which inductor current waveform is correct?

Hi

Please tell me which current waveform is correct. Thank you for the help.

Regards
PG

Hi PG

I am afraid that both waveforms are wrong.
But waveform 2 is closer to the right one. Only its trace between 0.1s to 0.2s is right. Its first part (from 0 to 0.1s) should be as you did. That is i(t) ~ t^2.
Your work is right but first you need to integrate from t0=0 to t=t so that you can get i(t) as a function of t. Then you find the value at 0.1s at which you got 2A which will be used to calculate the initial value (also at t=0, hence not equal to 2A) in the function of the second part (see the following line).
For the second part (from 0.1s to 0.2s), i(t) ~ -t (with the initial value at t=0, hint: you will find it equal to 4A) and as you already got, i(0.2s) = 0A.

Try to repeat your work to get the full function of i(t) for the two parts... Good Luck

Kerim

Consider that inductor current equals time integral of voltage. A linearly rising voltage thus must necessarily correspond to a quadratic increasing current.

Hi PK,

A member (Mr Howard Hansen) in Electronics_101 (a Yahoo group), has added a link I thought it can be useful to you in your free time:

Digilent Inc. - Digital Design Engineer's Source

Kerim

PS: I am not sure why edaboard says the link is for "Digital Design" because actually it is about lectures (for students) on analog instead.

Inductor behavior is complicated.

I'm a fan of the Falstad.com analog simulations. Here's the interactive java applet for an inductor, showing waveforms.

As you'll see a portion of your triangle wave is correct as post #2 stated. (You may be asked to allow network type communication. Click Okay.)

Inductor

I have videos on Youtube which portray inductor behavior dynamically. Showing flux loops, EMF icons, and current flow.

With DC pulses:

Inductor behavior with DC (Animated) - YouTube

With AC sine and square waves:

Inductor behavior with AC (Animated) - YouTube