Sistemas de conversão bifásicos baseados em retificadores com reduzido número de chaves controladas.

Abstract

This work focuses on the study of AC-DC converters unidirectional with reduced number of switches controlled who use a two-phase machine functioning as generator for supplying power to a load. In this context, In this context, six rectifiers configurations are investigated , two topologies that employ switches of the type IGBT and and four others who adopt bidirectional switches in current and voltage. The configurations that make use IGBTs have four legs consist of eight diodes and four controlled switches, while the topologies using bidirectional switches have two or three controlled switches connected between the converter’s legs. For all studied topologies, the dynamic models and/or analyzes of operating modes, developed the control and PWM strategies are presented. With regard the PWM strategies, for topologies using IGBTs, it applies once sine-triangle modulation in function of the polarity of the phase currents, topologies that use for bidirectional switches, it employs space vector modulation with sectors defined according to the direction of the currents. The control system operates regulating the DC-link voltage and and it uses a synchronization method that has the purpose to reduce distortion in the current at the zero crossing, ensuring currents of sinusoidal machine with high power factor. For comparison and performance evaluation of the topologies investigated are used two main criteria: harmonic distortions analysis in the current waveforms and semiconductor switching and conduction losses. Finally, simulation and experimental results are presented and discussed for the validation of the studied topologies.