Induction Heating
About a year ago
Justin and I visited a machine tool show in Houston. There we saw a 1.5kw induction
heater, among other interesting things. This reminded me of a tube based heater
I'd used some years ago and have since wanted to build one.
So, about a week later, I
constructed a 2kw MOSFET based, full bridge, induction heater.
The unit runs at 170vdc (rectified mains) with about 24,000uf worth of inverter grade electrolytics
to keep in clean. I decided to use a TL494 for the oscillator as I had quite a few
remaining for the SSTC projects. Pictured to the left is the two turn work coil
of the commercial 1.5kw heater cooking a piece of .5" steel.
Though
not currently as pretty, mine has no problem heating a sizeable price of steel.
The first of two pics is .25" rod being heated to ~1600F in about 10
seconds at 500w. The second shows the impedance matching transformer and work
coil. This seems to work better than a resonant tank. Average efficiency with
the current configuration is close to 60%.
Schematics
All schematics can be downloaded as either a .gif or .sch file. They where created in ExpressPCB's schematic program and are sized to print perfectly on a 8.5" x 11" sheet of paper in landscape layout.
2kw IGBT full bridge:
500w MOSFET half bridge:
Power supplies for above:
Created by Aron 11/02/02
