So, let’s start from the very beginning; it starts with electricity. When our high school teachers explain the fundamental idea of electricity to us as a flow of electrons, they’re usually talking about direct current (DC). We learn that the electrons work a similarly like a line of ants, marching along with pockets of electrical energy in the same way that ants carry sugar. That’s a good enough comparison for something like a simple flashlight, where we have a circuit (which is an unbroken electrical loop) linking a battery, a lamp, a switch and electrical energy is systematically transported from the battery to the lamp until all the battery’s energy is used up.
In bigger household appliances, electricity works a differently. The power supply that comes from the your wall outlet is based on alternating current (AC), where the electricity switches direction around 50–60 times each second (in other words, at a frequency of 50–60 Hz). It can be difficult to comprehend how AC delivers energy when it’s constantly changing its mind about where it’s going! If the electrons coming out of your wall outlet get, let’s say, a few millimeters down the cable then have to reverse direction and go back again, how do they ever get to the lamp on your table to make it light up? The answer is quite simple. Imagine the cables running between the lamp and the wall packed full of electrons. When you flick on the switch, all the electrons filling the cable vibrate back and forth in the lamp’s filament—and that rapid shuffling about converts electrical energy into heat and makes the lamp bulb glow. The electrons don’t really have to run in a circle to transport energy: in AC, they “run on the spot.”
What is an Inverter?
Most of the appliances we have in our homes are specially designed to run from AC power. Appliances that need DC but have to take power from AC outlets need an extra piece of equipment called a rectifier, typically built from electronic components called diodes, to convert from AC to DC.
An inverter does the opposite job, and it’s quite easy to understand the essence of how it works. Suppose you have a battery in a flash-light and the switch is closed, so DC flows around the circuit, always in the same direction, like a race car around a track. Now, what if you take the battery out and turn it around. Assuming it fits the other way, it’ll almost certainly still power the flashlight, and you won’t notice any difference in the light you get—but the electric current would be flowing the opposite way. Suppose you had lightning-fast hands and were swift enough to keep reversing the battery 50–60 times a second. You’d then be a kind of mechanical inverter, turning the battery’s DC power into AC at a frequency of 50–60 hertz. Of course, the kind of inverters you buy in electrical stores don’t work quite this way. Though some are indeed mechanical: they use electromagnetic switches that flick on and off at high speed to reverse the current direction.
How an Inverter Works?
We’ve just had a fundamental overview of inverters—and now let’s go over it once more in a bit more detail. Imagine you’re a DC battery and someone taps you on the shoulder and asks you to produce AC instead. How would you do it? If all the current you produce flows out in one direction, what about adding a simple switch to your output lead? Switching your current on and off, very rapidly, would give pulses of direct current—which would do at least half the job. To make proper AC, you’d need a switch that allowed you to reverse the current entirely and do it about 50‐60 times every second. Imagine yourself as a human battery swapping your contacts back and forth over 3000 times a minute. That’s some neat finger work you’d need to have!
In essence, an old-fashioned mechanical inverter boils down to a switching unit connected to an electricity transformer. Mechanical inverters are electromagnetic devices that change low-voltage AC to high-voltage AC, or vice-versa, using two coils of wire (called the primary and secondary) wound around a common iron core. In a mechanical inverter, either an electric motor or some other kind of automated switching mechanism flips the incoming direct current back and forth in the primary, by merely reversing the contacts. So that produces alternating current in the secondary—so it’s not so very different from the imaginary inverter I described out above. The switching device works a bit like the one in an electric doorbell. When the power is connected, it magnetizes the switch, pulling it open and switching it off very briefly. A spring pulls the switch back into position, turning it on again and repeating the process— all over again