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The direct torque control (DTC) of induction motor (IM) drive is featured by high ripples in the electromagnetic torque and stator flux profiles because they are controlled by two hysteresis regulators. Furthermore, the machine flux is not directly measurable. Hence, it is better to reconstitute it from the instantaneous electrical equations of the machine. Once the stator flux is estimated, we can guarantee a reliable sensorless DTC control. Thus, the purpose of this research work is to ensure fast response and full reference tracking of the IM under sensorless DTC strategy with desired dynamic behavior and low ripple levels.

In this work, an improved DTC strategy, which is DTC_SVM_3L, is suggested. The first step of the designed approach is to substitute the conventional inverter feeding the motor with a three-level inverter because it guarantees reduced switching losses, improved quality of voltage waveform and low-current total harmonic distortion rate. The second aim of this paper is to make the IM operate at a constant switching frequency by using the nearest three vectors-based space vector modulation (SVM) technique rather than hysteresis controllers. The third objective of this study is to conceive a sliding-mode stator flux observer, which can improve the control performances by using a sensorless algorithm to get an accurate estimation, and consequently, increase the reliability of the system and decrease the cost of using sensors. The stability of the proposed observer is demonstrated based on the Lyapunov theory. To overcome the load change disturbance in the proposed DTC control strategy, this paper exhibits a comparative assessment of four speed regulation methods: classical proportional and integral (PI) regulator, fuzzy logic PI controller, particle swarm optimization PI controller and backstepping regulator. The entire control algorithm was tested under different disturbances such as stator resistance and load torque variations.

It was ascertained that the IM, controlled with three-level inverter, exhibits good performances under the proposed DTC-SVM strategy based on a sliding-mode observer. The robustness of the suggested approach against parameter variations is also proved.

The theoretical development of the proposed control strategy is thoroughly described. Then, simulations using Matlab/Simulink software are launched to investigate the merits of the sensorless DTC-SVM command of three-level inverter-fed IM drive with different speed regulators.

Proposes the application of novel control strategy in power transistors (insulated gate bipolar transistors – IGBT) based on AC/DC/AC converter with active filtering function. Seeks to investigate the possibilities of operating drive system under distorted line voltage with unity power factor and reduced dc‐link capacitor.

A novel control strategy is proposed based on direct power and direct torque control with space vectors modulators scheme which seems to be most promising. This method is investigated, implemented and examined in the laboratory setup. Different working conditions are taken into consideration.

Provides information how the proposed system works under motoring and regenerating modes. Good behaviors of the system in steady state in transience are shown. Very good stabilization of the dc‐link voltage under transient is achieved. Almost sinusoidal line current is obtained. Very good compensation of nonlinear load is also achieved.

This is not an exhaustive investigation. The system should be tested with different input inductances (or LCL filters) and with reduced dc‐link capacitor. Moreover, laboratory tests with higher power should be performed in the future.

A useful source of information and an example of how a fully controlled AC/DC/AC converter with active filtering function works. It could be an important basis for a prototype for industry.

Although the direct power control with space vector modulator (DPC‐SVM) and direct torque control with space vector modulator (DTC‐SVM) schemes have been described in the literature separately, it is analyzed for the first time and investigated together for control of the AC/DC/AC converter. Additionally, active filtering provides a feature of power compensation. It could be the basis for a clean power system design.

The purpose of this paper is to describe a new method for selective harmonic elimination in a two-level three-phase inverter-fed direct torque controlled (DTC) permanent magnet synchronous motor (PMSM) drive to suppress unwanted resonant frequencies.

The design methodology is based on random space vector pulse-width modulation (RSVPWM) of PMSM drives. MATLAB simulations support the validity of suggested structure.

The simulation results of the proposed algorithm exhibit the development of a proper gap at the selected frequency in the frequency spectra of the motor input currents and voltages as well as lowering the ripples in the PMSM electromagnetic torque, stator current and flux linkage responses in compared with traditional DTC.

The proposed algorithm is a revised form of the RSVPWM technique used in a closed-loop structure along with a sliding mode speed controller which is capable to deal with nonlinear motor loads in an online manner. This study can be beneficial for the designers of AC motor drive system who attempt to find a modulation method that can create a selective gap in the power spectrum density of the motor input voltages and currents, therefore, promote an acoustically pleasant drive or alleviate unwanted motor vibrations.

The aim of the paper is to conduct an analytical study of a new method of induction motor torque and flux direct control with nonlinear controllers.

The method is based on the inverter state predictive determination in order to minimize the torque and flux errors.

The proposed method allows one to eliminate known DTC disadvantages, i.e. the hexagonal flux shape and nonsinusoidal current at a low motor speed, and also secures a decrease of torque and flux pulsation.

This new method enables a more precise reproduction of the motor torque and flux command signals, working with the same sampling frequency of the control processor as in the case of the standard DTC method. The decreased torque pulsations cause a decrease of the motor speed pulsation.

An innovative optimal control method is presented. The correctness of the initial assumptions as well as the expected final results have been verified in practice.

The aim of the paper is to conduct an analytical study of the two new methods of the permanent magnet synchronous motor torque and flux direct control with the predictive non‐linear torque and flux controller.

The method is based on the prediction of the torque and flux error vector in order to minimize the torque ripple and ensure the constant switching frequency.

The proposed methods ensure the torque and flux error vector minimization, reduction of the torque ripples, and constant switching frequency without deterioration of the dynamic properties of the standard direct torque control (DTC).

An innovative predictive DTC method is presented. The correctness of the analysis and main assumptions, as well as the expected final results have been verified in simulation.

The purpose of this paper is to obtain an accurate and robust estimation method of the rotor flux and speed for the sensorless induction motor (IM) drive with magnetizing reactance variations.

The sensorless IM drive with sliding mode flux and speed observer (SMO) is presented. Proposed estimation algorithm is extended with the additional magnetizing reactance estimator based on the magnetizing characteristic of the IM. The dynamical and steady‐state properties of the drive system in the low‐speed and in the field‐weakening regions are tested. The simulation results are verified by experimental tests, over the wide range of motor speed and drive parameter changes.

It is shown that the sensorless induction motor drive can work stable in wide speed range using the Sliding‐Mode Observer with additional magnetizing reactance estimator.

The investigation looked mainly at the speed estimation methodology with additional motor parameter estimator.

The proposed SMO can be easily implemented on digital signal processors. The implementation was tested in an experimental setup with DS1103 card. The fixed‐point realisation needs to be developed to obtain the practical application in the industrial drive systems.

The SMO with an additional magnetizing reactance estimator based on magnetizing characteristic of the IM is tested. This method of the speed and flux reconstruction can be applied in different electrical drives working in wide speed range, including very low‐speed region and field‐weakening region, too. The proposed solution is not sensitive to magnetizing reactance variations and is simple in practical implementation in the real‐time system.

This paper aims to propose an improved direct torque control (DTC) for the induction motor’s performance enhancement using dual nonlinear techniques. The exact feedback linearization is implemented to create a linear decoupled control. Besides, the fuzzy logic control approach has been inserted to generate the auxiliary control input for the feedback linearization controller.

To improve the DTC for induction motor drive, this work suggests the incorporation of two nonlinear approaches. As the classical feedback linearization suffers while the presence of uncertainties and modeling inaccuracy, it is recommended to be associated to another robust control approach to compensate the uncertainties of the model and make a robust control versus the variations of the machine parameters. Therefore, fuzzy logic controllers will be integrated as auxiliary inputs to the feedback linearization control law.

The simulation and the experimental validation of the proposed control algorithm show that the association of dual techniques can effectively achieve high dynamic behavior and improve the robustness against parameters variation and external disturbances. Moreover, the space vector modulation is used to preserve a fixed switching frequency, reduce ripples and low switching losses.

The theoretical, simulation and experimental studies prove that the proposed control algorithm can be used on different AC machines for variable speed drive applications such as oil drilling, traction systems and wind energy conversion systems.

The proposed DTC strategy has been developed theoretically and realized through simulation and experimental implementation. Different operation conditions have been conducted to check the ability and robustness of the control strategy, such as steady state, speed reversal maneuver, low-speed operation and parameters variation test with load application.

The aim of the research was to find out a method of adaptive speed control robust against variation of selected parameters of system like moment of inertia, time constant of torque control loop or torque coefficient of the motor.

The main goal of the research was achieved due to application of artificial neural network (ANN), which was trained on line on the base of speed control error. The good results were gained by elaboration of enough fast and precise training algorithm and proper ANN structure.

The work shows a structure of artificial neural network (ANN), applied as adaptive speed controller, and presents an algorithm of ANN training. Some versions of this algorithm were analysed and verified by simulation and experimental tests.

The research should be continued to determine a final version of training algorithm and its influence on controller properties.

The elaborated adaptive controller can be easily used by applying microprocessor system available now on the market. The proposed control solution is robust against parameters variation as well as their imprecise identification. The controller has ability of self‐tuning which can have great practical advantage.

Social implications are difficult to determine.

The paper presents a new solution of adaptive speed controller, which means a new ANN structure and new training algorithm.

This paper seeks to investigate the performance of a DTC strategy dedicated to the control of four‐switch three‐phase (B4) inverter fed induction motor drives. The major advantage of the B4 inverter is the reduced number of the involved power switches which opens up crucial cost benefits.

The principle of operation of the B4 inverter fed induction motor drive is recalled in a first step. Then, the basis of the proposed DTC strategy is presented. Following this, the synthesis of the corresponding vector selection table is carried out considering a subdivision of the space vector plan into sixteen sectors.

It has been found experimentally that the B4 inverter fed induction motor drive offers, under the proposed control strategy, interesting performance.

This work should be extended considering a comparison between the performance of B4 inverter fed induction motor drive under the proposed DTC strategy and those of the B6 inverter fed induction motor drive under the popular Takahashi DTC strategy.

The paper proposes a new DTC strategy dedicated to induction motor drives fed by B4 inverter. This reduced structure inverter is of great interest for large‐scale production industries such as the automotive one as far as cost‐effectiveness is concerned.

The aim of this paper is to propose a novel direct torque control (DTC) strategy for induction motor (IM) drives fed by three‐switch three‐phase inverter (TSTPI). The introduced strategy is based on the emulation of the operation of the conventional six‐switch three‐phase inverter (SSTPI).

The proposed strategy has been achieved thanks to suitable combinations of the six unbalanced voltage vectors intrinsically generated by the TSTPI, leading to the synthesis of the six balanced voltage vectors of the SSTPI. This approach has been adopted in the design of the vector selection table of the proposed DTC strategy which considers a subdivision of the Clarke plane into six sectors.

Simulation results have revealed that, thanks to the proposed DTC strategy, TSTPI fed IM drives exhibit interesting performance.

The results obtained by simulation should be validated by experiments.

The drawbacks associated with the application of unbalanced voltage vectors in previous DTC strategies dedicated to TSTPI have been eradicated thanks to the synthesis of six balanced voltage vectors using appropriate combinations of the TSTPI intrinsic ones.