Design Of Low Power Single Phase Photovoltaic Grid Connected Inverter Based On DSP

With the rapid development of economy, comes greater consumption of energy. Traditional petro energy is running out and resource crisis may break out at any time. Thus, the study and application of new resource is of great importance. Among the many new energy sources, solar energy is very potential for development. Now, photovoltaic power generation has become the world’s main way of using solar energy. PV grid becomes the main research field in the study of PV power generation.This article analyses the operation process and the central technology of the single phase bi-polar non-isolated type photovoltaic grid inverter, completed the hardware circuit design and software program of photovoltaic grid connected inverter compilation and experiment debugging.First, through the deep theory analysis of the DC-DC converter, the shortcoming of the ordinary Boost converter due to the hard-switch is pointed out. Thus, the ordinary Boost converter is abandoned and Boost-ZVT converter with soft-switch technology is applied in the photovoltaic grid inverter system. Detailed analysis of its operation is given, and key coefficient is calculated. Commonly used filter circuits is compared and a proper circuit is chosen and its key coefficient is calculated.Second, after the deep investigate of PV battery theory, a model of PV battery is built with Matlab/Simu Link. The output curve of the PV battery with the outer environment concerned is acquired. PV grid inverter’s MPPT, grid control and island effect is deeply investigated and the control strategy of this article is determined. Furthermore, the whole PV grid inverter system is built with Matlab/Simu Link, and its validity is tested.Third, after the confirmation of the system’s validity, completed the design of hardware and software of controller of small power single phase photovoltaic grid connected inverter. The central control chip is TMS320F2812. Signal sampling circuit, zero-crossing detection circuit and MOSFET drive circuit is acquired and control software program is compiled.Finally, a test platform is built and the photovoltaic grid inverter is tested. The output curves of the prototype is observed and the result shows that this photovoltaic grid inverter achieve the design function and achieve the designed purpose.