Chopper classification in power electronics Which chopper class (as per standard A–E classification) can operate in all four quadrants of the V–I plane, providing reversible voltage and reversible current (i.e., full four-quadrant operation)?

Introduction / Context:
Four-quadrant DC–DC conversion is required in high-performance drives and bidirectional energy systems. The standard chopper classes (A to E) describe how voltage and current polarities can be controlled. This question asks which topology inherently supports operation in all four quadrants of the voltage–current plane.

Given Data / Assumptions:

• Conventional chopper class definitions: A (first quadrant), B (second), C (I & II), D (I & IV), E (I, II, III, IV).
• Ideal switches and diodes are assumed to explain principle operation.
• Load can accept bidirectional current and voltage where applicable.

Concept / Approach:

To cover all four quadrants, the converter must be able to apply both polarities of average voltage to the load and allow current to flow in either direction, with controlled power flow in motoring and regenerating modes. The Class E chopper achieves this by combining switching legs and freewheel paths so that voltage and current direction can be independently set by gating patterns.

Step-by-Step Solution:

Verification / Alternative check:

Reviewing quadrant diagrams in standard power-electronics texts shows Class E as the only class covering I, II, III, and IV quadrants explicitly under controlled switching sequences.

Why Other Options Are Wrong:

Class A/B/C/D each miss at least one quadrant; they cannot independently reverse both voltage and current under control, hence not four-quadrant.

Common Pitfalls:

Confusing Class D (which reverses output voltage) with true four-quadrant capability; overlooking that current reversal under control is also necessary.

Final Answer:

Class E chopper