Device count in a single-phase fully controlled bridge rectifier How many thyristors are used in a single-phase fully controlled bridge (full converter) topology?

Introduction / Context:
A single-phase fully controlled bridge rectifier replaces all four diodes of a standard bridge with controllable devices to regulate the average DC output via firing angle control.

Given Data / Assumptions:

• Single-phase AC source.
• Full converter (not half-controlled).

Concept / Approach:
The full bridge consists of four arms. In a fully controlled design, each arm contains one SCR. Two SCRs conduct at a time (one from the top leg and one from the opposite bottom leg), commutating every half cycle.

Step-by-Step Solution:
Count arms in the bridge → 4.Replace each diode with an SCR → 4 SCRs total.Operation uses pairs conducting for 180° intervals with 90° phase shift in gating.

Verification / Alternative check:
Standard full converter schematics confirm four controllable devices.

Why Other Options Are Wrong:
2: Would be half-controlled (M-2) at best.
8 or 16: Excess for single-phase full bridge; such counts occur in multipulse or parallel arrangements.

Common Pitfalls:
Confusing single-phase with three-phase bridges (which use six devices).

Final Answer:
4