The Study Of Single-phase Photovoltaic Grid-connected Inverter Based On DSP

Energy is the source for human survival and development. As fossil fuels such as coal, oil and gas depleted rapidly, exacerbated the energy crisis and environmental pollution, the world are actively seeking and developing new, clean, safe and reliable renewable energy. Solar energy as a new energy, sustainable, clean, safe, noise-free, which application is not subject to geographical constraints. In the aspect of alleviating energy crisis and promoting the development of environmental economic, it has great significance. Grid-connected PV is an important area for solar energy applications, not only supplying power for the remote areas, also easing the tension of the grid electricity supply, it’s an important development direction in future.In photovoltaic system, photovoltaic cell arrays is a core component of the energy supply in the grid-connected PV systems simulation model, the photovoltaic cell simulation model is very important. Firstly, according to the mathematical model created by the working principle of photovoltaic cells, this thesis uses the Suntech’s STP0950S-36model to study, establishes a photovoltaic cell array simulation model by Matlab/Simulink, obtaining the characteristic curve of the solar light intensity and ambient temperature on the photovoltaic cell array model.Secondly, this thesis studies on using the fuzzy logic control technology to control maximum power point tracking of photovoltaic cells, given the fuzzy controller design process, using Matlab/Simulink fuzzy logic toolbox to simulate and analysis the Maximum Power Point Tracking to analysis fuzzy control simulation. Comparing with the constant voltage method, perturbation and observation method, incremental conductance method, adaptive duty cycle perturbation method, the simulation results show that:fuzzy control method tracks power rapidly, there is a good dynamic and steady-state performance, and the stabilize fluctuation is very small, which improved the stability of the system’s output efficiency.Again, according to the system performance requirements, this thesis uses TMS320F2812as the main chip, designs the inverter’s hardware circuit, including the main inverter circuit, DSP minimum system, system’s power supply circuit, AC and DC voltage and current detection circuit, IGBT select and its drive circuit, and phase-locked loop circuit. In hardware system, the DC output of the photovoltaic cells is converted to400V DC by boost circuit, then to220V AC by the full-bridge inverter. Then the detection circuit puts the voltage and current signal into DSP, which controls Boost circuit and DC-AC circuit to achieve the system merged into the grid.Finally, according to the hardware, the thesis designed the system’s software, including the main program and the timer interrupt subroutine, the digital phase-locked subroutine, selected running with independently or grid-connected subroutine, the maximum power point tracking subroutine, islanding detection subroutine, producing PWM subroutines, EEPROM subroutines, and software anti-jamming methods.