No Isolate Single-phase Inverter Design Based On FPGA

As the society develops, the energy consumption increases rapidly as well. Therefore, the fossil fuel already could not meet the global energy demand. In the meantime, the use of fossil fuel also produces significant amount of air pollution. Solar energy is a kind of clean renewable energy, which will not generate secondary pollution during its utilization. Photovoltaic power generation is one of the main forms of using solar energy, which converts sun light directly into electricity. As a result of continuous technological advance, the conversion efficiency of photovoltaic system has been increasing a lot during the past decade, which induces a boost of solar plant installation. In the future, the grid connected photovoltaic will obtain greater development.This paper first introduces the research background and significance of the photovoltaic electricity, then describes the gap between domestic and foreign development of solar photovoltaic and compare China PV industry with foreign PV industry. The second chapter analyzes the equivalent circuit of solar panels, the characteristic curves of the output of solar panels under different external conditions and summary the maximum power point tracking(MPPT) control methods and its characteristics. the frequency and phase of Panels output current to power grid should be same with the gird’s frequency and phase, then analysis grid voltage and current control methods.The third and fourth chapters analyses the non-isolated and isolated inverters, and analyses of the non-isolated inverter operation principles of the common-mode current in detail. Transformerless inverters can be divided into two categories: improved Hbridge inverter topology and improved neutral point clamped(NPC) topology. Then the output voltage characteristics at different operating environment have been analyzed.Finally, the overall schematic diagram and control diagram of the inverter system are generally described, as well as the problem of selecting driving circuit, filter circuit and booster circuit components. Altera’s Cyclone IV series FGPA(Field-Programmable Gate Array) development board is used to build a Phase-Locked Loop(PLL) module in Quartus11.0 to output the SPWM wave that controls the switches in inverter circuit and the MOSFET in boost circuit via the amplifier circuit. The SPWM output module and the inverter system module are built in the Matlab/Simulink software environment to watch the output voltage and current characteristic, and the results of theoretical analysis of the inverter are verified by the experiments.