PERFORMANCE ANALYSIS OF BOOST CONVERTER UNDER NONLINEAR SCENARIOS

Abstract

The project based on a closed loop PI controlled boost converter using the following two nonlinear operating points: saturation nonlinearity and dead-zone nonlinearity. Boost converter is much applied in power electronic applications to increase the voltage of low DC source to a higher voltage which is much regulated. While the theory is applicable, practical converter systems are subject to nonlinear behaviors and limitations in control which can act differently in overall performances and stability. This work, therefore, is based on the study of the effect such nonlinearities have on the dynamic response of a boost converter with a PI controller. The proposed system is based upon the use of a Proportional–Integral (PI) controller in a closed-loop system to control output voltage of the boost converter. The error between the reference voltage and the actual voltage output is continuously monitored by the controller and fed to the switching device to adjust the duty cycle to reduce the error to a minimum. The proportional portion of the feedback circuit provides better transient response and the integral portion removes steady-state error and enhances voltage regulation. In idealized systems, the duty cycle may be controlled between preselected limits, but, in practical systems, two upper and lower limits must be established because of the limitations of switching devices and of hardware. If the controller output exceeds these bounds, saturation occurs that can influence converter response and stability. Another nonlinear effect that is necessary to consider is the phenomenon of dead-zone nonlinearity, in which small control signals are not enough to give any response from the system. The PI controller shows a stable operating condition of the converter even in the presence of nonlinearities as shown by the simulation results. The voltage regulation of the controller is satisfactory and the dynamic response is quick while the steady-state error is negligible under different operating conditions. Saturation and dead-zone nonlinearities of the converter are then compared and their effects on converter performance are understood. The study points to the fact that nonlinear effects need to be taken into account when designing a controller; and that the design's ability to deal with nonlinear effects in a power electronic system can be improved by using PI control techniques.