Study On Vibration Energy Harvesting And Management Method For Self-powered Wireless Vibration Sensor Network

Mechanical monitoring wireless vibration sensor network is a distributed sensing network with self-organization,wide coverage and strong scalability.It has great potential in the field of mechanical vibration monitoring.Along with the wide application of mechanical monitoring wireless vibration sensor networks,traditional power supply methods such as wired powerline or battery,have been unable to meet the requirements for nodes working in special environments.The power supply problem restricts the development of wireless sensor network,and it is urgent for nodes to harvest energy from the environment to achieve self-power supply.Mechanical monitoring wireless vibration sensor network are exposed to a large amount of mechanical vibration,which makes it possible to harvest and accumulate vibration energy to power wireless sensor nodes.Aiming at the power supply problem in mechanical monitoring wireless vibration sensor network,the research on vibration energy harvesting and management method has been carried out to realize the self-power supply for wireless vibration sensor network.The main research work of this paper is listed as follows:Aiming at the problem that the current energy harvesting and management method can not achieve self-start when system energy is exhausted,a cold start-up method for vibration energy harvesting and management system is proposed,and a cold start-up circuit is designed.Firstly,the operation characteristics of components in vibration energy harvesting and management system are analyzed,and the energy characteristics of these components are derived.Then,according to these components' energy characteristics,a voltage threshold hysteresis window blocking circuit is designed to manage the low-power energy harvesting process.Given that the large-capacity storage capacitor is in a low-voltage state for long time during the cold start-up stage,a reliable reference voltage circuit has been designed to provide a reference for the voltage threshold hysteresis window blocking circuit.The undervoltage lockout circuit is designed to avoid the energy loss when storage capacitor powers the rear-stage load circuit,which improved the energy efficiency.The cold start-up circuit ensures that,even when system energy is exhausted,the vibration energy harvesting and management system can restart to normal operation without external power supply.For the single module energy harvesting and management method is unable to meet the dual demands of energy supply period and capacity under the high and low power modes of wireless vibration sensor network nodes.The dual module vibration energy harvesting and management method is proposed,and the dual module vibration energy harvesting and management circuit is designed.A full-bridge rectification and filtering circuit is designed to convert the AC energy generated by the piezoelectric energy converter into a relatively stable DC energy.The small and large energy storage capacity modules are designed respectively,corresponding to two energy harvesting modes,to meet the dual demands of large-capacity and short-storage cycle for mechanical vibration wireless sensor network nodes.Energy status monitoring and energy harvesting modes switching circuit is designed to monitor the energy level of the storage capacitor and switch the energy harvesting mode according to the working stage of nodes.The dual-module vibration energy harvesting and management circuit meets the dual demands of energy consumption and real-time of the wireless vibration sensor network on different working stages.Self-powered wireless vibration sensor network node system experimental test is conducted.The dual-module vibration energy harvesting and management system with cold start-up is coupled with the wireless vibration sensor network node to form a self-powered wireless vibration sensor network node and then be tested.The experimental results show that,relying on the vibration energy harvested by itself,the self-powered wireless vibration sensor network node is able to acquire vibration signal and upload the vibration signal data to the upper computer through the wireless module,achieved the goal of monitoring the running state of the mechanical equipment.