AC/AC converter

[henri]

Hi folks,


I have the following problem and I wonder if somebody can give me some clue.

On my electronic board I have an AC/DC converter with the following specifications.

Max. input voltage = 277 volt
Max. input current = 70-80 mA
Freq. = 60 HZ

However my input voltages vary from 120 to 600 volt.

What comes to my mind is to have a self adjuster circuit to detects the voltages below the 277 volt and let them pass through and adjust the higher voltage. For such purpose I believe that I need a step down transformer or a clamper circuit. But I have no idea if this is feasible or not!

On the other hand, I may better to have 2 voltage converters. (As I searched in the market there is no AC/DC converter in a wide range of 0-600 volt) One gives 90-290 volt and the other 300-600 volt. However, I need to have a device maybe a relay or so to detects if the voltage is below 277 or not.

In total, what do you think and in your opinion how do you guys solve such problem?

Thank you in advance.

P.S. The photo attached gives you a rough idea of what I think.

 

[crutschow]

What is the minimum input voltage at which the power supply will still operate?

 

[ronsimpson]

I have built power meters. It is easy to measure 90 to 600 volts but hard to find a power supply that can work over that range. I have built them but the price........

What I found is that in most cases of 440V and 600V there is a source of 110 or 220 near by. OR There are 600V to 110V transformers.

 

[dougy83]

You could use a servo-controlled voltage stabiliser; it regulates the output voltage by adjusting an autotransformer or series load with a motor. These tend to be pretty bulky.
You could use a voltage detector circuit controlling some relays to select an appropriate transformer tap, as you mentioned.
If your device can accept DC (e.g. if it simply rectifies the input voltage), then you can put a rectifier and DC-DC buck converter before your device. It has to be able to handle the 850VDC input, of course.

 

[ChrisP58]

Do you really have one single AC source that can vary that much? If so, and you ultimately need DC, the better thing would be to making your own Very Wide Range AC to DC converter. But, as ronsimpson said, such a converter won't be cheap. But it may likely be cheaper than an AC voltage regulator.

Or are you trying to make a single product that can be used in a variety of different locations. The locations may be 120, 240, 480, etc, but each location stays in it's own range. If that is the case, I would suggest a multi-tapped autoformer as your front end. Then just connect to the appropriate tap for a given location.

Questions:
1) What DC voltage and current do you actually need at the output?
2) Is this a one-off need, or is it a production item?