中文摘要：

非线性电介质作为电场调控材料在高电压绝缘结构中广泛应用,理论研究探明双层非线性介质界面极化特性与双层线性介质界面极化特性的差异对双层绝缘介质工程应用的合理设计具有重要理论意义。该文以a＋b E型非线性电导的双层非线性介质为研究对象,根据回路电压定律和电流连续性原理建立了非线性双层介质界面极化微分方程。通过推导得出了介质内的电场、界面电荷密度和全电流密度的动态解析解。结果表明：每一层介质电场强度和界面电荷随时间的变化规律有指数、双曲正切和双曲余切三种形式。对于指数形式,可用一个由材料属性、结构参数和外加激励电压幅值三个因素决定的时间常数来表征极化动态特性;对于双曲正切和双曲余切极化的动态特性,需用两个由上述三个因素决定的参数来表征,分别定义为松弛时间和初始时间。总电流密度由松弛时间不同的两个吸收电流和直流稳态组成,具有多种表现形式。

英文摘要：

Nonlinear dielectrics as the electric stress control materials has been widely applied in the high voltage insulation. Theoretical proving the interface polarization characteristics of double-layered nonlinear dielectrics and the difference form the interface polarization of linear dielectric have the important theoretical significance for rational design of double-layered insulation on engineering application. In this paper, based on the nonlinear dielectrics with a＋bE type nonlinear conductivity, the differential equation about interface polarization of double-layered nonlinear dielectrics was established according to the law of circuit voltage and the principle of current continuity. The dynamic processes of the electric fields of dielectrics, the interface charge density and the polarization currents had been deduced analytically. The results show that： the electric field of each layer dielectrics and the interface charge have three kinds of relaxation model, which are the exponential model, the hyperbolic tangent model and the hyperbolic cotangent model. For the exponential model, the dynamic characteristics of the polarization can be described with a relaxation time constant governed by the material properties, the structure parameters and the amplitude of applied voltage. For the hyperbolic tangent model and the hyperbolic cotangent model, the two time factors determined by the three parameters above are used to describe the dynamic characteristics of the polarization, can be defmed as the relaxation time and the initial time separately. The total current density in polarization including two absorption currents with different relaxation times and the DC steady state current, has a variety of relaxation forms.