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We address the problem of controlling the unsteady flow separation over an aerofoil, using plasma actuators. Despite the complexity of the dynamics of interest, we show how the problem of controlling flow separation can be formulated as a simple output regulation problem, so that a simple control strategy may be used. A robust multivariable feedback control is designed and tested in a configuration with two actuator/sensor pairs. Accurate numerical simulations of incompressible flows on a pitching NACA 0012 at Reynolds Re = 20, 000 are performed in order to illustrate the effectiveness of the proposed approach. Robust, fast flow reattachment is achieved, along with both stabilisation and increase/reduction of the lift/drag, respectively. The control system shows good dynamic performances, as the angle of attack is varied. The chosen output can be experimentally measured by appropriate sensors and the extension of the proposed approach to 3D configurations is straightforward. (C) 2017, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

This paper presents an advanced dynamic cooling strategy for multi-layer structured power electronic modules. An observer based feedback controller is proposed to reduce a power device or module's thermal cycle amplitude during operation, with the aim of improving reliability and lifetime. The full-state observer design is based on a developed Cauer type thermal model. The observer enables estimation and control of the temperature at reliability critical locations only measuring one accessible location. This makes the method particularly powerful and suitable for application in power systems. The designed strategy is confirmed experimentally. Although the experiment is developed for a specific application scenario, the proposed strategy is of general validity.

Generators working with variable speed, rather than fixed speed, have many advantages, which are well documented in the literature. Higher efficiency, better power to size ratio and less mechanical stress in the system are some of the characteristics of variable speed generators. In particular, variable speed diesel generators can be used to provide small highly portable generation systems for emergency vehicles and military/aerospace applications. Such systems can be used to feed stand-alone linear/non-linear loads if an adequate power converter interface is provided. Four-leg matrix converters can be used as the power electronic interface between variable speed generators and stand-alone loads. The fourth leg provides a neutral point for single phase loads and a path for the circulation of zero sequence currents. When non-linear loads are connected to the matrix converter output, relatively high harmonic distortion can be produced in the load voltage unless an appropriate control system is provided. In this paper the application of a repetitive control system to improve the quality of the load voltage is presented. Experimental results obtained from a prototype are shown and fully analysed.

This paper presents the development of an adaptive cooling methodology in which the thermal impedance of the power system is continuously varied as a function of both its power dissipation and ambient temperature. As compared with a fixed parameter cooling solution, such an approach enables for a reduction of the amplitude of thermal cycles and the improvement of overall system efficiency and operational lifetime. The study comprises of an initial theoretical part and of subsequent experimental proof-of-concept demonstration of the proposed cooling strategy.