Single-phase dual converter: mode comparison Regarding the transient response when switching quadrants, which statement is true for a single-phase dual converter?

Introduction / Context:
Dual converters provide reversible DC voltage (four-quadrant operation) by using two full converters connected back-to-back. Two common schemes are circulating-current and non-circulating-current modes, each with different dynamic behavior, losses, and filtering needs.

Given Data / Assumptions:

• Two converters: one set for positive average voltage, the other for negative.
• Circulating-current mode: both converters operate simultaneously with a small current circulating through an interphase reactor.
• Non-circulating-current mode: converters operate alternately with dead-bands to avoid overlap.

Concept / Approach:

Fast quadrant reversal requires that the output current can switch sign quickly without waiting for stored energy to dissipate or device intervals to end. With circulating current, both converters are already active, and the control simply shifts firing angles to move from positive to negative output, giving faster response at the cost of additional circulating-current losses and larger reactor requirements.

Step-by-Step Solution:

Verification / Alternative check:

Manufacturer application notes and textbooks consistently list dynamic response as a chief advantage of circulating-current dual converters.

Why Other Options Are Wrong:

Non-circulating mode has slower transitions due to dead-time. Equal response is not observed. Interphase reactor is needed in circulating mode but does not change the truth of the faster response claim.

Common Pitfalls:

Overlooking losses in circulating mode; confusing steady-state efficiency with transient speed.

Final Answer:

Quadrant change is faster in circulating current mode