A 50-KVA Adjustable-Frequency 24-Phase Controlled Rectifier Inverter

This paper describes a multiphase 50-kva silicon-controlled rectifier inverter that uses phase displacement of the outputs from four 3-phase bridge inverters to generate a 3-phase output waveform with low harmonic content. The output voltage is controlled over a wide range by simply changing the phase position of controlled rectifier gate signals. Low harmonic content is maintained in the unfiltered output wave over the complete voltage range. At one phase position the lowest harmonic of consequence present in the output waveform is the 23rd. Frequency of the inverter output is smoothly adjustable over the range of 50 to 500 cps. The static inverter offers this adjustable frequency, and adjustable voltage power supply with electronic precision. Frequency regulation is independent of supply voltage or load variations and only dependent upon a low power timing oscillator.