Chopper classes – operating quadrants According to the standard DC chopper classification, a Class D chopper operates in which quadrants of the voltage–current (V–I) plane?

Introduction / Context:
DC choppers are categorized by which quadrants they can realize for load voltage and current. This determines whether the converter can handle motoring/braking and directionality of current and voltage.

Given Data / Assumptions:

• Standard chopper types A, B, C, D.
• Ideal switching and appropriate freewheel paths assumed.

Concept / Approach:

Class A: 1st quadrant only. Class B: 2nd quadrant only (regenerative). Class C: 1st and 2nd quadrants (two-quadrant). Class D: 1st and 4th quadrants (two-quadrant with voltage reversal capability), often implemented as an H-bridge arrangement for bidirectional voltage with unidirectional current each path.

Step-by-Step Solution:

Verification / Alternative check:

Typical V–I locus diagrams in textbooks confirm Class D covers I and IV, enabling forward motoring and reverse motoring (depending on implementation).

Why Other Options Are Wrong:

• First only or second only correspond to Class A or B, not D.
• All quadrants require a four-quadrant topology beyond simple Class D.

Common Pitfalls:

Mixing up Class C (I and II) with Class D (I and IV).

Final Answer:

can operate in either first or fourth quadrant