sorry if I sound little noobish. Though I have a fairly good understanding of physics, I sometimes don't understand the electrical aspects.
Say there is a capacitor. This capacitor is expected to act as a storage buffer. By extension, the capacitor will have a "charge" interface and a "discharge" interface. There may or may not be an electrical circuit between these interfaces and the capacitor. The expected behavior of the system is, electrical energy may be input to the system via the charge interface, which will charge the capacitor, and energy may be simultaneously drawn also, via the discharge interface, which will draw energy from the capacitor, and this process can happen so long as the energy stored within the capacitor is within its maximum and zero. The actual path of the energy may be from the interface, through the circuit, to the capacitor, and back through the circuit to the other interface; or part of the energy may be routed from one interface to the other by the circuit, and the net energy difference between the two interfaces be actually sent to, or drawn from the capacitor.
Though I may think that this is possible, I'm not aware if any such system exists currently. The home inverter seems to be doing quite the same thing, but both the cycles don't happen at the same time though.
Edit: Yeah, a diagram will help me also to explain better what I have in mind.
The two interfaces are part of the circuit which shields the capacitor. This circuit may work in two possible ways, which I've mentioned as flow 1 and flow 2. In Flow 1, "all" of the energy which flows into/out of the system, does so through the capacitor. In Flow 2, the circuit redirects part of the energy flow in one interface to the other interface, and only the net difference between the energy flows is actually transmitted to/from the capacitor.
Hope this makes it more clear. Now, let me restate my question. Is such a system possible, importantly, such a circuit possible. Are any systems available today, which do exactly the same thing. And your own views on this is really welcome.
Best Answer
If at time $t_0$, the voltage across an unconnected capacitor is $V_0$, then the capacitor will charge if an externally applied voltage $V_B > V_0$ in a circuit or will discharge if $V_B < V_0$. One can't do both at the same time.
As an analogy, one can't simultaneously raise and lower the quantity of water in a tank, even though one might simultaneously add water to and drain water from a tank.