Component count – single-phase semi-converter In a single-phase semi-converter (half-controlled bridge) used for controlled rectification, how many thyristors are employed in the power circuit (excluding diodes)?

Introduction / Context:
A single-phase semi-converter (also called a half-controlled bridge) combines two thyristors and two diodes in a full-bridge configuration to achieve control during one half of each cycle while providing free conduction in the other half. Recognizing the device count is fundamental to topology identification and cost/performance tradeoffs.

Given Data / Assumptions:

• Standard single-phase semi-converter topology.
• Focus is on thyristor count only (diodes not counted).

Concept / Approach:

In the semi-converter, one leg of the bridge consists of thyristors (controllable devices) and the opposite leg consists of diodes (uncontrolled). This provides phase control in positive and negative half cycles via the controlled leg, while the diode leg completes the path without gating in the complementary half cycle.

Step-by-Step Solution:

Verification / Alternative check:

Power electronics texts depict the half-controlled bridge explicitly with two SCRs and two diodes.

Why Other Options Are Wrong:

• 4, 8, 16 imply other multi-pulse or multi-phase arrangements; they do not match the basic semi-converter.

Common Pitfalls:

Confusing a fully controlled bridge (4 thyristors) with the semi-converter (2 thyristors + 2 diodes).

Final Answer:

2