Common information

I created this induction heater based on this schematic from http://www.rmcybernetics.com:

BOM

One of the most important things would be the BOM I used. On the internet you’ll find a lot of suggestions. Due to the fact, that I want to use this heater as an induction furnace, I modified some parts so that the whole system can handle more power.

R1, R2: 220R, 5W (yes, a little bit overpowered)
D1, D2: UF4007
T1, T2: IRFP260N
C1: 1,98µF
- 6 x WIMA MKP10 630V 0,33uF in parallel
L1: as shown on http://www.rmcybernetics.com
- 6mm copper tubing with 60mm inner diameter – yes, we will need some active water cooling 🙂
L2: 2mH
- 1,5mm magnet wire on a ferrite toroid (ø37x21x13,3mm).

Power supply

I have two 24VDC/12,5A SMPSs in parallel. These bring sufficient power for heating medium pieces of iron until they’re glowing. For an induction furnace I will need more power to heat my graphite crucible to at least 700°C for melting aluminum (melts at 660,4°C).

Evolution of construction

Here I offer you the chance to have a look at my progress of creation. I hope this helps you to avoid some unnecessary mistakes.

Back to the roots – wood and metal!

Because my breadboard went on fire I had to change my prototyping platform. Yes, beyond the driving circuit there is a lot of power!

First (working) assembly

water cooling
circuit is working
insufficient cooling of T1 and T2
CAPs attached externally: a lot of heat on the wires and capacitors

But hey… its working! 😀

Next iteration

CAPs now mounted on L1 directly:
- better power/heat transfer
- water cooling affects capacitor temperature as well
T1, T2 cooling improved
- bigger heatsinks
- active fan powered by a LM317 circuit at about 12VDC (when I recoil the choke this can be removed)
T1, T2 cooling still not sufficient 🙁