부산대학교 도서관

A new hybrid non-linear current controller for imposing the output current of single-phase voltage source converters is proposed and studied. This hybrid controller, called “modulated hysteresis” controller, combines in one hand the robustness properties of a hysteresis controller and on the other hand the zero static error of a linear PI controller. In addition it allows the fixed frequency operation of the converter. To model the proposed non-linear current controller, different tools are developed. In a first step, a high frequency average model to study the average dynamic properties (bandwidth, time response, overflow) is proposed. To investigate the behavior of the current ripple due to the switching effect, a second model, based on the construction of a three-dimensional bifurcation diagram and the definition of a form function, is developed. It allows determining the nature of each cycle by studying the state trajectory during the corresponding switching period. Design rules of the parameters of this hybrid non-linear current controller are explained and its robustness properties are tested by numerical simulation and experimentation.