Study on Direct Torque Control Methods of a Doubly Fed Induction Machine Working as a Stand-Alone DC Voltage Generator

Pawel Maciejewski,Grzegorz Iwanski

doi:10.1109/tec.2020.3012589

Pawel Maciejewski, Grzegorz Iwanski

Open Access

https://doi.org/10.1109/tec.2020.3012589

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Abstract

The article presents a comparison of different Direct Torque Control methods of a Stand-Alone Doubly Fed Induction DC-Voltage Generator, with classic field oriented control used as a benchmark. The system consists of a doubly fed induction generator the stator circuit of which is connected to the DC-bus with a diode rectifier, and the rotor circuit converter is connected to the same DC bus. The main problem of this power generation system are large torque oscillations caused by a nonlinear diode rectifier connected to the stator. Three direct torque control algorithms are described as a means of reduction of this drawback with simultaneous control of DC bus voltage and stator voltage frequency. The methods differ by the second variable used for control in parallel to the torque control path. The selected second variable is the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> component of the rotor current vector, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> component of the stator flux or the stator flux module.

Highlights

The main application of a doubly fed induction machine doubly fed induction generator (DFIG) is AC power generation [1]
This paper presents a comparison of three direct torque control methods with PWM modulation for a stand-alone DC voltage generation DFIG system
The experimental studies were conducted with DFIG connected from the stator side to a 6-pulse diode rectifier and fed on the rotor side from a 2-level converter connected to the stator side DC bus (Fig. 10)

Summary

Introduction

The main application of a doubly fed induction machine DFIG is AC power generation [1]. Recently its use for DC voltage generation has been intensively studied [2][3][4][5][6]. Autonomous operation of DFIG for AC power generation has been studied in recent years [7][8][9]. In the case of the DFIG-DC system described in the paper, torque pulsations may be significant due to the nonlinear character of the diode rectifier. They can be eliminated with various techniques such as resonant controllers [3] and active filtration [2]

Results

Discussion

Conclusion