Buck converter design

Hi Team,

My Design inputs:-

1. input voltage range 1:- Vin min:316 Vdc, Vin nominal:587Vdc, Vin Max: 815Vdc
2. input voltage range 2:- Vin min:417 Vdc, Vin nominal:700Vdc, Vin Max: 1000Vdc
3. input voltage range 3:- Vin min:417Vdc, Vin nominal:800Vdc, Vin Max: 1200Vdc

output remains common for 3 diffrent input voltage range

1. Vout::300Vdc
2. Iout:2.26Adc
3. Pout:626W

I want to use conventional Buck converter(Not synchronous buck) so please help me for best pwm ic and suggest me best Design application note.