I am using EG8010 chip to create a 400V DC to 220AC inverter which does not use bulky transformers. I have used the exact same circuit shown in the data sheet of EG8010. The circuit works ok and output a good sine wave for low input voltages (I have tested it upto 80V). When I input 400V's however, the circuit seem to be very unstable and for no apparent reason, MOSFET's gets damaged. This happens even if there is no load connected to the output. The MOSFET's I am using are the ones recommended in the datasheet (IRF840) which have 500V mas VDS.
I've read in a different forum that this could be due to voltage spikes due to inductance of the load (for example the filter inductor). Could this be the case? If so, what would be the best solution avoid such spikes?
Schematics: https://www.lz2gl.com/data/power-inverter-3kw/eg8010_datasheet_en.pdf Please refer to Figure 6‐2 in that doc.