Question

Is N N Vo V's Vo Vs LOAD LOAD Figure 1 It has been shown in lectures that from the equality of power generation and power consumption, and as far as the average input/output voltages and currents are concerned, the buck and boost converters' operation in CCM (continuous current mode) are similar to the operation of the ideal AC transformers. So these converters may be considered as "ideal DC transformers". A buck converter operates with a duty cycle D 0.4, L 500 uH, C = 100 uF, and a switching frequency f= 20 kHz. Assuming that the source voltage is Vs 24 V and the load resistance is R= 20 Q, determine: a) the turns ratio n = N2 /N1 of this ideal DC transformer; b) the average output voltage Vo; the average input Is and output Io currents from the properties of ideal transformers; c) d) the power consumption Pi; e) at what value of the load resistance R will this buck converter stop operating as an ideal DC transformer? Hint determine_the_boundary between CCM and DCM (discontinuous qurrent moge)

Answer 1

Sol:- =7'hoニ R- 20n f aoktz Buck Converter: autput Hge Vo-Dys VIVS DVS てN - N2 outpet votge htxho 9 (l Outrut atrents T 0.48 T h.oxtroST (P) Poutey Grg.conption 9.6ス9-b

Rca- 33-23 9-7 olx 91 E 200 L(a-i) 2L (al ID 4TL Panap una ay Ccm