DC-DC Switch-Mode Supply Average output voltage Discontinuous or continuous mode of operation Ripple output voltage TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: AAAAA A A

DC-DC Switched Converter TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: AA

We can use Maple to solve for the six constants. The script can be run in Maple with: restart; currentdir("C:\\wattle\\courses\\PowerElectronics\\maple\\"); read "switchedDCrippleJuly2007.ma"; The pScpice script is: Fig7-4aDC2DC.sch

## Description: Step-down dc-dc converter Figure 7-4(a), page Power Electronics - Mohan, Undeland, and Robbins. ## The pSpice file to simulate the same circuit is Fig7-4aDC2DC.sch in pSpice/switchedMode ##restart; currentdir("C:\\wattle\\courses\\PowerElectronics\\maple\\"); read "switchedDCrippleJuly2007.ma"; Vin:=20: Dcyc:=0.5; #Duty Cycle T := 20*10^(-6): ton:=T*Dcyc: toff:= (1-Dcyc)*T: Rl:=100: Ls:=0.001: Cf:=0.0225*10^(-6); # lambda[1]:= ((-Ls/Rl)+sqrt(Ls*(Ls-4*Rl^2*Cf))/Rl)/(2*Ls*Cf): #roots of the characteristic equations lambda[2]:= ((-Ls/Rl)-sqrt(Ls*(Ls-4*Rl^2*Cf))/Rl)/(2*Ls*Cf): vcon:=t->Vin + k[1]*exp(lambda[1]*t) + k[2]*exp(lambda[2]*t); vcond:=unapply(diff(vcon(t),t),t); vcoff:=t->k[3]*exp(lambda[1]*t) + k[4]*exp(lambda[2]*t); vcoffd:=unapply(diff(vcoff(t),t),t); eq[1]:=vcon(0)=vc0; eq[2]:=vcond(0)=vc0d; eq[3]:=vcon(ton)=vcoff(0); eq[4]:=vcond(ton)=vcoffd(0); eq[5]:=vcoff(toff)=vc0; eq[6]:=vcoffd(toff)=vc0d; sol:=solve({eq[ieq] $ieq=1..6},{vc0,vc0d,k[ik] $ik=1..4}); VoltageRipple:=subs(sol,vcon(ton)-vcon(0));

Tutorial Problems Feel free to solve these problems using Maple, Maxima, or pSpice.