What is Meant by Inverter ?

inverter is basically  a device which converts ac voltage to dc voltage and we  will see this most often in our home when electricity goes off the inverter in our home will pass the the electricity

basically the curent is stored in battery is dc voltage a inverter is a device which will  turn dc to ac .

Now let’s talk more about Inverters!

Consider this circuit…

This is the simplest circuit I could think of to show you how an inverter actually works! Our aim is to basically swap the polarities of the points A and B in the circuit at a fast enough rate!

In this circuit S1$S_1$ , S2$S_2$ , S3$S_3$ and S4$S_4$ are 4 switches.

All you gotta do is follow one simple rule!

You can only turn on one pair of diagonal switches at a time. That means you can have these 2 possible cases…

• S1$S_1$ and S4$S_4$ are turned on while S2$S_2$ and S3$S_3$ are turned off.
• S1$S_1$ and S4$S_4$ are turned off while S2$S_2$ and S3$S_3$ are turned on.

Let’s analyze the first case…

I want you to observe the polarity of the points A and B. Let’s turn on S1$S_1$ and S4$S_4$

I have marked the direction of flow of current with arrows.

As you can see, the polarity of A is +$+$ve while the polarity of B is −$-$ve.

Now let’s think about what will happen in the second case…

I want you to once again observe the polarity of the points A and B. Let’s turn on S2$S_2$ and S3$S_3$ this time!

Just look at what happened with the polarities of A and B now! A was +$+$ve in the first case but now it is now −$-$ve! And B was −$-$ve in the first case but it is now +$+$ve!

So simply put, A and B just swapped their polarities! And that is exactly what we wanted! An output that changes it’s polarity!

But hold on! Our problem is not solved yet! The frequency of AC current in India is 50$50$ Hz. What that means is that in1$1$second, the output should change it’s polarity about 50$50$ times!! Mechanically, this is next to impossible! But there’s a way around it :)

The solution is to use these small 3-legged electronic components called Field Effect Transistors (FETs).

There are 2 types of FETs…

• n-channel
• p-channel

FET is a voltage controlled device that means, by controlling the voltage between gate and source, the output current gets varied.

I won’t get deep into the explanation of FETs for now. These can be used to switch circuits on and off with very short time lag. Unlike mechanical switches, these can toggle on and off unimaginably fast. That’s because of the absence of physical moving parts in these tiny devices. So, we use these FETs in place of our ordinary switches to get to that 50$50$ Hz mark!!

So now we have a circuit where the polarity of output changes 50$50$ times a second! There you have it!

An Inverter!!

Inverters can also be used with transformers to change the DC input voltage into a completely different AC output voltage (higher or lower).

What I just explained to you is a very basic circuit for an Inverter. Such type of inverters often produce square-wave output. That’s because the current is either flowing one way or the opposite way. It is instantly swapping over between the 2 states.

These types of sudden power reversals are quite brutal for some electrical appliances. In normal AC, the current gradually swaps from one direction to the other in a sine-wave pattern…

To produce this kind of smoothly varying AC output, we use Inductors and Capacitors to make the output current rise and fall more gradually than the abruptly changing square-wave output