Research And Design Of AC PV Module System Based On High Step-up Voltage Gain

With the increasingly serious problems of energy crisis and environmental pollution, the research and application of solar renewable energy has been widespread concern. Traditional PV power plant system uses a large number of solar panels in series to acquire a high voltage input in DC bus. But there are some problems, for example, the MPPT problems caused by the shadow would lead to power loss when the photovoltaic module do not match. Robert H. Wills et. proposed the concept of AC photovoltaic module based on these questions. AC PV module are defined that the single PV module and inverter are integrated together to constitute a photovoltaic power generation system which can connect directly with the load or grid. It can run whether grid connected or not. AC PV modules eliminate the power loss which are caused by the PV panels connected in the series, and are easy to achieve optimal coordination between the PV panels and inverter. It could get the optimal performance of the PV power generation system by optimized control. In addition, the best advantage of AC PV module is the plug-and-play function, and it could reduce the costs through mass production. The AC PV module becomes an important development trend of PV power generation system, and attaches great importance to researchers.Based on the DSP controller, a AV PV module system with low power was designed in this thesis. The major works are as follows:Firstly, this paper designed a two-stage AC PV module system, and made a detailed analysis of topologies and working principles, which to lay the foundation for the control strategy design of the system;Secondly, using multi-stage pulse control method to achieve the control of the high-gain DC-DC converter, and the carrier phase shift control method are used to control the hybrid clamp single-phase three-level inverter in the next stage. Besides, it also show a detailed analysis of the principle and the design process of the two methods; Thirdly, according to the above design, combined of the two control methods, we build a complete simulation model of AC PV module in MATLAB/SIMULINK using modulation of voltage closed-loop PI control strategy, and obtained the simulation results of the system;Fourthly, the hardware design including the DSP2812core control circuit, IGBT driver circuit, detection and protection circuit, buffer circuit was elaborated. And choosing the filter, power switches, DC bus capacitor, boost inductor devices according to the design principles of the main circuit parameters.Fifthly, based on the CCS3.3, it designed the multi-stage pulse control and carrier phase shift control program. Besides, the software design including voltage and current A/D sampling and correcting program, pulse selected interrupt subprogram, carrier phase shift interrupt subprogram, closed-loop PI control strategy was given.Finally, a200W AC PV module system prototype was designed. Debugging the prototype according to the experimental procedure, and to analysis the experimental waveforms and some errors during the process with the oscilloscope and computer. Finally we got the ideal experimental results.