Mohamed Redha SKENDER, Abdelhalim TLEMCANI
Research Laboratory in Electrical Engineering and Automatic (LREA),
University of Medea, Ain D’ heb, Medea, 26000, Algeria
skender_mohamed@yahoo.fr; h_tlemcani@yahoo.fr

Abstract: In this paper, a control algorithm of higher order sliding mode was developed for a series multi cells converter to force floating voltages across capacitors to stay in their reference. The results of simulations were validated experimentally by a converter that has been realized for this task.

Keywords: nonlinear control, converter, sliding mode control, algorithm, chopper.

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CITE THIS PAPER AS:
Mohamed Redha SKENDER, Abdelhalim TLEMCANI, Implementation of a New Super Twisting Mode Algorithm Controlled by Dspace: Application to Series Multicell Converter, Studies in Informatics and Control, ISSN 1220-1766, vol. 25(2), pp. 255-264, 2016. https://doi.org/10.24846/v25i2y201613

1. Introduction

The performances of electronic power converters have been evolving through the last decades, in an attempt to be more reliable and efficient. This has been carried out thanks to the developments of the semiconductor of power components and the new system of energy conversion. These high performances are directly linked to the converter’s topology and its power electronic components.

Multicell converters are currently embedded in many electric devices. Their aim is to convert an electrical energy shape (voltage /current / frequency) to another one.

This new topology presents two additional advantages: the possibility of a modular construction and the possibility of using components having large diffusion.

On the other hand, the following model must be simple to allow real time control and precise enough to achieve the desired behaviour. Because it’s based on continuous variables and discrete variables, multicell converter modelling is claimed to be difficult [19], [20]. According to previous studies, three types of models could be found.

The average model consists in calculating average value of all variables during one sampling period. Nevertheless, this model cannot represent the capacitors terminal voltage natural balancing; the harmonic model based on the decomposition in Fourier series of control signals, which determine the harmonics phase and amplitude across the switches, also determining the harmonic current of the load to determine the evolution of capacitor voltages; The instantaneous model considers all the switching over a period (discrete location). This model contains all information; it is generally used to validate controls or to use as observers [16], [19].

Various control methods have been proposed for the multicell converters, cite as nonlinear control based on input-output linearization [10], Robust Switching Control Systems with Input Delay [8], predictive control [5], [15], hybrid control [4], sliding mode control [1], [6], [17], Exponential Mapping Function [12].

In this work, we will apply and implement a new sliding mode controller to the load R-L connected to a multicell converter called super twisting mode. This control is very well adapted for this kind of converter, as we shall demonstrate in the subsequent sections.

Sliding mode control (SMC) [22] is a nonlinear control technique featuring remarkable properties of accuracy, robustness, and easy tuning and implementation.SMC systems are designed to lead the system states onto a particular surface in the state space, named sliding surface. Once the sliding surface has been reached, the sliding mode control keeps the states on the close neighborhood of the sliding surface. Hence The advantages of SMC are the dynamic behavior of the system can be adapted by the particular choice of the sliding function, and also the closed loop response becomes completely insensitive to uncertainties, disturbance and nonlinearity [23] [24]. Sliding modes based controllers have witnessed major development these last years. Such an interest in sliding modes controllers can be explained by their intrinsic robustness property and the relative ease of application (see for example [2] [3] [7] [9] [11] [13] [18]).

In order to evaluate the feasibility and constraints of the sliding modes algorithm, the realization of an experimental model was proposed to validate the actual performance of the algorithm. The realized maquette is sized for educational or research applications. The bench includes a Dspace1103 card, a multicellular converter of three cells, a DC motor or a RL load. This bench allows:

• Define and associate the different hardware and software
• Develop control programs
• Applied sliding mode control techniques.