Batteries take over AC voltage, which points should I tackle?

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Hi, I have a SMPS PSU in action into my 500W Class D IRS2092 currently, now i am thinking to addon a secondary supply which is 24Vdc battery into the circuit. The target is to switch over battery when the Main AC voltage disconnected and reconnect to AC automatically when AC voltage resume.

I am thinking which is a cheaper, smaller, and higher efficiency solution, should I invert the DC voltage into 220Vac or should i just boost it into 400Vdc similar to the PFC voltage?

Any other smaller footprint mosfet switch that are more suitable for this application? Because I think Relay is too slow to react, and the mechanical switch of Relay is not long lasting.

Hope you guys can enlighten me in this...


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Building something is great -- unless a satisfactory solution already exists.;) This is the sort of project that smart, full-time engineers with fully equipped labs find to be a challenge -- especially when you demand faster switch-over than a relay. How often does your power go out, anyway? What type of 24V battery are you proposing that is going to supply a 500W amp for very long? Remember, you probably can't test it adequately without building an even bigger programmable supply to simulate the incoming line power.

Every conversion exacts an efficiency penalty; every bank of filter caps imparts another time delay, both to detection and substitution.

Go straight from the battery to the 80V main rails. Its the only way to have a chance at glitch-less changeover. But it'll still be the kind of undertaking that'll turn your hair gray and keep you awake nights.



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Actually, aside from the voltages involved, this shouldn't be too difficult...

In the thumbnail below the device with the highest voltage (PSU or Battery) will power whatever device it's hooked up to.
So, if the PSU shuts down the batteries will take over automatically with no power drop out.

Mind you for a big old power amp, you're going to need some pretty serious diodes...


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You should be able to pick up a UPS with a dead or missing battery for next to nothing. Computer recyclers, scrap yards, thrift stores, surplus dealers, online ads; I just did a search for APC UPS on a local site and there's a 1000VA Smart-UPS for free and a Back-UPS 750 for $20.

If you want to build something, there are much more rewarding things to spend your money and time on.
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