| In recent years, due to the problems such as energy crisis and air pollution become increasingly serious, solar etc. green clean energy more and more be taken seriously by energy experts, solar power generation has become one of the mainstreams in green clean energy. With the continuous development of photovoltaic technology, photovoltaic grid power generation system in the high power density, high reliability, low cost, etc, has been a rapid development.Because of the centralized, string type photovoltaic power generation systems, with the disadvantage of hot spot, shadow, redundancy et al, then it has poor practicality in small places. With the advantage of thermal spot resistance, independent MPPT, plug and play, easy to modularization, high redundancy, the micro-inverter in the family, company, roof and other small applications has achieved more development, but also to be the inevitable trend of photovoltaic grid power generation systems. Therefore, in this paper, provides a detailed analysis on the principle of micro-inverter which configured interleaved flyback equipped with active clamp, and establishes the small-signal mathematical model by using the state-space averaging method, then designs the parameters of the controller of grid inject current and transformer load share by classical control theory and MATLAB software, finally according to the characteristics of the system, designs the MPPT of photovoltaic panels, and the decoupling capacitors which is to satisfied the maximum power utilization.According to the theoretical analysis of the working principle and mathematical model, firstly, verified the rationality of the main topology the controller parameter by PSIM simulation software. Then made a200W micro-inverter prototype, according to the characteristics of the control core TMS320F28335, designed the system of protection, auxiliary power supply and signal conditioning circuit, designed the software of the state machine, the digital current control loop, the digital load share loop, MPPT, phase-locked loop, anti-islanding protection et al, then established the micro-inverter experimental platform for the system topological structure, the circuit parameters and all kinds of control algorithm for validation. Through the theoretical analyzed above, adding to the fine-tuning in the process of debugging, the micro-inverter system basically met the requirements of the technical indicators. |
