# Power Electronics

I don’t understand this Engineering question and need help to study.

1. A DC chopper has a resistive load of 20 ohms and input voltage V_{s} = 220V. When the chopper switch remains on, its voltage drop *v*_{ch} = 4V and the chopping frequency is f = 2kHz. If the duty cycle is 50%, determine the;

- Average output voltage, V
_{a} - Rms output voltage, V
_{O} - Chopper efficiency
- Effective input resistance of the chopper, R
_{i} - Rms value of the fundamental component of output harmonic voltage

2. A buck regulator has an input voltage of V_{S} = 10V. The average output voltage , V_{a} = 20V and the average load current, Ia_{ = }0.8A. The switching frequency is 20kHz. If L= 200µH and C = 240µF, determine the;

- Duty cycle, k
- Ripple current of inductor, Δ
*I* - Peak current of inductor,
*I*_{2} - Ripple voltage of filter capacitor, V
_{c}

3. A chopper is feeding an RL load with V_{s} = 220V, R = 15Ω, L = 10mH, f = 1.5kHz and E= 0V. Calculate the;

- Minimum instantaneous current I
_{1} - Peak instantaneous load current, I
_{2} - Maximum peak-to-peak load ripple current
- Average value of load current, I
_{a} - Rms load current, I
_{o} - Effective input resistance seen by the source, I
_{i} - Rms chopper current, I
_{R}

4. A chopper has a load resistance, R= 0.30Ω, V_{S} = 500V, E= 0V. The average load current, I_{a}=150A, and chopping frequency, f= 500 Hz. Use the average output voltage to calculate the load inductance, L, which would limit the maximum load ripple current by20%.