| Along with the development of social production, the increasing of energy cost increase and the deteriorating of ecological environment, the global energy crisis is becoming more extrusive. As the cleanest, the most realistic, the richest and most large-scale development prospects of the use of renewable energy in the world, solar energy is extensive concerned by the various circles of society. In the use of solar energy, Photovoltaic Power Generation is the one of the main development direction. As photovoltaic cell components cost continues to reduce and photovoltaic power generation technology advances and improves, Photovoltaic Power will be supplement energy instead of alternative energy. Because there is no unified standard and power grade and applications are different, all sorts of topology structure of photovoltaic power generation system are using in photovoltaic industry. With the constantly of exploration and progress, independent power systems and grid generation system will be the mainstream. But the output voltage of independent power generation system and the inverter control of grid generation system are the two problems in the development of power industry at present. In this background, this paper analyzes photovoltaic power grid inverter. On the basis of predecessors, I do a detailed theoretical analysis what about some of some key issues such as the maximum power point tracking, the control strategy of photoelectric power generation system, modulation mode of photovoltaic power system. Based on this, I design an optimized scheme.First of all, photovoltaic power generation is analyzed. The serious environment which current photovoltaic power industry faces and hinders the development of photovoltaic power industry is understood. Photovoltaic energy system is introduced, and requirements for grid inverter of the photovoltaic grid power system are put forward.Second, photovoltaic power takes mainly advantage of the radiation energy of sunlight. The photovoltaic battery array collects radiant energy, and transforms it to electrical energy. The electrical energy is stored in energy storage system for supplying load or directly sent to the grid when its frequency is converted to power frequency. After a detailed analysis to electrical characteristics of photovoltaic cells, the mathematical mode and simulation based on the Matlab are made. And then I verify the electrical characteristics. The conversion efficiency of solar photovoltaic array can be fully increased, and the key technology is the maximum power point tracking (MPPT) technology. Through analyzing several common technologies about the maximum power point tracking, I design a variable step long conductivity incremental method which is used to improve solar energy utilization efficiency of photovoltaic power systemAgain, the main circuit of photovoltaic power system mainly contains of DC/DC converter, DC/AC inverter, the filter. The structure and work principle, characteristics of the main circuit of photovoltaic power system are analyzed. And based it, DC/DC converter is analyzed in detail, and the most appropriate topology structure boost converter is chosen from some commonly used topological structures. The power switch tube device is introduced, but division components will replace intelligent power module IPM because of costs and limitations. In the application of IGBT, it is necessary to build a buffer circuit for IGBT protection because of the increasing frequency of voltage and current. So the RCD buffer circuit is designed. The principle of it is analyzed in detail, and the circuit parameters are also calculated. According to the characteristics of the circuit, the structure of filter is choice and the design idea and design methods of the filter of the inverter circuits are analyses. The key parameters of the main circuit are calculated and it is tested by the simulation.Then, an optimization design is given to the control circuit of photovoltaic power grid inverter.A high efficiency driving circuit is designed, and its defects part is perfect. Negative bias circuits and the protection circuit are taken to guarantee the safe and stable operation of drive circuit. According to the characteristics of the signal which is required detected by the photovoltaic power system, the appropriate measure circuit is designed to ensure that the whole photovoltaic power system is monitored and controlled by control circuit; And, auxiliary power supply which can ensure the stability of the power supply voltage is designed to give control system a stable power supply; The method of inverter control are also discussed, and the double closed loop control scheme is put forward. Double closed loop controller includes average controller and the instantaneous controller. Among them, average controller is the outer ring, and the instantaneous controller is then insert ring. Average controller has the high output precision and the instantaneous can get fast dynamic performance control which can ensure that its output aberration rate is low. And a simulation is given to the control strategy, to verify its good results on harmonic control.Finally, based on a detailed analysis of the job characteristics and the principle of the drive circuit of the photovoltaic power system, SVPWM modulation technology is detailed discrete analysis. Finally SVPWM modulation technology is chosen to drive photovoltaic power system, and the implementation method is detailed designed. The spectral analysis is given to experimental waveform get by SVPWM modulation technology. The effect which carrier ratio and other factors take to harmonic is introduced. According to the control scheme, the hardware and software device of photovoltaic power grid inverter is designed by micro controller MB90562.The digital design is completed. Because the method of analog and digital combination reduces some executive process of software system, the execution speed of the system is speeding up. |
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