In a three phase half controlled rectifier with constant current load and freewheeling diode, what is the fraction of cycle the diode conducts? Consider firing angle (α) of thyristors greater than 60°.
- A. (α - π/3)/2π
- B. (α + π/3)/2π
- C. (α - π/3) × 3/2π
- D. (α + π/3) × 3/2π
Answer: C. (α - π/3) × 3/2π
Explanation: For α > 60° (π/3 rad) in a 3-phase half-controlled bridge, the freewheeling diode conducts for (α − π/3) across 3 commutations per cycle: fraction of cycle = 3(α − π/3) / 2π.