Buck-boost converter fed from split input supply
I have recently finished designing a buck-boost converter for a job that uses a split (+/-) input power supply. Load power is taken equally from both positive and negative input supplies and, the load is connected to 0 volts (mid-rail of the split input supply).
For a single rail supply, the standard approach would be this: -
I've not shown the MOSFET drive circuits because they're unimportant. So, my question is this: what design approach/topology would you choose when designing a buck-boost controller that operates from a split input power supply and drives a load connected to 0 volts.
I'm looking for a basic circuit idea like the one above i.e. no need to show drivers etc..
Olin came up with a solution using a transformer and thumbs-up for that but, I'm actually interested in a solution that doesn't use a transformer. I'm also interested in power levels of above 1 kW.
- The input supply is +/-250 volts DC.
- DC output is variable between 300 volts and 600 volts.
My recently finished solution seemed novel because I couldn't find it when searching the internet. Hence, I'm interested if anyone else has a standard solution that matches what I came up with.
Sorry for not making these things clear at the outset.