A Novel Interleaved Modified Y-Source DC-DC Converter for Grid-Connected Photovoltaic Inverters

Impedance-source converters have gained attention in photovoltaic (PV) systems due to their inherent voltage step-up capability. This study proposes a novel interleaved modified Y-Source (I-m Y-Source) converter specifically designed for grid-connected inverters used in low input voltage and low power PV applications. The topology reduces voltage and current stresses on power switches and lowers input current ripple. Integrated with a two-stage H-bridge inverter and a perturbation and observation (P&O) maximum power point tracking (MPPT) algorithm, the system was tested under six scenarios that combined various irradiance and temperature profiles across a wide range of conditions. Simulations confirm a stable DC-link voltage of 380 V with a convergence time of 0.5 s, achieving a ten-fold boost gain while keeping fluctuations limited to 38 V. The implementation of phase-shifted interleaving resulted in a 43% reduction in current ripple, while the voltage-boost switches operated under a low voltage stress of 98 V, corresponding to one-quarter of the DC-link voltage. Notably, MOSFET voltage stress remains nearly constant even as PV voltage decreases, enabling high step-up operation without additional semiconductor stress. Thermal and efficiency analyses reveal that the I-m Y-Source converter sustains 93.2% efficiency at 450 W, outperforming the non-interleaved topology by 7%, while loss distribution highlights the dominance of magnetic components, which account for over 60% of total losses. Overall, the converter demonstrates high robustness characterized by continuous current flow, low current ripple, reduced voltage stress and and high efficiency while achieving a total harmonic distortion (THD) below 5%, thereby making it a suitable candidate for PV microinverter applications.