Consider a simple defibrillator consisting of a capacitor which discharges across the two associated with the patient's chest electrodes in a period of 150 ms to about 5% of the fully charged voltage of the capacitor. The resistance of the chest between the electrodes amounts to about 100 Ω and the energy required for defibrillation be 200 J.
Since the voltage V0 of the battery is lower than the capacitor voltage required, it must be upconverted. One potential avenue a so-called step-up converter.
The switch S opens and closes periodically, where he closed a share g of the period and a fraction 1 - g is open. The period should be very small compared to the time constant of the capacitor-resistor system. The quantity g is called duty cycle.
The high-impedance resistor R represents the resistive behavior of the capacitor. All components must be assumed to be ideal.
Task (1):Estimate the capacitance of the capacitor and what voltage it needs to be charged for the operation at least.
Task (2):Derive is an expression for the maximum adjusting capacitor voltage after some time, depending on the sizes which occur.
2. The attempt at a solution
I don`t know how I should estimate the capacitance of the capacitor.
I can determine the voltage with this equation:
Value of the output voltage is greater than the input voltage
I can be derived, the output voltage across the inductor electricity:
ΔIL = (1/L) Ue t1 = (1/L)(Ua-Ue)(T-t1)
Is this right?
It would be very nice if somebody could help me.