In a wave energy generation system, MPPT (maximum power point tracking) control can maximize the output power of a WEG (wave energy generator) according to the change of the waves. Due to the irregular movement of the waves and the characteristics of the LMMHD (liquid metal magneto-hydrodynamic) generator, the output of the LMMHD WEG is characterized by low voltage, high current, and irregular variation. Therefore, to withstand the large current the PCS (power conversion system) needs to be designed in parallel with multiple modules, which needs to solve the problem of current sharing. On the other hand, a control system with fast response speed is needed for the MPPT to track wave changes quickly. In this paper, a system model of the LMMHD WEG is analyzed firstly, and an MPPT control strategy that can automatically identify the sea state and can automatically realize current sharing is proposed based on the output characteristics of LMMHD WEG. Then, a MPPT control system is designed for a given LMMHD WEG, and a simulation experiment with changing sea state is carried out in MATLAB/Simulink. The comparison between the experimental results and theoretical values verifies the validity of the proposed MPPT control method.
With the increase of human activities at sea, the human demand for marine energy is also increasing. Wave energy has the characteristics of wide distribution, high energy density and large reserves, and it is one of the most promising marine energy. Wave energy generation is the main method of wave energy utilization. The WEGS (wave energy generation system) can provide continuous power supply for ocean power users such as UUV (Unmanned Underwater Vehicle) underwater charging platform, subsea scientific observation network, and ocean ranch, etc., which can solve the power problem of marine users. However, because of the characteristics of random variation of the waves, the wave energy captured by the WEG is also randomly changing. MPPT control can maximize the output power of a WEG according to the change of the waves. (Hugo and Martinez 2016; Chen, Yang and Yang 2017; Zheng, Yang, Lin, Huang and Duan 2107).