The Design And Development Of Charge Controller For Photovoltaic System

Solar energy as a kind of green energy for sustainable development has becomethe nation, both inside and outside’s research focus, in particular, the introduction offeed-in tariff law, which greatly promoted the study of the domestic photovoltaictechnology, solar charge controller as a photovoltaic system important part, hasbecome a hot research.However, the exist photovoltaic charge controller, has a low the charge efficiency,not enough smart charging method, the maximum power point tracking wasinadequate, and the accuracy was low. This paper researched the core technology ofphotovoltaic charge controller conducted in-depth and meticulous, the main contentswere discripted as following:(1)This thesis studied the domestic and foreign research status and developmenttrend of photovoltaic charge controller, and analyzed on the equivalent circuit of thesolar cell, then a mathematical model was established according to the equivalentcircuit of the solar cell, and the characteristics of the solar cell output was studied onthe Matlab simulation model, the battery chemistry and structure, working principle,factors affecting the charging effect,were analyzed, the charging characteristics of thebattery was studied.(2)According to the technical specifications and performance requirements for PVcharge controllers designed overall program, the overall scheme of hardware andsoftware overall program for photovoltaic charge controller were described. Severalcommon charging technologies were analyzed, which according to the actual needs ofthe system proposed herein intelligent charging method, the charging process wasdivided into a maximum power charging, charge and floating charge over three stages.(3)The PV charge controller hardware system was designed the in detail, used theBuck-type DC/DC converter as the main circuit of PV charge controller andsynchronous rectification technology to improve the conversion efficiency of thesystem, the system control algorithms to meet the hardware requirements. The maincircuit component parameters calculation method and the selection of the main devicewere analyzed.(4)The PV charge controller software system was designed in detail, and thecharge control program, PWM program and data collection program were designed, several common MPPT algorithms were analyzed, the characteristics of the system forthe application proposed an improved MPPT algorithm, and simulation analysised theimproved MPPT algorithm on a simulation model.Finally, this paper designed a prototype solar charge controller, and made thecorresponding experiment on these improved algorithms and the charge controlstrategy, experiment results show that the improved algorithm had a track speedly, anda higher output stability, this design charged controller charging efficiency of up to90%, realized the desired targets.