Triggering series-connected SCR strings Which triggering method for series-connected SCRs commonly uses LASCRs (light-activated SCRs) or fiber-optic links to ensure simultaneous gating and high isolation?

Introduction / Context:
Series connection of SCRs is used to withstand higher voltages. Equalizing networks and reliable, simultaneous gate triggering are crucial to prevent over-voltage on individual devices. Optical methods (LASCRs or optically coupled gates) offer strong isolation and synchrony.

Given Data / Assumptions:

• High voltage stacks of SCRs.
• Need for high common-mode isolation and minimal skew.

Concept / Approach:

Optical triggering delivers identical light pulses to each device or uses LASCRs, ensuring minimal timing mismatch without the problems of transformer parasitics or ground loops.

Step-by-Step Solution:

Verification / Alternative check:

High-power converters frequently adopt fiber-optic gate drivers for IGBTs/SCRs for exactly these reasons.

Why Other Options Are Wrong:

Pure resistance or sequential triggering does not guarantee simultaneous turn-on across the stack; transformer coupling can work but is not what the question highlights about LASCR usage.

Common Pitfalls:

Assuming transformer coupling always suffices at very high voltages where isolation and timing skew are critical.

Final Answer:

Optical triggering