Power Inverters Explained - How do they work working principle IGBT

Hey guys Paul, here from an engineering mindset, calm down, in this video we're going to look at

power

inverters

to understand the basics of how

they

work

and where we use them. Remember that electricity is dangerous and can be fatal. Must be qualified and competent. To carry out any electrical

work

, a typical inverter looks like this. It has red and black DC terminals on the back and on the front we find AEC outlets. That is because there are two types of electricity, there is AC and there is DC, an inverter is used to convert DC or direct current into AC alternating current.

We can also convert AC to DC with the use of a rectifier, but we'll cover that in a separate video and I'll leave some links in the video description below. Next, the appliances in our homes are designed to run on an AC supply and draw it from outlets that provide AC electricity; However, electricity produced by things like solar panels and batteries produces DC electricity, so if we want to

power

our electrical devices from battery banks from renewable sources or even our car, then we need to convert DC electricity into AC electricity. and we do it with an investor.

Where have you seen

inverters

used or where would you like to use one? Let me know your thoughts and your Project Ideas in the comments section below to understand how an inverter works, we first need to understand some basics of electricity within a copper wire. We find copper atoms. These have electrons that can move to other atoms. They are known as free electrons because

they

are free. to move they will move randomly in all directions but this is of no use to us, we need many electrons to move in the same direction and we do this by applying a voltage difference across the wire, the voltage is like pressure and it will do so.

We push electrons when we connect a wire to the positive and negative terminals of a battery, we complete the circuit and the electrons begin to flow. We call this flow of electrons current, electrons always try to return to their source, so if we put things like lamps in the path of the electrons, they will have to pass through this and therefore do work for us , how to light this lamp. The electricity from solar panels and batteries is known as DC electricity and that is because this type of electricity flows in only one direction; it flows from one terminal directly to the other terminal.

If we reverse the battery, the electrons flow in the opposite direction. opposite. You can think of DC electricity as a river with the stream of water flowing in only one direction now in these animations. use an electron flow that goes from negative to positive, but you may be used to seeing a conventional current that goes from positive to negative. The flow of electrons is what is really happening. Mainstream was the original theory and is still widely taught today, just keep in mind which two and which. one we are using when we use on the scylla scope to observe the electrical waveform for DC we get this flat line at the maximum voltage in the positive region if we were to cut the power then the line will drop to zero if we turn on power on and Turning off the power repeatedly, we get a square wave pattern between zero and maximum, but if we set the switch to open and close for different periods of time, we would get a pulsating pattern with AC electricity, the electrons flow forward. and backwards constantly hence its name because the current of electrons alternates in direction you can think of this type of electricity lets the sea tide constantly enter and exit between the maximums of high tide and low tide if we follow the copper wires of back to the generator the wires are connected to some coils of wire that are located inside the generator inside a basic generator we also find a magnet in the center that is rotating the magnet has a north pole and a south pole or you can think of it as a positive and one negative half of the electrons in the wire are negatively charged, as you may already know, the magnets push or pull depending on the polarity, so as the magnets rotate past the coils, the positive and negative half , therefore, they will push and pull the electrons.

Within the copper coils and also through the connected copper wires, the magnetic field of the magnet varies in intensity, so that as the magnet rotates past the coil, the coil will experience a change in the intensity of the magnetic field, which will be from 0 to its maximum intensity. and then as it passes through the coil it will decrease back to 0, then the negative half comes in and attracts the electrons back with the same change in intensity. Therefore, each full rotation of the magnet will produce this wave pattern known as a sine wave, the voltage. It is not constant in this type of electricity, but moves repeatedly from zero to its peak, back to zero, then to the negative peak, and finally back to zero.

Frequency refers to how many times this AC sine wave repeats per second in North America and in some other parts of the world we find 60 Hertz electricity, which means that the sine wave repeats 60 times per second and as each wave It has a positive and a negative half, this means that its polarity will reverse 120 times per second in the rest of the world. We mainly find 50 Hertz electricity, so the sine wave repeats 50 times per second and therefore the current reverses 100 times per second. The inverter consists of a series of electronic switches known as IGBTs. The opening and closing of the switches are controlled by a controller that can open and close super fast in pairs to control the flow of electricity by controlling the path the electricity takes and how long it flows in the different paths we can produce AC electricity from from the DC source.

I'm going to animate them using some simple switches to make them easier to visualize remember that AC is where the current reverses the direction we saw earlier in the video. We can reverse the direction of the current by reversing the battery. We could reverse the battery very quickly to produce a rough AC supply, but an easier way would be to connect four switches or IGBTs across our load, like a lamp, if we open and close them in pairs, then we can produce AC electricity, so if we close which is one and four then the current flows in one direction and if we then open them and close which is two and three then the current flows in the other direction so we can use the controller to do this automatically over and over again, if we did that 120 times a second, we would get 60 Hertz of electricity and if we did that. 100 times per second and we would get 50 Hertz of electricity, since we have a low voltage input we will get a low voltage output to reach the 120 volts or 230 volts needed to power our appliances, we will also need a transformer to step it up. the voltage to a useful level when we look at this through an oscilloscope we get a square wave in the positive and negative regions, this is theoretically AC because it reverses direction, but in reality it doesn't look much like an AC sine wave, so, how can I improve this.

Remember earlier in the video when I said we can open and close the switch at different speeds and durations to change the waveform? Well, we can do that for this too. What we do is use a controller to quickly open and close. The switches several times per cycle in a pulsing pattern, each pulse varies in width, this is known as pulse width modulation, the cycle is divided into multiple smaller segments, each segment has a total amount of current that could flow, but by quickly pressing the switches we control the amount of flow that occurs per segment this will result in an average current per segment that we see increase and decrease which gives us a wave, therefore the load will experience a sine wave the more segments we have, The closer it will imitate a smooth wave we can control the output voltage by controlling how long the switches are closed, so we could, for example, generate 240 volts or 120 volts simply by shortening the opening and closing times.

We can also control the frequency by controlling the timing of the switches, so we could eg. output 60 Hertz 50 Hertz or 30 Hertz whatever is needed for the application, this is how we can take a 12 volt DC battery and convert it to a 120 volt or 230 volt AC supply using some pulse width modulation IGBTs and a transformer, but what? If we needed more power, we also have single-phase and three-phase AC electricity. Most homes around the world use single-phase electricity. Large commercial buildings and some homes, especially in Europe, will use three-phase electricity. Homes in North America. Use split phase electricity where a center tap transformer splits a single phase into two, providing two hot wires and one neutral.

We've covered how split phase electricity works in detail in our previous video. Check the links below with single phase We have a connection to a single phase of a generator, so we have only one sine wave, but with three phase electricity we have a connection to each of the three phases. The phases are coils of wire that were inserted into the generator at 120 degrees. Apart from the above, this means that the coils experience the peak of the rotating magnetic field at different times and it is this that gives us our three phases, each with a different sine wave that is slightly out of sync with the previous one.

Remember that electricity wants to return to its source in a complete circuit as current flows back and forth at different times in each of the phases, we can essentially connect the phases together and the current will move between the different phases As the polarity of each phase moves back and forth at different times, any excess will flow in the neutral back to the source if necessary, but that is only if the load on either phase is unbalanced. With a single phase, we have these large spaces between the peaks, but with a triphasic phase, these can combine to fill. spaces and therefore deliver more energy.

Larger applications require a three-phase inverter, for example to run compressors in a large cooling system. The DC supply in this case will be a rectified three-phase AC supply, meaning three AC sine waves are combined. together and pass through some diodes which prevent the electrons from flowing back, this makes it a wavy DC waveform. We then use a capacitor to smooth out the ripple on a constant DC supply. Now that we've covered this in great detail above, check out the links. below to convert clean DC into three phase AC we use three phase inverter for this we use 6i gbts again.

I'll animate them as simple switches for simplicity and also number them as follows to get the three phases we need. We open and close the switches in pairs to direct the flow of current from our supply and return paths that way the connected motor will experience alternating current for the three phase supply we time the switches to simulate the three phases let's see how this works first we close what it is one and six this will give us phase 1 to phase 2 then we close what is one and two this will give us phase 1 to phase 3 then we close what is three and two this will give us phase two and phase three then close which is three and four this will give us phase two and phase one then we close which is five and four this will give us phase 3 and phase one then we close which is five and six and this will give us phase 3 and phase two this cycle repeats over and over again, if we check this with an oscilloscope we now have a wave pattern that looks like AC except it is still a bit square, this will work fine for some applications but not all so again we need to use pulse. width modulation to create the sine wave, so we will use a controller to rapidly open and close the switches to vary the frequency and output voltage and that way we will get our three phase AC supply.

Well guys, that's it for this video, but to continue learning, then watch one of the videos on screen now and I'll see you there for the next lesson. Don't forget to follow us on Facebook, Twitter, Linkedin, Instagram and the hurtful mentality.