A rectifier converting AC to DC is easy enough to understand: Diodes let electricity only flow one way. But how in the world does an inverter convert DC to AC?
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The simplest way to do this is to chop the DC to where you essentially have a square wave (basically a switch turning on and off at the desired AC frequency). Then run that through capacitors to “smooth” the square into something resembling a sine wave. Then “level” the 0V to the middle of that wave and amplify that voltage (easily done with a center tap transformer, for example) and voila “AC” voltage at the output.
Nowadays, there are lots of electronic inverters that do this in a more efficient fashion but the principle is just about the same.
For many usages, the switching is all that’s needed.. you can make square wave relatively easily by just switching polarity… same way as with rectifiers you have half and full bridge ones. timing can be done with MOSFET or thyristors (or other semiconductors)
If you need sinus wave, you need to add more components components. Usually done with something called RLC (resistor, coil, capacitor)
If you want fancy read: https://www.electricaltechnology.org/2020/09/full-bridge-inverter.html
In real power delivery applications there are a couple different modulations. A modulation is just a strategy for wave shaping, given a particular equipment design.
This isn’t really eli5 at all, my apologies.
First, used in early tech and the most intuitive, is variable frequency drive. VFD uses switching to build a step waveform at 60 hz. It’s not usually just a flat square, most common designs use three states (plus, zero, minus) and feed it through a choke filter to make a sine wave. [here’s a visual explanation ](https://realpars.com/variable-frequency-drive/)
Second, probably the most widely used modulation, is space vector modulation. SVM isn’t programmed to generate voltage, it’s programmed to generate current. It watches the grid voltage and switches in response to it, in order to send current to the grid & create positive power flow. Don’t worry, it’s kind of a mind job. [a visual guide](https://www.switchcraft.org/learning/2017/3/15/space-vector-pwm-intro) – note this paper talks about synthesizing voltage, I maintain that output voltage comes from the grid and SVM is better described as a current source.
These are just the two most popular methods, there are more, that deserve more research. Wavelet modulation works a lot like an audio encoder, solves a lot of problems with VFD, and can do plenty of things SVM just can’t.
An inverter is a just set of switches and a controller which swaps the positive and negative connections around on a regular basis.
Filtering can be used to smooth out the abrupt changes when the switches reverse.
The simplest “inverter” might be an Arduino. You can get 10 V peak to peak using two pins just turning the digital output on and off in the right sequence.
When I worked as a wind tech I learned it’s not a smooth sin wave like when you have ac. The best way I can put it is it’s varying ranges of voltage that go up and down in increments and if I’m not mistaken that gets ran through a capacitor/filter of some sort to clean it up into useable energy. Hope I’m not wrong but feel free to let me know I always love learning new stuff and love to teach it the best I can and can’t really do a good job at teaching if what you preach is wrong.
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