Cycloconverter frequency capability A cycloconverter cannot provide an output frequency higher than the input supply frequency. Is this statement correct?

Difficulty: Easy

Correct Answer: True

Explanation:


Introduction / Context:
Cycloconverters directly synthesize low-frequency waveforms from a higher-frequency AC source by phase-controlled switching, without an intermediate DC link. Understanding their inherent frequency limit is fundamental in drives and large low-speed machine applications.



Given Data / Assumptions:

  • Standard grid-commutated cycloconverters (line-commutated).
  • Phase control of segments of the input waveform.
  • No forced-commutation high-frequency synthesis stage is used.



Concept / Approach:
Classic cycloconverters are step-down frequency converters; they construct each output half-cycle from many appropriately phased segments of the input. Since they select portions of the existing input cycles, the output fundamental cannot exceed the supply frequency.



Step-by-Step Solution:
Input frequency = f_s.Cycloconverter output is assembled by gating segments of the input → output fundamental f_o is a submultiple of f_s.Therefore f_o ≤ f_s, typically f_o ≪ f_s in practice (e.g., 10–20 Hz from 50/60 Hz).



Verification / Alternative check:
Applications such as large synchronous motor drives use cycloconverters specifically for low frequencies; for higher frequencies, DC-link inverters are preferred.



Why Other Options Are Wrong:

  • “False”: contradicts the direct selection principle.
  • Transformer turns ratio does not change frequency.
  • Load type or system phase count does not raise the maximum output frequency.



Common Pitfalls:

  • Confusing cycloconverters with matrix converters or PWM voltage-source inverters which can synthesize higher frequencies from a DC link.



Final Answer:
True


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