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I see a fair amount of questions on here about designing flyback converters, but I don't see any about designing a bidirectional DC/DC flyback converter, such that either side can be the primary and either side can be the secondary based on some controller.

I've read some research papers where people seem to have had success with this, but they never just give a full schematic and the voltage ratio has generally only been 1:1, when I'm hoping for a 1:6 low:high ratio.

I've run through a bunch of calculations for things, and I feel I have a decent understanding of the working of the system, but I'm afraid I'm getting a bit lost at how to actually turn these things into a workable circuit, particularly with respect to the transformer. Should I just buy and wind my own, or is there a better way to source one?

Also, does anybody make controllers that I could utilize that actively allow bidirectional operation control, or am I going to have to just program a microcontroller?

Lastly for specific questions I can think of at this exact moment, does anybody know of any tools or tutorials for bidirectional flyback converters? I've seen a few for traditional ones, but my searches for bidirectional are coming up empty.

Would definitely appreciate any pointers anybody out there happens to have, or any sort of general direction to progress my design - the literature is not being particularly helpful at the moment.

System Requirements

Low-side voltage: 9.044 V nominal, variable

High-side voltage: 54.264 V nominal, variable

Power: 98.0205 W absolute maximum, often much much lower

Operation: DCM/BCM preferred for higher efficiency

https://i.sstatic.net/HMO7K.png

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  • \$\begingroup\$ Does it need to use a transformer for isolation reasons; that requirement comes at both cost and loss in efficiency. \$\endgroup\$
    – Andy aka
    Commented Oct 13, 2022 at 17:20
  • \$\begingroup\$ Transformer is fine, a 5:120V or 12:60V sort of thing will be close enough. As for control, you'll need to either drive both gates from a common controller (switch + sync. rect., roles swapped as needed), or have them somehow autodetect roles, or have the rect. disabled (use body diode passively) and a controller on one or the other side takes charge. Possibly a pair of UC3843 or similar could be used that way? Depends on voltage ranges and desired logic. \$\endgroup\$
    – Tim Williams
    Commented Oct 13, 2022 at 18:05
  • \$\begingroup\$ When does one want a bi-directional power supply? What is the application? Is it for something like a battery powered device that can then charge that battery from the load side? \$\endgroup\$
    – Aaron
    Commented Oct 13, 2022 at 18:20
  • \$\begingroup\$ The application is differential power processing from solar cells in a PV-to-bus architecture. Hence the need for a bi-directional, isolated power supply - it needs to be able to process power in both directions. \$\endgroup\$
    – orangeandblack5
    Commented Oct 13, 2022 at 19:20
  • 2
    \$\begingroup\$ Solar and flyback sounds like a strange combination. Do you need to be able to transfer equal amounts of power in either direction? \$\endgroup\$
    – winny
    Commented Oct 13, 2022 at 20:13

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