Hi I am looking to produce 5v from a supply that varies from a turbine, this can be from 0 to 600 vdc, I need 5 v at about 500mA, will also need 12v and 15v, but if I knew how to get the 5 I could probably work out the rest.
A 2 stage resonant full or half bridge can give you the 5V from a wide input range - or a 2 stage buck converter - these will be special items though - not off the shelf.