Research And Design Of Photovoltaic System Based On MPPT Controller

Because the photovoltaic technology can convert the non-polluting and renewable solar energy into the storable electrical energy, it has received considerable attentions in the circumstance of energy shortage and environmental pollution. However, the low efficiency is always a problem in the photovoltaic technology. Hence, how to improve the solar cells’ utilization efficiency is the main research direction of the photovoltaic system.The MPPT(Maximum Power Point Tracking) is widely recognized as an effective way to improve the efficiency of the solar cells. In this paper, the hardware and software design are improved and optimized. The photovoltaic system based on MPPT controller is designed and implemented. The main work and the achievements of this paper are as follows:Firstly, according to the principles of solar cell, the mathematical models and the output characteristics of solar cells are studied. The simulation model of solar cells is established in Matlab/Simulink, and the influence from external environment is analyzed. Meanwhile, the simulation models of disturbance observation method, the incremental conductance method and the Buck conversion circuit are also created. By comparing the results of the two methods, the tracking effect of incremental conductance method is better, and the output power of solar cells is improved.Secondly, the Buck circuit is adopted as the main circuit in the design of the hardware circuit based on MPPT controller, and the MOSFET is used to replace the traditional freewheeling diode. This method not only can reduce the energy consumption, but also solve the problem of the diode heat dissipation. The microcontroller is used to implement the acquisition and processing of the solar cells’ output voltage and the current data. In the software design, the maximum power tracking can be realized by the means of incremental conductance combined with constant voltage start.Finally, the MPPT controller based on photovoltaic system is established, the hardware and the software are debugged and tested. The experiment results show that the system charges the battery properly. Compared with the normal charge controller, the MPPT controller can increase the output power of photovoltaic cells up to 6.88% at most.