The Design Of Household Type Grid PV Inverter

With the increasing policy attention in distributed photovoltaic power generation, miniaturization tendency of photovoltaic inverter industry is apparent. Therefore, household type grid photovoltaic inverter is researched in this paper:Depending on studies of topology, maximum power point tracking, islanding protection and control algorithms, a household type grid photovoltaic inverter is designed, and the basic requirements of a grid inverter are realized.The content of the paper can be summarized as follows:1. In system topology selection, various types of grid inverter topology are compared. Considering factors such as efficiency, EMC, two-levels structure without isolation transformer is adopted as the main structure, at the same time, IPM module is adopted in the practical design of hardware circuit, which enable the system more compact and reliable.2. In order to more efficiency use of solar energy resources, basic characteristic of photovoltaic cells and the MPPT algorithm are studied, the deficiency of traditional MPPT algorithm is improved, and the maximum power point tracking of the system is achieved.3. Based on comparison of unipolar PWM modulation, bipolar PWM modulation and unipolar dual frequency PWM modulation, most suitable PWM modulation method is achieved.4. Based on SOGI-PLL, a single phase system control strategy under the synchronous rotating coordinate system has been adopted, by which phase-tracking with the grid has been realized, and preferable control effect has been obtained.5. Aiming at islanding protection, an improved frequency deviation method is adopted, which enable preferable islanding protection ability.6. A 3kW grid photovoltaic inverter experimental platform is built. Subsequently, corresponding experiments are conducted, and satisfactory results are obtained.