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6 . POWER ELECTRONICS f BUCK Comveare® eeaes | 545 This problem is intended to familiarize you with one of the basic switching de-to-de converters--the buck converter (Fig. 1), fundamentals of its operation, assumptions usually made and practical limitations. + WM - & Fig. 1 Buck Switching dce-to-de Converter switched ° Switch $ is,periodically for interval DTs in position A and for interval D'T, = {1-D) T; fn position B, where f, 4 VT, is the switching frequency and D is defined as switch duty ratio. I. Let C=0 a. After a large number of cycles the inductor current becomes periodic and the steady-state is established as shown in Fig. 2. From the fundamental differential equations determine exactly the current levels I, and Ip characterizing this steady state. b. By assuming that R/L << f, 4n your answer to part (a) find the average inductor current I and determind an approximation to the inductor current ripple Ail 4 I,-l,- c. Qbtain an expression for the relative magnitude of the output voltage switching ripple aV/V. -y I, 
