Design and analysis of TOSMC-based BLSEPIC PFC converter for battery charging applications

In this research work a single stage Power Factor Correction (PFC) based battery charger using 1Φ AC-DC Non-Ideal Bridgeless Single Ended Primary Inductance Converter (BLSEPIC) has been designed. Small signal Modelling of BLSEPIC converter is done by considering the parasitic elements of the inductors, capacitors, switches and diodes. Transfer function of seventh order BLSEPIC converter is derived using state space averaging technique. To reduce the complexity of the controllers, the BLSEPIC converter model has been reduced using Hankel Matrix Approximation Technique. The Dual loop control strategy employing outer Grasshopper Optimization Algorithm (GOA) tuned PI controller and inner Third order Sliding Mode controller(TOSMC) ensures output regulation and input current shaping. The sliding surface co-efficients are calculated using control to input transfer function. The proposed control strategy for BLSEPIC converter is simulated for a linear load (resistive) and non-linear load (Battery) using MATLAB/Simulink software tool and results are illustrated for steady-state and dynamic conditions such as line, load and set-point variations. To summarise, a single phase 200W BLSEPIC converter controlled using GOA tuned outer PI and inner TOSMC feeding a resistive and battery load is simulated and the prototype model has been designed and developed to substantiate with the simulation results. The proposed system achieves nearby UPF operation with a source current THD of 2.9118% (Resistive Load) and 4.989% (Battery Load).