An innovative high-gain multi-stage non-isolated step-up converter controlled by optimal interval type-2 fuzzy system based maximum power point tracking

• An innovative high-gain multi-stage non-isolated step-up converter as boost converter to attain the targets of high-voltage gain, low current ripple, high efficiency and smooth dc voltage. • Increase the voltage gain using one dual-winding coupled-inductor, one switch and one medium frequency transformer to attain a cost-effectiveness structure. • An optimal interval type-2 fuzzy system based maximum power point tracking to transfer the maximum power of solar-energy module to the load side. • Multi-objective grey wolf optimizer to accurately control the photovoltaic system. • Results validation based on MATLAB/SIMULINK and lab prototype tests. In photovoltaic (PV)-based power generation systems, the conventional and interleaved boost converter undertakes a pivotal task by augmenting its low output voltage to high voltage level. These converters have some prominent drawbacks like low voltage gain, high current ripple, unsmooth dc voltage and insufficient efficiency. This paper aims to propose an innovative high-gain multi-stage non-isolated step-up converter (HGNISUC) to triumph over these drawbacks. The proposed structure has been generally constructed using a high-voltage gain dc-dc converter and a classic rectifier which can provide high voltage gain based on dual-winding coupled-inductor (DWCI). Its cost is significantly reduced due to utilization of only one switch and one medium frequency transformer. Since the proposed structure has been operated in the PV system, an optimal interval type-2 fuzzy system based maximum power point tracking (OIT2FS-MPPT) has been designed to transfer the maximum power of solar-energy module to the load side. Due to the multi-objective nature of the control problem, multi-objective grey wolf optimizer (MOGWO) is used to optimally tune the controller parameters. Finally, the performance of the proposed converter has been validated under both MATLAB simulation and lab prototype tests.