Power Electronics

# DC to AC converter or inverter working explained

## Dc to Ac converter, Overview:

DC to AC converter- Rechargeable batteries are the best option to store electrical energy as we generally do to backup our inner houses. We know that the electrical output of batteries is in the form of TC that is voltage and current at its terminals not changes its direction and remain constant in magnitude as far as energy is available in the battery. but most of the equipments we use in our houses run on AC. This is a format of electrical energy in which voltage and current vary in a periodic fashion.

Credit:

So to run these AC equipments through batteries a conversion is required known as DC to AC conversion or inversion. The circuit used for this purpose is popularly known as inverter. You can see that the voltage at the terminals of an AC load such as an AC motor can be altered by the continuously interchanging terminal of the battery, it is not possible for us to change polarity across the load manually and achieve switching frequency of 50 to 60 cycles per second.

This can be achieved by connecting four switches across the load in this manner the circuit shown here is popularly known as h bridge inverter circuit. Here the switches s1 s2 s3 and s4 are not simple switches these are electronic switches such as FET and IGBT’s which can be switched on and off frequently by means of control pulse also these switches have high frequency switching capability.

## Operation:

The basic operation of the circuit is very simple if s1 and s4 are turned on the left terminal of the AC load will be connected to the power supply. while the right terminal is connected to ground, current starts flowing through the load in one direction, let’s say the forward direction and the voltage across the load can be represented by +V. if s2 and s3 are turned on the reverse will happen the load gets energized in the reverse direction this time voltage across can be represented by -V.

## Let’s take a quick preview:

In the circuit we should never ever close the S1 and S3 or S2 and S4 at the same time. if we did that we just have created a really low resistance path between power and ground, effectively short-circuiting our power supply. So in this way unidirectional DC is converted to bi-directional AC, actually the circuit we use in inverters are not as simple as shown here, actual inverter circuits are quite typical and consists more elements like freewheeling diodes, capacitors, and transformer etc. the circuit shown here is simplified to make it easy to understand hope now you have a basic idea about how an inverter works.

Watch Video tutorial: