The research on application of variable universe fuzzy control to maximum power point tracking system

Solar energy is considered to be the world´s most promising new energy technologies. How to find the best control strategy to maximize the advantages of photovoltaic system will greatly promote the development of photovoltaic technology. The variable universe fuzzy control is applied to the maximum power point tracking (MPPT) control in this paper. The variable universe fuzzy control is different from the conventional fuzzy control. It has a superior feature over the latter. In order to increase the precision of control, we must significantly increase the number of fuzzy partition, thereby increasing the conventional fuzzy control rule that have a greater impact on the output of fuzzy controller. However, an increase in the number of fuzzy subset will increase the difficulty of the controller design. While variable universe fuzzy control can make use of the domain of contraction so as to achieve the same control as to increase the fuzzy subset. The error and error rate of change are selected as a variable universe fuzzy control of the two input variables and the duty cycle for the output variable. The photovoltaic power output error and error rate of change are detected in real-time, and then the two variables are entered to regulate their own input domain, and the contraction factor of the input domain and output domain are calculated. It can control the duty cycle superiorly. After the test of simulation, the variable universe fuzzy control can achieve higher level control precision, better speed tracking performance. The variable universe fuzzy control is proved one of the best control strategies.