Re: Uninterruptible Power Supplies

Thanks for your comments, but until now I just can't find the link for
UPS like www.smps.us for switching mode.
Does anyone knows special site where UPS control, filtering,
protection, power quality improvement and power drivingcircuits are
discussed?

Ian Stirling wrote:
Myauk <aungkokothet@xxxxxxxxx> wrote:
There are several sites for SMPS design to find every details, from
schemctics design to EMI/EMC considerations, but there are very few
sites about UPS!

I would like to know some details about UPS control circuity,
especially the off-line type and the autoshutdown scheme via COM port
where the battery is low.

The off-line type switches between the mains and the backed up
supply with a relay or something when the mains goes out.

As to the autoshutdown schemes, google for linux drivers to see how they
work.

This is the easy bit of the UPS.

Designing a UPS that will drive a resistive load is almost trivial.

A 12V-several hundred v inverter, and then a full bridge, for example,
driven with a modified sine-wave.

This is simple - you get current only flowing out of your drivers, and
it all just works.

The horribly complex bit is when you connect it to real-world loads.

Simple filliment bulbs will draw a large surge on switch-on.
99% of power supplies have capacitors in, and will also draw large
surges on switch-on.
Many will also have EMI suppression components that you have to charge
on each voltage step, and not kill due to overcurrent.

Then you've got motors.
Large surge currents, inductance, meaning that when you switch off, you
get current going the wrong way.
Not to mention that in some cases, you can get the motor feeding back
the current in the wrong direction at the wrong time, causing things to
explode...


Making an efficiant UPS is near trivial.
Making a UPS that can drive any load is trivial.
Making a simple UPS is trivial.
Making a cheap UPS is trivial.
Making a reliable UPS is trivial.

Making one that does more than 2 of the above is hard.
Doing 4 is really hard, 5 is really really hard.

.

Relevant Pages

  • Re: Uninterruptible Power Supplies
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    (sci.electronics.design)
  • Re: Uninterruptible Power Supplies
    ... schemctics design to EMI/EMC considerations, ... I would like to know some details about UPS control circuity, ... Simple filliment bulbs will draw a large surge on switch-on. ...
    (sci.electronics.design)
  • Re: Do UPSes protect from surges under this scenario?
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  • Re: Are PC surge protectors needed in the UK?
    ... Topologically the UPS is "between". ... > fact it would be same protection if both computer and UPS ... some computers can even act as surge ... Do you suppose that's by design? ...
    (sci.physics)