Being away from hands on electronics has left me rusty on formulas & calculations. I need someone to look at this guys website:
I have the circuitry for a 2.5kW induction heater, variable freq & duty cycle. I understand the resonant LC tank circuit, how to calcuIate the resonant freq. I understand the mechanical (dimension) calculations for a coils inductance. I understand that when you insert a metallic object into a tuned circuit, it changes the resonance/circuit resistance i.e. detunes it, all ham radio type stuff I learned years ago.
In the circuit depicted on the page, he adds the "matching inductor", and discusses why. But I have no idea how he calculates the value for it. I understand it may need to be change based on what the resistance created by the size & material of the object inserted in the field (which can be compensated for somewhat by the adjustable freq.) I'm hoping that someone can shed some light on the math or formula for calculating the inductor. Is it just a low pass filter? What am I missing here? TIA