Analysis of noise absorption characteristics of ceramic chip varistor according to the equivalent circuit model.

最近，各种电机都是由计算机控制的。因此，针对电机中出现的喘振噪声和高频噪声，采取相应的对策，对防止电机的误操作和损坏具有重要意义。与齐纳二极管相比，压敏电阻具有很多优点，如电压-电流曲线上的电极性对称性、大的静电容量和高的响应度。因此，它不仅是便携式电话、摄像机、CD-ROM、DVD-ROM和直流电机的防静电保护元件，也是防浪涌噪声的保护元件。尤其是氧化锌压敏电阻器，由于其在大电流区的外加电压与电流之间存在较大的非线性系数，因此更适合于吸声。然而，对于陶瓷压敏电阻的吸声特性研究还很少，本研究对其进行了模拟分析，为利用Definmin…设计陶瓷压敏电阻提供了数据陶瓷压敏电阻器的更多等效电路。等效电路的确定如下。在可变电阻器中，晶界层中的耗尽层引起了电压-电流的非线性，晶界层中的电阻值较小。因此，在电阻和电容器并联时表现为晶界等效电路，在小电阻时表现为晶界等效电路。在实际的压敏电阻中，陶瓷晶体被编织在一起。在本研究中，将上述晶界和晶内的等效电路编织在一起，给出了构成等效电路的阻值和电容值的确定过程。首先，利用PSPICE电路仿真软件，确定合适的电阻和电容的取值，并计算其介电特性和伏安特性。确定了电阻和电容的取值，使计算得到的介电特性和伏安特性与实验值吻合。较少

Recently, various motors are being controlled by a computer. Therefore, a countermeasure toward surge noise which occurs in the motor and the high frequency noise is important to prevent faulty operation of the machine and destruction. Varistor has a lot of advantages in comparison with zener diode, such as the symmetry of electric polarity in the voltage-current curve, the large electrostatic capacity and the high responsibility. Therefore, it is used as a protective component against not only the static electricity but also the surge noise for the portable telephone, video camera, CD-ROM, DVD-ROM and DC motor. Especially, ZnO varistor is available for the noise absorption, since it has a large non-linear coefficient between applied voltage and current at the region of a large current. However, the noise absorption characteristics have been hardly investigated.In this study, simulations were made to analyze it and to present the data for designing a ceramic varistor using the determin … More ed equivalent circuit of ceramic varistor. The equivalent circuit was determined as follows. In the variable resistor, the non-linearity of the voltage-current is being brought about by depletion layer in grain boundary layer, and comparatively small resistance value is shown in the grain. Therefore, the equivalent circuit of grain boundary was shown in parallel connection of resistance and condenser, and the equivalent circuit in the grain was shown at small resistance. In actual varistor, the ceramic crystal has been connected with braided. In this study, the equivalent circuit which showed in above-mentioned grain boundary and in the grain were connected braided.The decision procedure of the value of the resistance and the condenser which constitute equivalent circuit is shown in the following. At the first, values which is appropriate for the resistance and condenser were let in, and dielectric characteristic and voltage-current characteristic were calculated by the circuit simulator(PSpice). The values of resistance and condenser were decided so that the calculated dielectric characteristic and voltage-current characteristic were agree with experimental one. Less