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 Vs = 220V. When the chopper switch remains on, its voltage drop vch = 4V and the chopping frequency is f = 2kHz. If the duty cycle is 50%, determine the;

  • Average output voltage, Va
  • Rms output voltage, VO
  • Chopper efficiency
  • Effective input resistance of the chopper, Ri
  • Rms value of the fundamental component of output harmonic voltage

2. A buck regulator has an input voltage of VS = 10V. The average output voltage , Va = 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, ΔI
  • Peak current of inductor, I2
  • Ripple voltage of filter capacitor, Vc

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

  • Minimum instantaneous current I1
  • Peak instantaneous load current, I2
  • Maximum peak-to-peak load ripple current
  • Average value of load current, Ia
  • Rms load current, Io
  • Effective input resistance seen by the source, Ii
  • Rms chopper current, IR

4. A chopper has a load resistance, R= 0.30Ω, VS = 500V, E= 0V. The average load current, Ia=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%.