Question

In the figure shown below, the duty ratio of buck converter is $D_1$ and the duty ratio of boost converter is $D_2$. The input voltage of buck converter is 10V and the output voltage of boost converter is 30 V. Which of the following equation satisfies the correct relation between $D_1$ and $D_2$ ?

• A. $D_2$ = 3$D_1$
• B. $D_2$ + 3$D_1$ = 3
• C. $D_1$ + 3$D_2=3$
• D. $D_1$ = 3$D_2$

Answer 1

The correct option is C $D_1$ + 3$D_2=3$

Let, $V_1$= Output of buck converter = Input of boost converter
$V_1$ = 10$D_1$

Output of boost converter $=30V=\frac{V_1}{1-D_2}$

$30=\frac{10D_1}{1-D_2}$

or $3-3D_2=D_1$

or $D_1+3D_2=3$