Enhancing Photovoltaic Inverter Reliability Through Advanced Hardware Protection and Simulation Techniques

Power electronics converter reliability is an issue in today’s grid, and it is an issue that will only become more prevalent as the nation and world move toward greater renewable energy penetration. While a significant amount of research has been conducted pertaining to power electronics converter reliability, (1) there lacks a universal way to protect the most critical component in a power electronics converter—the power device—from the two most common failure modes—short- and open-circuit faults; and (2) there does not exist a tool that considers both the component- and system-levels of a photovoltaic (PV) inverter for the purposes of lifetime prediction. In response to this gap in research, this dissertation proposes a universal solution to protect power devices from short- and open-circuit faults. It also provides significant contributions to the development of a framework for PV inverter reliability modeling and lifetime prediction. First, an introduction is given, highlighting the importance of power electronics converter reliability. Second, a universal short- and open-circuit fault detection and protection scheme is developed. Third, a failure mode and effects analysis (FMEA) is conducted for a PV inverter. Fourth, a methodology is proposed for the construction of an environmental-based component-level reliability model. Fifth, a foundation for a simulation platform capable of predicting PV inverter reliability is built. Sixth, a simulation modeling method allowing for the usage of parallel computing in power electronics simulations is proposed. Seventh, a conclusion and future works section is provided, summarizing the work done in this dissertation and the work to be done in the future. The results of this dissertation identify flaws in current converter reliability while providing solutions to improve and predict reliability moving forward, supporting the continued growth of power electronics. The specific contributions of this dissertation are given by the construction of the following: (1) a novel, inexpensive, and universal method to protect and detect short-circuit and open-circuit faults on a sub-microsecond scale for a power converter’s power device; (2) an original failure mode and effects analysis for PV inverters encompassing component-level failures; (3) a lifetime modeling methodology for environmentally-affected components, resulting in a reliability model for PV inverter cooling fans including both electrical and mechanical subsystems; (4) a framework for a simulation platform capable of predicting power electronics system failures; and (5) a general method for simulating power electronics converters utilizing high-performance computing, allowing for the reduction of computation time while maintaining switching-level modeling accuracy.