Question

Consider a two-stage DC-DC converter, as shown in Fig. 1 iL RL rca Vi Viz Vcz Stage #1 Stage #2 i . Identify the type of converters in Stage #1 and Stage #2 (selecting from buck or boost). Meanwhile, identify if they are ideal converters or nonideal converters. If nonideal, please identify the potential power losses 2. Consider the switch position below, derive the corresponding transfer functions. Consider the load as Zoad Switch Position #1 in Stage #1 + Switch Position #1 in Stage #2 1) Gi(s) Vi2(s)/Vi(s) 2) G2(s) Vo2(s)/V2(s) 3) Zo(s) Vo2(s)//o2(s) Switch Position #2 in Stage #1 + Switch Position #1 in Stage #2 1) Gi(s) Vi2(s)/Vi(s) 2) G2(s) = V02(s)/Vids) 3) Zo(s) Vo2(s)//o2(s)

Answer 1

1.In both the stages the converters are Buck converters.They are non-ideal since internal resistance is given for inductor and capacitor in stages 1 and 2 respectively.The potential power losses are ohmic losses in R_L1 and r_C1.

2.Transfer functions for the given conditions are derived as follows.(All circuit parameters are converted into lapalce transforms)

キScotih Position #lin Stag+1 k with position fiage z - t(s) (さ CS) pplying vortage dliviston vule in stage1 cncvit i(S) CS G,CS Li C dis ion ule in Noo applying voltage Stage 2 crit, By applying curent division nue in parallei lbaueh at load side 12 (5) o2(3) 750ith psition #2in stage.! : #1 in star 2 clearty Vo9)- o Vi2CS) R SL No2(5) sre2+ 'bad 102( s) Scanned by CamScanner