Hi
I have designed a push pull SMPS with a 21.9v input and +/-400v output with an 80khz switching, with voltage mode control and type 3 feedback loop. The output is 18mA at 400v and 55ma at -400v, but I can not get the ripple below 5v and require below 0.25V. My transformer is a setup with 3 turns on the primary and 64 turns on the secondary 4 layers of 16 bifilar wound . I am using a RM10 core grade 3c90 with an Ae of 96.6mm2 and a B of 320mT. My primary wire is 0.71mm2 and secondary 0.15mm2.
I am not sure that If I have my calculations correct as my transformer and sense resistor are getting hot. I do get +/- 400v so my turns ratio is correct. I am not sure if my transforms should have 6/128 turns and would this help? and do I need to increase by secondary wire to be thicker to 0.2mm2?
my LC filter on the secondary is 22mH and 10uF at present but if I do the calculation I get 83mH and 30uF which seems too large or is these about right?
regards
Ross
