The crossover distortion seen here suggests an analog Class-B output stage and that surprises me, because a digital output stage would be much more efficient. Class-D in other words. I've built digital inverters using IGBTs that produced an output sinusoidal power wave with lower distortion than the mains power. Granted these were one-offs and probably not cheap enough for production, but modern IGBTs and MOSFETS should be cheap enough nowadays that medium-priced UPSes could just use Class-D as the default solution.
Assuming you really need a sinewave at the output at all. DC output UPSes are the most efficient way to go if you can bypass the switched-mode power supply at the input of your equipment. Which most equipment has these days unless AC motors are involved.
Also I probably should have actually addressed your Class B comment:
No, they're not Class B. It's all digital PWM stuff inside. But the duty cycle gets tiny near zero cross, there's very little power in the waveform there, and there's overhead to have a switching device on at all (this is much more noticeable for IGBTs).
So it ends up being a massive simplification to just not care about that section. And it's a simplification that works pretty great, so people do it!
We had to get this truly right in the inverter I mentioned in sibling comment (as it wasn't a grid-feed or backup inverter, it was doing Something Else™ *) and just that piece was actually way harder than the entire rest of the waveform output design.
* hopefully NDA-OK spoiler: let's just say I know way, way more than I'd like to about what's inside that Chroma 61507 mentioned in the article.
Phase-shifted full bridge is the way to go. (It might have another name in this area of power electronics, these things do have lots of names....)
We did a "big" inverter design a while back (500 VA was big for us; perhaps not for you). The guy who did the concept architecture suggested a PSFB design. He then quit to take a a great offer from a startup. Not really being a power electronics team, we hired a specialist consultant. The first consultant did... honestly, I don't know what he did. But it was weird. (This was a problem.) It wasn't a PSFB anymore. It also didn't work. The design then went through five more lead engineers and two more consultants, plus one more if you count me on the side watching and occasionally pitching in (I was the sister subsystem lead). It ended up being a full digitally programmable bridge and we had to figure out how to switch it. Guess how it ended up working?
Phase-shifted full bridge. Just like the first guy (and I!) said it should have been all along!
If built correctly this design also suffers no transition transients. You can switch the external power off/on all day and downstream equipment will never see a glitch.
The Luddites were mad not because the machines put them out of work but because the machines were supremely shitty. The machines were dangerous and they made lousy products that reflected a lack of pride in workmanship.
The Luddites were all for saving labor, but not if enshittified products and slavery to unreliable machines were the price.
Many Luddites were protesting labor conditions. At the time the majority of labor laws were being written by the capital class with the help of political leaders and the constabulary. Common complaints were working hours, child labor, safety, wages, and protection from furlough. There were some who protested the quality of the product the machines created... but I would say those are the minority.
Destroying the machines was a way to gain leverage for a class of people who had none. People had been using looms for centuries. It wasn't the technology that was the problem... that's what the victors, the capitalists, have written was the reason.
Dark Sky is the one that most grinds my gears. It was one of those unique apps that does something miraculous. Apple bought it and killed it for everybody that didn't use an iphone.
I used to use one of these for typesetting back when I was a printer. To justify, you had to type each line once in non-printing mode. Then you told the machine to retype it in printing mode and it would widen the spaces the correct amount. Or maybe you had to retype it manually again; I forget.
Anyway the output was much better than from an ordinary Selectric because of proportional letter widths.
Garbage collectors don't guarantee the absence of memory leaks. GCs remove one important source of memory leaks but it's still very possible in GC languages to use up all available memory unintentionally simply by holding onto things in a big data structure that you've forgotten about (often it's a cache). Weak pointers in conjunction with GC help a great deal with that problem but even so GC and weakness are not going to guarantee leak-prevention in all cases.
I still strongly prefer GC languages to the alternative.
It's like the situation with HIPAA rules in electronic health records: It wouldn't be impossible to write your own EHR system but if you do you have to spend a lot of money proving it meets HIPAA regulations or accept substantial liability. So companies just pay Epic $$$ because they promise HIPAA compliance.
Likewise with classroom software if you just use the "industry standard" enterprise crapware you've outsourced the accessibility liability to somebody else. If the software is hot garbage from a usability perspective, that's irrelevant.
And this is why we cannot have nice things in the enterprise space.
Assuming you really need a sinewave at the output at all. DC output UPSes are the most efficient way to go if you can bypass the switched-mode power supply at the input of your equipment. Which most equipment has these days unless AC motors are involved.
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