Question:
A forced commutated thyristorized step-down chopper is shown. Neglect the ON-state drop across power devices. Assume that the capacitor is initially charged to 50 V with the polarity
shown in the figure. The load current
\(I_l\)
can be assumed to be constant at 10 A. Initially,
\(Th_M\)
is ON
and
\(ThA\)
is OFFThe turn-off time available to \( T_{H4} \) in microseconds, when \( T_{H4} \) is triggered, is \_\_\_\_\_ (rounded off to the nearest integer).
\includegraphics[width=0.5\linewidth]{35.png}
A forced commutated thyristorized step-down chopper is shown. Neglect the ON-state drop across power devices. Assume that the capacitor is initially charged to 50 V with the polarity
shown in the figure. The load current
\(I_l\)
can be assumed to be constant at 10 A. Initially,
\(Th_M\)
is ON
and
\(ThA\)
is OFFThe turn-off time available to \( T_{H4} \) in microseconds, when \( T_{H4} \) is triggered, is \_\_\_\_\_ (rounded off to the nearest integer).
\includegraphics[width=0.5\linewidth]{35.png}
\includegraphics[width=0.5\linewidth]{35.png}
Show Hint
In chopper circuits, the capacitor's discharge time determines the turn-off duration for the thyristor.
Updated On: Jan 23, 2025
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Solution and Explanation
Given:
\[
C = 10 \, \mu F, \quad V_S = 50 \, \text{V}, \quad I_L = 10 \, \text{A}
\]
Step 1: Time constant for capacitor discharge:
\[
t_c = \frac{CV_S}{I_L}
\]
\[
t_c = \frac{10 \times 10^{-6} \times 50}{10} = 50 \, \mu s
\]
Final Answer: The turn-off time is \( 50 \, \mu s \).
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