A novel cycloconverter based on microprocessor digital control

In view of the relative advantage of using a current-source power convertor for many high-performance drives, a novel cycloconverter that is composed of double H bridge converters has been developed as a three-phase, sinusoidal current source of adjustable frequency. The power main circuit contains 20 thyristors and current control for two-phase H bridge converters are used to generate symmetrical three-phase currents. In this paper, the authors present the power main circuit, the operation pattern and discuss a microprocessor-based digital control cycloconverter (DCC) system that ensures high quality output. Among other aspects, the digital system facilitates stepping sinusoidal current model for the total distortion factor improvement, the method of current zero crossing, discrete compensation for feedback control, and online identification of the load parameter. A macromodel of thyristors for analog power circuit simulation using PSPICE has been developed. The novel cycloconverter has been experimented upon using an R-L load. The control strategies are elaborated upon, and simulation and experimental results are presented