Question

The fully controlled thyristor converter in the figure is fed from a single-phase source. When the firing angle is 0°, the dc output voltage of the converter is 300 V. What will be the output voltage for a firing angle of 60°, assuming continuous conduction?

• A. 210 V
• B. 300 V
• C. 100 $\pi V$
• D. 150 V

Answer 1

The correct option is D 150 V

For firing angle, $\alpha$, average output voltage of the converter is given by

$V_0=\frac{2V_m}{\pi }\cos \alpha$

when, $\alpha =0{}^{\circ }$

$V_0=\frac{2V_m}{\pi }\cos 0{}^{\circ }=300$

$\frac{2V_m}{\pi }=300$
when, $\alpha =60{}^{\circ }$

$V_0=\frac{2V_m}{\pi }\cos 60{}^{\circ }$
= 300 cos60° = 150 V