Modeling and Implementing a Digitally Embedded Maximum Power Point Tracking Algorithm and a Series-Loaded Resonant DC-DC Converter to Integrate a Photovoltaic Array with a Micro-Grid.

摘要

A DC-DC converter with an embedded digital maximum power point tracking (MPPT) algorithm for a photovoltaic (PV) application is presented in this thesis. The topology centers around a series-loaded resonant (SLR) converter using galvanic isolation that interfaces a PV array with a storage battery connected to the DC bus of an existing micro-grid. The SLR converter operates in discontinuous conduction mode to minimize the switching losses and for the linear relationship between switching frequency and converter output current. This feature allows for multiple SLR converters to be paralleled, improving the overall efficiency of a PV system by eliminating a central converter and instituting the concept of multiple micro-converters. The perturb and observe MPPT algorithm employed uses a single voltage sensor and schedules a switching frequency based on the PV array power feedback. The performance of the MPPT algorithm is compared to a similar algorithm that uses both a current and voltage sensor. In this thesis, the SLR converter control system was simulated, designed, and implemented in the laboratory. The experimental measurements show that the SLR converter presented is an ideal topology for a PV application.