Hello everyone, I have some questions on HW2 19.1 (traveling at the moment and running behind on homework):
19.1) The effect of the transformer on the inductor seems to be kicking my fo to be in the 800kHz range which seems awfully high. Did I do something horribly wrong? For Zo I have L/400 || C || Re. I get an answer that is very close to 19.31 except with a scaling factor (for the transformer and due to the input square wave having a DC offset).
Also, when I get to part D, my fs is less than fo when I assume n=1. For n=3 I get imaginary values for F. I would have expected an fs higher than fo since that is assumed above. I also would have expected fs and fo to be very close...
thanks for your input,
charlie
2 comments:
Charlie,
I'm getting fo=820kHz as well. So at frequencies below this the input impedance reacts capacitive and the input current will lead the voltage. I started simulating this problem and am seeing something similar so I think you're headed in the right direction. If not hopefully someone will chime in.
I do have some questions myself. Did you have an input model like the book that has the factor of n or do you have the input model and then a transformer model between it and resonant tank? Hopefully this is clear.
Hey Jares, sorry it took me a while to get back to you. I do have the input modeled with n (pertaining to the harmonic value, not transformer n) and my input model looks very similar to the book. And separately I created another 'node' or block that handles the transformer ratio which appears after the input block.
I think I figured out my issue, and was miscalculating Qe. Thanks for confirming.
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