scholarly journals Improvement of direct torque control applied to doubly fed induction motor under variable speed

Author(s):  
Hala Alami Aroussi ◽  
Elmostafa Ziani ◽  
Manale Bouderbala ◽  
Badre Bossoufi

<span>This work is dedicated to the study of an improved direct torque control of the doubly fed induction motor (DFIM). The control method adopts direct torque control 'DTC' because of its various advantages like the ease of implementation which allows a good performance at transient and steady state without PI regulators and rotating coordinate transformations. To do this, the modeling of the motor is performed. Subsequently, an explanation of the said command is spread out as well as the principle of adjusting the flux and the electromagnetic torque according to the desired speed. Then, the estimation method of these two control variables will be presented as well as the adopted switching table of the hysteresis controller model used based on the model of the multilevel inverters. Finally, the robustness of the developed system will be analyzed with validation in Matlab/Simulink environment to illustrate the performance of this control.</span>

Author(s):  
Najib El Ouanjli ◽  
Aziz Derouich ◽  
Abdelaziz El Ghzizal ◽  
Mohammed Taoussi ◽  
Youness El Mourabit ◽  
...  

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.


The most universally used electric motor is an induction motor fed with three phase supply and eighty percent of mechanical power utilized by industries is given by three phase asynchronous ac motor. Direct torque control method is one such technique for controlling flux and torque of an asynchronous motor fed with PWM VSI. Without any complex control algorithms, it provides easy commands for the control of induction motor flux as well as torque. We are demonstrating the principle of DTC of an asynchromous motor using three level hysteresis controller in this paper. Philosophy of DTC with aforementioned control method has been simulated using MATLAB/Simulink.


Author(s):  
Huzainirah Ismail ◽  
Fazlli Patkar ◽  
Auzani Jidin ◽  
Aiman Zakwan Jidin ◽  
Noor Azida Noor Azlan ◽  
...  

<p>Direct Torque Control (DTC) is widely applied for ac motor drives as it offers high performance torque control with a simple control strategy. However, conventional DTC poses some disadvantages especially in term of variable switching frequency and large torque ripple due to the utilization of torque hysteresis controller. Other than that, performance of conventional DTC fed by two-level inverter is also restricted by the limited numbers of voltage vectors which lead to inappropriate selection of voltage vectors for different speed operations. This research aims to propose a Constant Switching Frequency (CSF) torque controller for DTC of induction motor (IM) fed by three-level Neutral-Point Clamped (NPC) inverter. The proposed torque controller utilizes PI controller which apply different gain for different speed operation. Besides, the utilization of NPC inverter provides greater number of voltage vectors which allow appropriate selection of voltage vectors for different operating condition. Using the proposed method, the improvement of DTC drives in term of producing a constant switching operation and minimizing torque ripple are achieved and validated via experimental results.</p>


Author(s):  
Jagdish Gangadharrao Chaudhari ◽  
Sanjay Bhauraoji Bodkhe ◽  
Mohan V. Aware

In this paper, an improved proportional integral stator resistance estimation for a direct torque controlled induction motor is proposed. This estimation method is based on an on-line stator resistance correction regarding the variations of the stator current estimation error. In fact, the input variable of the PI estimator is the stator current estimation error. The main idea is to tune accurately the stator resistance value relatively to the evolution of the stator current estimation error gradient to avoid the drive instability and ensure the tracking of the actual value of the stator resistance. But there is an unavoidable steady state error between the filtered stator current modulus and its estimated value from the dq model of the machine which is due to pseudo random commutations of the inverter switches. An offset has been introduced in order to overcome this problem, for different speed command values and load torques. Simulation results show that the proposed estimator was able to successfully track the actual value of the stator resistance for different operating conditions


2012 ◽  
Vol 203 ◽  
pp. 226-230
Author(s):  
Peng Chen ◽  
Jian Yang Zhai ◽  
Zheng Zhu

Combining with some fuzzy of the direct torque control and the fuzzy control which is often used in the traditional AC motor control,we put forward a direct torque control theory based on the fuzzy rule. The brushless doubly-fed machine(BDFM) closed-loop control system with the direct torque control based on the fuzzy rule is simulated by using of the Matlab/Simulink software, and the simulation results show that the closed-loop control method is correct and effective.


2014 ◽  
Vol 573 ◽  
pp. 155-160
Author(s):  
A. Pandian ◽  
R. Dhanasekaran

This paper presents improved Fuzzy Logic Controller (FLC) of the Direct Torque Control (DTC) of Three-Phase Induction Motor (IM) for high performance and torque control industrial drive applications. The performance of the IM using PI Controllers and general fuzzy controllers are meager level under load disturbances and transient conditions. The FLC is extended to have a less computational burden which makes it suitable for real time implementation particularly at constant speed and torque disturbance operating conditions. Hybrid control has advantage of integrating a superiority of two or more control techniques for better control performances. A fuzzy controller offers better speed responses for startup and large speed errors. If the nature of the load torque is varied, the steady state speed error of DTC based IM drive with fuzzy logic controller becomes significant. To improve the performance of the system, a new control method, Hybrid fuzzy PI control is proposed. The effectiveness of proposed method is verified by simulation based on MATLAB. The proposed Hybrid fuzzy controller has adaptive control over load toque variation and can maintain constant speed.


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