| 摘要 |
A thyristor cycloconverter for frequency changing a 3-phase input supply to, commonly, a single-phase or 3-phase output supply. The output frequency can be near to, and even higher than, the input frequency without intolerable harmonics. A local oscillator generates a reference wave of output frequency, single-phase or 3-phase. Each reference wave is regularly sampled, twice each input supply cycle, and the sampled value stored to provide a step-form modified reference wave. Thyristor firing pulse trains are generated, during the period of the appropriate input supply commutation intervals, following the instants of amplitude equality of each step-form modified reference wave and each supply phase. A comparator provides a pulse output during alternate successive wave crossings. Output supply positive half-cycle thyristor firing pulse trains commence from the pulse trailing edges and negative half-cycle thyristor firing pulse trains commence from the pulse leading edges. Output supply frequency and amplitude are controlled according to frequency and amplitude of the reference waves.
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