Single and Three Phase Rectifier · Power Electronics · GATE EE
Marks 1
1
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).
GATE EE 2022
2
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
$$i(t) = 10\sin \left( {\omega t - {\pi \over 3}} \right) + 4\sin \left( {3\omega t - {\pi \over 6}} \right) + 3\sin \left( {5\omega t - {\pi \over 3}} \right)$$
The input power factor, (rounded off to two decimal places), is _________ lag.
GATE EE 2022
3
The waveform of the current drawn by a semi-converter from a sinusoidal AC voltage
source is shown in the figure. If I0 = 20 A, the rms value of fundamental component of the
current is ___________A (up to 2 decimal places).
GATE EE 2018
4
A single phase fully controlled rectifier is supplying a load with an anti-parallel diode as
shown in the figure. All switches and diodes are ideal. Which one of the following is true
for instantaneous load voltage and current?
GATE EE 2018
5
A phase-controlled, single-phase, full-bridge converter is fed from a $$230$$ $$V,$$ $$50$$ $$Hz,$$ $$AC$$ source. The fundamental frequency in $$Hz$$ of the voltage ripple on the $$DC$$ side is
GATE EE 2017 Set 2
6
In the circuit shown, the diodes are ideal, the inductance is small, and $${{\rm I}_0} \ne 0.$$ Which one of the following statements is true?
GATE EE 2017 Set 2
7
The figure below shows the circuit diagram of a controlled rectifier supplied from a $$230V,$$ $$50$$
$$Hz,$$ $$1$$-phase voltage source and a $$10:1$$ ideal transformer. Assume that all devices are ideal. The
firing angles of the thyristors $${T_1}$$ and $${T_2}$$ are $${90^ \circ }$$ and $${270^ \circ },$$ respectively.
The $$RMS$$ value of the current through diode $${D_3}$$ in amperes is ________________.
GATE EE 2017 Set 2
8
A half-controlled single-phase bridge rectifier is supplying an $$R$$-$$L$$ load. It is operated at a firing angle $$α$$ and the load current is continuous. The fraction of cycle that the freewheeling diode conducts is
GATE EE 2012
9
The fully controlled thyristor converter in the figure is fed from a single-phase source. When the firing angle is $${0^ \circ }$$, the $$dc$$ output voltage of the converter is $$300V.$$ What will be the output voltage for a firing angle of $${60^ \circ }$$, assuming continuous conduction?
GATE EE 2010
10
A single $$-$$ phase fully controlled thyristor bridge $$ac$$ $$-$$ $$dc$$ converter is operating at a firing angle of $${25^ \circ }$$ and an overlap angle of $${10^ \circ }$$ constant $$dc$$ output current of $$20$$ $$A$$. The fundamental power factor (displacement factor) at input $$ac$$ mains is
GATE EE 2007
11
A single phase full $$-$$ wave half $$-$$ controlled bridge converter feeds an inductive load. The two $$SCR's$$ in the converter are connected to a common $$DC$$ bus. The converter has to have a free wheeling diode
GATE EE 2007
12
A single $$-$$ phase half wave uncontrolled converter circuit is shown in figure. A $$2$$ -winding transformer is used at the input for isolation. Assuming the load current to be constant and $${V_{in}} = {V_m}$$ $$\,\sin \omega t,$$ the current waveform through diode $${D_2}$$ will be
GATE EE 2006
13
A three - phase diode bridge rectifier is fed from a $$400$$ $$V$$ $$RMS$$. $$50$$ $$Hz$$, three $$-$$ phase $$AC$$ source. If the load is purely resistive, then peak instantaneous output voltage is equal to
GATE EE 2005
14
The circuit in figure shows a full-wave rectifier. The input voltage is $$230$$ $$V$$ $$(rms)$$ single-phase ac. The peak reverse voltage across the diodes $${D_1}$$ and $${D_2}$$ is
GATE EE 2004
15
The circuit in figure shows a $$3$$ $$-$$ phase half $$-$$ wave rectifier. The source is a symmetrical, $$3$$ $$-$$ phase four $$-$$ wire system. The line-to-line voltage of the source is $$100 V.$$ The supply frequency is $$400$$ $$Hz.$$ The ripple frequency at the output is
GATE EE 2004
16
A fully controlled natural commuted $$3$$-phase bridge rectifier is operating with a firing angle $$\alpha = {30^0}.$$ The peak to peak voltage ripple expressed as a ratio of the peak output $$dc$$ voltage at the output of the converter bridge is
GATE EE 2003
17
A six pulse thyristor rectifier bridge is connected to a balanced $$50Hz$$ three phase $$ac$$ source. Assuming that the $$dc$$ output current of the rectifier is constant, the lowest frequency harmonic component in the $$ac$$ source line current is
GATE EE 2002
18
$$AC$$ to $$DC$$ circulating current dual converters are operated with the following relationship between their triggering angles $$\left( {{\alpha _1}} \right.$$ and $$\left. {{\alpha _2}} \right).$$
GATE EE 2001
19
A thyristorised three phase fully controlled converter feeds a $$dc$$ load that draws a constant current. Then the input $$ac$$ line current to the converter has
GATE EE 2000
20
Resonant Converter's are basically used to
GATE EE 1999
21
In a dual converter, the circulating current
GATE EE 1997
22
In a $$3$$ - phase controlled bridge rectifier, with an increase of overlap angle the output $$dc$$ voltage
GATE EE 1996
23
A single phase diode bridge rectifier supplies a highly inductive load. The load current can be assumed to be ripple free. The ac supply side current waveform will be:
GATE EE 1995
24
A three phase $$ac$$-to-$$dc$$ diode bridge rectifier is supplied from a three-phase, $$440V$$ source. The rectifier supplies a purely resistive load. The average $$dc$$ voltage across the load will be ___________ $$V$$.
GATE EE 1995
25
The output voltage of a six - pulse double star rectifier is the same as that of a three - phase half wave rectifier
GATE EE 1994
26
Referring to the figure the type of load is
GATE EE 1994
27
In the circuit shown in fig, $$L$$ is large and the average value of $$'i'$$ is $$100A.$$ The thyristor is gated in the half cycle of $$'e'$$ at a delay angle $$\alpha $$ equal to ___________.
$$e\left( t \right) = \sqrt 2 .00\,\,\sin \,\,314t$$
$$e\left( t \right) = \sqrt 2 .00\,\,\sin \,\,314t$$
GATE EE 1992
Marks 2
1
A single-phase half-controlled bridge converter supplies an inductive load with ripple free load current. The triggering angle of the converter is 60°. The ratio of the rms value of the fundamental component of the input current to the rms value of the total input current of the bridge is _________ (rounded off to 3 decimal places).
GATE EE 2024
2
A single-phase full-controlled thyristor converter bridge is used for regenerative braking of a separately excited DC motor with the following specifications:
| Rated armature voltage | 210 V |
| Rated armature current | 10 A |
| Rated speed | 1200 rpm |
| Armature resistance | 1 Ω |
| Input to the converter bridge | 240 V at 50 Hz |
The armature of the DC motor is fed from the full-controlled bridge and the field current is kept constant.
Assume that the motor is running at 600 rpm and the armature terminals of the motor are suitably reversed for regenerative braking. If the armature current of the motor is to be maintained at the rated value, the triggering angle of the converter bridge in degrees should be __________ (rounded off to 2 decimal places).
GATE EE 2024
3
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 $$V_0$$ across the load in volts is __________ (Round off to 2 decimal places).
GATE EE 2023
4
For the ideal AC-DC rectifier circuit shown in the figure below, the load current magnitude is Idc = 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).
GATE EE 2022
5
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 $${V_0} = {{{V_m}} \over {2\pi }}\left( {3 + \cos \alpha } \right)$$, 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).
GATE EE 2018
6
The figure below shows an uncontrolled diode bridge rectifier supplied form a $$220$$ Z$$V,$$ $$50$$ $$Hz,$$ $$1$$-phase $$ac$$ source. The load draws a constant $${{\rm I}_0}$$ $$=14A.$$ The conduction angle of the diode $${D_1}$$ in degrees (rounded off to two decimal places) is ______________.
GATE EE 2017 Set 1
7
A single-phase bi-directional voltage source converter (VSC) is shown in the figure below. All
devices are ideal. It is used to charge a battery at 400 V with power of 5 kW from a source Vs = 220 V (rms), 50 Hz sinusoidal AC mains at unity p.f. If its AC side interfacing inductor is 5 mH and the
switches are operated at 20 kHz, then the phase shift (δ) between AC mains voltage (Vs) and
fundamental AC rms VSC voltage (VC1), in degree, is _________.
GATE EE 2016 Set 2
8
A full-bridge converter supplying an RLE load is shown in figure. The firing angle of the bridge
converter is 120º. The supply voltage $$${v_m}\left( t \right) = 200\pi \sin \left( {100\pi t} \right)\,V,$$$ $$$R = 20 Ω, E = 800 V$$$The
inductor L is large enough to make the output current IL a smooth dc current. Switches are lossless.
The real power fed back to the source, in kW, is __________.
GATE EE 2016 Set 2
9
In the given rectifier, the delay angle of the thyristor $${T_1}$$ measured from the positive going zero crossing of $${V_s}$$ is $${30^ \circ }$$. If the input voltage $${V_s}$$ is $$100$$ $$sin$$ $$\left( {100\,\pi t} \right)$$ $$V,$$ the average voltage across $$R$$ (in Volt) under steady-state is ________.
GATE EE 2015 Set 2
10
A fully controlled converter bridge feeds a highly inductive load with ripple free load current. The input supply $$\left( {{V_s}} \right)$$ to the bridge is a sinusoidal source. Triggering angle of the bridge converter is $$\,\alpha = {30^0}.$$ The input power factor of the bridge is ____________.
GATE EE 2014 Set 2
11
A diode circuit feeds an ideal inductor as shown in the figure. Given $${V_s} = 100\,\,\sin \,\left( {\omega t} \right)V,$$ where $$\omega = 100\pi $$ rad/s, and $$L=31.83$$ $$mH$$. The initial value of inductor current is zero. Switch $$S$$ is closed at $$t=2.5$$ $$ms.$$ The peak value of inductor current $${i_L}\left( {in\,\,A} \right)$$ in the first cycle is __________.
GATE EE 2014 Set 3
12
A three-phase fully controlled bridge converter is fed through star-delta transformer as shown in the figure.
The converter is operated at a firing angle of $${30^0}.$$ Assuming the load current $$\left( {{{\rm I}_0}} \right)$$ to be virtually constant at $$1$$ $$p.u.$$ and transformer to be an ideal one, the input phase current waveform is
GATE EE 2014 Set 3
13
The figure shows the circuit diagram of a rectifier. The load consists of a resistance $$10\,\Omega $$ and an inductance $$0.05$$ $$H$$ connected in series. Assuming ideal thyristor and ideal diode, the thyristor firing angle (in degree) needed to obtain an average load voltage of $$70$$ $$V$$ is _______________.
GATE EE 2014 Set 1
14
A solar energy installation utilize a three – phase bridge converter to feed energy into power system through a transformer of $$400V/400 V,$$ as shown below. The energy is collected in a bank of $$400$$ $$V$$ battery and is connected to converter through a large filter choke of resistance $$10\Omega $$.
The maximum current through the battery will be
GATE EE 2011
15
A solar energy installation utilize a three – phase bridge converter to feed energy into power system through a transformer of $$400V/400 V,$$ as shown below. The energy is collected in a bank of $$400$$ $$V$$ battery and is connected to converter through a large filter choke of resistance $$10\Omega $$.
The $$kVA$$ rating of the input transformer is
GATE EE 2011
16
The input voltage given to a converter is
$${V_i} = 100\sqrt 2 \,\,\,\sin \,\,\,\left( {100\pi t} \right)\,\,V$$
The current drawn by the converter is
$${i_i} = 10\sqrt 2 \,\,\,\sin \,\,\,\left( {100\pi t - {\pi \over 3}} \right)\,\, + 5\sqrt 2 $$
$$\sin \left( {300\pi t + {\pi \over 4}} \right)\,\, + \,\,2\sqrt 2 \,\,\sin \left( {500\pi t - {\pi \over 6}} \right)A$$
$${V_i} = 100\sqrt 2 \,\,\,\sin \,\,\,\left( {100\pi t} \right)\,\,V$$
The current drawn by the converter is
$${i_i} = 10\sqrt 2 \,\,\,\sin \,\,\,\left( {100\pi t - {\pi \over 3}} \right)\,\, + 5\sqrt 2 $$
$$\sin \left( {300\pi t + {\pi \over 4}} \right)\,\, + \,\,2\sqrt 2 \,\,\sin \left( {500\pi t - {\pi \over 6}} \right)A$$
The input power factor of the converter is
GATE EE 2011
17
The input voltage given to a converter is
$${V_i} = 100\sqrt 2 \,\,\,\sin \,\,\,\left( {100\pi t} \right)\,\,V$$
The current drawn by the converter is
$${i_i} = 10\sqrt 2 \,\,\,\sin \,\,\,\left( {100\pi t - {\pi \over 3}} \right)\,\, + 5\sqrt 2 $$
$$\sin \left( {300\pi t + {\pi \over 4}} \right)\,\, + \,\,2\sqrt 2 \,\,\sin \left( {500\pi t - {\pi \over 6}} \right)A$$
$${V_i} = 100\sqrt 2 \,\,\,\sin \,\,\,\left( {100\pi t} \right)\,\,V$$
The current drawn by the converter is
$${i_i} = 10\sqrt 2 \,\,\,\sin \,\,\,\left( {100\pi t - {\pi \over 3}} \right)\,\, + 5\sqrt 2 $$
$$\sin \left( {300\pi t + {\pi \over 4}} \right)\,\, + \,\,2\sqrt 2 \,\,\sin \left( {500\pi t - {\pi \over 6}} \right)A$$
The active power drawn by the converter is
GATE EE 2011
18
The circuit shows an ideal diode connected to a pure inductor and is connected to a purely sinusoidal $$50$$ $$Hz$$ voltage source. Under ideal condition the current waveform through the indicator will look like
GATE EE 2009
19
A single phase fully controlled converter bridge is used for electrical braking of a separately excited $$dc$$ motor. The $$dc$$ motor load is represented by an equivalent circuit as shown in the figure.
Assume that the load inductance is sufficient to ensure continuous and ripple free load current. The firing angle of the bridge for a load current of $${{\rm I}_0} = 10\,\,A$$ will be
GATE EE 2008
20
A single - phase half controlled converter shown in the figure feeding power to highly inductive load. The converter is operating at a firing angle of $${60^ \circ }.$$
If the firing pulses are suddenly removed, the steady state voltage $$\left( {{V_0}} \right)$$ waveform of the converter will become
GATE EE 2008
21
A three phase fully controlled bridge converter is feeding a load drawing a constant and ripple free load current of $$10$$ $$A$$ at a firing angle of $${30^ \circ }.$$ The approximate Total Harmonic Distortion $$(\% \,\,THD)$$ and $$r.m.s$$ value of fundamental component of the input current will respectively be
GATE EE 2008
22
A single phase full bridge converter supplies a load drawing constant and ripple free load current. If the triggering angle is $${30^ \circ },$$ the input power factor will be
GATE EE 2008
23
A single $$-$$ phase, $$230$$ $$V$$, $$50$$ $$Hz$$ $$ac$$ mains fed step down transformer $$(4:1)$$ is supplying power to a half $$-$$ wave uncontrolled $$ac$$ $$-$$ $$dc$$ converter used for charging a battery ($$12$$ $$V$$ $$dc$$) with the series current limiting resistor being $$19.04\,\Omega $$. The charging current is
GATE EE 2007
24
In the circuit of adjacent figure the diode connects the $$ac$$ source to pure inductance $$L.$$
The diode conducts for
GATE EE 2007
25
A single - phase bridge converter is used to charge a battery of $$200$$ $$V$$ having an internal resistance of $$2\,\,\Omega $$ as shown in figure. The $$SCRs$$ are triggered by a constant $$dc$$ signal. If $$SCR$$ $$2$$ gets open circuited, what will be the average charging current?
GATE EE 2006
26
A solar cell of $$350V$$ is feeding power to an $$ac$$ supply of $$440$$ $$V,$$ $$50$$ $$Hz$$ through a $$3$$- phase fully controlled briodge converter. A large inductance is connected in the $$dc$$ circuit to maintain the $$dc$$ current at $$20A.$$ If the solar cell resistance of $$0.5\Omega ,$$ then each thryristor will be reverse biased for a period of
GATE EE 2006
27
A $$3$$ $$-$$ phase fully controlled bridge converter with free wheeling diode is fed from $$400$$ $$V$$, $$50$$ $$Hz$$ $$AC$$ source and is operating at a firing angle of $${60^ \circ }.$$ The load current is assumed constant at $$10A$$ due to high load inductance The input displacement factor $$(IDF)$$ and the input power factor $$(IPF)$$ of the converter will be
GATE EE 2006
28
Consider a phase $$-$$ controlled converter shown in figure The thyristor is fired at an angle $$\alpha $$ in every positive half cycle of the input voltage. If the peak value of the instantaneous output voltage equals $$230$$ $$V,$$ the firing angle $$\alpha $$ is close to
GATE EE 2005
29
A phase - controlled half - controlled single - phase converter is shown in figure. The control angle $$\alpha = {30^ \circ }$$
The output $$dc$$ voltage wave shape will be as shown in
GATE EE 2003
30
In the single phase diode bridge rectifier shown in fig, the load resistor is
$$R = 50\Omega .$$ The source voltage is
$$V = 200sin\omega t,$$
Where $$\omega = 2\pi \times 50$$ radians per second. The power dissipated in the load resistor $$R$$ is
$$R = 50\Omega .$$ The source voltage is
$$V = 200sin\omega t,$$
Where $$\omega = 2\pi \times 50$$ radians per second. The power dissipated in the load resistor $$R$$ is
GATE EE 2002
31
A three phase thyristor bridge rectifier is used in a $$HVDC$$ link. The firing angle $$\alpha $$ (as measured from the point of natural commutation) is constrained to lie between $${5^ \circ }$$ and $${30^ \circ }$$. If the $$dc$$ side current and $$ac$$ side voltage magnitude are constant, which of the following statements is true (neglect harmonics in the $$ac$$ side current and commutation overlap in your analysis)
GATE EE 2002
32
A half-wave thyristor converter supplies a purely inductive load, as shown in figure. If the triggering angle of the thyristor is $${120^ \circ }$$, the extinction angle will be
GATE EE 2001
33
A $$3$$-phsae, fully controlled, converter is feeding power into a $$d.c.$$ load at a constant current of $$150A.$$ The $$r.m.s$$ current through each thyristor of the converter is
GATE EE 1998
34
When the firing angle $$\alpha $$ of a single phase, fully controlled rectifier feeding constant $$d.c.$$ current into a load is $${30^ \circ }$$ , the displacement power factor of the rectifier is
GATE EE 1998
Marks 5
1
A three phase diode bridge is used to provide rectified output from a $$400V,$$ $$50$$ $$Hz,$$ $$3$$- phase supply to a $$R$$ $$-$$ $$L$$ load with $$10\,\,\Omega $$ resistance and $$300$$ $$mH$$ inductance.
Determine the
(a)$$DC$$ level of the output voltage
(b) $$RMS$$ value of the diode current
(c) $$RMS$$ value of the source current, and
(d) Apparent power drawn from the mains
Determine the
(a)$$DC$$ level of the output voltage
(b) $$RMS$$ value of the diode current
(c) $$RMS$$ value of the source current, and
(d) Apparent power drawn from the mains
GATE EE 1999
2
An $$SCR$$ is connected in series with a $$300V$$ $$ac$$ supply and a $$300$$ ohms load resistor calculate
(a) The reading of a moving coil ammeter connected in series with the load and
(b) The reading of a moving iron voltmeter connected across the $$SCR$$ for firing angle of $${45^ \circ }$$
GATE EE 1997