The study of 5Khz Mosfet and tuning into the resonant harmonics

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The study of 5Khz Mosfet and tuning into the resonant harmonics
« on November 23rd, 2015, 09:06 AM »
Below we have screen shots of a Mosfet driven at 1 volt. The 50% duty cycle is nothing to write home about with just a dominant 3rd harmonic @ 15Khz but I want you to pay particular attention to the voltage amplitude of the fundamental frequency 5Khz especially when I steal the first harmonic with a band pass filter.
At 50% duty cycle there is no 10Khz harmonic to be able to choke out at all but as we progress up to 60% and then 80% duty cycle then the 10Khz, 15Khz 20Khz come out to play as a percentage of the 1 volt which are devided by current and diminish into nothing.
Now, look what happens at 20% duty cycle, we get the same harmonics but when I take away the 2nd harmonic of 10Khz with a band pass filter, the amplitude of the fundamental frequency remains the same.
This just proves we are throwing money down the drain with CMC chokes and that energy can be harnessed.
It is interesting to note that if you build a VIC and the chokes are self resonant at 10Khz you can tune your system into the self resonance of those chokes just by tuning the duty cycle in and out which creates more harmonics for you to use, those that understand my thread on the square law of voltage and harmonics in a current free algorythm will understand how important this is.
Mosfets hate being run unbalanced, the more unbalanced they run the more dirty they run and we get more energy to multiply into high voltages. A 45% duty cycle will create enough harmonics in coils to run into thousands of volts. A 20% duty cycle will throw it into 40,000 to 60,000 volts in resonant coils because the harmonic distortions go well beyond the 8th harmonic.
Realistic harmonics would be 8th as a maximum but as you go up in voltage amplitude more harmonics come into the equasion.


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Re: The study of 5Khz Mosfet and tuning into the resonant harmonics
« Reply #1, on November 23rd, 2015, 09:39 AM »Last edited on November 23rd, 2015, 09:42 AM
@ 20% duty cycle the 2nd harmonic @ 10Khz is responsible for over 50% of the total distortion of the fundamental frequency. Capture that frequency into a self resonant choke that has opposing magnetic flux fields and the voltage will be 90 degrees out of phase with the cancelled current field. Send that voltage into a tuned transmission line and you will win.