Method for Maximum Power Control of Direct-drive Wave Power Device Based on Fuzzy Sliding Mode Control

Marine wave energy is a new type of clean energy. In order to improve the generation power and wave energy conversion efficiency of the direct-drive wave power generation system, a maximum power control method based on fuzzy sliding mode control was proposed. The method aimed at solving the problems of large output ripple and poor system stability of the commonly used proportional-integral-derivative(PID) control method. In addition, the reaching law parameters were adjusted in real time according to the running state. At the same time, while realizing maximum power tracking, the output ripple was weakened; the tracking error was reduced, and the control quality of the system was improved. In this paper, the permanent magnet linear generator was used as the power generation device, and a system dynamics model was established. The main frequency of irregular waves was estimated by fast Fourier transform (FFT), and the expected current tracking curve was designed to meet the maximum power strategy. On this basis, the conventional PID and sliding mode control methods were compared with the proposed fuzzy sliding mode maximum power control method. The results show that the fuzzy sliding mode control method has improved power and shown better accuracy and stability.