| With the development of sensing technology,wireless sensor networks have become a hot spot for current applications.Frequent battery maintenance becomes a bottleneck problem for the development of wireless sensor networks.For the power supply problem of wireless sensor networks,environmental energy harvesting technology becomes a green and feasible solution.The natural environment is abundant in solar energy and wave vibration energy.However,solar energy cannot be harvested around the clock due to length of day and weather factors,and wave vibration energy has characteristics such as randomness,so a single form of energy cannot guarantee stable power supply for wireless sensor networks.This paper investigates the power generation system of wave energy and solar energy composite harvesting,which solves the efficient harvesting of vibration energy in ultra-low frequency wave environments and designs low-power composite energy harvesting circuits to provide stable electric power for wireless sensing networks in marine environments.The research in this paper focuses on:For ultra-low frequency wave vibration energy harvesting,this paper proposes a piezoelectric vibration energy harvester for multi-directional and ultra-low frequency waves driven by a rotating rolling ball.The energy harvester is designed to float on the water’s surface;it will be tilting vibration in the corresponding direction once driven by the wave from any direction.The energy harvester converts the vibration wave energy into electrical energy due to the basic characteristics of frequency up-conversion.A simulation wave device is used to evaluate the proposed harvester’s performances.Simulation and experimental results are in good agreement.The energy harvester can harvest energy from single-direction or multi-direction excitation(<2Hz).When the external frequency is 0.9Hz,and the external load is 47KΩ,the power output of the whole energy harvester is 6.32 m W.A non-time-division multiplexing single-inductor synchronous electric charge extraction circuit(NTD-SECE)is designed.For the case where two types of energy exist simultaneously in a circuit,NTD-SECE no longer takes the traditional timedivision multiplexing or priority setting approach to handle different energy sources.NTD-SECE can extract multiple energies at the same time.At the same time,NTDSECE uses a single control circuit to deal with the control logic of different energy sources.The results show that NTD-SECE can extract energy from photovoltaic and multiple piezoelectric by non-time division multiplexing,the maximum power is450 m W.This paper realizes the composite harvest of solar energy and wave vibration energy,and provides a feasible method for powering wireless sensing networks in the marine environment,which has greater application prospects in marine environmental monitoring. |
