Narrow Results

The averaged switch modeling approach is a powerful method for representing the behavior of a wide variety of converters through equivalent circuits. The model is not linear and it is common to perform a small signal linearization about an operating point and design a linear controller. Models obtained with such method involve considerable approximation and produce results that are limited for high performance controller designs. In this paper a piecewise affine approximation technique is introduced for modeling PWM converters. This model is much more precise in predicting the dynamic response of averaged nonlinear model comparing the linear model. This paper also presents a piecewise linear controller synthesis method for PWM converters described by the proposed PWA model. The proposed controller is very efficient and effective. The design method is well suited for converters having a wide range of variation about their operating point. A simulation example on buck-boost converter is presented to demonstrate the performance of the proposed method for modeling the dynamics of the converter and designing the appropriate controller.

For a fully digital control of PWM converters, considerable research has been done based on the predictive current control (PCC) scheme. However, it requires a large amount of calculation in the step of experimental implementation. Besides, when compared with the classical linear control scheme, the sampling interval of the PCC scheme must be shorter to obtain the same control performance for current. Due to this, a digital signal processor with excellent performance is required. This paper proposes an improved simplified model PCC scheme for three-phase PWM converters. The main objective is to simplify the PCC scheme. Also, the proposed control scheme is able to reduce the calculation time without affecting the performance. Simulations and experiments are carried out to investigate the presented novel predictive current control scheme. The results indicate that the three-phase PWM converter has excellent static and dynamic performance with the proposed scheme. Besides, the calculation time can be obviously shortened.

The approach to research the uncertainties and the regularities of nonlinear system behavior is developed in the paper. The peculiarity of the approach is connected with modifying the experimental bifurcation diagrams that allows to identify and to analyze certain aspects of the nonlinear dynamics evolution. The variety and the interrelation of the modified bifurcation diagrams are shown. Attention is focused on estimating the limits of the zone within which the nonlinear system behavior is characterized by the uncertainty and on making visible the particular tendencies of dynamics evolution within this zone. The results obtained on the experimental setup of PWM buck converter are used for illustrations. In particular, the uncertainty zone is assumed to be the unit of measurement to estimate the operating process stability margin. It is demonstrated that the properties corresponding to the practical experience appear as per this assumption.