Design and implementation of a low-cost single-ended primary-inductor converter (SEPIC) for enhanced maximum power point tracking in a photovoltaic system

This study presents the implementation of a Single-ended Primary-inductor Converter (SEPIC) converter-based maximum power point tracker (MPPT) in a photovoltaic (PV) system. The SEPIC converter, known for its wide operating range and non - inverted output, presents a suitable option as a DC-DC converter interface between the PV array and load. A modified Incremental Conductance (IC) algorithm is implemented on dSPACE DS1104 controller board based on 50 kHz PWM to perform global MPP tracking. The purpose of the modification is to allow the IC algorithm to converge to the global maximum power point under partial shading conditions by initializing the algorithm near the estimated global peak. For performance verification, the setup is extensively tested using an indoor PV emulator under static and dynamic conditions. Under partial shading conditions, its performance was benchmarked against the conventional IC algorithm. Results indicate that the prototype achieves efficiency of over 98% in both static and dynamic tests for EN50530-defined c-Si and thin film modules. On boot-up, the tracker can locate the maximum power point within 2-3 seconds. This study addresses the need for cost-effective MPPT solutions to maximise PV energy extraction under dynamic and partial shading conditions, leveraging SEPIC converter versatility to enhance performance and accessibility.