Post History
maximum input current (IL1) reaches to 321mA in the simulation which is decided by V1/2 x π x f x L1 (f being resonant frequency). Given that both capacitor and inductor have equal magnitude i...
#3: Post edited
by
Andy aka
·
2025-06-30T20:33:58Z (about 1 year ago)
> why total impedance seen by V1 is not addition of inductor and capacitor impedances but only inductor impedance?- **Impedance** is a steady state AC parameter and it's much more mathematically complicated when circuits are driven with a transient voltage step change. You need to use Laplace transforms for example.
- > In series LC resonance both impedances (XL=XC) cancel each other then how come current does not reach infinity ?
- Because your input voltage is a transient step change and not a continuous sinewave at the resonant frequency.
- > maximum input current (IL1) reaches to 321mA in the simulation which is decided by V1/2 x π x f x L1 (f being resonant frequency).
- Given that both capacitor and inductor have equal magnitude impedance at resonance, you can also see that the same formula applies for the capacitive reactance. So, what is your point exactly? You found a formula that worked and stopped right there without delving more deeply? Maximum current also occurs when the capacitor voltage also equals the input step voltage (and inductor voltage is zero). All these things are related and a little bit more complicated than just simple observations.
- > why total impedance seen by V1 is not addition of inductor and capacitor impedances but only inductor impedance?
- **Impedance** is a steady state AC parameter and it's much more mathematically complicated when circuits are driven with a transient voltage step change. You need to use Laplace transforms for example.
- > In series LC resonance both impedances (XL=XC) cancel each other then how come current does not reach infinity ?
- Because your input voltage is a transient step change and not a continuous sinewave at the resonant frequency.
#2: Post edited
by
Andy aka
·
2025-06-30T12:42:46Z (about 1 year ago)
- > why total impedance seen by V1 is not addition of inductor and capacitor impedances but only inductor impedance?
**Impedance** is a steady state AC parameter and is irrelevant for circuits driven with a transient step change.- > In series LC resonance both impedances (XL=XC) cancel each other then how come current does not reach infinity ?
- Because your input voltage is a transient step change and not a continuous sinewave at the resonant frequency.
- > why total impedance seen by V1 is not addition of inductor and capacitor impedances but only inductor impedance?
- **Impedance** is a steady state AC parameter and it's much more mathematically complicated when circuits are driven with a transient voltage step change. You need to use Laplace transforms for example.
- > In series LC resonance both impedances (XL=XC) cancel each other then how come current does not reach infinity ?
- Because your input voltage is a transient step change and not a continuous sinewave at the resonant frequency.
#1: Initial revision
by
Andy aka
·
2025-06-30T12:40:46Z (about 1 year ago)
> why total impedance seen by V1 is not addition of inductor and capacitor impedances but only inductor impedance? **Impedance** is a steady state AC parameter and is irrelevant for circuits driven with a transient step change. > In series LC resonance both impedances (XL=XC) cancel each other then how come current does not reach infinity ? Because your input voltage is a transient step change and not a continuous sinewave at the resonant frequency.