Achiever Study Plan ESE-2018:Power Electronics Quiz 7

The figure below shows an uncontrolled diode bridge rectifier supplied form a 220 V, 50 Hz 1-phase ac source. The load draws a constant current I_o = 14 A The conduction angle of the diode D₁ in degrees is ___________.

A single phase voltage source of magnitude V_s and frequency w (rad/s) is connected to an inductance L through an antiparallel back-to-back pair of thyristors. The forward and reverse conducting thyristors are fired at an angle of from the positive going and negative going zero crossings of the supply voltage respectively, in each cycle.
Obtain an expression for the inductor current in each cycle for a given value of a. The voltage drop across the thyristors, when either of them is in conclusion, may be assumed to be negligible.

For perfectly balanced operation a certain three phase ac power electronic circuit generates odd harmonic currents of order five and seven in the three phases of the ac mains. Identify which of these harmonics form a positive-sequence system, and which form a negative-sequence system.

A three phase voltage source inverter supplies a purely inductive three phase load. Upon Fourier analysis, the output voltage waveform is found to have an hth order harmonic of magnitude α_h times that of the fundamental frequency component The load current would then have an h-th order harmonic of magnitude