Investigations on performance improvement of closed loop controllers of DC DC converter

Abstract

The field of power electronics is currently experiencing unprecedented growth. The exponential growth in power converters is due to several factors, paramount among them being technological advancements made by the semiconductor device industry, which has led to the introduction of high speed and high power converter topologies. Generally, power converter based systems consist of source, load, sensing units, and the controller. Development of closed loop controllers is essential for regulation of the power transfer process. Out of different forms of power conversion, DC DC power conversion is widely utilized in various fields like medicine, military, aerospace, launch vehicle, transportation, telecommunication, computer peripherals, robotic actuators, and renewable energy power systems. This thesis limits its purview to the study and analysis of Buck-Boost, and#262;uk and SEPIC converters, resulted in enhanced performance such as larger voltage gain ratio, high power density, and decreased ripples in load voltage, and inductor current. Buck-Boost, and#262;uk and SEPIC converters whose characteristics are modeled and its performance aspects are reported in this thesis. The open-loop behavior of Buck-Boost, and#262;uk and SEPIC converters need modeling and simulating the converter using modeled equations. The closed loop control of these converters have PID controller. PID controller parameters are obtained from Ziegler-Nichols step response method. These converters can be analyzed using the state equation. The mathematical model of SEPIC, and#262;uk and Buck-Boost converters for simulation using SIMULINK has been carried out with/without SimPower System Elements. The open-loop and closed-loop results are compared. The design of fuzzy controllers are based on heuristic knowledge of the converter and tuned using trial and error. Fuzzy controller is designed for Buck-Boost, and#262;uk and SEPIC converter. In power converter, the conduction losses and switching losses are reduced using the passive elements switched capacitors. newline