A comparative control study for a maximum power tracking strategy of variable speed wind turbine is provided. The system consists of a direct drive permanent magnet synchronous generator (PMSG) and an uncontrolled rectifier followed by a DC/DC switch-mode step down converter connected to a DC load. The buck converter is used to catch the maximum power from the wind by generating an efficient duty cycle. Distinct Maximum Power Point Tracking (MPPT) algorithms are analyzed and compared: a classical Proportional-Integral controller (PI) and two based Fuzzy Logic Controllers (FLC), including a conventional Fuzzy-PI and an Adaptive FLC-PI. The main aim of the presented study is to develop an advanced control scheme for wind generators to ensure a high level operating of the system and a maximum power extraction from the wind. This is achieved by analyzing the behavior of the system under fluctuating wind conditions employing Matlab Simpower Systems tool.Simulation results confirm that the Adaptive FLC-PI controller algorithm has better performances in terms of dynamic response and efficiency especially in comparison with the ones of a PI controller under variable wind speed. KEYWORDS DC-DC buck converter, fuzzy logic controller (FLC), maximum power point tracking (MPPT), permanent magnet synchronous generator (PMSG), proportional integral (PI) controller, wind turbine

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A Robust controller designed by employing internal model control (IMC) is presented for permanent magnet synchronous motor (PMSM) drive with estimation of both the rotor speed and the load torque with a predictive state observer. It is to achieve accurate control performance in the presence of uncertainties and system parameters variation. The Experimental results prove that the IMC controller with the presence of the predictive state observer greatly improves the performances of the speed loop and simplifies the design procedure. The robustness of this scheme is analysed, and the bounds of control parameters that ensure the drive stability are obtained. Keywords:Internal model control, permanent magnet synchronous motor, PI controller, speed estimator. IntroductionDuring these last decades, the PMSM found a very great interest in many industrial applications, due to considerations of cost, size, low maintenance, speed capability and simplicity of design. However, the PMSM presents a coupled non-linear multi variable control structure which requires a complex nonlinear control in order to achieve good dynamic performances [1][2][3][4][5].The machine drive systems with high performances must allow the development of control strategies which offer a strict follow-up in position and in speed. Moreover, these performances must be insensitive to the variations of the machine parameters, especially the mechanical parameters such as the inertia moment of the rotating mass.Improved and robust control of these processes is becoming necessary due to increasing competition and environmental considerations. Also, the availability of advanced technology and inexpensive computing power are a consequent for design and implementation of advanced control strategies. Many control techniques have been proposed and analyzed for nonlinear processes, and a good review of these is available in literature [6][7][8]. Linear internal model control as a general structure that uses a model in parallel with the process has become very popular among practicing engineers [9][10][11][12][13][14][15][16][17][18].IMC was widely used in the chemical industries, mostly in the form of proportionalintegral-derivative (PID) controllers, in which a clear tradeoff between closed loop performance and robustness to model uncertainty is provided [12][13][14]. Besides its industrial importance, IMC also provides a convenient theoretical framework for understanding the performance limitations due to non minimum-phase behavior and model uncertainty [15][16][17][18].In this work, an IMC strategy is proposed and applied to the PMSM speed control with estimating the rotor speed and load torque.

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This paper presents an experimental study of the RST method applied to control the speed of a Permanent Magnets Synchronous Motor (PMSM) supplied with a vectorial PWM (Pulse Width Modulation) inverter. The RST is used together with a predictive state observer in order to estimate the load torque. The experimental results prove that the presence of this observer allows a better control of the actuator behavior while guaranteeing robustness characterized by a good insensitivity with respect the parametric variations. Keywords -Control of Drive, Permanent MagnetSynchronous Motor (PMSM), Robust control, Robustness, DSP. I. Nomenclature V sd , V sq Stator winding d, q axis voltage respectively i sd, i sq Stator winding d, q axis current respectively i sd * , i sd * Reference stator current winding d, q axis current respectively ω The electric speed of the rotor * ω Reference rotor speed ω Estimated rotor speed θ Rotor position Φ f Permanent flux R s Stator phase resistance L sd , L sq T he stator inductances of the axis d and the axis q J inertia of the turning parts f c Viscous friction coefficient p Poles pairs number. r C Load torque r Ĉ Estimated load torque s Laplace operatorII. Introduction Permanent magnet synchronous motors (PMSMs) are of great interest especially for industrial applications in lowmedium power range, since it has superior features such as compact size, high torque/weight ratio, high torque/inertia ratio and absence of rotor losses [1-2]. However, the performance of the PMSM is very sensitive to external load disturbances and parameter variations in the plant. To overcome these problems several control strategies such RST controller associated to the load observer, have been proposed for speed control of a PMSM.The vector control method, known as a cascade type regulation, was widely used [3-4-12] and [16]. The advantages of this method are given in [7][8][9][10][11][12][13]. For this, two loops are adopted in order to obtain the desired outputs. Initially, we release the internal loop which ensures the current control. Then, the synthesis of an external loop allows the speed control [4][5][6][7][8][9][10][11].However, the presence of external disturbances and parametric variations in the motor, limit the dynamic performances of the traditional vector control method, to use conventional regulators PID. In addition, a theoretical question is asked: is it possible to develop a simple control strategy which exploits the advantages of the vector control method of the PMSM and overcoming the problems involved in the limitations of the conventional approaches.Actually, the concept of the RST is very important in the analysis of the transient stability in fact that it is able to improve the performances obtained with traditional PID regulator, decoupling the axes (dq) while considering the presence of the parametric variations [16].The main purpose of this paper is to conceive an empirical environment containing a digital computer (Dspace 1104) allowing the implementation of the RST control. This cont...

The aim of this work is to improve the dynamics and to overcome the limitation of conventional fixed parameters PI controller used in induction motor (IM) field-oriented control (FOC). This study presents and implements a RST and an adaptive fuzzy controller (AFC) to enhance variable speed control. Theoretical background of theses controllers is outlined and then experimental results are presented. Practical implementation has been realized on a board with a 1.1 KW IM supplied by 10 KHz space vector pulse width modulation current regulated inverter used as power amplifier consisted of 300V, 10A IGBT and Matlab/Simulink environment. Test benches have been established under different operating conditions in order to evaluate and compare the performances of the PI, IP, and polynomial RST and adaptive fuzzy controllers. Parameter variations for the rotor and the inertia moment variation were done in order to compare and verify the robustness of each controller. High dynamic performances and robustness against parameters variation were obtained with the use of both RST and AFC.

This article proposes a digital control strategy of the RST type combined with a PI regulator of a synchronous servomotor with permanent magnets supplied by a voltage inverter controlled by the vector PWM technique whose robustness of the regulators is studied by the µ-analysis technique, and the estimation of the mechanical quantities is carried out using an observer by the Kalman filter. This study presents a detailed theoretical analysis and the simulation and experimentation results obtained clearly show the effectiveness of the proposed control strategy.