Nonlinear dynamics of power electronic converters

Abstract

Power converters in power electronic systems are used to control and convert electric power based on the requirement of specific applications During this conversion switching of power devices and presence of reactive elements makes the system nonlinear Practically all the power electronic converter systems are inherently nonlinear because of the feedback controlled switching Inherent nonlinear characteristics of switching devices presence of non ideal capacitances and inductances make the power electronic systems nonlinear Power Electronic converters are basically piecewise switched circuits which are operating in standard topologies usually fixed and the toggling is done in a repeated manner This results in nonlinear time varying operation Hence there is a need to use nonlinear methods for analysis and design Even though understanding the effects of nonlinear dynamics in the system is difficult it is essential to analyze systems with regard to conversion and utilization of electric power The switching action in power electronic converters is based on the feedback control such that the output variable is maintained as per requirement even under the presence of disturbances in supply systems as well in load The device is switched on at the start of the clock pulse and it is switched off according to the comparator action either in current control topology or voltage control topology The former uses outer voltage feedback loop and inner current feedback loop whereas the latter uses only voltage feedback The feedback control involves a number of nonlinear components such as PWM controller comparator and digital controllers comparator and digital controllers This feedback control circuit along with the topology chosen determines the dynamic behaviour of the converter system newline