The use of wind energy for electric power generation provides a clean and renewable source. Therefore there is an increasing interest in developing and exploiting natural energy generation system. Switched reluctance generators (SRGs) have the potential to be a robust and highly efficient electrical conversion system for variable-speed wind applications. This study presents a new approach for optimising performance of a SRG intended for variable-speed direct drive wind turbine applications. DC bus voltage level and phase voltage switching angles have been identified as control variables affecting power generation. Owing to highly non-linear characteristics of SRG, iterative simulation of the generator model on the range of control variables can be used for finding output power profile. Since it is a multidimensional search space, the number of iterations is very big. Differential evolution (DE) strategy has been introduced to find optimal firing angles and DC bus voltage level under multiple operating conditions. Optimisation of the control variables is performed using a machine model based on the measured characteristics. Selected operating points are experimentally tested using a 4 kW 1500 rpm SRG prototype. DE algorithm is a viable alternative for generating optimal control in multidimensional optimisation of SRG wind energy generation.

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This paper proposes and develops a new direct voltage control (DVC) approach. This method is designed to be applied in various applications for AC drives fed with a three-phase voltage source inverter (VSI) working with a constant switching time interval as in the standard direct torque control (DTC) scheme. Based on a very strong min(max) criterion dedicated to selecting the inverter voltage vector, the developed DVC scheme allows the generation of accurate voltage forms of waves. The DVC algorithm is implemented on a dSPACE DS1104 controller board and then compared with the space vector pulse width modulation technique (SVPWM) in an open loop AC drive circuit. To demonstrate the efficiency of the developed algorithm in real time and in closed loop AC drive applications, a scalar control scheme for induction motors is successfully implemented and experimentally studied. Practical results prove the excellent performance of the proposed control approach.

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information [3], [4], [8].In Direct Torque Control, the torque and stator flux '. are regulated to their command values by selecting,thti adequate switching state. In its original version, the DTC scheme makes no difference between-a very large and relatively small error of flux andor torque. The switching states chosen for the large error that occurs Abstract-This paper proposes a new approach for direct torque control (D.T.C) based on fuzzy logic concept. The developed fuzzy logic controller (F.D.T.C) uses mainly the input\output data. The real-time implementation is here described and the experimental and simulation results are compared. A sufficient agreement between the two results have been obtained. dlqs dqr (2) vqS = R, lqS + L, y + L , -O = R, tdr +I,, dldr + L , -+my (L, lqr +L, t q s ) dl dlds dtqr dlqs dt dt O=R, lqr +L,-+ L , --C O~ (L, I& +L, I & ) dt dl

Speed sensorless control schemes have potential benefits for industrial applications because they contribute to reducing process cost and they avoid using fragile sensors as encoders or resolvers in hostile environment. In addition, simplicity, reliability, and fast response of control structures to signal commands are much-needed features. In this paper, a new Speed Sensorless Direct Control (SSDC) technique allowing the achievement of these objectives is proposed. This technique combines Field Oriented Control (FOC) and Direct Torque Control (DTC) properties in the same approach. The estimated speed is reached only according to the measured current and voltage of the stator. DTC is extended to speed sensorless direct control with any notable modification. The proposed scheme is implemented to the induction machine benchmark and evaluated in real time under various possible scenarios of use. Experimental results show that the proposed SSDC has interesting capabilities to conduct induction motor in real time operation with good accuracy.

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