- #1
Nat3
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Confused about voltage induced across inductors :(
Hi,
As you may have gathered from the topic title, I'm rather confused about inductors I have another topic going regarding boost converter design, which involves an inductor, but as this confusion/question/observation is really specifically related to an inductor and not the boost converter as a whole, I decided to start a new topic for it.
My confusion is this: Why does the voltage induced across an inductor depend on the duty cycle of the applied DC signal and not the on/off frequency? It seems like the induced voltage is directly related to the rate of change of current, which is the frequency, because of this equation:
[itex]V_L = L\frac{dI_L}{dt}[/itex]
On the right hand side of the equation is the rate of change of the current, which is dependent on the frequency, right?
I built a little circuit in Multisim and here are the results:
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_7149.png
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_7504.png
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_12719.png
To my total confusion, changing the DC signal frequency does not change the voltage across the inductor. Doesn't this completely contradict the above equation??
Changing the duty cycle, while keeping the frequency constant, resulted in:
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_13683.png
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_7149.png
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_6835.png
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_5867.png
So changing the duty cycle changes the voltage induced across the inductor.
What's going on here?
Hi,
As you may have gathered from the topic title, I'm rather confused about inductors I have another topic going regarding boost converter design, which involves an inductor, but as this confusion/question/observation is really specifically related to an inductor and not the boost converter as a whole, I decided to start a new topic for it.
My confusion is this: Why does the voltage induced across an inductor depend on the duty cycle of the applied DC signal and not the on/off frequency? It seems like the induced voltage is directly related to the rate of change of current, which is the frequency, because of this equation:
[itex]V_L = L\frac{dI_L}{dt}[/itex]
On the right hand side of the equation is the rate of change of the current, which is dependent on the frequency, right?
I built a little circuit in Multisim and here are the results:
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_7149.png
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_7504.png
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_12719.png
To my total confusion, changing the DC signal frequency does not change the voltage across the inductor. Doesn't this completely contradict the above equation??
Changing the duty cycle, while keeping the frequency constant, resulted in:
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_13683.png
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_7149.png
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_6835.png
http://www.roboticsguy.com/uploads/gallery/album_13/gallery_1_13_5867.png
So changing the duty cycle changes the voltage induced across the inductor.
What's going on here?