Traditional methods of maximum power point tracking (MPPT) control like conductance increment method have disadvantages of larger static error and fluctuation, while after adding fuzzy control, the dynamic performance of the system can be improved, but as the universe of the fuzzy controller is fixed, the control is rough and the fluctuation is still big relatively. In this paper, the variable universe fuzzy control method is used in MPPT control. The advantages of this method are that the settings of rule tables need less experience, and the variable universe is obtained by changing the input scaling factors, so as the control is more flexible, the response time is shortened, and the static error and fluctuation are greatly reduced. As the result, the photovoltaic loads can be well protected and the utilization ratio of the solar energy is improved. In this paper simulations are presented in both changing and fixed environments, and the superiority of the variable universe fuzzy control in MPPT is proved from the points of output power and load voltage.
