Closed loop PI control of DC-DC Cascode Buck-Boost converter

Two Buck-Boost Converters are used to design a DC-DC Cascode Buck-Boost Converter where IGBT as the active switch. The two Buck-Boost Converters are named as top semi stage and bottom semi stage. The voltage input to the bottom semi stage converter is given directly by means of DC supply and the voltage input to the top semi stage is given by means of DC supply and the output voltage of the bottom semi-stage Converter and the output voltage is given by sum of voltage output of top semi stage and bottom semi stage. Hence, the proposed Cascode Converter can be used to achieve very high output voltage gain in a single stage rather than using more number of cascaded converts without high duty ratio. Operating principle and steady state analysis are discussed in detail in this paper and the voltage gain is compared with conventional Boost, Buck-Boost and Cuk Converter. Dynamic analysis of complete circuit is analyzed and MATLAB/Simulink simulation is done and finally to verify the proposed cascode converter laboratory experiment of 50W has been implemented to test both the simulation and experimental result. PI Controller is employed to control the output voltage of the converter to the reference point.