Design and Performance Analysis of Effective Controllers for Multi-level DC to DC Cascaded Boost Converter

Abstract

In this article, an investigation of effective controllers for Multi-level DC to DC Positive Output Cascaded Boost Converter operating in continuous conduction mode is carried out. The positive output cascaded boost converter is recently designed converter which increases the output voltage in geometric progression with simple structure and has better voltage transfer gain in comparison with conventional converter. In this study, two level cascaded positive output boost converter (TLCPOBC) using super lift technique was considered and the results were compared with single level cascaded positive output boost converter (SLCPOBC) to show the importance and need of Multilevel converters in DC to DC applications. Due to switching mode operation, the characteristics of TLCPOBC were non-linear in nature. In addition, during line and load variations, the system was not stable and converters behaved drastically. Therefore, an effective controller is essential to enhance the dynamic characteristics of converter. Linear controllers like Proportional Integral Controller (PI) and Proportional plus Proportional Integral Controller (P plus PI) were considered in this study. Here, PI controller acts as Single Loop Controller (SLC) whereas, P plus PI acts as Multi Loop Controller (MLC). The main advantage of MLC over SLC is that it may regulate both output voltage and inductor current of TLCPOBC which improves the performance of the system over a wide range of operating conditions. Using Ziegler -Nicholas tuning method, the parameters of controllers were obtained by the state-space equations of TLCPOBC. The performance of controllers is verified in MATLAB/Simulink models and results are validated to show the importance of an effective controller for TLCPOBC.