Research On The Theory Of Mechanical Vibration Energy Harvesting And Its Excitation Response Characteristics

Vibration mechanical energy,due to its wide range of existence and various forms,has been gradually regarded as an emerging clean energy with great regeneration potential.In recent years,environmental vibration energy harvesting technology have also emerged as the times require.Generally speaking,vibration energy harvesting technology mainly includes five categories:piezoelectric vibration energy harvesting,triboelectric vibration energy harvesting,electrostatic vibration energy harvesting,electromagnetic vibration energy harvesting and hybrid vibration energy harvesting.Among them,electromagnetic vibration energy harvesting technology can be subdivided into linear electromagnetic vibration energy harvesting and rotary electromagnetic vibration energy harvesting.Among all technical categories,rotary electromagnetic vibration energy harvesting has become a unique research hotspot in the field of vibration energy harvesting due to its superior performance in power output.Although the rotary electromagnetic vibration energy harvesting technology has been studied and discussed by many scholars,these studies are almost only focused on the research and analysis of a vibration energy harvesting device,and lack of systematically summarizing the internal energy harvesting mechanism of the vibration energy harvesting system.Secondly,the current research on rotating electromagnetic vibration energy harvesting technology lacks the exploration of the following two key aspects:（1）How to determine the influence of various parameters of the energy harvesting system on its power output performance under different excitation modes;（2）How to evaluate the power output performance of the vibration energy harvesting system.In response to the above problems,this thesis has carried out the following innovative researches:1.The equivalent theory of normalized vibration-electric coupling model-based vibration energy harvesting is proposed.Normalization includes structure normalization,motion normalization,and energy normalization.The vibration energy harvesting system with different structures can be normalized into an energy harvester which has ternary modules of input,rectification and output through structure normalization;the motion conversion from two-way vibration to one-way rotation is realized through motion normalization;the kinetic energy in the form of different external vibrations can be transformed into electrical energy through energy normalization.Based on typical structure combination,structural design,dynamic analysis and electrical analysis have been carried out,and a vibration-electric coupling model of mechanical vibration energy harvesting system has been established.Based on the vibration-electric coupling model,the equivalent theory of energy harvesting is extracted,that is,the mechanical vibration energy harvesting system can be equivalent to a spring-mass-damping system with an equivalent mass of m_eq,an equivalent damping coefficient of c_eq and an equivalent stiffness of k_eq,which provides a theoretical basis for the follow-up study of vibration energy harvesting.2.Study the dynamic response characteristics of power output and parameter adjustment priority sequence for optimal design of mechanical vibration energy harvesting system in free vibration mode.Combined with the stable dynamic response model of the free vibration system and the vibration-electric coupling model,the dynamic power output solution model of the energy harvesting system in the free vibration mode is established.Based on the numerical simulation method,the power output of the energy harvesting system is simulated and analyzed.The influence of the parameters of equivalent mass,equivalent damping and equivalent stiffness on the power output performance of the system is studied,which can provide guidance for the optimal design of the energy harvesting system in the free vibration mode.3.Study the dynamic response characteristics of power output and parameter adjustment priority sequence for optimal design of mechanical vibration energy harvesting system in forced vibration mode.Based on the stable dynamic response model of the forced vibration system and the vibration-electric coupling model,a solution model for the power output of the energy harvesting system under three typical forced vibration modes is established.The numerical simulation method is used to simulate and analyze the power output of the energy harvesting system.The influence of the parameters of the components of equivalent mass,equivalent damping and equivalent stiffness on the power output performance of the system is studied,which can provide guidance for the optimal design of the energy harvesting system in the forced vibration mode.4.Based on the MTS test platform to establish a mechanical vibration energy harvesting system power output test and evaluation system.First,the prototype of the mechanical vibration energy harvesting system is manufactured,and the power output performance test platform of the energy harvesting system based on MTS equipment is built,and the power output performance test of the energy harvesting system under different excitation modes is carried out.The test results show that:under sine,square and ramp wave excitation,when the excitation frequency is constant,with the increase of the excitation force amplitude,the voltage output of the mechanical vibration energy harvesting system becomes higher;However,when the amplitude of the excitation force remains unchanged,under three different external input excitations,the change of the excitation force frequency has little effect on the power output of the mechanical vibration energy harvesting system;As the external resistance increases,the voltage across the resistor obtained from the mechanical energy harvesting system is also greater,but only when the resistance of the external load is equal to the internal resistance of the motor,the system output power is the highest;After the boost and voltage regulation process,the mechanical energy harvesting system can be boosted to the same voltage value and remains stable,but when the excitation force amplitude and frequency are larger,the energy harvesting system will reach the stable state sooner.Finally,through comparing the power output of the energy harvesting system with the power consumption requirements of each sensor,it is concluded that the mechanical vibration energy harvesting system has the potential to provide power for low-power loads such as sensors.