High power electrostatic generator with rotor of piezoelectric strips

The paper discusses a multipole ESG with rotor of piezo-electric strips. The polarization of a strip, bent due to rotation, causes an ac in a resistor connected across electrode pairs. With rotor of PZT-5 or ZnO crystal, the calculated power of the generator is above 3 and 22 kW, respectively, under vacuum insulation strength of 10 kV/mm.     

Analytical modeling for the design of a piezoelectric rotating-mode motor

This paper deals with the analytical modeling of a rotating-mode motor. The modeling, based on an equivalent electric circuit, is established by using geometrical and electromechanical parameters for the different parts of the motor. It gives electromechanical characteristics and other useful values for motor design. Numerical simulations and measurements from a real transducer validate the analysis.     

A MEMS-based piezoelectric power generator array for vibration energy harvesting

Piezoelectric power generator made by microelectromechanical system (MEMS) technology can scavenge power from low-level ambient vibration sources. The developed MEMS power generators are featured with fixed/narrow operation frequency and power output in microwatt level, whereas, the frequency of ambient vibration is floating in some range, and power output is insufficient. In this paper, a power generator array based on thick-film piezoelectric cantilevers is investigated to improve frequency flexibility and power output. Piezoelectric cantilevers array has been designed and fabricated. The cantilevers array can be tuned to the frequency and expanded the excited frequency bandwidth in ambient low frequency vibration. Serial connection among cantilevers of the array is investigated. The prototype generator has a measured performance of 3.98 μW effective electrical power and 3.93 DC output voltage to resistance load. This device is promising to support networks of ultra-low-power, peer-to-peer, wireless nodes.     

Fabrication and performance of MEMS-based piezoelectric power generator for vibration energy harvesting

A MEMS-based energy harvesting device, micro piezoelectric power generator, is designed to convert ambient vibration energy to electrical power via piezoelectric effect. In this work, the generator structure of composite cantilever with nickel metal mass is devised. Micro-electronic-mechanical systems (MEMS) related techniques such as sol-gel, RIE dry etching, wet chemical etching, UV-LIGA are developed to fabricate the device and then its performance is measured on vibration testing setup. The investigation shows that the designed device is expected to resonantly operate in low-frequency environmental vibration through tailoring the structure dimension. Under the resonant operation with frequency of about 608 Hz, a first prototype of the generator result in about 0.89 V AC peak-peak voltage output to overcome germanium diode rectifier toward energy storage, and its power output is in microwatt level of 2.16 μW.     

Design, fabrication and performance of a new vibration-based electromagnetic micro power generator

This paper presents a new vibration-based electromagnetic micro power generator fabricated using microelectromechanical systems (MEMS) technology, which can convert ambient vibration energy into electric power. The microgenerator consists of a permanent magnet of NdFeB, a copper planar spring and a two-layer copper coil. ANSYS modal analysis was used to predict the resonant frequencies and resonant vibration modes of the spring-mass system. The detailed fabrication processes of the microgenerator are given. Experimental results show that the prototype microgenerator can generate open-circuit voltage of 60 mV ac peak–peak with 121.25 Hz input frequency and the acceleration of 1.5g (g=9.8 m/s²). The experimental and simulated results were compared and discussed.     

Single-chip multiple-frequency VHF low-impedance micro piezoelectric resonators

This letter reports on the design, fabrication, and testing a new class of low-impedance multiple-frequency micromechanical resonator using piezoelectric transduction mechanism. The resonator is fabricated out of a 3-/spl mu/m-thick silicon layer on a silicon-on-insulator wafer with a low-temperature post-CMOS compatible process. Two types of low-impedance resonators using the same design principle are presented here. The center frequency of the novel resonator is set by the lithographically defined in-plane dimension of the device (width of bar or radius of disk). The 200-/spl mu/m-diameter disk-shaped resonator is measured to have an impedance of 1.6 k/spl Omega/ at the resonant frequency of 45.4 MHz, with a quality factor of 1100. The bar-type resonator is measured to have an impedance of 920 /spl Omega/ at 60 MHz, exhibiting a Q factor of 1400.     

Distributed piezoelectric guided-T-wave generator,design and analysis

In this work, the definition and design of a specific wave generator concept is presented. The generator aims at providing well referenced T waves for structural health monitoring applications. A distributed network of piezoelectric patches network is considered. Shear effects is the most pertinent effect. An array of 16 piezoelectric stacks is found to be relevant. The numerical simulation confirms the finding. An experimental test bench is also provided in order to validate the concept. The ability of the distributed system in generating pure T waves is discussed. The concept is also employed in order to assess the distributed system overall performances. Numerical and experimental results confirm some specific features in the wave reflection coefficient based on the interaction between the damaged waveguide dynamics and torsional waves propagation.     

Analytical piezoelectric charge densities in GaAs MESFETs

The orientation effect in GaAs MESFETs is related to the piezoelectric charge due to stress in overlayers. This brief describes an analytical method for the calculation of the piezoelectric charge in GaAs MESFETs on (100), (011), (1¯1¯1¯)Ga, and (111)As substrates     

A miniature generator using piezoelectric bender with elastic base

Nowadays green energy devices such as vibration generators attempt to harvest energy from environment. A lot of studies dealing with vibration generators put emphasis on mechanism designs or power generation methods, but few on lowering the resonant frequency of power generation systems. This study proposes that elastic bases attached to vibration generators can lower natural frequencies, so as to make natural frequencies closer to ambient vibration frequency. Therefore, this study investigates miniature electric generators consisting of piezoelectric benders and elastic bases. To install the elastic base, this work uses a spring with prescribed stiffness and a board with given mass between the piezoelectric bender and a vibration source to make the resonant frequency of piezoelectric benders close to the frequency of ambient vibration. Analytical derivation is carried out to obtain optimal mass and stiffness. Accordingly, more electric power can be generated from piezoelectric generators using an elastic base with appropriate mass and stiffness. According to experimental results, using an elastic base increases 376 times generated power compared with no elastic base. In the presence of the elastic base, the power increases 132% when a point mass is added.     

小型大功率纳秒脉冲发生器设计--模块化脉冲源(MPS)之一例

本文提出了模块化脉冲源的新的设计观点和产品方向,并将ＭＰＳ规范为包含十种类型高速脉冲源的电子产品系列。通过实例－小型化大功率纳秒脉冲发生器的研制成功,印证了ＭＰＳ的设计观点。     

Modeling of electromagnetic power output in a vibration-induced micro-generator with a silicon-based helical micro-spring

This paper develops an electromagnetic power output model in a vibration-induced micro-generator with a silicon helical micro-spring to predict the electricity output. The generator consists of a movable ferro-platinum permanent magnet membrane on the micro-spring, a winding copper induction coil and two glass spacers. This model considers the coupling issues of mechanical kinematics and electromagnetism that convert mechanical energy to electric energy through vibration. Analytical formulas are developed to predict analyze the values in the spring constant of the helical micro-spring, a three-dimensional magnetic field of electromagnetic induction and the parasitical damping coefficient. Good agreement between the analysis and experiment: 82.6% precision for power output, 6.2% difference for current output and 9.6% deviation for voltage output are demonstrated at 60 Hz vibration frequency with a 0.03 mm vibration amplitude. From a series of analytical results, it is known that a 4.2 times power output can be achieved by controlling the oscillator with an appropriate vibration amplitude and the best-designed load resistance.     

功率型压电陶瓷振子的研制及应用

介绍了功率型压电陶瓷振子的研制过程。采用二次水磨加黏合剂造粒方法，并使用超细ＺｒＯ２，使烧结温度降低，从而减少ＰｂＯ的挥发。作者对铌锂锆钛酸铅系统做了大量的配方筛选工作，确定了性能满足使用要求的配方（Ｐｂ１－ａＳｒａ（Ｌｉ１／４Ｎｂ３／４）０．１２Ｚｒ０．４６Ｔｉ０．４２Ｏ３）。叙述了功率型压电陶瓷振子在超声清洗、超声焊接、超声钻孔等方面的应用。     

Analytical loss model of power MOSFET

An accurate analytical model is proposed in this paper to calculate the power loss of a metal-oxide semiconductor field-effect transistor. The nonlinearity of the capacitors of the devices and the parasitic inductance in the circuit, such as the source inductor shared by the power stage and driver loop, the drain inductor, etc., are considered in the model. In addition, the ringing is always observed in the switching power supply, which is ignored in the traditional loss model. In this paper, the ringing loss is analyzed in a simple way with a clear physical meaning. Based on this model, the circuit power loss could be accurately predicted. Experimental results are provided to verify the model. The simulation results match the experimental results very well, even at 2-MHz switching frequency.     

Analytical modeling of the partially-depleted SOI MOSFET

An analytical model for the partially-depleted (PD) silicon-on-insulator (SOI) MOSFET above threshold was developed. In contrast to previous models, this model includes front-back interface coupling with all the possibilities associated with it (accumulated, neutral, and depleted back interface). The model applies to tied-body as well as floating-body devices; however, thermal and edge effects are neglected. Interface coupling and floating-body effects are integrated together in a new “unified” algorithm. The “pseudo-two-dimensional” approach (which was used successfully to model lateral fields in bulk-Si devices) is extended to SOI devices. The model is extremely physical and thus highly predictive. Good agreement with experiment was obtained over a wide range of channel lengths and back gate voltages. Because of the model's neglect of thermal effects, however, disagreement was observed at high current levels. A brief physical interpretation of the results is also presented     

倾斜镜系统动态耦合数学模型的建立方法

主要探究了在传感器采样频率较高(如高速相机、位置传感器)、倾斜镜动态特性不可忽略的情况下,如何基于实验数据建立开环倾斜镜系统的动态耦合数学模型的问题。分析了系统的动态特性以及输入与输出之间的耦合,提出了基于倾斜镜系统的输入输出数据、采用子空间辨识算法建立倾斜镜系统动态耦合数学模型的方法,并通过实验评估了模型的准确性和建模方法的可行性。实验结果显示,通过该方法所建立的倾斜镜动态耦合模型的VAF值达到95%,模型准确性相比传统的静态模型有了很大提高,验证了建模方法的可行性。研究成果可用于闭环倾斜镜系统优化反馈控制器的设计,提高系统对于光束偏移矫正的性能。     

微功耗升压式开关电源MIC2141

一、概述 MIC2141是一种适用于三或四节镍氢电池或一节锂电池供电的微功耗升压式DC/DC变换器,其特点是输出电压Vo受外电压Vc控制。此变换器工作频率是330kHz,占空比18％,采用门控振荡器结构。 该变换器能用于输出电压必须动态调整的应用,输出电压Vout与控制电压Vc的关系为Vout=6Vc,即Vc在0.8～3.6V时输出电压Vout为4.8～22V。外部仅需要三个元件就可以工作,静态电流为70μA,既节省空间又满足便携式产     

Self-tuning turbine generator control for power plant

This paper describes advances in electromechanical control of power generation plant. It features self-tuning control techniques for automatic voltage regulation (AVR) and governor control. These are highly non-linear systems. Consideration is given to the practical realisation of the proposed algorithms, in terms of execution speed and robustness. The algorithms are tested on a laboratory micromachine which is a physical representation of a 500 MW generator. Industry standard hardware is used for the assessment. Results indicate that significant improvements in regulation performance can be made, using currently available microcomputer based AVR and governor hardware.