Closed loop Buck & Boost Converter Mathematical Modeling, Analysis and Simulation using MATLAB

Abstract

This article presents the converter circuit analysis, mathematical modeling followed by deriving its average state space equations. The model so obtained is simulated in MATLAB in open loop and closed loop configuration and changes in the output are observed. Specifically, Buck & Boost converters with & without its controller at steady state and study of their transient responses to the changing inputs with a controller design and its implementation on SIMULINK model is presented here. The method used to control the output of the converter is Proportional and Integral error correction that is a PI controller which is used to reduce errors and stabilize the variable input fed to the Buck or Boost converters. The tool used to design the controller parameters is PID Tuner application in in MATLAB. The analyses plots derived using the tool lets us examine the controller performance in time and frequency domain. The advantage of the tool used is, it allows user to interactively refine the performance of the controller to adjust loop bandwidth and phase margin or to favor a set-point tracking or disturbance rejection. The designed converters are analyzed in current mode control and voltage mode control to switch on/off. The long term goal is to have a sophisticated controller design for buck & boost converters for the application where variable input is fed to them, so as to allow its simulation to fully understand how the converters behave when controller is implemented. The model tested here are of the similar nature that are being used in standalone solar or wind energy generation & distribution systems. The variable nature of the input tested here with Buck & Boost converters reflects the variable nature of the output of the renewable energy sources and that broaden the scope of these converters to be implanted with such standalone energy systems