High current power supply design - Page 1
Forum section: electronics / projects

author: BitShard
author_rank: Contributor
timestamp: August 11, 2017, 03:03:45 pm
content: Hi all,I need to control the power delivered to two ~1 ohm ESR loads on separate circuits at between 4v - 15v. One load (0.6 ohm ESR) will consume about 400W of power at peak operation, the other (1.9 ohm ESR) will consume about 120W. Considering that I want to be able to plug this "directly" (I can wire an IEC) into a wall socket (240v AC) what would my best option for AC/DC power supply be? I see some modular ones around the internet for >$300, though I was hoping to spend much less than this, perhaps I could do something with a PC power supply?The second stage of the design would be to regulate the DC voltage coming from the primary power supply (above) to within the range of about 4v or less, up to about 15v. Ideally the primary power supply would output >20v DC, so I could use a buck controller to drop the voltage, coupled with a low pass filter. If I were to use a PC power supply however, the output would be 12v, which would mean that I would need a boost converter in series with a buck converter to get the desired range.Could anyone perhaps point me in the right direction for finding an appropriate primary power supply, please? Once I know what I'm working with it'll be easier to figure out how the second half of the circuit works.

author: evava
author_rank: Regular Contributor
timestamp: August 11, 2017, 04:39:20 pm
content: CPS1660 from Aliexpress?https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20170811083327&SearchText=cps1660I have got it and it just works.I do not tested it extensively, and to be honest I do not dare to load it fully for a long time.For 500-600W it could be feasible.

author: BitShard
author_rank: Contributor
timestamp: August 11, 2017, 05:38:08 pm
content: That's still fairly expensive, though I came across these while looking:https://www.aliexpress.com/item/ALLISHOP-Suply-Switch-720W-DC-24V-30A-Switching-power-Supply-adapter-for-LED-Strip-AC-100/32679269883.htmlIt's only good to an operating temperature of 40C though, and well, I live in Australia. I wonder if there's a similarly priced, but less wun-hung-lo version somewhere.

author: Marco
author_rank: Super Contributor
timestamp: August 11, 2017, 06:55:14 pm
content: A Meanwell will set you back more than the Gophert and these supplies often have only limited range on their current limiting.

author: BitShard
author_rank: Contributor
timestamp: August 11, 2017, 07:42:22 pm
content: Hey Marco, thanks for the reply. I was hoping for something a little more embedded systems style. I'd prefer the primary power supply to be a constant voltage source, around 650-750W, check the aliexpress links

author: BitShard
author_rank: Contributor
timestamp: August 13, 2017, 12:08:53 am
content: Is this going to be a death sentence if I plug it in? Keeping in mind I'm only going to be pulling ~600Whttps://www.aliexpress.com/item/mean-well-power-suply-48v-1200w-ac-to-dc-power-supply-ac-dc-converter-high-quality/888946148.html

author: mzzj
author_rank: Super Contributor
timestamp: August 14, 2017, 09:19:02 am
content: Quote from: BitShard on August 13, 2017, 12:08:53 amOther than catching on fire or giving you an electric shock its probably reasonably safe to use.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 14, 2017, 04:10:44 pm
content: What budget are you looking at?I'm kind of afraid to ask, what with all these Ali Express links being thrown about.A bench supply will do that for $2000 or less, and it'll work right out of the box.Well, beware of shitty cheap bench supplies that aren't actually capable of rated load. The good ones probably start in the $500 range, or less if you find a nice vintage, brand name supply.You could make a custom converter module, but that would cost a lot of time, and may not be reliable (if you're not too skilled in such arts). There may be adjustable modules that fit the bill, which may be Chinese junk or proper quality things, with prices scaling to suit. Don't know so much about that, offhand.An AC-DC power supply module will get you the base supply (12V would be possible with a SEPIC or buck-boost topology, 24V with buck), but not a wide range of control unless it's made for that, in which case what you have is probably a bench supply.A power supply module could perhaps be modified for the adjustable range, but that would also require quite some time and skill (firstly to reverse-engineer the existing design, then to make the appropriate modifications to it).Tim

author: mzzj
author_rank: Super Contributor
timestamp: August 15, 2017, 12:22:00 pm
content: Surplus server power supplies have been popular for something like this if you want to go cheap.Unfortunately its either 12 volts or 48 volts then.ie. 12v 100Ahttp://www.ebay.com/itm/New-In-Open-Box-Dell-1200W-Power-Supply-DPS-1200EB-w-Power-Cord-/282606358770?epid=1103561720&hash=item41cca6d0f2:g:21gAAOSwHLNZQDRfor 48v 600Whttp://www.ebay.com/itm/Delta-DPS-600TB-1-A-Intel-E34413-005-006-600W-48-V-DC-Input-Redundant-PSU-GG3-E-/121977928078?hash=item1c6673798e:g:SHwAAOSw1XdUYTk7Connectors and starting the damn thing can be bit of a problem, worth checking in advance if someone as already work out the connector details...

author: BitShard
author_rank: Contributor
timestamp: August 17, 2017, 05:57:54 pm
content: T3sl4co1l, I was hoping to keep the budget under a few hundred dollars. The lower the better, in saying that though, I do have plenty of time (and skill). I realise that it's not evident in my OP, but the power output of the circuit would have to be controlled by an MCU. I'm not too concerned with the primary supply being adjustable, I can build circuits to modify the voltage after it's DC (legally).mzzj, That looks pretty close to something I could use. Thankyou!