Dual Direct Torque Control of Doubly Fed Induction Machine

Abstract

The present paper proposes a novel Doubly Fed Induction Machine (DFIM) control strategy using Direct Torque Control (DTC) linked with two Switching Tables in order to control electromagnetic torque of DFIM via stator and rotor flux vector. The proposed scheme is described clearly and simulation results are reported to demonstrate its effectiveness. The entire control scheme is implemented with Matlab/Simulink.Keywords: Dual direct torque control, doubly fed induction machine, switching tables. IntroductionDue to its excellent speed controllability, reduced converter size, high performance and relatively low cost compared to other machines [2]. Doubly-fed induction machines have been proposed in the literature, among other industrial applications as motor in high power applications such as traction, marine propulsion or as generator in wind energy conversion systems like wind turbine, or pumped storage systems. Several methods of control are used to control the doubly fed induction machine among which the vector control or field orientation control that allows a decoupling between the torque and the flux, in order to obtain an independent control of torque and the flux like DC motors [3]. Therefore, decoupling the control scheme is required by compensation of the coupling effect between qaxis and d-axis current dynamics. It is well known that vector control needs quite complicated to on line coordinate transforms to decouple the interaction between flux control and torque control in order to provide a fast torque control. In recent years an innovative control method, called direct torque control has gained the attraction of researchers.Direct torque control (DTC) strategy was introduced by Takahashi to give a fast and good dynamic performance and can be considered as an alternative to the field oriented control (FOC) strategy [4]. Therefore, in recent years the industrial application areas of the high performance AC drives based on DTC technique have gradually increased due to the following advantages over the field oriented control technique, such as Excellent dynamic performance, precise and quick control of stator flux and electromagnetic torque, absence of co-ordinate transformation, which reduce the complexity of algorithms involved in FOC, robust against machine parameters variations and no current control loop.In this study a new Dual-Direct Torque Control scheme is developed with flux model of DFIM. Two Switching Tables (ST) linked to VSI are defined for stator and rotor flux vector control. We propose separate control of stator and rotor flux. In fact, in order to applied DTC strategy to this configuration, we define a first switching table to control the stator flux vector, and a second switching table to control the rotor flux vector. The next part of the control strategy makes possible to control interaction between both flux vectors. Consequently, we are able to control the electromagnetic torque and to regulate the mechanical speed [3]. The performance of such a scheme depends on the error...

Improved control strategy of DFIG-based wind turbines using direct torque and direct power control techniques

“…DTC was introduced by Takahashi (1984) in Japan and then in Germany by Depenbrock (1985) [33][34][35][36][37][38] and has proved to be a powerful method for the control of induction machines. As compared to stator flux oriented control or field oriented control (FOC), DTC implementation minimizes the use of machine parameters 32,9,[39][40][41][42] while conserving the merits of fast transient response characteristics, it provides a systematic solution to improve operating characteristics of the machine and voltage inverter source 43 .…”

“…The application of DTC to the DFIG has been discussed in 13,37,[44][45][46][47][47][48][49][50] Consequently, the voltage vector r V can be written in the following form 53,51 :…”

“…The magnitude of the rotor flux is estimated from its components along the α and β axes 53,29,37,[44][45][46][47][48][49]51 .…”

Fuzzy super twisting algorithm dual direct torque control of doubly fed induction machine

“…In [3], Ourici the author proposed to introduce the dual-FOC used inthe rotor and stator of the DFIM simultaneously. Bonnet [4], and Boumaraf [5] use the flux model of DFIM with second switching table in the rotorto improve the DDTC. The DDTC suffers from disadvantages ofvariation in the switching frequency, flux and torque ripples.…”