Question

A three-phase semi-converter circuit is given a supply of 400 V. It produces at the output terminals an average voltage of 381 V. Find the rectification efficiency of the converter circuit.

(a) 99.65 %

(b) 95.25 %

(c) 91 %

(d) 86.5 %

This question was addressed to me during an interview.

My doubt stems from Three Phase Converters-3 topic in division Converters of Power Electronics

Answer 1

Correct answer is (b) 95.25 %

To elaborate: Rectification efficiency = Pdc/Pac

Pdc = Vo x Io  . . . (both average values of output current and voltage)

Pac = Vrms x Irms    . . .  (both rms values of input current and voltage)

For a semi-converter Irms = Io

Therefore, Rectification efficiency = 381/400 = 95.25 %.