Power Semiconductor Devices · Power Electronics · GATE EE
Marks 1
1
If the following switching devices have similar power ratings, which one of them is the fastest?
GATE EE 2024
2
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?
GATE EE 2023
3
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?
GATE EE 2022
4
Four power semiconductor devices are shown in the figure along with their relevant
terminals. The device(s) that can carry dc current continuously in the direction shown when
gated appropriately is (are)
GATE EE 2018
5
For the power semiconductor devices $$IGBT, MOSFET,$$ Diode and Thyristor, which one of the following statements is TRUE?
GATE EE 2017 Set 1
6
A steady dc current of 100 A is flowing through a power module (S, D) as shown in Figure (a). The V-I characteristics of the IGBT (S) and the diode (D) are shown in Figures (b) and (c), respectively. The conduction power loss in the power module (S, D), in watts, is ________.
GATE EE 2016 Set 1
7
Figure shows four electronic switches $$(i), (ii), (iii)$$ and $$(iv).$$ Which of the switches can block voltages of either polarity (applied between terminals $$‘a’$$ and $$‘b’$$) when the active device is in the OFF state?
GATE EE 2014 Set 1
8
The typical ratio of latching current to holding current in a $$20$$ $$A$$ thyristor is
GATE EE 2012
9
Circuit turn-off time of an $$SCR$$ is defined as the time
GATE EE 2011
10
Figure shows a composite switch consisting of a power transistor $$(BJT)$$ in series with a diode. Assuming that the transistor switch and the diode are ideal, the $$I$$-$$V$$ characteristic of the composite switch is
GATE EE 2010
11
An $$SCR$$ is considered to be a semi - controlled device because
GATE EE 2009
12
The conduction loss versus device current characteristic of a power $$MOSFET$$ is best approximated by
GATE EE 2005
13
A bipolar junction transistor $$(BJT)$$ is used as a power control switch by biasing it in the cut-off region (OFF state) or in the saturation region (ON state). In the ON state, for the $$BJT.$$
GATE EE 2004
14
The triggering circuit of a thyristor is shown in figure. The thyristor requires a gate current of $$10$$ $$mA,$$ for guaranteed turn-on. The value of $$R$$ required for the thyristor to turn on reliably under all conditions of $${V_b}$$ variation is
GATE EE 2004
15
Figure shows a thyristor with the standard terminations of anode $$(A),$$ cathode $$(K),$$ gate $$(G)$$ and the different junctions named $$J1, J2,$$ and $$J3$$. When the thyristor is turned on and conducting
GATE EE 2003
16
Figure shows a $$MOSFET$$ with an integral body diode. It is employed as a power switching device in the ON and OFF states through appropriate control. The ON and OFF states of the switch are given on the $${V_{DS}} - {{\rm I}_s}$$ plane by
GATE EE 2003
17
The $$MOSFET$$ switch in its on - state may be considered equivalent to
GATE EE 1998
18
The uncontrolled electronic switch employed in power electronic converters is
GATE EE 1998
19
In a commutation circuit employed to turn off an $$SCR$$, Satisfactory turn-off is obtained when.
GATE EE 1998
20
If a diode is connected in anti - parallel with a thyristor, then
GATE EE 1997
21
Which semiconductor power device out of the following is not a current triggered device?
GATE EE 1996
22
The Triac can be used only in
GATE EE 1996
23
Which of the following does not cause permanent damage of an $$SCR?$$
GATE EE 1996
24
Figure, show two thyristors each rated $$500A$$ (continuous) sharing a load current. Current through thyristor $$y$$ is $$120A.$$ The current through thyristor $$x$$ will be nearly __________ $$A.$$
GATE EE 1995
25
A switched mode power supply operating at $$20$$ $$kHz$$ to $$100$$ $$kHz$$ range uses as the main switching element
GATE EE 1994
26
A triac can be triggered by a gate pulse of __________ polarity
GATE EE 1994
27
The thermal resistance between the body of a power semiconductor device and the ambient is expressed as
GATE EE 1993
Marks 2
1
The $$SCR$$ in the circuit shown has a latching current of $$40$$ $$mA.$$ A gate pulse of $$50$$ $$\mu s$$ is applied to the $$SCR$$. The maximum value of $$R$$ in $$\Omega $$ to ensure successful firing of the $$SCR$$ is ____________.
GATE EE 2014 Set 2
2
Thyristor $$T$$ in the figure below is initially off and is triggered with a single pulse of width $$10\mu s.$$ It is given that $$L = \left( {{{100} \over \pi }} \right)\mu H$$ and $$C = \left( {{{100} \over \pi }} \right)\mu F.$$ Assuming latching and holding currents of the thyristor are both zero and the initial charge on $$C$$ is zero, $$T$$ conducts for
GATE EE 2013
3
Match the switch arrangements on the top row to be steady $$-$$ state $$V$$ - $$I$$ characteristics on the lower row. The steady state operating points are shown by large black dots.
GATE EE 2009
4
A $$1:1$$ pulse transformer $$(PT)$$ is used to trigger the $$SCR$$ in the adjacent figure. The $$SCR$$ is rated at $$1.5$$ $$kV$$, $$250$$ $$A$$ with $${{\rm I}_L} = 250\,mA,\,\,{{\rm I}_H} = 150\,mA,$$ and $${{\rm I}_{G\max }} = 150mA$$ with $${{\rm I}_L} = 250\,mA,$$ $${{\rm I}_{G\min }} = 100mA.$$ The $$SCR$$ is connected to an inductive load, where $$L$$ $$=150$$ $$mH$$ in series with a small resistance and the supply voltage is $$200$$ $$V$$ $$dc.$$ The forward drops of all transistors/diodes and gate $$-$$ cathode junction during $$ON$$ state are $$1.0V$$
The minimum approximate volt $$-$$second rating of the pulse transformer suitable for triggering the $$SCR$$ should be: (Volt - second rating is the maximum of product of the voltage and the width of the pulse that may be applied)
GATE EE 2007
5
A $$1:1$$ pulse transformer $$(PT)$$ is used to trigger the $$SCR$$ in the adjacent figure. The $$SCR$$ is rated at $$1.5$$ $$kV$$, $$250$$ $$A$$ with $${{\rm I}_L} = 250\,mA,\,\,{{\rm I}_H} = 150\,mA,$$ and $${{\rm I}_{G\max }} = 150mA$$ with $${{\rm I}_L} = 250\,mA,$$ $${{\rm I}_{G\min }} = 100mA.$$ The $$SCR$$ is connected to an inductive load, where $$L$$ $$=150$$ $$mH$$ in series with a small resistance and the supply voltage is $$200$$ $$V$$ $$dc.$$ The forward drops of all transistors/diodes and gate $$-$$ cathode junction during $$ON$$ state are $$1.0V$$
The resistance $$R$$ should be
GATE EE 2007
6
An $$SCR$$ having a turn ON time of $$5\,\,\mu \,\,\sec $$, latching current of $$50$$ $$mA$$ and holding current of $$40$$ $$mA$$ is triggered by a short duration pulse and is used in the circuit shown in figure The minimum pulse width required To turn the $$SCR$$ ON will be
GATE EE 2006
7
The figure shows the voltage across a power semiconductor device and the current through the device during a switching transition. Is the transition a turn ON transition or a turn OFF transition? What is the energy lost during the transition?
GATE EE 2005
8
An electronic switch $$S$$ is required to block voltages of either polarity during its OFF state as shown in figure (a). This switch is required to conduct in only one direction during its ON state as shown in the figure (b).
Which of the following are valid realizations of the switch $$s$$?
GATE EE 2005
9
A $$MOSFET$$ rated for $$15 A,$$ carries a periodic current as shown in figure. The ON state resistance of the MOSFET is $$0.15$$ $$\Omega .$$ The average ON state loss in the $$MOSFET$$ is
GATE EE 2004