Direct torque control of doubly fed induction motor using three-level NPC inverter

Najib El Ouanjli,Khalid Mezioui,Aziz Derouich,Youness El Mourabit,Abdelaziz El Ghzizal,Mohammed Taoussi,Badre Bossoufi

doi:10.1186/s41601-019-0131-7

Abstract

This article presents the direct torque control (DTC) strategy for the doubly fed induction motor (DFIM) connected to two three-level voltage source inverters (3LVSIs) with neutral point clamped (NPC) structure. This control method allows to reduce the torque and flux ripples as well as to optimize the total harmonic distortion (THD) of motor currents. The use of 3LVSI increases the number of generated voltage, which allows improving the quality of its waveform and thus improves the DTC strategy. The system modeling and control are implemented in Matlab/Simulink environment. The analysis of simulation results shows the better performances of this control, especially in terms of torque and flux behavior, compared to conventional DTC.

Highlights

In the mid − 1980s, the direct torque control strategy of induction machine was introduced by Takahashi to overcome the problems of conventional controls such as scalar control (SC) and field oriented control (FOC) [1, 2]
The stator and rotor currents of the doubly fed induction motor (DFIM) are illustrated in Fig. 7h, the results show that the motor currents are sinusoidal
5 Conclusion In this paper, we have presented the direct torque control for a doubly fed induction motor connected to two three-level voltage source inverters with neutral point clamped (NPC) structure

Summary

Introduction

In the mid − 1980s, the direct torque control strategy of induction machine was introduced by Takahashi to overcome the problems of conventional controls such as scalar control (SC) and field oriented control (FOC) [1, 2]. DTC is based on the direct regulation of electromagnetic torque and flux of the machine This control is characterized by good torque dynamic response, high robustness and less complexity than other controls [3]. The electric equations of DFIM in the reference frame (α,β) are given by [17]: Stator voltages: The new DTC switching tables of the DFIM connected to two 3LVSIs with NPC structure is designed to give better performance, while retaining the merits of the conventional DTC namely robustness and simplicity.

Direct torque control strategy

V V a b c

Conclusion

9.87 Variable frequency of 4 kHz