INCREASING THE ENERGY PARAMETERS OF THE MAINS SUPPLY BY ACTIVE RECTIFIERS IN THE COMPOSITION OF FREQUENCY CONVERTERS

Abstract

The total power consumed by electrical loads from the electric mains consists of their two components – active and reactive. Most electric drives of modern industrial enterprises operate with a reactive power index of 0.7–0.8. This leads to increased consumption of full power, which increases the load on the mains supply. Modern electric drives are built according to the principle: power supply – rectifier – DC link-inverter – asynchronous motor. Full power consumption occurs at the junction of the “power supply-rectifier”, where the required active power factor of the converter device can be formed. The higher the active power factor, the lower the reactive component in the total energy consumed. Thus, the article proposes a solution to the problem of creating highly efficient converter devices for powering electric motors with the formation of the necessary power factor, since frequency-controlled electric drives of modern mechanisms in industrial enterprises are the main consumers of electricity, which have a significant impact on the state of the supply network. The article considers the possibility of increasing the power factor of the mains input of electric drives with two-link frequency converters based on active (controlled) rectifiers with current inverters and voltage inverters. New methods of control of active rectifiers based on the use of AC rectifiers on fully controlled thyristors GTO, GCT, as well as IGBT transistors with pulse width adjustment are proposed. The variants of the construction of these rectifiers and the results of modeling the proposed control methods are presented, confirming a decrease in the passive components of the mains current, and as a consequence, an increase in the power factor of the network input. The simulation results are performed in the MATLAB 10 program, and are the basis for confirming the method of increasing the active power factor at the network input of a controlled frequency converter with a two-link structure.