Ability to run on 120V/220V?

MaxHeadRoom

Joined Jul 18, 2013
28,619
I wouldn't have though that would be a concern.
Equip is shipped all over the world, e.g. most PC's and power supplies etc. with customer selectable supply voltage.
As already mentioned, the size of the supply to accommodate these will be very large.
I am assuming you intend having one operating voltage for each independent accessory itself?
Max.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
I think if this were me, I would produce a N.A. 120v domestic model and a 230v version for export, the compressor would have the right voltage rated motor as well as the other equipment.
This would avoid both a large/heavy supply and the necessity of extra design.
Max.
 

panic mode

Joined Oct 10, 2011
2,715
power cords can be changed by simply plugging in different one.

switching 15A (or whatever) is not a problem. plenty of relays to choose from.

next thing is to sense difference in voltage. This can be as simple as as use of DPDT relay rated for higher voltage. and to avoid over-voltage transient on power-on, timer can be used to introduce delay and activate output after 1-2 seconds. by that time voltage sensing relay would already be in steady state.

i don't see anyone traveling with own AC but after experiencing what Europeans consider "an airc-onditioner" or "cold" drink, i sure was thinking about it ... more than once. love them cold, not just mildly cool ;)
 
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You might take a look at this IC: https://www.st.com/resource/en/datasheet/avs10cb.pdf There are lots of app notes etc that surround the product. This is for 120/240 switching. Transformers are either 0-120-240 (or other taps) and 120/240 series/parallel.

Switchmode power supplies that have a wide input such as 85-285. They cover 85 because of the 100 VAC in some parts of japan and 285 because of 277nused for lighting in NA.

The AC (120 or 240) is either full or half wave rectified. So, 120 full wave rectified and 240 half rectified yeild the same DC to start with, the DC-DC converter uses that value as the from value.
 

dendad

Joined Feb 20, 2016
4,452
120 full wave rectified and 240 half rectified yeild the same DC to start with, the DC-DC converter uses that value as the from value.
Not so. 120VAChalf wave rectified is the same as 120VAC full wave rectified, assuming no load. So about 170V peak.
240VAC is about 340V peak
What they do is to use 120VAC into a voltage doubler, and 240VAC into a full wave bridge. A clue is the power supplies have 2 high voltage caps in the primary supply. The rectifier circuit is basically the same. just the feed point is changed.
 

Reloadron

Joined Jan 15, 2015
7,501
115 230 VAC PSU.png
What they do is to use 120VAC into a voltage doubler, and 240VAC into a full wave bridge. A clue is the power supplies have 2 high voltage caps in the primary supply. The rectifier circuit is basically the same. just the feed point is changed.
Above is a cut away portion of a switched 115 / 230 VAC input PSU. I believe it illustrates what dendad is getting at. Note what the selector switch does in this case. I doubt you will find this design used much anymore and most new switch mode power supplies have auto voltage and run between 90 and 250 VAC at the AC input. The above was only a 200 watt ATX form factor PSU too.

I also have to agree with Max in that for high power applications on a new product design I would likely just make an export and domestic version, especially where frequency of mains power will drive a motor (compressor or such).



Just My Take....
Ron
 

MisterBill2

Joined Jan 23, 2018
18,176
I basically wanted to be able to run an air conditioner, battery charger, and a few other devices from wall power in the US or Europe without having to change anything about my system so someone doesn't have to be aware of what they're doing, they can just plug it in.
Such a changeover can be done with relay switching of transformer taps, a method that would be fine even for air conditioners. That is a lot different from just having an automatic changeover for a switchmode power supply. This sudden change to include an Air conditioner puts a whole different scheme on the whole project.
 

shortbus

Joined Sep 30, 2009
10,045
The new "inverter based welders" do this. And they do it by changing the input cord. Since 120V and 240V have different plugs, they need different cords. When you choose the correct cord and plug it into the machine it connects the correct inputs for that voltage automatically.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
I basically wanted to be able to run an air conditioner, battery charger, and a few other devices from wall power in the US or Europe without having to change anything about my system so someone doesn't have to be aware of what they're doing, they can just plug it in.
I still stand by the idea of two versions for each country/jurisdiction, should be all that much cheaper to produce also.
For something such as asked for, to select/switch the power automatically would put the manuf. cost way up!.
Max.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
Another consideration if the project includes asynchronous motors (A/C etc), is the difference in motor rpm the frequency will make.
Max.
 
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