Hello, I'm looking for and alternatives for my Fuling dbz312b003.7l2dk. It's a 3.7kw 15 amp inverter.

It's for a 3kw 400hz 24k rpm spindle running on 220v single phase. I the inverter I have doesn't seem to hold in memory and has some very unpredictable behavior. The manual is also not clear at all. Any suggestions are greatly appreciated.