Research Onawide-bandwidth And Low-frequency Energy Harvesters Based On Composite Magnetoelectric Materials

Through energy harvesting technology, energy of vibration in the environmentis converted to electricity, then powering for electronic components. This will makeelectronic devices are self-powered ones, and can provide power source for a longtime. Using MEMS technology, the power is integrated into electronic device. Itprovides favorable conditions for making electronic devices to be more intelligentand portable.Among different types of energy harvester, including wind, solar, thermalenergy, energy of vibration, etc, the application of vibration has a extremely broadprospect. By the research and analysis about the status of the vibration energyharvesters, found that the vibration energy harvesters have a lot of advantages, suchas simple structure, good compatibility with MEMS, output large power density anddon’t need start-up power and so on. Also there are some disadvantages:1) in orderto obtain a higher output, the energy harvesters have to resonance with theenvironmental vibration. But the natural frequency of the vibration energy harvestersis identified,2) the natural frequency of the vibration energy harvesters is muchhigher than the environmental vibration, must take appropriate measures to reducethe natural frequency of the energy harvester. Therefore, the purpose of this paper isto study a kind of vibration energy harvester, which has characteristics ofwide-bandwidth and low-frequency.A new vibration energy harvester is presented. Collector mainly composed oftwo parts, an energy converter and a bi-stable system. Terfenol-D/PZT/Terfenol-Dcomposite magnetic transducer is the main components of the collector. This paperanalyzes the energy conversion process and the complex method of the compositemagnetic transducer. With the magnetostrictive effect and the piezoelectric effect,mechanical energy is converted into electrical energy, when the compositetransducer moved in magnetic field.Design the measure of the energy collector. Energy conversion of transducer isclosely related to the intensity of the air gap magnetic field of the permanent magnet.In this paper, by using ansys software, the permanent magnet air-gap magnetic circuit is simulated. Through the theoretical analysis, get the most importantparameters of the bi-stable system. The designed energy collector showed significantbi-stable characteristics, when the permanent magnet spacing d less than5.5mm, bysimulation of matlab. Use the simulink toolbox. Take d=5mm, input a sine signalwith noise, getting the displacement response of the system. The displacement has abi-stable characteristic. Resonant frequency of the system has been expanded.The circuit of vibration energy harvesting is completed. This circuit is used forstoring the output irregular, volatile energy of the collector, to provide a stablepower supply for electronic components. Chose MAX1795chip, the chip can adjustthe voltage from the2V to5.5V.Experimental verification has been done. Under the input signal is20Hz sineexcitation, respectively, taking d=5mm and d=7mm, the experiment is done. Itshows that when d=5mm the output voltage performance bi-stable characteristics,and it is larger, and also the response is wider. Through energy collection circuittesting to achieve the stable output voltage of3.3V.