multiple output half bridge cross regulation

[electrophysics]

Hi
i'm designing a half bridge based converter of around 300 watt output power. it has multiple outputs. it has 5 outputs excluding auxiliary supply winding which power chip on primary side. i have simulated it on PSpice. but not proper regulation of all outputs using simple coupled inductor technique like used in ATX power supplies. i don't want to use magnetic amplifiers to post regulate the outputs. the lowest output voltage is +5v and highest output voltage is 70v

i have an idea that if suppose some output voltage V1 goes low, its dutycycle should be increased by conduction of mosfets on primary side. but same increased duty cycle goes to other output voltage say V2 (as they share the same transformer core) which suppose is already stable and don't require high duty cycle. thus this increased duty cycle should be clipped in some way on V2 side and not on V1... similarly if output V2 is low and output V1 is stable it will command primary side mosfets to increase duty cycle but this increased duty cycle is impressed on V1 as well which was already stable. thus now duty cycle should be clipped on V1 winding side.

any idea how to implement it.

 

[grizedale]

DN62 from ti.com states that coupled inductors are needed for current mode control......but it says mult outs are better with voltage mode.

Cross regulation is generally very poor unless , as you say, mag amps etc are used.