2. For the push-pull converter: a) Sketch the voltage waveform vLx, and b) Derive the expression for output voltage on the basis that the average inductor voltage is zero.

Fina l-Exam : Power Electronics Academic Year: 202 1-2022 Group: I4GEE (E E and EA) Date: Friday, 4 th 2022 Venue: MSTeam Problem s: 1. A forward converter has the following parameters: Vs = 170 V, N1/N 2 = 10, N1/N3 = 1, Lm = 340 µH, Lx = 20 µH, R = 10 Ω, C = 10 µF, D = 0.3, and the switching frequenc y is 500 kHz. a) Why does this converter need to operate in high frequency? b) Determine the expression of output voltage by using two different methods c) Determine the expression of output voltage ripple d) By using the provided data, sketch all the waveforms of cur rents (iLx, i1, i2, i3, iLm, and is) which correspon d to the real values in this problem. 2. For the push -pull converter : a) Sketch the voltage waveform vLx, and b) Derive the expression for output voltage on the basis that the average inductor voltage is zero. 3. A Buck converter has an input of 6V and an output of 1.5V. The load resis tor is 3 Ω, the sw itching frequency is 400 kHz , L = 5 µH and C = 10 µF. c) Determi ne the duty ratio d) Determine the average , peak and rms inductor current e) Determine average source current f) Determi ne the peak and average diode current. 4. a) Dra w a 3 -phase diode rectifier for resistive load b) Sket ch input volta ge waveforms Van, Vbn , and Vcn c) Sket ch the output line -to-line voltage d) What is the electrical period of output volt age? e) What is the exp res sion of an output angular frequ ency as function of input angular frequency ?