| Since the invention of the steam engine in 18 th century, human being has entered the industrial age. With the increasing fossil energy consumption demand of petroleum and coal, on the one hand, industrialization brought us into the great industrial civilization, always resulting in warming, environmental pollution and other related ecological problems at the same time. On the other hand, due to the limited reserves and non-renewable of fossil fuels, energy is coming. It's imminent to the development of clean and renewable energy. As the representative of the distributed energy, the wind and solar energy are taken into the human's vision. In recent years, because of its characteristics such as clean, sustainable, distributed energy have more rapid development in the world. Distributed energy can not be directly connected to the grid, due to due to its own characteristics, such as the energy outputs are direct current or alternating current with high harmonics. Then it's necessary to use the inverter device and filter device to connect to the grid. It's one of the key technologies to the study of the single-phase grid filter in this paper.First of all, the paper analyzes the harmonics of the output of single-phase grid connected inverter. The harmonics are generated by the switching tube of the inverter bridge arms. The specific harmonic content is determined by the control mode and frequency of the switching tubes, and the effectiveness of the L type and the LCL type filter in the grid connected inverter is explained. As the grid-connected current required to achieve the international standards and national standards, and the need for both filter performance, power factor and loss requirements, in as far as possible to meet the above requirements. In the restricted conditions, the basic design principle of capacitance and inductance, resonant frequency, damping resistor are set. The key parameters of LCL filter are designed for a grid connected inverter with a power of 600 W. And actually a discrete LCL filter device is produced. The mathematical model of the LCL type filter is analyzed qualitatively, which shows the effectiveness of the mathematical model of the harmonic suppression. A single phase grid connected inverter system based on 600 W is designed by software simulation platform, which verifies the correctness of the design of the key parameters of the LCL type filter before. At the same time, compared with the same inductance, the LCL filter has better filtering effect than the L filter.Secondly, the paper puts forward a new type of planar integrated LCL filter structure, aiming at the defects of large volume and low power density of the LCL filter. By using the E type magnetic core and PLT magnetic core of ferrite material and the technology of planar integrated, two inductors and one capacitor of the LCL filter are combined. Then this paper introduces the design process to produce a set of planar integrated LCL filter device for a grid connected inverter with a power of 600 W.Then, the paper also points out the defects of the vertical LCL filter, and proposes another new type of plane integrated LCL filter structure. The integration of two inductors and a capacitor is realized by planar magnetic integration technique. Then this paper introduces the other design process to produce a set of planar integrated LCL filter device for a grid connected inverter with a power of 600 W.Finally, a set of 600 W single-phase grid connected inverter experimental platform is set up, and the single L type, vertical type LCL and two kinds of planar integrated LCL filter are tested. Their various performances are compared, and the theoretical deduction and design of the former are verified. |
PDF Full Text Request