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Comments on Buck-boost converter fed from split input supply

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Buck-boost converter fed from split input supply

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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: -

Image alt text

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..


Edited section

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.

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3 comment threads

It seems you still use the single-ended topology but integrate current offset error with Hall, Rs or ... (2 comments)
Andy, the input to the buck-boost is between the Vin+ and Vin-. I'm guessing that the load will be b... (3 comments)
Does that mean you want it direct coupled but behave like a transformer AC coupled? Then the PFM or... (2 comments)
Andy, the input to the buck-boost is between the Vin+ and Vin-. I'm guessing that the load will be b...
Nick Alexeev‭ wrote about 2 years ago · edited about 2 years ago

Andy, the input to the buck-boost is between the Vin+ and Vin-. I'm guessing that the load [a 3-phase motor?] will be between Vout and GND. Is the output always above GND? Or Can it be below GND too?

Nick Alexeev‭ wrote about 2 years ago

You've mentioned 1kW output. Is it going to be high current (say 30V, 33A) or high voltage (say 500V, 2A) ?

Andy aka‭ wrote about 2 years ago · edited about 2 years ago

It's a dc output that is unspecified but about 1 kW. The input supply is around +/-250 volts DC. There is no 3-phase connection. Output is variable between 300 volts and 600 volts. Thanks for asking.