discharge calculations

Discussion in 'General Electronics Chat' started by saturatEd, Nov 20, 2008.

  1. saturatEd

    Thread Starter New Member

    Nov 12, 2008

    This is a question ideal for homework section, but since I'm just doing this out of hobby, I guess it does not belong there.

    I'm trying to find a way to get the right equation for a certain situation.

    Here is the circuit:


    First of all ignore the values of voltage, capacitance etc, I just used these in a circuit simulation program, to draw the schematics. Also, the other voltage source is simply used to charge the capacitor, it is not used during discharge, so ignore it.

    The circuit is suppose to use a slightly underdamped discharge to turn of a thyristor. It does successfully in simulations, but I'd like a way to quantify the results and know exactly the current every moment.

    Below is the diagram is the formula for an RLC discharge circuit, but it assumes no other sources of voltage.

    The problem here is at the beginning of the discharge I have certain current passing through the resistor through the thyristor. And in simulations it visibly alters the discharge, and slows it down a bit until the current rises enough to shut down the thyristor, then the system is just a basic RLC discharge circuit.

    Can someone help me to formulate the right expressions for the current as a function of time in such a system?