Here is the basic Inverter circuit, copied and repeated on many sites across the web, I know it says 300watts but larger transformers and higher rated transistors/mosfets will get you part of the way.
If I recall , the Maplin (uk) inverter project had the option to slave additional units together in order to achieve higher power outputs.
Basically you use the same time base / wave form source to drive many smaller transformers in synch.
https://www.aaroncake.net/circuits/inverter.htm
Inductive loads, such as motors should not be used with this type of circuit , apart from that it should be fine for most applications.
Somebody will have to help me out here , but i believe it is to do with the start up current requirements for AC motors , a PWM controller may make it posibble.