A Study Of A Low-power-consumption Buck Piezoelectric Energy Harvesting System

The wireless sensor network is considered as one of the most important technology in the 21st century.With the increasing application of the wireless sensor network nodes,the power supply of the wireless sensors is attracting more and more attention.The traditional method is to use a battery as the power supply for the wireless sensor.However,battery has some limitations,due to the limited energy stored in the battery.It cannot meet the need of long-term operation.And if the wireless sensor is installed in a harsh environment or in which human are difficult to reach,it is difficult to replace the battery.Therefore,it is of great significance to study the vibration energy harvesting in the environsment.The vibration in the environment exists everywhere,such as the walking of the human body and the vibrations of industrial machines.Researches on piezoelectric energy harvesting that have been carried out already show that using piezoelectric materials to obtain energy from mechanical vibrations is feasible and has great application prospects.Piezoelectric material has a power density up to several hundred mW/cm3,and can offer nicrowatts to milliwatts of power in the environment,which can meet the needs of many electronic systems.At present,the most popular technologies for converting vibration energy into electricity are based upon electrostatic,electromagnetic and piezoelectric transducers.Among them,piezoelectric transducers achieve the energy conversion taking advantage of the piezoelectric effect of piezoelectric materials.Due to its high power density,simple structure,convinience to achieve integration,it has attracted extensive attention in the past decades.Since the piezoelectric energy harvester generates an alternating voltage,the peak amplitude voltage can reach tens of volts or even hundreds of volts.In order to improve the efficiency of energy harvesting,a rectifying and buck conversion is required.As the vibration level is usually variable.Under different vibration amplitudes,there exists an optimal rectifier voltage to harvest the energy for maximum power,and the input voltage of the buck stage will also change.Therefore,this paper presents a low-power-consumption buck energy harvesting system for the high-voltage piezoelectric energy harvesters,the system can adapt the piezoelectric output voltage of different vibration amplitudes and frequencies to achieve maximum power point tracking.The system is based on DC-DC buck converter and low-power controller technology,the buck converter applies a zero-current switching technology,and the controller operates under the ultra-low-power mode for most of the time,therefore the average power consumption of the controller and the whole circuit system is effectively reduced.The experimental results show that buck control system can achieve self-powered when the peak voltage of the piezoelectric element is only 6V,and the maximum power generated is as low as 16?W.