20A 24v Bench Power supply design

[VoidsWarranties]

my goal is to build a 0-48v DC 600w psu.  I know micros and ics never use this much but every once in a while i get some motors or other high current things to play around with.  For the main power i have a 600w 24v at 25A switch mode power supply and a 240w 24v at 10A switch mode too that i prefer not to use.  It will be arduino controlled with an lcd with volt current and watt readouts and pre-programmed voltages all of witch the arduino will handle.  my question is how to get current and voltage regulation the best thing i came up with is buying a buck/boost (one that has voltage and current regulation) converter off ebay and controlling it with the arduino.  how to control it i am not quite sure, most use 10k trim pots but only use 2 pins.  i have looked into digital pots but the ones on ebay only have 100 wiper points i could use multiple witch i dont have a problem with but i was hoping for something more simple.  the next two things are current and voltage sensing for the arduino.
I found an arduino 30Acurrent sensor on ebay (ebay#281683074851).  For voltage i was thinking of using a digital pot in a voltage divider. tell me what you think of it.

thanks in advance.

[rx8pilot]

How do you plan to take an off the shelf fixed 24v power supply and make it variable 0-48v? Maybe I read this too fast?

[VoidsWarranties]

I was going to use the buck/boost converter witch I forgot to mention that it would be an adjustable converter


Sent from my iPhone using Tapatalk

[VoidsWarranties]

I am not sure how to parallel dc-dc converters to get the 600w. from what I have read it can be quite difficult


Sent from my iPhone using Tapatalk

[MosherIV]

Hi

From the questions and suggestions you are asking/making it sounds like this is well beyond your capabilites at the moment. I suggest you lower your ambitions and start with a lower power psu for your project.

Doing it with bought in modules will be very expensive and also very complex.

Try doing a lower power psu for micro work and tackle the high power psu later when you need it. Try a 0.1-25V  0.01-1A for the micro work.

Typically, you rely on the voltage regulation of the switcher and use a seperate current monitor circuit, when the current monitor reaches the current limit, the current limit circuit sets the voltage lower to the smps voltage control. You probably will not find this in pre built modules, you will have to design and build this.

Good luck

[rx8pilot]

I am not sure how to parallel dc-dc converters to get the 600w. from what I have read it can be quite difficult

Yes, it can for sure. It sounds like you are looking for a serial arrangement though to get 48v. In that case, they would need to be isolated at least.

The Buck/Boost converter.....is it already designed to to be adjusted 0-24v or do you plan top modify it? What model? Schematic? AC input? DC input? Is your primary goal to have a power supply or a learning experience?

[VoidsWarranties]

http://m.ebay.com/itm/200W-10A-Constant-Current-Voltage-DC-7-32V-12v-TO-1-28V-5v-19v-Buck-Converter-/221964888557?nav=SEARCH

This is close to the type of the converter I was looking at of course higher voltage but I have had the go up to 50+ volts before when I upped the trim pot resistance


Sent from my iPhone using Tapatalk

[rx8pilot]

I would be shocked if that thing could meet half specs claimed. You would still have to get 30-ish volts to the primary side and then you would have to isolate them and then you would have to pull the pots and use a D/A, PWM, digital pot or something to control the voltage with an MCU.

Maybe it could supply ( a messy) 8A at 5 volts continuously. Try 8A at 24 volts and its lifespan may be measured in seconds. When is fails - is it going to pass the input voltage through and blow up your project? Who knows. Since you are in the USA, you may consider an HP eBay deal. I got two 500W HP power supplies that are really fantastic. One of them was about $75. Brutally strong, clean. with delicate digital adjustments.

The earlier question is do you want a power supply or a learning project? This approach is likely to experience smoke a few times. Possibly destroying your projects along with it. You will be wiser and more capable after blowing a few things up and spending hours trying to figure out why - but it will be a distraction from whatever you where planning that needs the power supply.

[VoidsWarranties]

Mainly learning as I am trying to repair my old psu


Sent from my iPhone using Tapatalk

[VoidsWarranties]

Plus I have drawn 130w from a 150w eBay buck converter and it is still working


Sent from my iPhone using Tapatalk