# AC-DC converter

Thread Starter

#### imaaaadd

Joined Jan 31, 2023
1
I'm trying to design a AC to DC converter but with 12V 60 Amps needed a stable current stable voltage at the output any idea on how heat dissipation should be and how can we have stable current and voltage without Spike's?

#### Ian0

Joined Aug 7, 2020
6,965
I'm trying to design a AC to DC converter but with 12V 60 Amps needed a stable current stable voltage at the output any idea on how heat dissipation should be and how can we have stable current and voltage without Spike's?
Do you need stable voltage or regulated voltage? They are not the same.
Only the load you connect can ensure a stable current.
What is it for? Charging batteries?

#### Papabravo

Joined Feb 24, 2006
19,825
For that level of power, you will need to dissipate 720 watts. Since no power conversion scheme is 100% efficient, the input power consumption will be higher. There are three basic methods of heat transfer. they are in no particular order:
1. Radiation
2. Conduction
3. Convection
I see no reason not to use all three of them, but without a proposed schematic for this design how can you make any progress? How do you know there will be instability or spikes?

#### Ian0

Joined Aug 7, 2020
6,965
I assumed that this was a power supply for some sort of pre-existing load that dissipated 720W, and that he wished to power said load in a way that didn‘t dissipate anywhere near 720W in the power supply. But who am I to wonder? Your guess is as good as mine.

#### LowQCab

Joined Nov 6, 2012
2,872
Please explain what problem You are trying to solve.
You will then probably get ~5 to ~10 different ways to go about solving it.

Please explain why You have concerns with "Spikes".
What are your Electrical / Electronic capabilities ?
Why are You asking for your particular performance specifications ?
How much space do You have to work with ?
What is the "Duty-Cycle" of this Power-Supply ? ( Minutes / Hours / Days )
What is your budget for this project ?
Must the Voltage be adjustable ?, Automatic ?, or Manual ?
Must the Voltage "Ramp-Up" and "Ramp-Down" smoothly ?, or no Switch at all ?
Do You want Electronic-Current-Limiting,
or Electronic-Circuit-Breaker,
or a simple (but expensive) Fuse ?
( You are basically making a small Electric-Welding-Machine,
so Current-Limiting is a very important consideration ).
.
.
.

#### ronsimpson

Joined Oct 7, 2019
2,600
amazon I know it is only 50A but the point is you can not build this supply for $54. amazon-80A$107

#### MisterBill2

Joined Jan 23, 2018
14,191
an interesting inquiry, this one. You want a 12 volt DC 60 amp power supply, with an unspecified regulation and an unspecified ripple voltage and unspecified operating condition. That can be obtained using a commercial mains transformer intended to provide a stepdown from 240 volts to 120 volts. Just feed the 240 volt side with 120 volts and the secondary will deliver 60 volts.
The current rating will still need to be 60 amps because that will be the secondary current. The secondary watts will be 60 x 120=7200 watts. So you will need a 7500 watt transformer. Not light or cheap.
Use a 100 amp rectifier bridge to convert the AC to DC, to avoid needing a custom transformer.
Now you have a stable 60 volt DC supply. Of course, there will be some ripple voltage but no spikes.
The challenge is that most residential circuits are only 20 amps, and your supply will draw 30 amps at full load.
So substitute a 480 volt to 120 volt transformer, still a stock item, and feed it 240 volts and the supply will only draw 15 amps from the 240 volt supply.

Last edited:

#### BobTPH

Joined Jun 5, 2013
6,277
So substitute a 480 volt to 12 volt transformer
Presumably, you mean 480 to 120.

#### MisterBill2

Joined Jan 23, 2018
14,191
You caught my mistake. Yes, a 480mto 120 volt "controls transformer", because those are made for the folks who run production lines where down time is expensive. So they last even after many long years of constant use.

#### MisterBill2

Joined Jan 23, 2018
14,191
The switch mode supply shown in post #6 would be good, but for 60 amp constant duty use I recommend two of them in parallel. That will not only provide an adequate safety margin, it will allow running at a lower power density, always good for reliability. And it will be probably 50 pounds lighter than using a transformer, like I suggested. But the switchers may not last as long as the transformer supply.
But I see no response to the questions asked Tuesday nor any answers to my questions.

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