Inertia-driven wave energy converter for Marine buoy power supply: motion response and energy conversion characteristics

Marine buoys operating in deep-sea environments frequently face power shortages, necessitating the urgent development of new power supply solutions to meet their increasing energy demands. This study proposes an Inertia-Driven Wave Energy Converter (IDWEC) that utilizes the motion of a sliding body to drive a generator for electricity production. The paper investigates the motion response and energy conversion characteristics of the IDWEC-buoy integrated system. Firstly, a mathematical model for the energy conversion of the integrated system under both regular and irregular waves is established. Subsequently, the Boundary Element Method (BEM) is employed to analyze the effects of wave period, power take-off (PTO) damping, spring stiffness, the horizontal distance between the centers of gravity of the IDWEC and the buoy, and wave direction on the system performance. A physical model of the IDWEC-buoy integrated system is constructed, and wave tank tests are conducted to validate the reliability of the numerical results. Finally, based on the 2022 South China Sea wave scatter diagram, the daily average power generation of the IDWEC under real-sea wave conditions is estimated. Research results indicate that the IDWEC-buoy integrated system exhibits three distinct resonant frequencies. The resonant frequency can be adjusted by varying the mass of the sliding body or the spring stiffness, enabling matching with the wave conditions in the target sea area to enhance power output. When the sliding mass is small, the optimal spring stiffness approximately satisfies ω²m. Under optimal spring stiffness, maximum power output occurs when the relative displacement amplitude of the sliding body equals precisely half the stroke length (L/2). The daily average power generation of the IDWEC under South China Sea random wave conditions is predicted to be 455.92 Wh, which meets the daily energy consumption requirements of the sensors on the buoy. This work confirms that the IDWEC can provide an efficient and sustainable power solution for buoys.