A hybrid step-up converter for PV integration with wide input variation acceptability: comprehensive performance and reliability assessment

Abstract

Abstract A high-step-up DC–DC converter (DDC) is commonly used in micro-grids, renewable energy source (RES) integration, uninterruptible power supplies, hybrid vehicles, and other applications to deal with intermittency in power sources. Solar photovoltaic (SPV) is a prominent RES due to its many benefits, but its output voltage must be enhanced for high-voltage (HV) applications; hence, various topologies are suggested for desirable gain in the literature. Nevertheless, contemporary topologies exhibit restricted gain, higher device stress, analysis on restricted performance metrics, constrained handling capacity for input variations, relatively lower reliability, and suboptimal device utilization. This work investigates a new Z-source with switched-capacitor (HZSSC)-based hybrid step-up converter to solve the aforementioned restrictions and adapt PV voltage dynamics. Additionally, this paper presents MIL-HDBK-217F-based methodology for evaluating converter-level reliability, assessing the implications of device parametric variation on overall reliability, conducting a detailed analysis of figure of merits, performing thermal modeling, and executing small-signal-modeling to demonstrate operational efficacy. In-depth mathematical analysis of both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are conducted. The detailed comparison analysis shows that the suggested converter outperforms traditional converters in voltage-gain, voltage-stress, device-utilization, and reliability. Additionally, a 400 W, 220 V laboratory-scaled prototype shows 68 % reliability after 20 years. The hardware test outcomes validate the accuracy of both the mathematical investigation and simulation findings.