If you superimpose the 3 sinewaves, you will see that there is always at least 1 top and 1 bottom switch on at any given time. You are correct with your comment. No current can flow with a single switch on.
For whatever it's worth, the vertical line should be a capacitor; not a "short" as some have suggested. Probably a mistake when drawing the diagram from the design engineer to the "tech writer". Happens ALL the time. As to "theory" being unnecessary and hardware is all one needs, is a nice sounding thing but it is totally false. If one does not understand "theory" they will never "know" what is going on; thus they will always do things by trial and error. A very common thing, but a sad thing at the same time and highly inefficient approach. Learn the theory and it becomes a blessing. Oh indeed yes. The diagram WITH a capacitor (instead of the straight vertical line) is exactly HOW all VFD's work. IE: a single, double or triple phase AC voltage fed into the VFD is converted to a DC voltage; but it is choppy and needs a filter to smooth it out. The capacitor does that. Some add coils to improve the filtering. Then the filtered DC is fed to 6 special HIGH speed transistors (acting like switches). These transistors are "fired" (turned on and off) in a manner that each pair of these transistors will create a 3 phase voltage; albeit is made up of pulses (rather than sine waves); whose "width" (time on or off) creates a voltage that the motor thinks is 3 phase AC. Believe it or not. It is this phenomenon that makes the thing work. Also and very important; there is control circuitry (not shown) that feeds timed "signals"; that turn on the switches faster or slower; that allows a motor to have a constant AC voltage; yet its speed can be varied from off to maximum speed smoothly. But the voltage stays the same. "Absolutely brilliant" as the "Brits" would say. When wired and programmed properly, it is one of THE most awesome technological creations; since electricity was discovered I do believe.
"Believe it or not" For me it's weird (I'm not saying the principel of operation isn't true): the instantaneous output voltage is really a pulse train with variable duty cycle and changing polarity, yet the motor still works as if it was a sinusoidal waveform.
instead of capacitor you have shown a short
Really good explanation!
In video which type filter we can use
Thank you for this clearance , can I have the power point that you used in your lesson?
Please explain to me how when only switch (1) is closed current flows? This is my only question HOW?!!!
If you superimpose the 3 sinewaves, you will see that there is always at least 1 top and 1 bottom switch on at any given time. You are correct with your comment. No current can flow with a single switch on.
Good Video! Thank you!
Nice dead short after the filter.....
For whatever it's worth, the vertical line should be a capacitor; not a "short" as some have suggested. Probably a mistake when drawing the diagram from the design engineer to the "tech writer". Happens ALL the time.
As to "theory" being unnecessary and hardware is all one needs, is a nice sounding thing but it is totally false.
If one does not understand "theory" they will never "know" what is going on; thus they will always do things by trial and error. A very common thing, but a sad thing at the same time and highly inefficient approach. Learn the theory and it becomes a blessing. Oh indeed yes.
The diagram WITH a capacitor (instead of the straight vertical line) is exactly HOW all VFD's work.
IE: a single, double or triple phase AC voltage fed into the VFD is converted to a DC voltage; but it is choppy and needs a filter to smooth it out. The capacitor does that. Some add coils to improve the filtering.
Then the filtered DC is fed to 6 special HIGH speed transistors (acting like switches). These transistors are "fired" (turned on and off) in a manner that each pair of these transistors will create a 3 phase voltage; albeit is made up of pulses (rather than sine waves); whose "width" (time on or off) creates a voltage that the motor thinks is 3 phase AC. Believe it or not.
It is this phenomenon that makes the thing work. Also and very important; there is control circuitry (not shown) that feeds timed "signals"; that turn on the switches faster or slower; that allows a motor to have a constant AC voltage; yet its speed can be varied from off to maximum speed smoothly. But the voltage stays the same.
"Absolutely brilliant" as the "Brits" would say.
When wired and programmed properly, it is one of THE most awesome technological creations; since electricity was discovered I do believe.
"Believe it or not" For me it's weird (I'm not saying the principel of operation isn't true): the instantaneous output voltage is really a pulse train with variable duty cycle and changing polarity, yet the motor still works as if it was a sinusoidal waveform.
Great video, thumbs up!!!
thnx , nice explanation.
I don't think the people generating this video understand the concept of a half bridge and how an inverter really works.
Чисто с технической точки зрения видео полный бред.
Show some real hardware working circuit rather than boring theoretical stuff
bad