Research Of Photovoltaic Grid-connected Inverter With MC9S12

With global energy shortage and growing environmental pollution problems, to find a rich reserve, non-polluting new energy has become an important strategic plan for the world.Solar energy as an efficient green energy, has been widely applied in human. At present, the photovoltaic power generation technology is one of the best of a promising, but also the mainstream of solar photovoltaic power generation applications.Grid-connected photovoltaic inverter is a core part of the grid, and its main function is to issue the DC solar panel into AC into the grid. This design idea is first issued by the photovoltaic cells by high-frequency inverter converts direct current into high frequency sinusoidal voltage. Use the voltage source-current source transformation properties of immittance converter.Transform the input high frequency high voltage into high frequency sinusoidal current,and then after the high-frequency transformer isolated and the current level transformed,using frequency converter to do split phase modulation,then three-phase sinusoidal current is output.Thereby the purpose of the current type to the network is achieved.Compared to the traditional current-mode inverter, using this method not only eliminates the side of DC reactor, and using high-frequency transformer to replace the work frequency transformers, which reduced the volume of the isolated transformer and output filter.It is not only realize the current sine wave and the same phase of voltage of the inverter network,is conducive to the device miniaturization and reducing costs, but also achieved wide range of DC voltage regulation and improve the dynamic performance of the system is more suitable for PV grid.In this paper, the theoretical analysis and simulation based on the design of the entire system of hardware, software, control strategies and debugging methods in detail.In the hardware design with freescale company 16 MC9S12XS128 chip microcontroller as the core of the controller main control circuit and sampling and regulate circuit, power supply circuit,PWM driver circuit and the keyboard and display control circuits and other peripheral circuits vice.Control strategy in the software introduces the variable step size optimization and prediction of the disturbance observer based on the power law method of combining maximum power point tracking;Adopt direct current 2-ring control high frequency inverter,and then difference frequency method used to achieve control of cycloconverter phase current photovoltaic grid;At the same time using passive island detection and active frequency shifts (AFD) combination of gudao detection method, has realized the island effect without blind detection.Describes the development of tools and experimental testing method.By comparing a large number of simulations and some experiments to verify the correctness of the package.This topic by department of jiangxi province graduate science & technology innovation fund (Fund No.:YC09A034) funding.