Comparative Study of Frequency Converters for Doubly Fed Induction Machines

Abstract

The efficient utilization of energy sources seems to be one of the most challenging problems for designers and scientists alike. This challenge particularly applies to power electronics, where the increasing value of energy density leads to demands for optimization processes and better exploitation (and distribution) of available power sources. As a result, the implementation of frequency-controlled systems is more often in the spotlight. The systems with doubly fed induction machines and a frequency converter in the rotor circuit are typical representatives of these demands. In a wide spectrum of power electronic systems, frequency converters are often used that have a constant current, a diode rectifier, and a thyristor inverter. This article provides a novel approach to modeling methodology, and presents a unique comparison of four different frequency converter schemes that are connected to a doubly fed induction machine. This article presents the modeling methodology itself, as well as the results based on an asynchronous generator motor fed by different frequency converters, a spectral analysis of the output voltage of the used frequency converters, and a comparison of the different technologies. Based on the above, this paper recommends the use of a multistage-multilevel frequency converter scheme.

Kinetic energy of the swinging separator driven by a linear electric motor

“…All these positive aspects of grain cleaning are realized by using a linear asynchronous motor in the drive [1,[10][11][12]. Some diffi culties in using linear electric motors in different fi elds are related to the need to develop an electronic control unit [30][31][32][33][34]. Such a device must provide the required motion law of the linear motor stator in accordance with the technological conditions of the machine [35][36][37][38].…”

Open-Circuit Fault-Tolerant Characteristics of a New Four-Phase Doubly Salient Electro-Magnetic Generator

“…To improve the reliability of the system, various machines and converters have been studied. However, these studies mainly concentrate on permanent magnet synchronous machines [3], induction machines [4], and their converters [5][6][7]. Many of them proposed a good fault-tolerant performance of the multi-phase machine.…”