Evaluation of the effectiveness of incomplete phase pulse width modulation algorithms in the converter-electric motor system

Abstract

Aim. This study evaluates the effectiveness of incomplete-phase algorithms for pulse width modulation of three-phase voltages in frequency control of electric drives, using integral current dispersion in the load as the criterion. Materials and methods. This study examines pulse width modulation processes in frequency-controlled electric drives, focusing on the converter-electric motor system. Methods from electric circuit theory are used, with proposed algorithms illustrated through drawings, and these drawing can be implemented in the matrix laboratory software. Results. The process of pulse width modulation in the converter-electric motor system is considered. It is demonstrated that to minimize the number of switching keys in the frequency converter, incomplete-phase pulse width modulation algorithms are beneficial. Expressions for local dispersion of the interphase current in single-phase and two-phase modulation are analyzed. An expression for local current dispersion in a three-phase bridge circuit load is derived, and the concept of integral current dispersion in a three-phase load is derived. Indicators for evaluating the effectiveness of algorithms for incomplete-phase pulse width modulation are proposed. Graphs the efficiency coefficient, characterizing incomplete-phase pulse width modulation with a minimum number of switching of key elements in the function of the amplitude coefficient and in the function of the relative frequency of modulation are constructed. Conclusion. The results aid in developing algorithms for controlling frequency converters in asynchronous electric drive systems.