Semi-converter feeding a purely resistive load How do the output voltage and output current waveforms compare?

Introduction / Context:
A single-phase semi-converter (half-controlled bridge) is often used for DC outputs with reduced reactive effects. With a purely resistive load, the current follows the instantaneous applied voltage without phase shift. Recognizing this is key for predicting power factor and waveform quality.

Given Data / Assumptions:

• Semi-converter topology supplying a purely resistive load.
• Negligible device voltage drops for conceptual clarity.
• Instantaneous current i(t) = v_out(t) / R.

Concept / Approach:

For a resistive load, there is no energy storage. Therefore, the current through the load is proportional to and in phase with the applied voltage at every instant. Regardless of the firing angle, whenever the converter applies a positive voltage segment, the current mirrors that shape exactly, scaled by 1/R. When the converter output is zero, the current is also zero.

Step-by-Step Solution:

Verification / Alternative check:

Oscilloscope traces for R loads show current and voltage crossing zero simultaneously with identical wave shapes during each conduction interval.

Why Other Options Are Wrong:

Claiming they can never be similar contradicts resistive behavior. Limiting similarity to small firing angles is unnecessary. Ambiguous dependence on conduction mode is irrelevant for a strictly resistive load.

Common Pitfalls:

Confusing R loads with RL loads (where current lags and shapes differ). Assuming device commutation effects change the fundamental R-proportionality.

Final Answer:

They are exactly similar (same shape and phase)