Three-phase series inverter switch count A 3-phase series inverter (thyristor-based commutation) typically requires how many thyristors for three-phase output generation?

Introduction / Context:
Different inverter topologies (voltage-source, current-source, series/parallel commutated) use different device counts. A 3-phase series inverter generates three-phase output with controlled commutation of thyristors. The device count question checks familiarity with practical implementations comparable to the classic three-phase bridge structure.

Given Data / Assumptions:

• Each phase needs positive and negative half-cycle generation through controlled devices.
• Commutation is provided via series (resonant) networks.
• We consider a symmetrical three-phase output with conventional legs.

Concept / Approach:

The functional arrangement maps to a six-device structure akin to a three-phase bridge: each phase leg requires an upper and a lower controlled path. In series (resonant) inverters, commutation circuits are added, but the number of main thyristors to synthesize three-phase power remains six in common configurations.

Step-by-Step Solution:

Verification / Alternative check:

Standard references draw three-phase thyristor inverters with six controlled devices, regardless of the exact commutation method (series or parallel resonant auxiliary networks).

Why Other Options Are Wrong:

3 thyristors cannot synthesize all three legs; 12 refers to special multi-level or redundant schemes; “3 or 6” is ambiguous and not standard.

Common Pitfalls:

Confusing auxiliary commutation switches with main devices; counting diodes as thyristors.

Final Answer:

6 thyristors