Multiphase (interleaved) chopper operation In a multiphase chopper system designed to reduce output ripple, how do the individual chopper units operate?

Introduction / Context:
Multiphase (interleaved) choppers are used in high-power DC supplies and motor drives to reduce current ripple, decrease filter size, and share device stress. Understanding the operating mode of each phase is fundamental for ripple calculations and controller design.

Given Data / Assumptions:

• Multiple identical chopper legs (phases) feeding a common DC output.
• Common input DC source, usually with proper input/output filtering.
• Objective: minimize ripple by phase interleaving.

Concept / Approach:

Interleaving staggers the switching instants among parallel legs. Each leg carries a fraction of the load current and turns on at a unique phase angle within the switching period. This produces ripple cancellation at the output, effectively increasing the ripple frequency and lowering ripple amplitude. Therefore, legs operate in parallel but not simultaneously in time—each fires in turn (one at a time in a time-shifted sense).

Step-by-Step Solution:

Verification / Alternative check:

Ripple-frequency multiplication equals m times the per-phase switching frequency; this is only achieved when phases are interleaved, not when all switch simultaneously.

Why Other Options Are Wrong:

(a) Series connection is uncommon for choppers intended for ripple reduction. (c) Simultaneous operation forfeits ripple cancellation benefits. (d) Mixed behavior contradicts the design objective; consistent interleaving is required.

Common Pitfalls:

Equating 'parallel' with 'simultaneous' switching. In interleaving, they are parallel paths but time-shifted for ripple minimization.

Final Answer:

In parallel and one at a time (interleaved time-sharing)