Cascade H Bridge DC supply question

Thread Starter


Joined Feb 11, 2019
So use to be an enthusiastic hobbyist in the late 70's & early 80's and now returning 40+ years later after being distracted by a career in software engineering. My first project is trying to build a high power 5KW+ transformer-less inverter for my camper-van using a multi-phase, multi-stage boost converter design.

I'm pretty happy with my DC-DC stages and am now looking at the design for the DC-AC stage. Initially I was drawn to an S6 H Bridge design but recently I'm more attracted by a cascaded H bridge approach. The problem is a cascaded H bridge appears to need separate isolated DC supplies for each sub-bridge i.e. I can't use a single DC supply to create the required DC inputs.

My question is can I potentially solve the single supply issue by treating each stage of an interleaved boost converter as a potential isolated DC source or will the problems of effectively connecting the outputs of boost converters in series still happen? I've attached a diagram of what I'm roughly thinking that hopefully explains it better.

I realise that by breaking the interleaves I'll be increasing the ripple but given the power I'm trying to supply requires multiple phases anyway my plan would be to make every "isolated" output be the combination of two phases.