A Study On The Photovoltaic Maximum Power Tracking System Using A Fuzzy Controller

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. At the same time, as a developed branch of intelligent controlling techniques, the fuzzy logic control has much more advantages than conventional methods. Consequently, it is significant to research on tracking the maximum power point of the PV array using a fuzzy controller.The result of this paper is a maximum power tracking system of PV using a fuzzy controller, which obtainsmaximum power from PV array despite of the fluctuations of the array temperature and irradiation and raise the efficiency of conversion to as much as 88%. In this paper, a model of the solar cell using MATLAB is established based on its Volt-Ampere characteristics. Moreover, a new modified adaptive maximum power point tracking(MPPT) method which includes automatic parameter tuning and directly uses the DC/DC converter duty cycle as a control parameter is introduced and shown good performance in both the steady state and tracking speed. However, this control algorithm is so complex that the idea that applies fuzzy logic control to MPPT system is suggested. The detail about designing a fuzzy control for the system is proposed and a simulation is carried out with MATLAB to test the effect of the controller and perfect simulated results are obtained.The MPPT system, consisting of a Boost-type DC/DC converter, is implemented by 32 bit DSP(TMS3202407A), and adopts two loops control structure. The internal voltage loop is actualized by the digital PI algorithm to control the output voltage of the DC/DC converter. The external current loop is executed to calculate maximum power point current by fuzzy control method and adjust the duty cycle of the PWM signal for the DC/DC converter. The load module that decides which load should be connected or which not according to the current power, and the detecting module that answers for the security of the system are also designed in the paper. The interface design methods including software and hardware of thesystem are presented in the paper, and experimental results are given at last which reveal that the fuzzy controller results in better tracking performance.