I was modelling a RLC-paralell network in ORCAD to simulate its natural response.
A natural response is the discharging of either the capacitor or the inductor (or both) when they are brought to some DC-value and the source is cut off.
What I find strange is an abrupt change of the voltage across the capacitor. I expected an exponential waveform for the voltage, but the voltage "jumped".
How much resistance do you have in your model? And where?
The waveform is a damped sinusoid and the voltage across the cap will not change instantaneously. You must include some resistance in series with the inductance to insure that the initial conditions do not include an infinite current in the inductor. Without series resistance the exitation voltage is divided by zero and most computer programs do not like that. It sounds like the program is having trouble with your model. Bob
kristine wrote: > I was modelling a RLC-paralell network in ORCAD to simulate its > natural response. >
Is this "DC-value" a current source driving the RLC parallel network? A voltage source will not work very well because L must be 0VDC.
What are your L , C, and time scale? The capacitor voltage will go from ~ +100mV and possibly dip negative in a half sinusoidal waveshape before exponentially approaching 0V. If your time scale is too large compared to sqrt(LC), then this may be the jump you are seeing.
I've tried different resistor values and different sources.
In the inductor path there is a resistance of 1 Ohm, the paralell branch has
10 Ohm. There is also a 10 Ohm resistance in series with the source (a VPULSE initially at 1 V falling to zero by some picoseconds).It still changes the voltage abruptly across the capacitor !?
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