A single-phase semiconverter supplies a highly inductive R–L load and includes a freewheeling diode across the load. Compare the shapes of output voltage and output current waveforms.

Introduction / Context:
In semiconverters (half-controlled bridges) feeding highly inductive loads, current tends to be smoothed by inductance while voltage remains pulsed. A freewheeling diode provides a path during source non-conduction, further decoupling current shape from the instantaneous source voltage.

Given Data / Assumptions:

• Highly inductive load ⇒ large L, current ripple small.
• Freewheeling diode (FD) across load.
• Phase-controlled thyristors determine when source applies positive voltage.

Concept / Approach:

Output voltage v_o(t) is a chopped sinusoid (or zero during freewheeling), whereas output current i_o(t) is nearly continuous due to the inductor storing energy and because the FD maintains a current path when the converter is not supplying voltage. Thus v_o(t) and i_o(t) are generally dissimilar in shape.

Step-by-Step Reasoning:

Verification / Alternative check:

Waveform sketches from standard texts show pulsed v_o with near-continuous i_o for large L and an FD.

Why Other Options Are Wrong:

• “Are similar/identical”: contradict inductive smoothing and freewheeling action.
• “Only if α = 0”: even at α = 0, v_o is sinusoidal-rectified while i_o is smoothed.
• “May be similar”: not for highly inductive loads with FD.

Common Pitfalls:

• Assuming resistive-load intuition carries over to inductive cases.
• Ignoring FD role in maintaining current when source is off.

Final Answer:

are not similar