List of top Electrical Engineering Questions on Power Electronics

If \(\alpha\) is ratio \(\frac{\text{T}_{\text{ON}}}{\text{T}}\) of chopper, then the ratio of input voltage to output voltage of step down and step-up chopper respectively are
For a step-down Type A chopper, the waveforms of input current I and output current \(\text{I}_\text{o}\) respectively are
The number of pulses per half cycle of PWM inverter is changed, then
A dc motor is connected to a 214 V rms (L-L), 3-\(\phi\), 50 Hz line using a 3-\(\phi\) bridge converter. If the firing angle is \(\frac{\pi}{6}\), full load armature current is 2500 A and armature resistance is 4 m\(\Omega\), then the back emf is
In the first quadrant of V-I characteristics of Uni-Junction Transistor, the slopes of characteristic are in the following sequence
The triggering pulses for 1-\(\phi\), full wave converter using Zero Crossing Detector, pulse amplifier and gate pulse isolation transformer, are obtained during
A 3-\(\phi\) semi-converter with R-L load consists of _____ diodes and operates in _____
A 3-\(\phi\) fully controlled converter can be operated as a semi-converter, if
(a) One of the input ac supplies is disconnected and the thyristors connected to it are triggered at 180 degrees.
(b) One of the input ac supplies is disconnected and the thyristors connected to it are triggered at zero degrees.
(c) A free-wheeling diode can be connected across the load in the same direction of thyristors
(d) A free-wheeling diode can be connected across the load in the opposite direction of thyristors
Choose the correct answer
The input dc voltage of a 1-\(\phi\) full bridge inverter is 141.4 V and its duty ratio is 0.49. Then its approximate average and rms voltages are
The fundamental frequency and peak voltage of an inverter are f and \(\text{V}_\text{m}\) respectively. When it contains all odd harmonics, then its frequency and rms voltage of \(5^{\text{th}}\) harmonic are
A 3-\(\phi\), 50 Hz synchronous motor is to be operated at constant flux by frequency control. If frequency is decreased by 4% of rated frequency at the same flux, then the voltage should be
A power diode is open circuited, and a reverse dc voltage is applied to get a faster turn-off time. During reverse recovery time
(a) When current is negative peak, voltage is zero
(b) When voltage is negative peak, current is zero
(c) When current is negative peak, voltage is not zero
(d) When voltage is negative peak, current is not zero
Choose the correct answer
Power MOSFETs are extremely popular in
In IGBT an improved Miller feedback effect is seen (compared with MOSFET) because, ratio of gate-collector capacitance to gate-emitter capacitance is