I have been building an induction heater based off this schematic. I have tried using irfp250m mosfets. Works like a charm. But whenever I put a too big piece of iron inside the coil, the mosfets soon self destruct. However if I place a smaller piece in the coil, it heats up orange hot. The power supply isn’t the problem here. It’s a 48v 50a telecom switching power supply. So I wanted to increase the amount or iron I can put in the coil. I went out and got me some more unique mosfets. First one I got is a 2SK1812. Worked perfectly while idling, however self destructs when something is placed in the coil. Even the smallest piece that worked with the irfp250m. The 2sk1812 is rated for a higher voltage and amperage, so why didn’t it work? Is it the RDS on? Does the switching speed(Trr) matter?
Ok so I was like on these won’t work so I replaced the blown 2sk’s with 2 beefy APT43M60L 600v 45A N ch mosfets. These ones worked but got hot really fast. That is definitely the RDSon causing that. But still doesn’t work with the same chunk of iron that the irfp250m mosfets did well with. The apt43’s also self destructed.
So why did these problems happen? And what are some mosfets that could work with high power induction heater?