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Mains powered to 0-250 or 0-300 Vdc at 0.5Amp

pikstart

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Hi.

I 'd like to design an SMPS power Supply, driven from mains (230Vac or ideally 100-260 Vac) an be variable DC output from 0 (or so) up to 250 or ideally 300 Vdc and up to 0.5 ampere of current.

Since it is a bit difficult project, it is better to start on a proven and working design if any.

Anyone done something close to this please?
Thanks in advance
 
First you say you'd 'like to design' an SMPS. Then you say you want to 'start on a working and proven design'.
If you've got a working and proven design, then there's not really anything for you to design, is there?

It sounds like you're asking somebody else to give you THEIR design, not do your own design.
 
First you say you'd 'like to design' an SMPS. Then you say you want to 'start on a working and proven design'.
If you've got a working and proven design, then there's not really anything for you to design, is there?

It sounds like you're asking somebody else to give you THEIR design, not do your own design.
Hi Barry.

Thank you for taking the time to reply.

Surely none working circuit cannot cover the requiremens one may have.

The specs were stated roughly so that I can modify heavily on a high voltage circuit.

My current design uses a SCR controled rectification, so that the difference from output voltage to that on the smoothing cap is relatively low and the pass transistor has the lowest power to dissipate in heat, about 5-8 watts. With a small fan the heat sink is kept really small and cool.

But still, the regulator circuit is a classic linear regulator, having a large expensive toroid transformer, with a very aggresive hit on the smoothing capacitor when SCRs are conducting. Also the transformer is clicking and has to be dipped in varnish.

Have done low power SMPS as DC/DC inverters of low voltage but not such high voltage one. Kinda scary I may say and I better work on a design that can be redesigned to the needs. Also the variable output voltage puzzles me if can be supported by a SMPS circuit.

Sorry if i sounded like a lazy copycat... Not my intention.
 
Boost PFC followed by 1/2 bridge LLC to give you a fixed 380V output....then from there you use dual cascaded buck to give you 0VOUT to 300Vout.
To get the variable vout, just use an error amp outside your controller, and make the reference to it variable, to suit your wanted vout.

Use LLC for the 380Vout as it is good for high vout as no ringing on diodes of LLC
 
The buck-boost converter steps up or down depending on how you adjust duty cycle.
It inverts polarity.

My simulation has 1kHz switching although you may want to use higher frequency. Your switching device must be able to tolerate high voltage.

buck-boost (AC supply diode-brid cap) 1kHz load 300V 500mA.png
 
Of course topologies suggested above are worth considering. In addition there's the flyback converter which provides isolation via transformer. The secondary has swapped polarity (signified by dots near the coils). It conducts while the primary is shut off.

Not shown is a snubbing network. Not shown is a means of regulation. (Simply vary duty cycle manually to accommodate variable supply and variable output.)

This simulation illustrates your 2X step-up (140 VDC input, 300 VDC output, 0.5A):

flyback 140VDC supply 300VDC out 500mA.png
 


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