The Load Characteristics Of Piezoelectric Power Generation System

With the rapid development of MEMS and sensing network, people pay more and more attention to their energy supply, and piezoelectric power generation system can collect and storage energy from the environment, then it can apply to the actual load, it has a lot of advantages, such as green without pollution, strong anti-interference ability, so it has been paid attention by more and more people.Now at home and abroad,people have a corresponding research achievements respectively in three parts:the piezoelectric vibrator, the piezoelectric energy storage circuit, piezoelectric application, but there is a few research on piezoelectric power generation system, especially in the load characteristic of piezoelectric power system research, therefore this topic will have a research on the load characteristic of piezoelectric power system from the theory and experiment, the paper mainly has done the following work:First, it briefly introduced the basic theory of piezoelectric power generation, including piezoelectric effect, piezoelectric materials and piezoelectric equations,the piezoelectric vibrator way, support and incentives of the piezoelectric vibrator. Then it gets the natural frequency of the piezoelectric vibrator by ANSYS software,and briefly describes the frequency characteristics of the piezoelectric vibrator.By establishing the electrical equivalent model of piezoelectric vibrator and load, it gets the optimal load by using the first kind of piezoelectric equation and also there is a maximum output power under the optimal load,and it theoretically analyzed the resistance load characteristics of the piezoelectric power generation system.Then, from the perspective of the experiment,the author completed the following experiments:(1)get the natural frequency of piezoelectric vibrator by resonance method,and it coincide to the theoretical analysis;(2)the relationship between the excitation frequency and the piezoelectric power generation, through the experiment it discovered that in the natural frequency,the piezoelectric vibrator can get the biggest output;(3) the load characteristic experiments of piezoelectric power generation system, when the peak-to-peak value of the vibrator’s output is17.5V,the energy storage capacitor is0.1F,the load is pF、μF magnitude,it costs approximately18and19minutes respectively when the energy storage capacitor is full of electricity,while the load is0.1F,it costs about35minutes;when the load resistance is equal to or greater than47K,it costs about22minutes when the energy storage capacitor is full of electricity,the load resistor is20k needs38minutes,when the load resistor is10k,it needs40minutes and the voltage is stable at2.6V,the whole circuit achieve to dynamic balance;when the load resistor is16k,the vibrator has the maximum output power:0.67mW;(4)the stability experiments of piezoelectric vibrator,under the natural frequency,the vibrator’s output may distortion with the increment of the exciting force,and in severe cases the vibrator may break.Finally,use ADT7410temperature sensor as load to observe the phenomenon when using vibrator to supply energy for one and two sensors respectively. When the vibrator’s peak-to-peak output voltage is32V,the energy capacitor is0.47F,the vibrator can be sustained and steady for a ADT7410temperature sensor;when peak-to-peak output is35V,the capacitor is0.47F,the vibrator also can be sustained and steady for two ADT7410temperature sensors.Through the experiment we found that when the energy storage capacitor’s voltage is greater than2V, the capacitor can be sustained and steady for ADT7410power supply, and when the piezoelectric vibrator is in the process of vibration,it can supply for ADT7410temperature sensor continuously and smoothly.