EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: mcinque on September 06, 2022, 11:49:03 am
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Let's take an online, pure sinewave UPS, so an inverter working all the time the UPS is on.
As far I understand, an online UPS is basically two things, a charger and an inverter.
AC mains is rectified and used to charge UPS batteries. Then the power from the batteres goes thru an inverter (H bridge and signal processing) and reach the device to be powered.
If AC mains fails, the inverter will continue to work until the batteries keep a certain voltage.
But what's the common way an inverter may fail? Overvoltage? Undervoltage? Let's assume signal processing fails or some component of the H bridge fails, or the PWM fails. What could happen, catastophically?
I expect:
Square or distorted wave instead sine (signal processing fail)
Incorrect frequency (not 50/60Hz)
Overvoltage or undervoltage (PWM fail)
DC output
What do you expect? And what are the typical failure modes of this devices in your opinion?
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Poor design causing some semiconductor switch to go BOOM and short circuit, rendering the thing totally inoperable, possibly triggered by some weird edge condition, or just aging / random failure.
Temperature/aging related wear of poorly dimensioned parts (such as electrolytic capacitors).