Single-phase full converter with source inductance (overlap) During the overlap interval in a fully controlled bridge supplied by a source with inductance, how many thyristors conduct simultaneously?

Introduction / Context:
With source inductance, the current cannot change instantaneously when devices commutate. In a single-phase full converter, this creates an overlap period where both the outgoing and incoming devices conduct together. Counting the devices conducting clarifies current paths and voltage drop during overlap.

Given Data / Assumptions:

• Single-phase full-controlled bridge (four SCRs).
• Finite source inductance causing finite overlap angle μ.
• Continuous current operation.

Concept / Approach:

In normal conduction without overlap, one device from the top leg and one from the bottom leg conduct (two devices). During overlap, the incoming pair turns on before the outgoing pair turns off because source inductance resists current transfer, so both pairs conduct at once.

Step-by-Step Solution:

Verification / Alternative check:

Equivalent circuit during overlap shows shorted DC link (output voltage tends toward zero during μ), consistent with four devices conducting simultaneously.

Why Other Options Are Wrong:

1 or 2 devices describe non-overlap conditions; 3 devices is not the standard conduction state in a symmetrical bridge.

Common Pitfalls:

Forgetting that overlap reduces output voltage because of simultaneous conduction paths and source inductance.

Final Answer:

4