodic event captured in the screen with great resolution and view-ability.

Please disregard this if you have other reasons for not using the cursors and I apologize for interrupting!

partzman

[itsu]

All right, so the mean power during the pulse is 4.478W
The scope shows 447.8mW mean power, but this is 10x too low because the current vertical scale is set to 50mA/div, while in fact 500mA flows through the 0.1Ω CSR when the scope trace is deflected 1 division ( IMPORTANT: please confirm this ).

So, if we multiply 4.478W * 4ms (the width of the ON-period), we obtain the input energy for 1 ON-pulse equal to 17.91mJ.

Let's see how that compares to the triangular/sawtooth method:
I estimate the interpolated peak current (blue Ch2) as approximately 650mA, so the input energy for 1 ON-pulse equals 12.4V * 650mA * 4ms * ½ = 16.12mJ

Both methods are pretty much in agreement.

P.S.
When setting up the Math trace to multiply 2 channels, make sure that the vertical scale/amplitude of these channels is set as high as possible, as it avoids inaccuracies due to multiplying two quantization errors introduced by the ADCs, which leads to large round-off errors.

Yes, thats confirmed.

Itsu

[itsu]

Itsu,

Just browsing and ran across this thread and would like to make a comment in regards to your TDS3054 scope.  I'm sure you are aware of this but the scope is capable of vertical or horizontal cursor measurements of any of it's functions. To access, press the front panel "Quick Menu" and then select desired cursor function in the "Cursor" screen menu.

If you are using the "sample" acquisition mode and are concerned about enough samples on the screen, select an "average" acquisition and set for "8" which I have found found to be more than adequate. You can now accurately measure one complete cycle of the periodic event captured in the screen with great resolution and view-ability.

Please disregard this if you have other reasons for not using the cursors and I apologize for interrupting!

partzman

Hi Partzman, thanks for your interruption,  no problem.

I know the TDS3054 scope is capable of vertical or horizontal cursor measurements like amplitude and timing, but to my knowledge not for doing "power"
calculations using the MATH function, but i will take a look at your suggested settings.

Regards Itsu

[partzman]

Itsu,

Yes, it will do the "Math" channel in mean, rms, or any other function between vertical cursors.  Use the Math menu to select the channels and function you wish.

I've attached a sample scope shot from my TDS3034 which has the Math set to CH1 x CH4. I have selected the result to be in "mean" watts which is the correct result for this particular measurement. In this example, the power is -125.8mvv mean for one cycle as seen. The result in 'mvv' which is really 'mw' because I am multiplying two voltages because I was using an AM503 current probe amplifier for this test.

Hope this helps!

partzman