I know very little about SMPS and need to make a reliable SMPS with these data.
Input voltage can vary from 230VAc to 500Vac (230,380,440,480 500).
Output should be 24VDC at 2A.
FlyBack design is proper if you consider only needed power output. But for input voltage 500V you shoud be used switch transistor with operating voltave above 1600V wich is quite dificult to obtain and not reliable. In my opinoin, best aproach is to use half bridge topology.
The HV Fets inside the Power Integrations TOPSwitch family has 700V limit. I like very mutch these compact solutions, but your wide input voltage needs some particular solution.
Check the appnote below, a discrete SMPS is described step by step. For your case, I think is the best.
:lol: Use standard UC 3842 In flyback mode with a mosfet rating of 900 volts( 2SK 727 or eqvivalent)
using a higher voltage mosfet will ensure working of SMPS from 90 t0 300 VAc.
availibility of standard components is also easy.
:roll:
Usually with 50W power output the flyback topologies is preferred for the lowest cost part list but for your design you should select a topologies with less voltage stress on the primary power switch. Double transistor forward converter let a Vds on power mosfet of Vin(dc). Mosfet with a rating of 900V should be easily avaiable. Wher did you get a line voltage of 500Vac?
the output power is simply 48W and hence not a big deal, flyback can be used. but the problem as i see is is Vdc max of arround 500V . i would suggest that you try double ended fly back scheme. here you will have advantage that the ovltage across the switches dose not exede Vdc. IR make IRFPG50 can be used . these are 1kV,6A Mosfets.
for more details check out "switch modepower supply by Abraham Pressman"
You can use the viper from ST. you can buy it at Farnell.
www.st.com/stonline/stappl/productcatalog/app?path=/comp/stcom/PcStComOnLineQuery.showresult&querytype=type=product$$view=table&querycriteria=RNP139=432.0
The moment you applied power to that cct you would have a nice light show.The L296 is only rated for 50V max at its vcc pin you have it tied to a 700V rail your transistor would also vaporise,pretty well everything you have wired to that 700v would blow caps included.
In order to use a buck you would need cascaded stages for such a large input/output differential.