I'm given a full bridge rectifier circuit with values for power, industance, and RMS input voltage: [P = 380 W, L = 85 uH, Vs = 115 V].

The question states to 'select' output resistance for a simulation, but I am unsure if it's possible to calculate this. It might be that it is asking to select an arbitrary number.

I'm guessing that it can be calculated using:

$$

R = V_s^2/P = 34.8 \varOmega

$$

I am wondering if the voltage drop across the inductor can be omitted at steady state. Is this the correct way one would determine the load resistance?

## Best Answer

Assuming negligible losses in the inductor and rectifier and a low value for C, your calculation is good.

As the source is 115V I'm assuming the frequency is 60Hz, so L has a reactance of 0.032Ω - insignificant compared to R. Assuming silicon diodes with suitable ratings the rectifier should be dropping about 1.4V - again an insignificant amount.

The capacitor is a wild card - if large enough to hold the voltage up between peaks then DC output voltage could get close to 160V, and R might have to be much higher (67Ω?).