GATE 2019 EE – Question 35
The output voltage of a single-phase full bridge voltage source inverter is controlled by unipolar PWM with one pulse per half cycle. For the fundamental rms component of output voltage to be 75% of DC voltage, the required pulse width in degrees (round up to one decimal place) is ________.
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Correct answer: 113
Explanation
For a centred pulse of width $\beta$ per half cycle, the fundamental rms is $\frac{2\sqrt2}{\pi}V_{dc}\sin\frac\beta2=0.75V_{dc}$. So $\sin\frac\beta2=0.833$, $\frac\beta2=56.4^\circ$ and $\beta\approx112.9^\circ$.