List of top Power Electronics and Drives Questions asked in GATE EE

The circuit shown in the figure has reached steady state with thyristor $T$ in OFF condition. Assume that the latching and holding currents of the thyristor are zero. The thyristor is turned ON at $t=0 \, \text{sec}$. The duration in microseconds for which the thyristor would conduct, before it turns off, is ................. (Round off to 2 decimal places). \begin{center} \includegraphics[width=0.45\textwidth]{27.jpeg} \end{center}

The single-phase rectifier consisting of three thyristors $T_1, T_2, T_3$ and a diode $D_1$ feed power to a 10 A constant current load. $T_1$ and $T_3$ are fired at $\alpha = 60^\circ$ and $T_2$ is fired at $\alpha = 240^\circ$. The reference for $\alpha$ is the positive zero crossing of $V_{in}$. The average voltage $V_O$ across the load in volts is ............ (Round off to 2 decimal places). \begin{center} \includegraphics[width=0.5\textwidth]{29.jpeg} \end{center}

All the elements in the circuit shown in the following figure are ideal. Which of the following statements is/are true? \begin{center} \includegraphics[width=0.65\textwidth]{21.jpeg} \end{center}

A semiconductor switch needs to block voltage $V$ of only one polarity ($V > 0$) during OFF state as shown in figure (i) and carry current in both directions during ON state as shown in figure (ii). Which of the following switch combination(s) will realize the same? \begin{center} \includegraphics[width=0.5\textwidth]{10.jpeg} \end{center}

The chopper circuit shown in figure (i) feeds power to a 5 A DC constant current source. The switching frequency of the chopper is $100 \,\text{kHz$. All the components can be assumed to be ideal. The gate signals of switches $S_{1}$ and $S_{2}$ are shown in figure (ii). The average voltage across the 5 A current source is:} \begin{center} \includegraphics[width=0.5\textwidth]{08.jpeg} \end{center}

The voltage at the input of an AC-DC rectifier is given by $ v(t) = 230\sqrt{2} \sin(\omega t) $ where $ \omega = 2\pi \times 50 \, \text{rad/s} $. The input current drawn by the rectifier is given by \[ i(t) = 10 \sin\left(\omega t - \frac{\pi}{3}\right) + 4 \sin\left(3\omega t - \frac{\pi}{6}\right) + 3 \sin\left(5\omega t - \frac{\pi}{3}\right) \] The input power factor (rounded off to two decimal places) is _________.

A 3-phase grid-connected voltage source converter with DC link voltage of 1000 V is switched using sinusoidal Pulse Width Modulation (PWM) technique. If the grid phase current is 10 A and the 3-phase complex power supplied by the converter is given by $ (-4000 - j3000) \, \text{VA $, then the modulation index used in sinusoidal PWM is _________. (round off to two decimal places)}

The steady state current flowing through the inductor of a DC-DC buck boost converter is given in the figure below. If the peak-to-peak ripple in the output voltage of the converter is 1 V, then the value of the output capacitor, in μF, is _________. (round off to nearest integer)

Consider an ideal full-bridge single-phase DC-AC inverter with a DC bus voltage magnitude of 1000 V. The inverter output voltage $ v(t) $ shown below, is obtained when diagonal switches of the inverter are switched with 50% duty cycle. The inverter feeds a load with a sinusoidal current given by, $ i(t) = 10 \sin(\omega t - \frac{\pi}{3}) $ A, where $ \omega = \frac{2\pi}{T} $. The active power, in watts, delivered to the load is ________. (round off to nearest integer)

For the ideal AC-DC rectifier circuit shown in the figure below, the load current magnitude is $ I_{\text{dc}} = 15 \, \text{A} $ and is ripple free. The thyristors are fired with a delay angle of 45°. The amplitude of the fundamental component of the source current, in amperes, is ________. (round off to two decimal places)

A single-phase full-bridge diode rectifier feeds a resistive load of 50 $\Omega$ from a 200 V, 50 Hz single-phase AC supply. If the diodes are ideal, then the active power, in watts, drawn by the load is _________. (round off to nearest integer)

A charger supplies 100 W at 20 V for charging the battery of a laptop. The power devices, used in the converter inside the charger, operate at a switching frequency of 200 kHz. Which power device is best suited for this purpose?

A boost converter operates at 25 kHz with a duty cycle 0.6. Input is 15 V, load is 10 $\Omega$. Assuming ideal components, compute the equivalent input resistance $R_{in}$ seen by the source. (Round off to 2 decimal places.)

Consider the buck-boost converter shown. Switch Q operates at 25 kHz with a duty-cycle of 0.75. Assume diode and switch are ideal. Under steady-state, the average current flowing through the inductor is $\underline{\hspace{1cm}}$ A.

A single-phase full-bridge inverter fed by a 325 V DC produces a symmetric quasi-square waveform across 'ab' as shown. To achieve a modulation index of 0.8, the angle $ \theta $ expressed in degrees should be $\underline{\hspace{2cm}}$ .
(Round off to 2 decimal places.)
(Modulation index is defined as the ratio of the peak of the fundamental component of $ v_{ab} $ to the applied DC value.)