Transient Process Analysis for Accurate Frequency Converter Performance in Agro-Industrial Applications

Abstract

Currently, frequency control of an asynchronous electric motor using a frequency converter is widely used in the agro-industrial sector to implement the technological process. To maintain the set parameters of the technological process, automatic control systems and various regulators are used as part of an automated electric drive. To determine the coefficients of the regulators, a mathematical model of the automatic control system is compiled. The structure of the system is represented as separate links with own transfer function, the value of which is known in advance. At the same time, the transfer function of the frequency converter is determined rather inaccurately, which affects the adjustment accuracy of regulators and increases the adjustment time of the regulators. To simplify and improve the quality of control settings, the article develops a methodology for determining the frequency converter transfer function. To do this, a physical simulation of the operation of an asynchronous electric motor was carried out together with a frequency converter in a transient process. The obtained transient data was collected by a data acquisition board and analyzed using a fast Fourier transform in the Mathcad software environment. The paper develops and applies a technique for analyzing the transient process in a frequency converter in the frequency domain using a complex fast Fourier transform with a “moving” rectangular window. As a result of the research, a transfer function for a specific frequency converter was obtained.