I went through all this myself some time back.
dear Warpspeed,
Recently I got also interested in IH.
Searching through the internet I came across an old forum thread where you (if you are the same Warpspeed
) partially documented the building of your induction furnace.
I got the impression if a DIY-er can ever build a usable induction furnace, you can.
May I ask how far did you get with your project?
I happen to have practically all necessary components for such a project including power semiconductors, cooling unit and a (hopefully) suitable tank capacitor, the only missing part is the proper knowledge :lol:
I choose the frequency to be also around 20 kHz, mostly because my tank capacitor is 10uF.
Power is coming from a regulated DC power supply (max 160V, 93A, I know it is not ideal, but maybe a good starting point).
The tank is driven by four IGBT-s through a coupling transformer.
The oscillator is TL494. My original idea was to regulate the power by PWM, that's why I used TL494, but later I discowered that this is not suitable in this kind of application. Still it is good enough for oscillator since it has push-pull output with dead-time control.
I plan to use PLL for freq control.
I got to the point to be able to heat a piece of metal red-hot (feeding 1.5kW into the circuit, but I know the efficiency is really bad), but of course it is still far away from the final goal.
I would be glad to hear about your experiences in DIY induction furnace!
rgds, Jozsef