HYBRID CASCADE FREQUENCY CONVERTERS AND THE FEATURES OF THEIR CONTROL

Structures and control algorithms of hybrid cascade frequency converters are offered. These converters contain powerful high-voltage and less powerful low-voltage converter blocks. In high-voltage blocks are used diode rectifiers and three-phase VSI inverters working with low frequency PWM. The low-voltage active rectifiers and the single-phase inverters are used in low-voltage blocks which work with high frequency PWM. Diode rectifiers are connected to mains through choke, active rectifiers are connected to networks through the transformer. The transformer is executed on partial capacity of loading that allows to improve weight-dimensions properties of the equipment and to reduce energy losses. Low-voltage blocks of frequency converters, besides transmission of electrical energy to load and it recuperation, filter phase currents of mains and load. The operating mode of the converter and balancing of load currents is considered at emergency switching-off of one of low-voltage blocks of frequency converter.

Authors: A. G. Vorontcov, V. V. Glushakov, M. V. Pronin

Direction: Electrical Engineering

Keywords: 3 level frequency converter, cascade multi-level converter, hybrid converter, diode rectifier, AFE, VSI, distortions of currents, emergency mode, simulation

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