Phase Controlled Rectifiers Practice Questions

The input voltage $\mathrm{v}(\mathrm{t})$ and current $\mathrm{i}(\mathrm{t})$ of a converter are given by, $\mathrm{v}(\mathrm{t})=300 \sin (\omega \mathrm{t})$ $\mathrm{i}(\mathrm{t})=10 \sin \left(\omega \mathrm{t}-\frac{\pi}{6}\right)+2 \sin \left(3 \omega \mathrm{t}+\frac{\pi}{6}\right)+\sin \left(5 \omega \mathrm{t}+\frac{\pi}{2}\right) \mathrm{A}$ Where, $\omega=2 \pi \times 50 \mathrm{rad} / \mathrm{s}$ . The input power factor of the converter is closest to

An ideal sinusoidal voltage source $\mathrm{V}(\mathrm{t})=230 \sqrt{2} \sin (2 \pi \times 50 \mathrm{t}) \mathrm{V}$ feeds an ideal inductor L through an ideal SCR with firing angle $\alpha=0^{\circ}$ . If $L=100 \mathrm{mH}$ , then the peak of the inductor current, in ampere, is closest to

A single-phase triac based $A C$ voltage controller feeds a series $R L$ load. The input $A C$ supply is $230 \mathrm{~V}, 50 \mathrm{~Hz}$ . The values of $\mathrm{R}$ and $\mathrm{L}$ are $10 \Omega$ and $18.37 \mathrm{mH}$ , respectively. The minimum triggering angle of the triac to obtain controllable output voltage is

The single phase rectifier consisting of three thyristors $T_{1}, T_{2}, T_{3}$ and a diode $D_{1}$ feed power to a $10 \mathrm{~A}$ 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 $\mathrm{V}_{\text {\in }}$ . The average voltage $\mathrm{V}_{o}$ across the load in volts is _____ (Round off to 2 decimal places).

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 $t=0$ sec. The duration in microseconds for which the thyristor would conduct, before it turns off, is ___ (Round off to 2 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).

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

The voltage at the input of an AC-DC rectifier is given by $v(t)=230\sqrt{2}\sin \omega t$ where $\omega = 2 \pi \times 50$ 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, _________ lag.

In the circuit shown, the input $V_{i}$ is a sinusoidal $\text{AC}$ voltage having an $\text{RMS}$ value of $230\;V\pm 20\%$ . The worst-case peak-inverse voltage seen across any diode is ____________V. (Round off to 2 decimal places.)

The waveform shown in solid line is obtained by clipping a full-wave rectified sinusoid (shown dashed). The ratio of the $\text{RMS}$ value of the full-wave rectified waveform to the $\text{RMS}$ value of the clipped waveform is _______________. (Round off to 2 decimal places.)

A single-phase, full-bridge diode rectifier fed from a 230 V, 50 Hz sinusoidal source supplies a series combination of finite resistance. R, and a very large inductance, L, The two most dominant frequency components in the source current are:

A single-phase, full-bridge, fully controlled thyristor rectifier feeds a load comprising a 10 $\Omega$ resistance in series with a very large inductance. The rectifier is fed from an ideal 230 V, 50 Hz sinusoidal source through cables which have negligible internal resistance and a total inductance of 2.28 mH. If the thyristors are triggered at an angle $\alpha = 45^{\circ}$ , the commutation overlap angle in degree (rounded off to 2 decimal places) is_____.

Consider the diode circuit shown below. The diode, D, obeys the current-voltage characteristic $I_D=I_S\left ( exp\left ( \frac{V_D}{nV_T} \right )-1 \right )$ , where $n \gt 1, V_T \gt 0, V_D$ is the voltage across the diode and $I_D$ is the current through it. The circuit is biased so that voltage, $V \gt 0$ and current, $I \lt 0$ . If you had to design this circuit to transfer maximum power from the current source ( $I_1$ ) to a resistive load (not shown) at the output, what values $R_1 \; and \; R_2$ would you choose?

Thyristor $T_1$ is triggered at an angle $\alpha$ (in degree), and $T_2$ at angle $180^{\circ} + \alpha$ , in each cycle of the sinusoidal input voltage. Assume both thyristors to be ideal. To control the load power over the range 0 to 2 kW, the minimum range of variation in $\alpha$ is:

A six-pulse thyristor bridge rectifier is connected to a balanced three-phase, 50Hz AC source. Assuming that the DC output current of the rectifier is constant, the lowest harmonic component in the AC input current is

A fully-controlled three-phase bridge converter is working from a 415V, 50 Hz AC supply. It is supplying constant current of 100 A at 400 V to a DC load. Assume large inductive smoothing and neglect overlap. The rms value of the AC line currentin amperes (round off to two decimal places) is ________.

A single-phase fully-controlled thyristor converter is used to obtain an average voltage of 180 V with 10 A constant current to feed a DC load. It is fed from single-phase AC supply of 230 V, 50 Hz. Neglect the source impedance. The power factor (round off to two decimal places) of AC mains is________

A phase controlled single phase rectifier, supplied by an AC source, feeds power to an R-L-E load as shown in the figure. The rectifier output voltage has an average value given by $V_{0}=\frac{V_{m}}{2 \pi}(3+ \cos \alpha),$ where $V_{m}=80\pi$ volts and $\alpha$ is the firing angle. If the power delivered to the lossless battery is 1600 W, $\alpha$ in degree is________ (up to 2 decimal places).

The waveform of the current drawn by a semi-converter from a sinusoidal AC voltage source is shown in the figure. If $I_0$ =20 A, the rms value of fundamental component of the current is ___________A (up to 2 decimal places).