Recently I'm working on project of induction heating,,, I have H-bridge inverter, the mosfets which i am using is 20n60c3, my switching frequency is 1.5khz, i need to increase voltage level to as maximum as i could ,,, but i started experimenting with 30 Vdc over resistive load of 40 ohm, I was planning to reach 514V dc gradually but when i reach 30Vdc i am experimenting large current spikes over the resistive load, not to mention higher current and voltage spikes over inductive load of 11.3mH which is the coupling toroid, the spikes appears at the transient of every half cycle. Current spikes are really so severe,, Dead band is 14 us, Any help please?