Control of a multilevel frequency converter of a power-efficient electric drive

Abstract

The paper is devoted to an investigation of the control algorithms of a high-voltage electric drive, the converting part of which is represented by the well-known multilevel Series Connected H-Bridge Voltage Source Converter (SCHB VSC) topology. The control algorithm in the framework of the method forming a Space Vector Pulse-Width Modulation (SPWM) is based on the known principle of choosing the three nearest vectors on the voltage diagram of the converter and calculation of the durations of their switching per modulation cycle. A technique that is the same for all converters of creation of a switching algorithm of power valves based on this principle was proposed. The technique uses the principle of a “centered” SPWM with minimization of switching component of the losses in IGBT inverters of the converter cells. The technique of uniform distribution of the switching load by the cells in the phases of the converter and the method of estimation of the power efficient of a high-voltage electric drive and comparison of SPWM based on the results of the computer modeling were proposed. Results of the integrated simulating and modeling test of a 17-level SCHB VSC composed of a high-voltage variable-frequency electric drive, showing a decrease in the total power losses in the power modules of the converter with a modulator of the developed structure of the space-vector PWM by 43–46% compared to the traditional algorithm of sinusoidal PWM, were obtained.