DC-DC Converters

I really am starting to hate lazy guests. First explain to me why I should do your work? Don't give me that you...

And please turn off the caps lock key.

Plenty to choose from on ebay,

http://shop.ebay.com.au/i.html?_kw=28&_kw=dc&_kw=dc

http://cgi.ebay.com.au/600w-grid-tie-inverter-14v-28v-dc-240v-ac-solar-wind-/330501205234?pt=AU_Boat_Parts_Accessories&hash=item4cf3682cf2

or Alibaba.com

http://www.alibaba.com/showroom/28v-dc.html

and yup Rule 75.. lol

Question is too vague please explain, do you want to copy a design ?

I want to use this as the input in a high voltage power supply being designed by me which needs to operate from 24-28 VDC input. I have the design for 280 VDC to 10 KV DC converter. I wish to copy a design or purchase the unit. It should be small in size for OEM useage.

Another good answer. Actually I felt your posting on "Why Not DC" was more appropriate here. I guess it should now be up to the OP to find a way to implement this in India.

Thanks very much, redfred. Yes, the "DC transformer" in my other post is interesting and quite useful, but with the IR2805s chip it's limited to voltages below 100V (IR does make 600V self-oscillating drivers, like the IRS2153 and IRS21531, but they're slower parts, e.g., with 0.6us deadtime). That circuit also has the disadvantage that all the converted energy is carried by the inductor, which charges in one portion of the cycle and discharges in the other. This forces one to use larger inductors (like the big one shown in my PCB drawing), and limits the maximum operating power.

By contrast, the circuit in my latest post, above, is a half-bridge converter, which transmits power on both halves of the cycle. It uses a real transformer, which does not require energy storage, and therefore can be smaller than the storage inductor in my previous post (the output inductor shown in the drawing above is small, and simply provides a little bit of optional filtering). It also has the advantage of being easily used for high output voltages and with high voltage ratios. Since the output has a diode bridge rectifier, rather than a MOSFET synchronous rectifier, the circuit can operate in one direction only, and hence is not capable of DC transformer operation.

The half-bridge converter is attractive in that, although it has a nominal 50% duty cycle, helping to prevent transformer DC-current saturation, the transformer is intrinsically AC coupled, so the capacitive-divider node simply moves up or down a bit to insure honest 50:50 waveform areas to the transformer primary. It's self-correcting.

There are plenty of 12/24 V to 240 volt 300watt inverters available and they cost next to nothing, put a bridge rectifier and suitable sized capacitor and there is your 280VDC.

Ebay, Alibaba are first port of call on line but most major electronics emporiums carry them.