Abdelkarim Ammar | University Mohamed Khider of Biskra, Algeria (original) (raw)

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Papers by Abdelkarim Ammar

– The field oriented based vector control (FOC) and the direct torque (DTC) are well used control... more – The field oriented based vector control (FOC) and the direct torque (DTC) are well used control strategies in modern AC systems these days. They can create a decupled flux and torque control and achieve good performance for AC motor drives. However, both of them have a number of limits and drawbacks, such as the dependence of machine parameters of the vector control and the high flux and torque ripples of DTC. This work present a hybrid control strategy for induction motor bases on combining the principles of the two techniques, in order to benefit from their advantages and limit their disadvantages and gain high performance. Besides, this work aims to design a sliding mode observers for speed/flux as sensorless algorithm to improve the reliability and decrease the cost control system. Different results of this combined strategy will be investigated by numerical simulation using Matlab/Simulink.

The Field Oriented Control (FOC) and the Direct Torque Control (DTC) are the well-known control s... more The Field Oriented Control (FOC) and the Direct Torque Control (DTC) are the well-known control strategies in the modern AC systems nowadays. However, both of them have a number of limits, such as the dependence on machine parameters of the vector control and the high ripples of DTC. This work presents a hybrid control strategy for induction motor (IM) based on the combining of the two techniques in order to benefit from their advantages and achieve high performance control. Besides, a Model Reference Adaptive System (MRAS) observer will be used for speed estimation to improve the reliability and decrease the cost of the control system. Furthermore, the IM energy optimization will be treated as the second objective of this paper. A proposed model based strategy will be used for loss minimization. This strategy bases on online adjusting of the rotor flux magnitude reference and choosing an optimal value for each applied load torque. The proposed algorithm will be investigated by simulation and experimental implementation by using Matlab/Simulink with real time interface (RTI) based on dSpace 1104 board. Keywords— Induction Motor, Field Oriented Control (FOC), Direct Torque Control (DTC), Loss Model control (LMC), Model reference adaptive system (MRAS), dSpace 1104.

the AC drives direct torque control (DTC) is used to obtain high performance decoupled torque and... more the AC drives direct torque control (DTC) is used to obtain high performance decoupled torque and flux control. The SVM based direct torque control is a common solution which used to solve the conventional DTC's problems such as the high torque ripples and variable switching frequency. However, this control technique bases on stator flux orientation and PI controllers. This paper aims to improve the SVM-DTC performance by replacing the PI controllers by high order sliding mode controllers. Theses controllers are based on second order super twisting strategy, they can overcome the classical PI problems which are represented in robustness against parameters variation and external disturbance. Furthermore, super twisting algorithm reduces the chattering effect and keep the same properties of the first order sliding mode control. Another point, this paper presents a design of load torque observer based on second order sliding mode control in order to estimate the load value and reduce the cost and the uncertainties of control system. The simulation and experimental results of robust SVM-DTC control method are presented using Matlab/Simulink with real time interface using dSpace 1104 bored.

The AC drives Direct Torque Control technique (DTC) has been designed to obtain a high performanc... more The AC drives Direct Torque Control technique (DTC) has been designed to obtain a high performance flux and torque control. Due to its downsides, this paper present an insertion of the space vector modulation (SVM) in order to improve the classical DTC for induction motor (IM) drive. SVM can reduce the high torque and flux ripples by producing a fixed switching frequency. This technique is known by load angle SVM-DTC or closed loop torque control. Furthermore, the IM energy optimization will be treated in the second objective of this paper. A proposed model based strategy will be used for loss minimization, consequently an efficiency optimization. This strategy bases on online adjusting of the reference of rotor and stator flux magnitude and choosing an optimal value for each applied load torque. The proposed optimized SVM-DTC algorithm will be investigated by simulation and experimentally by using Matlab/Simulink in real time environment which based on dSpace 1104 board.

The AC drives Direct Torque Control technique (DTC) has been designed to obtain a high performanc... more The AC drives Direct Torque Control technique (DTC) has been designed to obtain a high performance for flux and torque control. Because of some downsides, this paper presents an insertion of the space vector modulation (SVM) in order to improve classical DTC strategy and reduce the high torque and flux ripples by producing a fixed switching frequency. This technique is known as load angle SVM-DTC. Furthermore, the sensorless application is the second part which will be treated in this paper. A design of an adaptive observer will be presented and coupled with DTC control scheme for speed/flux and load torque estimation. It can improve the control performances by decreasing the cost and increasing the reliability of the global control system by reducing the number of sensors. The proposed sensorless control method will be investigated experimentally by using Matlab/Simulink in real time environment using dSpace 1104.

Direct Torque Control is a control technique in AC drive systems to obtain high performance torqu... more Direct Torque Control is a control technique in AC drive systems to obtain high performance torque control. The conventional DTC utilizing hysteresis comparators suffers from high torque ripples and variable switching frequency. The most common solution to those problems is to use the space vector modulation. In this paper a modified direct torque control of induction motor scheme is presented. The modifications include torque and flux ripples reduction. This technique is known as SVM-DTC. It is based on stator flux orientation and space vector modulation (SVM). In the other hand this paper aims to design a sliding mode observer for speed/flux estimation which improves the control performances by using a sensorless algorithm in order to decrease the cost and reliability of the system. The theoretical principles, simulation and experimental results of sensorless control method are presented using Matlab/Simulink with real time environment using dSpace 1104.

Abstract— Direct Torque Control (DTC) is one of the most excellent strategies of torque control f... more Abstract— Direct Torque Control (DTC) is one of the most excellent strategies of torque control for induction machine. it aims to provide a decoupled control of torque and flux by the selection of optimum inverter switching tables, there is no need for any complex transformation of current or voltage. However, each vector selected from the switching table may cannot produce the required accurate stator voltage vector to provide the desired torque and flux, this results the ripples in the torque and flux waveforms. This paper reports an improved DTC scheme based on extended switching table to reduce torque fluctuations, where the circular flux vector is divided into twelve sectors of 30 degrees. The design present also proposed observer based on sliding mode approach in order to improve control scheme performance without using sensors for speed and stator flux estimation that increase the cost and reduce reliability. The simulation and experimental results are
presented. The platform used for real time control is d-SPACE
1104 along with MATLAB-SIMULINK.

Abstract— Direct Torque Control (DTC) is one of the most excellent strategies of torque control o... more Abstract— Direct Torque Control (DTC) is one of the
most excellent strategies of torque control of an induction
machine. it aims to provide a decoupled control of torque and
ﬂux. However, during steady state, notable torque, flux, and
current ripples occur. it influences greatly the speed estimation,
speed response, and also in increases acoustical noise. In this
study, direct torque control (DTC) of induction motor is
evaluated based on space vector modulation (SVM), it is able to
reduce the acoustical noise, the torque, flux, current, and speed
rippels. This proposed method based on utilising tow PI
controllers for torque and flux is designed to achieve estimated
torque and flux with good tracking and fast response with
reference torque, in addition, design of PI controllers are used to
optimize voltages in d-q reference frame that applied to SVM.
The simulation Results of proposed DTC-SVM give excellent
performances in steady and transient states as compared with
classical DTC.

Direct Torque Control (DTC) is one of the most excellent strategies of torque control of... more Direct Torque Control (DTC) is one of
the most excellent strategies of torque control of an
induction machine. it aims to provide a decoupled control
of torque and flux. However, during steady state, notable
torque, flux, and current ripples occur. it influences
greatly the speed estimation, speed response, and also in
increased acoustical noise. In this study, direct torque
control (DTC) of induction motor is evaluated based on
space vector modulation (SVM), it is able to reduce the
acoustical noise, the torque, flux, current, and speed
rippels. This proposed method based on utilising tow PI
controllers for torque and flux is designed to achieve
estimated torque and flux with good tracking and fast
response with reference torque, in addition, design of PI
controllers are used to optimize voltages in d-q reference
frame that applied to SVM. The simulation Results of
proposed DTC-SVM give excellent performances in steady
and transient states as compared with classical DTC.
Another point of this paper is the presentation of speed
control and the production of the reference torque by
using a fuzzy logic speed controller. The response of the
fuzzy PI is compared with classic PI speed controller.
Results, shows that the fuzzy PI speed controller has a
better response in a wide range area of motor speed.
Combining the characteristics of DTC-SVM scheme and
the fuzzy logic speed controller can give a high
performance controlled induction motor drive.

Conference Presentations by Abdelkarim Ammar

The AC drives Direct Torque Control technique (DTC) has been designed to obtain a high performanc... more The AC drives Direct Torque Control technique (DTC) has been designed to obtain a high performance for flux and torque control. Because of some downsides, this paper presents an insertion of the space vector modulation (SVM) in order to improve classical DTC strategy and reduce the high torque and flux ripples by producing a fixed switching frequency. This technique is known as load angle SVM-DTC. Furthermore, the sensorless application is the second part which will be treated in this paper. A design of an adaptive observer will be presented and coupled with DTC control scheme for speed/flux and load torque estimation. It can improve the control performances by decreasing the cost and increasing the reliability of the global control system by reducing the number of sensors. The proposed sensorless control method will be investigated experimentally by using Matlab/Simulink in real time environment using dSpace 1104.