Hi Welshman, looks good, seems a bit like re inventing the wheel though. I can't help but wonder what sort of load you want to run from it that would require you to do so much work on a working inverter.
What you have done looks great, I am just curious as to what you intend to run with it that needs that much power.
Also here is a question, I know that many of us do stuff like mountain climbers, Just because we love tinkering. But was the extra cost worth it in the end.
Would it have been cheaper to have split your power circuits and to have bought two inverters, one for each circuit.
In the end it doesn't matter that much, I just find using a small inverter for small loads and a big inverter for big loads uses less standby power and adds in some insurance for the time when the electronics turn to smoke.
In Tasmania our power suppliers found that out when they sold our electricity, in the form of running the dams dry ( we mostly have hydro power here). Along came a drought, then our extension lead linking us to the rest of Australia blew up, and presto, Oh we have a problem Huston.
Fortunately for our Hydro company and the Government we had very heavy rains in winter that just, and only just managed to save their backsides.
The cable took 6 months to repair.
Sometimes, as in the case of your buck converter I think it is best to keep things simple. Transformers are great, proven reliable and pretty easy to diagnose when things go pear shaped.
Anyway, keep on telling us how it goes.
Interested to know how much more power you can get out of it, compared to the standard unit.
Cheerio
Pete