Design And Experiment Research On A Circular Piezodisc Energy Generator Excited By Rotary Magnets

With the development of the research on piezoelectricity, there exists domestic and overseas interest in applications of specific environment. To meet the increasing demands of rotating mechanism for self-powered monitoring system, a novel piezodisc generator excited by the coupling effect between rotating magnets and those fixed on the piezodisc is presented. This paper introduces its structure principle and analyze the influence of the output voltage for the piezoelectric harvester. The prototypes are made and the measurement results show the key factors of electricity generation performance. Specific researches are listed below:1. For the deficiencies of existing rotary piezoelectric generators, in this work, a high-intensity、broad band circular piezoelectric generator is proposed. The circular piezoelectric vibrator is the transducer of piezodisc generator, the structure parameter, boundary conditions, and the dynamic characteristics of vibration and vibration have greater impacts on generating capacity, bandwidth and output power. A circular piezoelectric vibrator theoretical model is established. The power generation performance of the boundary conditions under concentrated load is simulated. The influence of its power generation capacity, such as piezoelectric vibrator thickness ratio, radius ratio and Young’s modulus of the material is specifically studied in order to provide the theoretical basis for the choice of the piezoelectric vibrator.2. The energy of Rotating piezoelectric generator comes from the magnetic excitation in permanent magnetic force. In this paper the magnetic force of the permanent magnet is simplified calculated. By the way of the lower magnetic testing of different gap and COMSOL Multiphysics Simulation, results are simplificated and the simplified formula are obtained. Combined with the output voltage response and the impact of the circular piezoelectric transducer, piezoelectric characteristic is obtained. The spacing of magnet is changed by the excitation force between the magnets. The speed of plate is influenced by changing the piezoelectric ceramic, thus providing the base of piezoelectric generator. 3. An analytical model of the circular piezodisc energy generator is established. This paper introduces the principle of the generator and thus selects the appropriate piezoelectric transducer. Researches on the influence of system factors on the maximal voltage and total energy generated from the piezodisc at one excitation are investigated mainly. The research results show that both the output voltage and effective speed-band can be enhanced with increasing magnet size or decreasing the distance between the magnets. Besides, the thickness of the piezodisc exerts also great influence on the generated voltage and electric energy. Both the maximal voltage and total electric energy can be enhanced with using a thin piezodisc at low speed or a thick piezodisc at high speed. The influence of the number of the rotating magnets on the exciting force as well as the output voltage of the piezoelectric harvester was investigated theoretically and experimentally. The results show that there is optimal gap ratio for the excitation force to achieve maximum. Besides, the voltage waveform generated from the piezoelectric harvester under once excitation depends on the number of the rotating magnets and rotating speeds.The waveform of the output voltage and the overall performance of the generator are also compared.4. Each piezoelectric vibrator corresponds to a optimal rotary speed that makes the energy and output power into maximum. With the decreasing of piezoelectric vibrator thickness, the optimal rotary speed reduces while energy and output power increases. Select a good magnet configuration which makes the output voltage high enough to charge the capacitor in different speeds, after a period of time, the voltage of the capacitor reaches stable. The difference is that both the charge rate and the voltage raises with the increasing of the rotary speed. In the power test experiment, one piezoelectric vibrator has the same optimal load at different rotary speeds, and the output voltage increases with the load increasing. Although, the various tendencies are different, all tend to reach the open circuit voltage eventually.