High Voltage, Variable 300Volt DC, 300mA SMPS

[Ioannis]

Hi.

I would like to improve my current design of a Power Supply that is mainly linear with SCR rectifier control and has these specs:

Line power 120 or 230 Vac
Output variable 40 to 220 Volt DC
Current max 400mA

There is a torroid Xformer that outputs 200Vac, this is rectified by SCR and then a P-channel MosFet controls the output voltage. A circuit compares the output voltage with the rectified voltage on the filter capacitor and controls the SCRs so that voltage drop on MosFet is not more than 7-10 volts, so that Power Loss is kept at minimum.

I'd like to make a better design and use switch mode topology, with cheaper ferrite Xformer. What would you recommend to use and have similar specs?

Thanks,
Ioannis

[jbb]

You know… the solution you’ve got sounds pretty good. I expect it’s got quite good ripple and noise characteristics, but is a bit heavy.

Do you really need another design?

I ask because designing a switch mode converter for a laboratory supply is quite a lot of effort. If you only need a small number, it may be best to get more of the same one you’ve already got.

If you really want to pursue a switched mode design, I suggest you have a read of https://magna-power.com/learn/white-paper/current-fed-power-processing where they make quite a good argument in favour of a current fed architecture.

[jonpaul]

A walk down memory lane.....

My 1960s (high school/college) 0-400V 250 mA tube lab supply.

Based on the classic RCA tube manual and Heathkit linear series regulator

Your thoughts?

Have a great day !

Jon