Sheet 4
Exercise 1:
The buck dc-dc converter of Fig. 1 a has the following parameters:
Figure 1
Assuming ideal components, calculate (a) the output voltage Vo, ( b) the maximum and
minimum inductor current, and (c) the output voltage ripple.
Imin=0.25
was vaild.
0 the assumption of CCM
∆
∆
1
8
1.75
0.25
1.5
VL=Ldil/dt
∆
∗ 1
Exercise 2:
Buck Converter Design:
Design a buck converter to produce an output voltage of Vo=18 V across a R=10Ω load resistor.
The output voltage ripple must not exceed 0.5 percent (∆
/
. The dc supply is Vin=48 V.
Design for continuous inductor current. Specify the duty ratio, the switching frequency, the
values of the inductor L and capacitor C, the peak voltage rating of each device, and the rms
current in the inductor and capacitor. Assume ideal components.
Vo=D.Vin=D*Vs in CCM
L Lmin CCM
L
Average current IL=Vo/R
DCM
2
Peak capacitor current=delta IL/2
IC,rns=Ipeak capacitor/sqrt(3)