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《Mechatronics》2006,16(1):1-12
This paper first presents an equivalent circuit model of a new disc-type ultrasonic motor and discusses its applications in evaluation of the stator’s frequency characteristics. The equivalent circuit analysis is based on the principle of ultrasonic motor operations and is conducted from the viewpoint of the mechanic vibration of the piezoelectric ceramic disk. Furthermore, because drift of the piezostator characteristics will cause variation of the motor speed, a controller is thus necessary in order to produce a constant output speed. In this research, the speed control scheme is implemented by using current modulation, so the revolutional speed will be kept constant. Meanwhile, the frequency behaviour of the proposed motor and its consequences on speed control scheme are discussed. Finally, a 3-D mechanical element with an extra electrical degree of freedom is employed to simulate the dynamic vibration modes of the linear piezoelectric, mechanical and piezoelectro-mechanic behaviours of a metal disc structure embedded with a piezoelectric actuator. In piezoelectric finite element formulation, a discretized equation of motion is developed and solved by using the integration scheme to explain why an adaptive boundary condition, a simple support condition with three non-equal-triangular (120°–90°–150°) fixed points near the edge for the mechanical design of a new disc-type piezoelectric ultrasonic stator, is defined so that a lateral elliptical motion of the contact point between stator and rotor can be realized for driving the rotor. 相似文献
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为得到压电振子精确的等效电路,将等效电路参数设为复数,即每一电路元件参数包含实部和虚部两部分,其中实部部分意义与传统参数意义相同,而虚部部分表示相应的机械、介电及压电损耗。为得到等效电路参数,给出了等效电路参数与压电材料参数之间相互关系。通过仿真和实验两种方法对复数模型与传统模型进行了性能比较,验证了复数等效电路模型的有效性和精确性。 相似文献
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异质结双极晶体管高频噪声建模及分析 总被引:1,自引:1,他引:0
提出了一个T等效异质结双极晶体管高频噪声电路模型.该模型是对通常用在硅双极晶体管中的Hawkins噪声模型进行改进得到的,主要的改进包括发射极理想因子、发射极电阻、内部BC结电容、外部BC结电容和其它寄生元素对器件噪声性能的影响.为了从等效噪声电路模型中计算出精确的噪声参数,采用了噪声相关矩阵法来计算噪声参数,从而避免了在等效电路变换中可能产生的简化和复杂的噪声测量.进一步利用该模型分析了等效电路元素对器件最小噪声系数的影响,分析计算结果和物理解释一致.同时通过基于异质结双极晶体管器件物理的公式,给出了器件参数对器件最小噪声系数的影响. 相似文献
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自由振动压电振子的一种复参数等效电路 总被引:1,自引:1,他引:1
将复数概念引入到等效电路元件参数中,并以自由振动压电振子的一种常用振动模——纵向长度伸缩振动模为例,给出了一种复参数等效电路,并推导了等效电路参数与压电材料参数之间相互关系。等效电路元件参数的虚部表示压电振子机械、介电、及压电损耗。给出了由复参数等效电路模型作出的阻抗圆图与由振动理论给出的阻抗圆图以及由传统模型所作出的阻抗圆图。结果表明,新的复参数模型优于传统模型,是一种精确的等效电路。 相似文献
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《Mechatronics》2021
This paper presents a modeling framework for permanent magnet linear synchronous motors based on magnetic equivalent circuits. In comparison to the commonly used dq0 model, the proposed modeling approach is able to systematically include magnetic saturation effects and has no restriction to harmonic motor quantities. In contrast to existing work, a differential magnetic equivalent circuit network is used to describe the stator quantities and the complete model is derived using a graph-theoretic approach. Furthermore, the resulting model is calibrated with measurements on a test bench and validated with additional measurement scenarios. 相似文献
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德拜极化电池作为一种双电层电容器模型的评估。其电路元件与发生在DLC内的化学反应有关,其参数值可通过DLC的交流阻抗测量并应用采用非线性最小二乘法定位技术的计算机程序加以处理来获得。研究了在不同直流偏置电平和制造过程中的电路元件值的差异,并将德拜极化电池在缓慢放电和脉冲负载中的性能与实际电路以及采用经典等效电路模拟的结果进行了对比。 相似文献
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提出了一个T等效异质结双极晶体管高频噪声电路模型.该模型是对通常用在硅双极晶体管中的Hawkins噪声模型进行改进得到的,主要的改进包括发射极理想因子、发射极电阻、内部BC结电容、外部BC结电容和其它寄生元素对器件噪声性能的影响.为了从等效噪声电路模型中计算出精确的噪声参数,采用了噪声相关矩阵法来计算噪声参数,从而避免了在等效电路变换中可能产生的简化和复杂的噪声测量.进一步利用该模型分析了等效电路元素对器件最小噪声系数的影响,分析计算结果和物理解释一致.同时通过基于异质结双极晶体管器件物理的公式,给出了器件参数对器件最小噪声系数的影响. 相似文献
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该文在深入分析超声电机运行机理的基础上,从定子、接触区域和转子3方面建立了超声电机等效电路模型。综合现有超声电机等效电路模型的优缺点,考虑摩擦耦合对超声电机的影响,并结合转子振动方程,提出了摩擦层与转子的等效电路模型;对转子侧等效模型进行优化,使其与定子模型结合成完整的电机模型。基于所建立的模型理论,对等效电路进行仿真,仿真结果表明了转子对整个电机电气特征的影响。通过对实际超声电机的测试及其与仿真波形的对比,验证了所提出的行波型超声波电机等效电路模型的正确性,为进一步开展超声电机驱动器和控制器的设计提供了模型基础。 相似文献
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S. G. Suchkov D. S. Suchkov D. S. Chaikovskii 《Journal of Communications Technology and Electronics》2007,52(2):239-242
A new equivalent circuit of a surface-acoustic-wave (SAW) interdigital transducer (IDT) is proposed. A method using this circuit for calculation of the device’s gain-frequency characteristic and impedance is described. The fingers of the transducer can be arbitrarily shaped and positioned. The electrode current is obtained via the rigorous calculation of the SAW-related charge in the piezoelectric substrate and of the charge induced by the former charge in the transducer electrodes. The method allows design of SAW devices with an arbitrary complex finger structure and a multilayer substrate. 相似文献
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目前通过导纳圆获取压电换能器等效参数的方法较复杂,导致阻抗分析仪成本高,结构复杂,体积大及便携性差。为了更简单准确地测量压电换能器的等效参数,该文从压电换能器等效电路出发,提出了两种通过给定4个特定频率即可直接推导出换能器等效参数的方法。方法一的算法简单,只需测量4个特定频率下换能器两端电压、电流有效值;方法二需要在此基础上获得电压、电流的相位差。通过仿真分析结果表明,方法一的测量误差较大;方法二与阻抗分析仪PV520A测量结果相比其误差小于1.5%,测量精度较高。 相似文献
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与传统的电磁变压器相比,压电变压器具有高升压、无电磁污染等特点。由于压电变压器的工作原理复杂,除了Rosen型压电变压器,对于其他压电变压器的理论研究较少。对一种驱动部分以及发电部分都是横场模式的横横式压电变压器进行了理论研究。从Mosen等效电路出发,利用泰勒展开,建立了能反映压电变压器实际工作情况的集总式等效电路图;并在此基础上,给出了一种只用机械品质因数Qm、电学品质因数Qe及机电耦合系数k三个量来表征变压器电学性能的方法。由于Qm、Qe、k的测量方法早已标准化,尺寸、负载对变压器的影响可归结为Qe对电学性能的函数,因此有望简化设计过程。 相似文献
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Ki-Wone Seo Saehoon Ju Hyeongdong Kim 《Electron Device Letters, IEEE》2002,23(6):327-329
The finite-difference time-domain (FDTD) technique has been applied to analyze electromechanical phenomena of thin-film bulk acoustic wave resonators (TFBARs) for the first time. To simulate several TFBARs that have one-dimensional (1-D) piezoelectric material variations, current-driven governing equations are discretized in spatial and temporal domain. The impedance characteristics are obtained by the proposed method and compared with the analytical solutions of the 1-D Mason model. Also, the values of lumped elements for the Butterworth Van Dyke (BVD) equivalent circuit are extracted. The results show that the proposed scheme has the potential to analyze the characteristics of arbitrary piezoelectric material embedded structures 相似文献
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对于关断角控制型软启动器的三相晶闸管交流调压电路,将其等效为一个随关断角而变化的电抗,结合异步电机简化模型,得出软启动器主电路的等效电路。在此基础上,分析了关断角与电机定子电流、电磁转矩、最大电磁转矩和临界转差率的关系,进一步得到电机的启动电流可由关断角进行控制的结论。仿真结果验证了理论分析的有效性和可行性。 相似文献
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An approach to determining an equivalent circuit for HEMTs 总被引:9,自引:0,他引:9
Shirakawa K. Oikawa H. Shimura T. Kawasaki T. Ohashi Y. Saito T. Daido Y. 《Microwave Theory and Techniques》1995,43(3):499-503
A simple way to determine a small-signal equivalent circuit of High Electron Mobility Transistors (HEMTs) is proposed. Intrinsic elements determined by a conventional analytical parameter transformation technique are described as functions of extrinsic elements. Assuming that the equivalent circuit composed of lumped elements is valid over the whole frequency range of the measurements, the extrinsic elements are iteratively determined using the variance of the intrinsic elements as an optimization criterion. Measurements of S-parameters up to 62.5 GHz at more than 100 different bias points confirmed that the HEMT equivalent circuit is consistent for all bias points 相似文献
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