Hello,
I am fairly new to electronics and need some advice regarding impedance matching.
I wish to impendance match a half bridge to a parallel tuned circuit (LC) Via series inductor ie LCLR netwowk. Here is a link to what I am trying to achieve.
Questions :- How does one find the impendance of the Half-Bridge? How do I calculate the L-match inductance / capacitance required to match the inverter (h-bridge) to the load?
Regards SRG
It's more or less equal to the on resistance of the FETs... plus some inductance thrown in for good measure. BUT: He's not trying to match the impedance of the half-bridge to that of his coil; he's considering the half-bridge to be (approximately) an ideal voltage source, and therefore trying to drop the impedance of the coil so that he can get decent amounts of power into it while using reasonable voltages (hundreds of volts rather than thousands of volts).
You have to know what his "work resistance," R, is. I suspect he determined this empirically -- it's going to be a little different depending on exactly what you insert. I'd imagine he first ran the circuit without the matching network and simply measured the power consumption at resonance to ascertain R (he probably chose the total capacitance -- some of which eventually becomes part of the matching network -- to resonate his coil at, say... 150kHz). He probably then did a few "back of the envelope" calculations to see whether or not building a matching network to 10 ohms was reasonable and discovered that, yes, it was. (The main point here is: A lot of his design appears to have been done empirically.)
---Joel
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