Question

Consider a phase-controlled converter shown in figure. The thyristor is triggered at an angle $\alpha$ in every positive half cycle of the input voltage. If the peak value of the instantaneous output voltage is 200 V, then the firing angle $\alpha$ is

Answer 1

$V_{0}sin\omega t=200V$ at firing angle $\alpha$

$sin\alpha =\frac{200}{200\sqrt{2}}$

$\alpha =si{n}^{-1}\left(\frac{1}{\sqrt{2}}\right)={45}^{\circ }or{135}^{\circ }$

If $\alpha ={45}^{\circ }$ then peak value of instantaneous output voltage is $200\sqrt{2}V$. But given peak value of instantaneous output voltage is 200 V, which means thyristor has been triggered at

$\alpha ={135}^{\circ }$