Theoretical Modeling And Analysis Of Novel Wave Energy Piezoelectric Generator

In recent years, with the continuous development of ocean resources, marine wireless sensor network technology plays a great role in ocean monitoring. The large number of nodes and the wide range of distribution result in energy supply difficulties. This paper presents a novel wave energy piezoelectric generation device, and its model is proposed. The paper also analyzed the influence of the main parameters of the device on output power of PZT bimorph cantilever.First, this paper proposed a point-absorber wave piezoelectric converter with based on reaction disc. The primary transducer mechanism use an oscillating float, intermediate conversion adopts a mechanical structure, secondary transducer conversion is designed to the form of a rotating piezoelectric generator. Inside the rotary piezoelectric generator, the piezoelectric bimorph cantilevers are installed to a circularly array around the rotary wheel, the piezoelectric bimorph cantilevers can vibrate by the less contact permanent magnetic force. The structure of the device is simple.Secondly, based on the linear potential flow theory and making use of boundary element method, this paper solves the hydrodynamic problems of the wave energy piezoelectric generator. The first-order wave force on the floating body, the radiation damping and added mass of the float is calculated by the WAFDUT1.4procedure. This paper adopted the Morison formula to calculate the fluid damping force of the reaction plate. The permanent magnet force considering the rotation angle between two magnets is analyzed.Thirdly, the theoretical model and equations of the device which includes the damping plates, floating body, gear and rack, rotary piezoelectric generator, is proposed. The motion response of the system is calculated, and the influence of spring stiffness, dimensions of reaction disc, wave height and wave period on output power was analyzed by numerical methods. This paper also analyzed the conversion efficiency of the device, the conversion efficiency is2.05%in the case of H=1.8m for wave height,L=1.8m for the side length of reaction plate, k=400N/m for spring stiffness.finally, the mooring system for wave energy piezoelectric generator is designed, the mooing cables can be approximately modeled as catenary lines in analysis. This paper proposed the design process of mooring system, and numerical static analysis and dynamic analysis of the mooring system are presented. Comparisons are given among the unmoored device, the one mooring line system and the two mooring lines system. Results show that there is only a slight difference in relative motion between float and reaction disc when introducing different number of the mooring lines. So the number of mooring lines was found not to affect very significantly the power absorbed.