Problems with Solutions for Power Electronics | ECE 481, Assignments of Electrical and Electronics Engineering

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19-1 Exercise 19 Step-down/Up de-de (Buck-Boost) Converter 4 in _ Vv q - d + | v 3h C= R, L L ; ° load ~ ~ t ‘cA + Nominal Values: Va =8.5V L=10uH r= 10mQ2 C= 100yF Rload = 8 2 fs = 100 kHz switch duty ratio D = 0.75 Problems 1. In steady state, obtain the following waveforms using Buck-Boost: (a) vLandiL (b) Vo, ig and ig. Obtain ip waveform and by means of Fourier analysis, obtain its harmonic components as a ratio of its average value Ip. Increase the load resistance to 80 2. Obtain vi, and if, waveforms in the discontinuous conduction mode [Hint: use V(o) = 28 V and IL(O) = 0]. Check if the results agree with the analytical calculations. After 10 ms, change the load resistance as a step from its nominal value of 8 Q to 80 Q. Obtain vl, iL and vp waveforms as they reach their new steady state values. Obtain the peak-to-peak ripple in the output voltage and check to see if the results agree with analytical calculations. Calculate the rms value of the current through the output capacitor as a ratio of the average load current Ip. Reference: Section 7-5, pages 178 - 184.