Inverters, How do they work ?


Inverters have taken a prominent role in the modern technological world due to the sudden rise of electric cars and renewable energy technologies inverters convert DC power to AC power they are also used in uninterruptible power supplies control of electrical machines and active power filtering this video will explain how to get a pure sinusoidal electric power output from DC power input in a step-by-step logical manner an alternating current periodically reverses its direction For this reason the average value of an alternating current over a cycle will be zero Before proceeding to sine-wave production Let’s see how a square wave alternating current is produced in fact the old type inverters used to produce simple square. Wave as their output Let’s build an interesting circuit as shown with four switches and one input voltage This circuit is known as full bridge inverter the output is drawn between points a and B To make this circuit analysis easier let’s replace this actual load with a hypothetical load Just note the current flow when switches s 1 and s 4 are on and s 2 and s 3 are off Now just do the reverse and observe the current flow It is clear that the current flow is the opposite in this case as is the output voltage across the load This is the basic technique that produces a square wave alternating current We all know that the frequency of the AC supply available in our homes is 60 Hertz This means that we need to turn the switch on and off 120 times in a second, which is not possible whether manually or by using mechanical switches We introduce semiconductor switches such as MOSFET for this purpose they can turn on and turn off Thousands of times per second with the help of control signals we can turn transistors on or off very easily The square wave output is a high approximation of sine wave output old inverters used to produce them That’s why you hear a humming noise when you run your electric fan or other appliances using square wave power They also heat up electric equipment modern inverters produce pure sinusoidal output, let’s see how they achieve it a Technique called pulse width modulation is used for this purpose the logic of pulse width modulation is simple Generate the DC voltage in the form of pulses of different widths in regions where you need higher amplitudes It will generate pulses of larger, width The pulses for the sine wave look like this Now here is the tricky part. What will happen if you average these pulses in a small time interval You will be surprised to see that the shape of the averaged pulses looks very similar to the sine curve The finer the pulse is used the better shape the sine curve will be Now the real question is how to make these pulses and how do we average them in a practical way? Let’s see how they are implemented in an actual inverter Comparators are used for this purpose Comparators compare a sine wave with triangular waves one comparator uses a normal sine wave and the other comparator uses an inverted sine wave the first comparator controls s1 and s2 switches and the second comparator controls s3 and s4 s 1 and s 2 switches determine voltage level at Point a and the other two switches determine voltage level at point B You can see that the one branch of comparator output is fitted with a logic not gate This will make sure that when s1 is on s2 will be off and vice versa This also means that we can never turn on s1 and s2 at the same time Which will cause the DC circuit to short-circuit? Turning s1 gives cell voltage at Point a and turning on s2 gives zero voltage at the same point Same is the case for point B The switching logic of PWM is simple when the sine wave value is more than the triangular wave comparator produces one signal, otherwise zero signal Now observe voltage variation at first comparator according to this logic control signal of one turns on the MOSFET The voltage pulses produced at Point a are shown Apply the same switching logic and observe the voltage pulses generated at point B Since we are drawing output voltage between point A and B the net voltage will be the difference between a and B This is the exact pulse train we need to create this sine wave the finer the triangular wave the more accurate the pulse train will be Now the next question is how do we practically implement the averaging? To make it exactly sinusoidal energy storage elements such as inductors and capacitors Are used to smooth the power flow they are called passive filters Inductors are used to smoothen the current and capacitors are used to smoothen the voltage With an inverter bridge a good pwm technique and a passive filter You can generate sinusoidal voltage and operate all of your appliances without any fuss The inverter technology we have explained so far has only two levels of voltage What if we introduce one more voltage level this will give better approximation of the sine wave and can reduce? Instantaneous error such multi-level inverter technology is used in high precision applications like wind turbines and electric cars Inverters used in the electric cars have intelligent frequency and amplitude control in fact Frequency controls the speed of an electric car and amplitude controls the power of it this way inverters act as the brain of electric cars by producing electric power ideal for driving conditions We hope this video provided you with a good introduction to the workings of inverters we request your support at patreon.com So that we can continue to produce free educational videos. Thank you

100 thoughts on “Inverters, How do they work ?

  1. Nice video it is nice information. Sir plz explain about mppt solar charge controller in your nxt video.

  2. Amazing video sir! Thank you so much for your amazing efforts.
    I humbly request you to make a video on Op-amps and their working.
    Thank you once again.

  3. But where did the triangular and sine wave came from? And if we already have a sine wave then what’s the point form the inverter😲?

  4. So if no right Angels in nature DC be nature then why we hear ac or are it just speakers makes much cents if only have a dollar . Like your electric cars and no solar or wind charger it's genius

  5. I made a inverter using an Arduino, DDS and a power amplifier, to create a perfect sine wave and different frequencies

  6. One point which I didn’t understand. Inductor smoothes the current while capacitor voltage?? Please explain

  7. You should have left the 'S' labels in the animation from point 1:16 … without them it's a bit hard to follow.

  8. So why wouldn't they use the wheels rotors roof trunk hood under hood have little windmills and cars would be free energy . If magntized planets or sun in tranny would probably power your house from the car

  9. Man books take forever to explain this. It's like reading my own report when I'm done explaining a point but have to hit the word count.

    You guys took 7mins. Amazing!

  10. Couple of issues.
    1) You CAN switch a mechanical switch at 60 Hz. The switch might wear out, but it is perfectly possible to do it mechanically.
    2) Ceiling fans do not use inverters as they are wired directly into the main house supply line via the switch and breaker panel.
    PS 60 Hz switches 60 times per second NOT 120. That's why it is called 60 Hz not 120 Hz. You might want to fix that.
    PPS Uninterruptible Power Supplies (UPS's) out put DC not AC as computers and ALL electronic devices use DC. The have a transformer inside that both alters the voltage and turns it into DC.

    For a tech channel, you people are sadly uninformed on this topic.

  11. Muito bom o vídeo, quando for possível faça um vídeo em português para melhor entendimento.

    Esse legendado ficou um pouco rápido de ler (risos)
    Parabéns 👏👏

  12. You Said comparators compare sinusoidal and triangular waves, from where are they applied to the input of comparators.
    we can use only that power that is stored in battery, but actually it gives DC,so how are sinusoidal and triangular waves are provided.
    Please answer this question .

  13. 4:20

    if we already got a perfect sin wave, why would we need to control some transistors to modulate a sin wave while the first one can just be amplified?

  14. great video but 1 small complaint: you didn't put echo on your voice when you said "full bridge inverter"

  15. Anyone besides me notice at 2:00 the MOSFETs are hooked up incorrectly? The two low side ones have the Gate pin on the load, while the two high side ones have the gate pin to the suppy power.

  16. Nice video.
    Need help for design & development consideration of Inverter used in EVs application.
    Waiting for your positive response.
    Thanks

  17. Video glossed over key details – the generation of (how?) triangular and sine waves into the comparators.

  18. Make video on solar charge controller it will be very helpful. Your all video are very very informative.
    Thanks alot

  19. How a dc motor work….since for a motor to rotate we always need a.c signal for polarity…..can you please explain this…

  20. AC is not defined by having an average value of 0 as indicated in 00:39, but due to the fact that polarity reverses, causing the current to alternate direction. Your depiction of NOT AC examples is incorrect.

  21. Wait… why would a ceiling fan ever use square wave power? They're almost always (always in my experience) hardwired in to the house circuit, which is A/C from the power company.

  22. Why is the electric car powered by an AC induction motor? It seems like too many conversion steps are involved. Wouldn't it be much easier to power the car with a DC motor, and use PWM (pulse width modulation) switching to chop up the DC battery voltage to control the speed of the car?

  23. wait a minute
    so u still had to feed a sin wave into the comparators to drive the mosfets to create a sin wave using DC
    then whats the whole point of using a sin wave to create another sin wave

  24. I'm confused here, as far as I see both the triangular and the sinusoidal waves are produced within the comparators, and the comparators are producing the averaged sine wave based on which one of the two is larger. But where is the dc-voltage that we wanted to invert into AC in the first place?

  25. This was a really good supplemental on Inverters for me, thank you for creating the video! Additionally, I have found Toshiba has a fairly decent DC-AC document that also notes applications.

  26. Triangular signal is generated with a VCO to be able to synchronize the inverter with the domestic line voltage using a PLL and the sinusoidal signal could be generated with a DAC converter

  27. Oh i wise to learn this type of education for years and years. Coz i'm wishing to learn so much of electronics but due to lack of special electronics school around my state i'm at its to the limits and was stuck in the middle. thnks alot for the free video you made..

  28. So the Triangular wave is used as Reference input for the comparator???
    If so then the frequency of AC signal will be a function of the triangular signal???

  29. I just feel dumb😂. I thought I was not the only one who didn't understand but passing through the comments I feel really dumb😂

  30. بسم الله الرحمن الرحمن الرحيم
    من باب المذاكرة:
    هل من الممكن أن ترسل لي كيفية توصيل الدائرة؟
    Can you send how to connect a circuit on a board؟

  31. بسم الله الرجمن الرحيم
    ثلاثة دوائر:

    three circuits
    المقارن، comparator
    mosfet
    passive filtering

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