单轴静压条件下高压多层陶瓷电容的容值变化

Capacitance Variation of High-Voltage Multilayer Ceramic Capacitors Under Uniaxial Static Pressure

针对高压陶瓷电容在外力作用下的容值漂移,提出外力作用下陶瓷电容容值变化的主要原因为材料介电性能的变化,而不是电容间距的变化。针对高压电容的应用场景,通过唯象热力学理论模型分析介质材料在相应场强下受外力时的介电性能变化,张应力将引起材料介电常数增大,压应力将引起材料介电常数减小。进一步的单轴试验结果与有限元仿真结果表明,平行于内电极方向的压力将使介质材料产生张应力,引起材料介电常数增大,导致电容容值升高;垂直于内电极方向的压力将使介质材料产生压应力,引起材料介电常数减小,导致电容容值降低。研究结果证明了通过材料唯象热力学理论模型来分析外力作用下陶瓷电容容值漂移的正确性,为高压陶瓷电容在更加复杂环境条件下的适应性分析与设计提供指导。

In view of the capacitance drift of the high-voltage ceramic capacitor under external force,it is proposed that the main reason for the capacitance change of the ceramic capacitor under external force is the change of dielectric properties of the material,rather than the change of capacitance spacing.For the application scenarios of the high-voltage capacitor,the change of the dielectric properties of dielectric materials under external force under certain field strengths is analyzed by the theoretical model of phenomenological thermodynamics.Tensile stress increases the dielectric constant of materials,and compressive stress decreases the dielectric constant of materials.The results of further uniaxial tests and finite element simulations show that:the pressure parallel to the inner electrode produce tensile stress,leading to the increase of the dielectric constant and rising capacitance of the dielectric material;the pressure perpendicular to the inner electrode causes the dielectric material to produce compressive stress,thus reducing the dielectric constant of the material as well as the capacitance.The research results prove that the theoretical model of phenomenological thermodynamics can be used to analyze the capacitance drift of the ceramic capacitor under external force,which may provide important guidance for the adaptability analysis and design of high-voltage ceramic capacitors under more complex environmental conditions.