Novel sinusoidal pulsewidth modulation schemes for voltage-source inverters with fluctuating input voltage

The optimum waveform parameters of pulse position and pulse widths for voltage-source inverters with fluctuating input voltage are proposed. Eight types of modulation schemes are described for synthesizing the optimum low-distortion output waveforms, of which the harmonic spectra and the peak fundamental-value are almost insensitive to the input-voltage fluctuation, with a minimum voltampere rating of inverter input filter. For fluctuating inverter input voltage with insufficient filtering, the type-VII and the alternative type-III modulation schemes are found to be especially suitable for practical implementation. Detailed descriptions of the suggested circuits with dual-feedback control for implementing two such modulation schemes are given. A peak-value detector that can rapidly produce the peak value of the inverter output voltage with a minimum time constant is also proposed. The theoretical results of the proposed approaches with one-loop self-regulating property are experimentally verified and compared with the conventional method