BMS can't turn on while loading at 0.2A

Hello,

I reviewed your schematic and see that you don't have preload resistors on the outputs.  To keep this design in regulation under no load conditions generally requires 1 to 2 mA of pre loading to keep the design in regulation.

The PSR controllers require an extremally clean aux signal with less than 100 mV of ringing while the converter is delivering energy.  Any ringing during this time could trigger and OVP and prevent your design from starting up.  You can resolve this generally by adding an RC snubber across the output rectifier and/or auxiliary rectifier diode on the primary.

There is application note discussing the common issues with these types of controllers/converter and how to resolve them.  You can the application note at the following link.

I would also suggest ordering the UCC28730-552 10 W evaluation module. So you can have a reference what the VSENSE, CS, VDD DRV signals too.  

If you have not evaluated the VSENSE, CS, VDD, VSESE and VDD on your converter you probably should.  This will tell you weather the converter is shutting down due to over current or over voltage protection.

There is also an Excel design tool and a Mathcad design tool that you can use to double check your design.  Please go to the following link and search on software to find these tools.

http://www.ti.com/product/UCC28630/toolssoftware

Regards,