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1

Sensorless DTC of induction motor using improved neural network switching state selector controller

Messaif I., Berkouk E. M., Saadia N.

Archives of Control Sciences

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2010

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Vol. 20, no. 4

435-456

EN

The paper deals with development of sensorless Direct Torque Control (DTC) system based on neural network. This network is built to solve the task of proper switching states selection based on information about electromagnetic torque and stator flux (position and magnitude) of induction motor. In fact, this technique which uses conventional switching table is not convenient for one-line and real time control for its high computation time. In order to avoid this problem a solution based on neural network is proposed. Well trained Artificial Neural Network structure can replace successfully the switching table. However, in the Neutral-Point-Clamped topology, it has an inherent problem of Neutral Point Potential (NPP) variation. In this way, a Neural Network-Direct Torque Control technique has been applied and the estimated value of the Neutral Point Potential is used, which is calculated by motor currents. This control strategy offers the possibility of selecting appropriate switching state to achieve the control of Neutral Point Potential. Simulation results verify the validity of the proposed method.

2

Feedback control of three-Level PWM rectifier: Application to the stabilization of DC Voltages of five-level NPC active power filter

Abdelkrim T., Berkouk E. M., Benslimane T., Benamrane K.

Archives of Control Sciences

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2010

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Vol. 20, no. 3

317-339

EN

One of the most important drawbacks of the three phases five-level NPC (Neutral Point Clamped) Active Power Filter (APF) is the neutral point balance. As the consequence, the capacitors voltages of the input DC bus of the APF are not equal which constitutes the major limitation for the use of this power converter. In order to stabilize these DC voltages, it is proposed in this paper to study the cascade constituted by three phases three-level PWM rectifier-clamping bridge filter-five-level NPC APF. In the first part, the authors present a topology of five-level NPC Voltage Source Inverter (VSI), and then, they propose a model of this converter and its PWM control strategy. In the second part, the modeling and control of three-level PWM current rectifier is presented. In the third part, to remedy to instability problem of the input capacitors DC voltages of the APF, the authors propose feedback control of the three-level PWM rectifier followed by clamping bridge filter. After that, the sliding mode regulator used to control the active filter is developed. The obtained results are full of promise to use this topology of APF in high voltage and high power applications.

3

Novel digital PWM strategies of multilevel voltage source inverters

Beriber D., Talha A., Berkouk E. M., Francois B., Boucherit M. S.

Archives of Control Sciences

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2009

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Vol. 19, no. 1

43-57

EN

In this paper, two novel algorithms of algebraic PWM strategies for seven-level Neutral Point Clamped (NPC) Voltage Source Inverter (VSI) are presented. These algorithms use a control model of the inverter. In the first part, the authors develop a model of this inverter, without assumption on its control, by using design method associated to Petri nets and switching functions. In the second part, knowledge and control models of this converter are reviewed by using respectively instantaneous and continuous equivalent switching functions. In the last part, two algebraic PWM control strategies of the inverter are proposed. The obtained results are full of promise to use these digital strategies to control seven - level NPC VSI used in high voltage and high power applications as electrical traction.

4

New direct space vector modelling and control of five-level three-phase inverters

Bouhali O., Berkouk E.M., François B., Saudemont C.

Archives of Electrical Engineering

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2005

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Vol. 54, nr 2

159-182

EN

A simple direct modulation strategy that enables to copy directly modulated waveforms onto output voltages of a five-level three-phase inverter is presented. The modelling shows that the modulated multilevel voltage is obtained by combination of eight different three-level functions, which are called modulation functions. Therefore, a space vector modulation without using a Park transform is explained. Based on this algorithm, the location of the reference voltage vector can be easily determined. Then, the voltage vectors are selected to generate corresponding levels and simultaneously their durations are calculated. Simulation results for a three-level and five-level three-phase inverters are presented to verify the performance of the proposed space vector modulation.

PL

W artykule przedstawiono prostą metodę modulacji szerokości impulsów (MSI) pozwalającą na kształtowanie napięcia w 3-fazowym, 5-poziomowym falowniku MSI na podstawie bezpośredniego odwzorowania sygnałów modulowanych. Modelowanie wykazało, że wielopoziomowe napięcie modulowane otrzymuje się dzięki kombinacji ośmiu różnych funkcji 3-poziomowych zwanych funkcjami modulacji, co umożliwia modulację wektora przestrzennego bez stosowania transformacji Parka. W oparciu o przedstawiony algorytm można łatwo wyznaczyć położenie wektora napięcia odniesienia i, następnie, określić wektory napięć dla generacji odpowiednich poziomów oraz ich przedziały czasowe. Przedstawiono rezultaty symulacji falowników 3-fazowych 3- i 5-poziomowych weryfikujące proponowaną modulację wektorową.