I want to make variable power supply whose input is 400V D.C which is to be varied from 100-400V through a control voltage of 0-10V. Please give some suggestion on how to implement this design.
I think you can use step down converter.
make one supply voltage about 12-15V to supply control section. and sample voltage with use of 2 resistor (voltage divider).
you can use LM494 (for example) to make control section.
Can you supply more info please, like the available input current, the desired output current, the environment temperature, maximum size and other important factors?
If you are happy with the output current of less than 100mA, here is an interesting concept of the HV voltage regulator .. see picture below ..
As I said, this is just a concept .. but it can be modified to take 0-10V control voltage ..
If you are interested, say so ..
---Ambient temperature for operation:0° to 60°C
---Input voltage as mentioned earlier is:400Vdc Regulated (which is the o/p of a PFC circuit). Currcnt o/p is 0.6 amps (240W)
---The control voltage is variable from 0Vdc to 10Vdc and would source 50mA.
---Size is not a constraint.
---O/p is to be changed from 100Vdc to 400Vdc. Maximum current to be 0.5 amps @400VDC.
--- The o/p has to be isolated from the 400DC supply.
Are you looking for continuous variation among the output voltage range. Or is it a stepped, like only some standard voltages in the range ?
I think if you want this much of output power you have to go for something like an SMPS of a computer. Better to design a SMPS converter. Because this way you can always convert from one DC voltage to another DC voltage with out much loss.
(In SMPS a continuous pulse train from the input DC level is created using an oscillator circuit. Then this signal averaged (or rectified) to get a different voltage level. Usually they will be varying the frequency of th e pulses and properties of the pulses to control the output voltage.)