Power Elec

Description

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, 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 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, ΔI
• Peak current of inductor, I2
• Ripple voltage of filter capacitor, Vc

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 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, 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%