I have voltage on my neutral wire for a 220 volt ac inverter and blew up some of my house appliances
It sounds like this is a custom-made piece of electronics, so I would contact the manufacturer to find out how you're supposed to use it. It may be defective or maybe there is a misunderstanding of how it is supposed to function.

As a side note, I think it's dangerous to have a US-style 110V outlet wired with 220V... that's just asking for an injury or fire when someone plugs something into it. There are standard receptacle shapes for 220V (such as those used by generators, clothes driers, etc.). Also, the outlet itself and anything you plug into it is probably not rated for the higher voltage, even if you know what you're doing.