Research On Theory And Key Technologies Of Piezoelectric Vibration Generator For Improving Generating Capacity

In order to provide the continuous system of electric power service, equipments of power generation and supply need the ability of fault diagnosis and self-recovery. On-line monitoring system of wireless sensor network is widely used for performance is stable and reliable and move is convenient and flexible. But, for the number of nodes is large and it is difficult for the generator to stop to replace device, the traditional power supply way of battery can not meet requirements. Piezoelectric cantilever generator manufactured by micro-electric-mechanical system technology can provide energy to various low-power electronic devices continuously. Since there are shortcoming that theoretical base is weak and requirement of environment vibration frequency is harsh, widespread use of piezoelectric cantilever generator is limited to a certain extent. In view of the above problems, this article analyzes in depth electromechanical coupling mechanical model with distribution parameter and studies technology of shunt capacitors and generator array integration. This article strives to improve the ability of piezoelectric cantilever generator with finite volume.1. For enhancing theoretical model accuracy and generating capacity of finite volume of piezoelectric generator, the distributed mass are intorduced to model based on electromechanical conversion characteristics. Based on distributed parameter mechanical model, electromechanical coupling between vibraion and voltage is studied, and electromechanical coupling term is introduced to steady voltage response and relative lateral displacemnt response, and the precise distributed parameters mechanical model is established. Meanwhile, for analysis the accuracy of mechanical model, and finite element simulation software is adopted to study the characteristic of natural frequency and open-circuit voltage. Combining the theoretical calculation, the influence of structure and materical parameters to generating capacity is studied and optimal structure is designed. Generating capacity of unimorph, bimorph in series and bimorph in parallel are analyzed by test, and energy conversion efficiency of piezoelectric generator with finite volume is increased.2. The method of shunt capacitor regulating the natural frequency of piezoelectric generator overcome the flaw of volume increscent which adopt mechanical method to regulate natural frequency of piezoeletric generator. The influence law of material and structural parameters to natural frequency regulation range of piezoeletric generator by shunt capacity is studied, and optimization case of material and structure is proposed which enlarge the piezoelectric beam’s natural frequency regulation range. Frequency regulation range and generating capacity is consider comprehensively, optimal frequency regulation method is proposed to increase energy harvesting efficiency. For saving cost and reducing the volume of natureal frequency regulating device, Binary capacitor array is studied to achieved the continuous regulation of natural frequency.3. Influence law of lumped masses to factors of motion control equation, quality normalization function, modal response, excitation, electromechanical coupling term etal are studied, then mechanical model of distribution parameters of piezoelectric cantilever generator with lumped mass is established. Transfer function of amplitude-base acceleration and characteristics of natural frequency are analyzed, and the generator array of high output energy density is studyed. According to the goal of the lowest cost, the minimum volume and the largest generating capacity, and composite vibration generator which integrate shunt capacitor and generator array is proposed.