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GATE 2020 EE – Question 21

Power Electronics · Single and three-phase configuration of uncontrolled rectifiers · 1 mark · Multiple choice

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:

  1. 50 Hz, 0 Hz
  2. 50 Hz, 100 Hz
  3. 50 Hz, 150 Hz
  4. 150 Hz, 250 Hz

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Correct answer: (C) 50 Hz, 150 Hz

Explanation

A very large inductance makes the load current constant, so the source current is a square wave at 50 Hz. A square wave contains only odd harmonics, and the most dominant are the fundamental (50 Hz) and the third harmonic (150 Hz).