Research On High-performance Off-grid Photovoltaic Electrical Energy Conversion System

The development and utilization of new energy technologies play a crucial role in solving the current global energy shortage and environmental pollution problems. And solar energy is the most clean and an inexhaustible source of energy. The photovoltaic power generation system is drawing more and more attention by researchers in China and abroad. On the basis of Analyzing and summarizing the research status of the photovoltaic power generation system at home and abroad, a single-phase PV off-grid power generation system platform was constructed; several of its key technologies were researched; a novel DC/DC converter was proposed; the simulation, design, experiment of DC/AC converter were completed. The former DC/DC converter was focused on.First, the research status and market prospects of photovoltaic power generation system at home and abroad were summarized, and a brief description was made; the main structure of several PV inverter topologies were compared and analyzed; a structure that apply to the project was summed up.Then, a circuit topology that combines boost circuit and phase-shift full-bridge series resonant circuit on the basis of phase-shift full-bridge circuit was proposed. It has a relatively simple circuit structure with the advantages of high efficiency, high output input gain, the same control circuits with phase-shift full-bridge series resonant circuit, and makes up the shortcomings of the phase-shift full-bridge series resonant circuit to some extent. Made a detailed analysis of the working conditions of the circuit, and found the ways to achieve ZVS conditions with mathematical models; studied the existing problems and proposed solutions.At last, Mathematical model of the post inverter circuit was given; and the capacitor current inner loop, the instantaneous voltage outer loop control strategy was selected; detailed controller design process was calculated, then the discretization of the controller was given. Finally, a simulation based on MATLAB/Simulink system was made, then an experiment was done to test and verify.A1000W prototype was developed, and the results indicate that the converter has a good performance, and verify the correctness of the analysis and calculation.