Research Of Household-Type Photovoltaic Inverter Software System

Nowadays, with the increasing burden on energy exhaustion and environment, as a cleanly and renewable energy, solar energy has become a hotspot in the whole world. At the same time, the technique of the PV (Photovoltaic) conversion has come into the applied level on a large scale. In the future, the application of the PV will take on an exciting status. The only drawback is that the initial installation cost is considerably high. To overcome this problem, two essential ways that increase the efficiency of conversion for PV array and maximize the output power from the PV array can be adopted. Consequently, the maximum power point tracking technology will be greater development in the future, and it will be to provide strong support for the development of photovoltaic system. This paper focus on the maximum power point tracking technology in photovoltaic power generation. The main content are as follows.1. The DC/DC converter in the photovoltaic inverter were researched. The paper has analyzed Boost converter, and studied the main principle, established the simulation model and constant pressure closed-loop control, got the transfer function, and raised the way of the implement of digital Boost constant pressure controller.2. There are some difference in the PV array output specific property between the local shadow conditions and conventional environment. In this paper the research are focused on the rules of PV array output characteristic influenced by the local shadow conditions. This study presented the mathematical models of the photovoltaic modules and the photovoltaic array under partially shaded conditions, and compared the output characteristic under partially shaded conditions by Matlab/Simulink module. According to I-V, P-V curves through modeling and simulation, the output characteristics of the photovoltaic array under partial shadow reacted preferably. The results presents that the influences of partial shadow on output characteristics of PV array are different and are dependent on different number and distribution of shades as well as illumination. 3. To research and analyze the maximum power point tracking technology, we analyzed the work principles of several existing maximum power point tracking control algorithm, and compared the advantages and disadvantaged. The two classical MPPT algorithms, such as Perturbation and Observation (P&O), Incremental Conductance Algorithm (ICA), were compared. For the two algorithms, we scanned voltage variable with different duty cycle steps, and then watched the two key dependent variables. The simulation results show ICA is slightly better than P&O, but the size of the tracking step will affect the dynamic and static performance, and the trade-off design was more difficult to find Finally, we has putted forward the architecture and the flowchart of software design to MPPT under DSP.