How Pulse Width Modulation works in a VFD
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- เผยแพร่เมื่อ 9 พ.ค. 2024
- Pulse width modulation uses transistors which switch the DC voltage on and off in a defined sequence to produce the AC output voltage and frequency. Most VFD’s today utilize insulated gate bipolar transistors or IGBT’s.
#Drives #VFD #PulseWidthModulation
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Incredible. You just accomplished in 4 minutes what my teacher couldn't do in a whole semester!
hahaha
My sentiments exactly.
We are same bruh😂😂
Thankx for covering this so simply.
We're glad you find it helpful! Let us know if you or your company are interested in learning more about KEB automation. Have a great day!
Jason Bourne explaining some VFD theory...
Mike does look a bit like Jason Bourne from the movie series. Hahaha!
Dude... Your technique for teaching is really cool... Stay blessed man... And keep up the good work🤘🏻
Thanks for the compliment. We're glad you enjoy this teaching method.
Many many thank you for given a valuable speech in short time
Excellent explanation of the pulse with modulation, I have finally understood the operation
This what I am searching for more than one month
Great talk about VFD now i fully understand how it works😉 good job👍👌
Great explained and at least a good start for newcomers! Thanks Mike!
Thanks Richard,
Yes, it is a general overview of how PWM works for newcomers. We are glad you like it. Look for more videos on similar topics soon. Have a great day!
Very helping and easy to understand
Thank you for explaining it in an easy fashion.
You're welcome. :)
Whats thr fashion.. How he explains like this???
Great explanation, watching from Kenya
Excellent demonstration..
Such great explanation
Very well explained! Thanks
Wonderful explanation
Very well explained
phenomenal
Good lecture!
The ultimate basics
Thanks, Lucas rem. :)
that was kind of so easy explanation pf the theory...guys voice was also heavy and clear
Glad it helps you, Rahulsinh Chavda! We will continue making videos to help explain engineering concepts. Have a great day!
Thanks! A very nice explanation.
Glad it was helpful!
Very good explanation
Nice GURUJI(teacher in INDIA
Well done!
good job from Bangladesh
easy and quiet explanation thaanks
Thank you for the comment, ElectRoniK Interest. :)
very good, thanks
Good explanation....concept clearing 👍👍👌
Thank you! We are glad you find it helpful. If you're interested in our VFDs or any one of our automation products, you can contact us at kebamerica.com :)
Thank you!
You're welcome!
great explanation !!!🤩
We're glad it was helpful!
very good
cool teaching
Nice sir
Great 👍
Thanks
You're welcome.
This control by bus sensing voltage?? Example the output is 678, and data from bus sensing wi set for 400v example, so the microcontroler change pwm for the igbt or fet??
Very interesting basics I like! Any video on how these frequencies can affect motor vibration?
I’m not sure what you’re referring to. PWM shouldn’t affect motor vibration.
@@KEBAmerica harmonics of the frequency and their relationship with the environment will cause vibration.
please make a video explaining how IGBT converts AC TO DC and back DC to AC in regenerative mode and current birection
hi, excelent video, i have a doubt, in some system like VRF conditioner , it's says that the compressor use DC voltage, but in this video you say that is AC voltage after the inverter , so why i can't test the compressor with AC voltage directly without using the inverter module? Thanks and sorry for the trouble
Thanks for you question. Based on your comment, here is what we think will help:
You can test the compressor directly with the AC voltage and skip using the VFD (typically still use a motor starter), but then you lose the Variable Voltage Variable Frequency output of the VFD. Without the VFD they would only have the option for off or full speed with nothing in between.
If you have further questions, find a local KEB Representative near you here: www.keb.de/contact/contact-worldwide
@@KEBAmerica How come only 2 IGBT
Nice video, but I just still dont understand how the smooth sine wave is made from pulses :( Thank you for answer
EDIT: I'd like to simplify my answer a bit since I got a little carried away with that info. The Pulse-width modulation allows us to MIMICK a sine wave when the pulses are at extremely high rates. The IGBT does not pulse at a constant rate, it follows the rate relative to the values of a sine wave. Well as close as it can get. And it can get pretty close. Think of how the individual pixels in your monitor are squares. Well when you, the observer see these squares in a pattern, and those squares are small enough, you have the illusion of a curved line. the more pixels you have (or pulses for the analogy), the more realistic that curve seems. When you are working with less pixels, the image begins to look choppy and at a low enough resolution , you can actually see the pixels as squares.
When you change the time between pulses, you change the AVERAGE values of the mimicked sine wave. These values are actually known as Pulse-Width modulation. It is not a true sine wave, but when you have energy pulsing extremely fast AND reversing direction, it can be perceived as a sine wave. So, even though your DC voltage is still technically 650vdc at the input, with pulse-width modulation, you are essentially limiting the amount of voltage the load receives, as well as switching the flow of electricity by taking advantage of electrons wanting to flow back to it's source at it's most efficient route. This results in a 480VAC voltage.
Yes, it's hard to comprehend how electrical pules from IGBTs switching on and off can create a waveform that can control industrial motors. Perhaps you would like to read more on our blog article here: www.kebamerica.com/blog/pulse-width-modulation-in-vfds/
how can we change the width of duty cycle in our applications?
Mostly great video. In the beginning you labeled the AC to DC component a "converter" this is inaccurate. It is properly called a "Full Wave Bridge Rectifier, with ripple control". It might be helpful to draw the changes from 480V 60Hz, to DC, to new synthetic AC output.
Also, is it not possible now to use true sine Wave inverter circuit? Given advanced in inverter technology, I'm sure that's how the new VFDs work. That is, instead of using simple modified sine wave, created through choppy DC. It uses a computer to draw the sine wave like an etch-a-sketch just super small strait lines making a very close approximation of a genuine curve.
Hey Warren,
Thanks for the detailed analysis! Yes, technically it is a full wave bridge rectifier. We call it the converter section as a general statement because it converts the AC to DC. We then call the DC to AC output of the IGBT’s as the inverter is it inverts the DC back to AC for the variable voltage and frequency output. These are general terms. Some people call the entire unit an inverter. Mike is just clarifying that there are two stages to the process. AC to DC and the DC back to AC for the variable output. This lightboard video series is meant to a general overview of highly technical topics. Have a great day!
That is correct, the fact of the matter is tht they are generally all called converters. AC/DC Converter (Rectifier, can be full wave or half wave) and DC/AC Converter (Inverter). In a VFD there is no need for a controlled Rectification, just fullbridge Rectifier then throttle the output using Inverter IGBT's as you have correctly shown us.
Excellent explanation , but I still can't understand 1 thing that seems contradictory : how can torque stay constant when power is being increased ? I mean , doesn't an increase in power mean the rotor/shaft is gonna spin faster , ie higher torque ?
If torque is constant, only speed needs to increase for power to increase.
Power = Speed x Torque
Would vfd work with a drum motor
It depends on the type of drum motor. We have demonstrated a VFD powering a drum motor for a conveyor belt in a previous video here: th-cam.com/video/xo69RjHzWNE/w-d-xo.html
Sir
You make nice videos
But I'm looking for a deep videos on working principle of 6 IGBT in VFD
I'm from India
Thank you for your compliment. We offer an overview of general topics in these lightboard videos. If you would like to know more information there are plenty of other TH-cam videos and online courses that go deeper into how IGBTs work. If you are interested in seeing how KEB products can help power a specific machine application we are more than willing to work with you. You can find a local KEB rep here: www.keb.co.uk/contact/contact-worldwide
Holy shit 16,000 times per secound!!!!
Yeah, technology is amazing. It's pretty much just magic. It's definitely a product of science and engineering, but to the average person it's hard to understand how electronics can operate so quickly and reliably. :) Thanks for watching!
Your description is good, however the characterization of the IGBT as "Open" could be quite misleading. Rather, use the word "Conducting" to prevent misunderstandings as "open" usually means a broken circuit.
The reason that the plumbing analogy is often confusing to beginning electronics students. A valve closed stops flow>>> A transistor closed allows flow.. Rec. A valve open allows flow... A valve closed stops flow...
TRUE
Just a note, when you say rms and instead you are drawing and refering to a sin wave that's the 1th armonic you are messing with definitions and not being precise, the rms would be the value that has to be calculated and it's Am/sqrt(2) where Am is the amplitude of the wave you drew
Pretty sure he's talking about the root mean square of the DC pulses forming the sine wave. Not the RMS of the sine wave for a clean AC system which is the DC equivalent of the sine waves
After quickly refreshing my memory, the definition of RMS: "the arithmetic mean of the squares of a set of numbers" ~wikipedia. In this case the RMS (sine wave half cycle) is the arithmetic mean of the square of the set of positive pulses (duration and maginitude)
Why Dc Voltage is more that input AC ?
Hello again, Bishant,
The simplest answer is because the DC voltage has to be higher than the AC output for the PWM to work. Thus the AC input must be rectified up to a higher DC voltage. I hope this helps. Thanks for the comment!
KEB America, Inc. that's the question. How it becomes higher ? How DC is more
If you want to know more details, a TH-cam comment isn't the best place to learn specifics on topics like six diode bridge rectifiers. Here is a good place to learn more in-depth how and why this works: www.electronics-tutorials.ws/power/three-phase-rectification.html
Hope this helps!
@@bishantkumar12589 the peak value of a sine wave is highter than the rms value of it.
I think your calculations are wrong, you confuse the three-phase current with the single-phase current when you multiply by 1.4. In the end, from 678 V you have +/- 678 V, that is 1356V.