How inverter works?
In this post, you will get info about, How inverter works? So let’s Start – Due to the quick emergence of electric cars and renewable energy technologies, inverters have acquired a key part of the modern technological world. Inverters convert DC power to AC power or how to convert dc to ac. They’re also utilized in uninterruptible power supply, electrical machine control, and active power filtering, as explained in this article.
How does an inverter work?
How to get a pure sinusoidal electric power output from DC power input?
An alternating current reverses its direction in a rational, step-by-step manner. As a result, before moving to sine-wave creation, the average value of an alternating current across a cycle will be zero.
Let’s have a look at how a square wave alternating current is generated, and how old-style inverters used to do it. Wave as a result of their work
Let’s create an intriguing circuit with four switches and one input voltage, like indicated. The output of this circuit is drawn between points a and B, and it is known as a full-bridge inverter. To make the circuit analysis process go more smoothly.
Let’s substitute a hypothetical load for this actual load. Simply note the current flow when switches 1 and 4 are on and switches 2 and 3 are off. Now do the opposite and see the current flow. In this situation, the current flow is clearly in the opposite direction, as is the output voltage across the load. This is the fundamental method for creating a square wave alternating current.
The frequency of the AC supply in our homes is 60 Hertz, as we all know. This requires turning the switch on and off 120 times in a second, which is impossible to do manually or with mechanical switches. With the help of control signals, we introduce semiconductor switches such as MOSFETs, which can turn on and off thousands of times per second.
Transistors are incredibly simple to turn on and off. The square wave output is a close approximation of the sine wave output produced by classic inverters. When you use square wave power to drive your electric fan or other appliances, you’ll hear a buzzing noise. Modern inverters create pure sinusoidal output, which heats up electric equipment.
Let’s see how they go about doing it. For this, a technique known as pulse width modulation is used. The logic of pulse width modulation is simple: generate DC voltage in the form of pulses of various widths in areas where bigger amplitudes are required. It will produce pulses with a wider breadth. The sine wave’s pulses look like this. This is when things become a little complicated.
What happens if you average these pulses over a short period of time? You’ll be shocked to learn that the averaged pulses have a shape that resembles the sine curve. The sine curve will have a better shape if the pulse is finer. The actual question now is:
How to make these pulses and How do we average them in a practical way?
Let’s take a look at how they’re used in a real inverter. This is accomplished through the use of comparators. A sine wave is compared to triangle waves via comparators. A normal sine wave is used in one comparator, while an inverted sine wave is used in the other. The first comparator controls the s1 and s2 switches, while the second comparator controls the s3 and s4 switches. The s1 and s2 switches decide the voltage level at point a, while the other two switches determine the voltage level at point B.
One branch of the comparator output is fitted with logic not a gate, as can be seen. This ensures that when s1 is turned on, s2 is turned off, and vice versa. This also means that s1 and s2 can never be turned on at the same time.
Which will cause the DC circuit to short-circuit?
When you turn on s1, you get cell voltage at Spot a, and when you turn on s2, you get zero voltage at the same point. The same is true for point B. One signal is produced when the sine wave value is larger than the triangular wave comparator; else, zero signal is produced. As a result of the logic control signal that turns on the MOSFET, observe the voltage variation at the first comparator.
The voltage pulses generated at Point an are depicted. Apply the identical switching logic to point B and examine the voltage pulses that result. The net voltage will be the difference between a and B because we are drawing output voltage between points A and B. This is the exact pulse sequence required to generate a sine wave. The pulse train will be more accurate if the triangle wave is finer. The following question is:
How do we put the averaging into practice?
Passive filters smooth the power flow by converting it to a sinusoidal shape using energy storage devices like inductors and capacitors. The current is smoothed with inductors, while the voltage is smoothed with capacitors. A good PWM approach and a passive filter are used with an inverter bridge. You may easily generate sinusoidal voltage and use it to power all of your equipment. There are only two voltage levels in the inverter technology we’ve discussed so far.
What if we introduce one more voltage level this will give a better approximation of the sine wave and can reduce it?
In high-precision applications such as wind turbines and electric cars, and instantaneous error, such as multi-level inverter technology, is used. In fact, electric car inverters include intelligent frequency and amplitude management. An electric car’s speed is controlled by frequency, while its power is controlled by amplitude. Inverters serve as the brain of electric vehicles, delivering electric power that is optimal for driving situations.
We hope that this article gave you a good understanding of how inverters work.