在直流偏置电压下的材料介电常数测试系统设计

摘要

集成型电磁干扰滤波器是抑制电力电子传导电磁干扰的一种有效手段，其结构中多采用高介电常数材料。为预测高介电常数材料在电力电子运行环境下的性能，需要完成其在该环境下的测试。因此提出了一种可用于阻抗测试仪器的直流偏置下电容测试电路，可以测量高直流偏置电压下的电容阻抗。根据电容自放电时间常数的大小，分成两种工作模式，可以完成材料在电力电子应用环境下的介电常数性能测试。以此测试电路为工具对 CaCu3Ti4O12陶瓷材料的介电常数特性进行了测试。通过建立电阻、电感和电容的高频模型，利用解析法提取其寄生参数，并将其用于测试数据的处理。通过一个实例测试，对测试系统的有效性进行了验证。%Integrated EMI filters, in which the high permittivity material is used, play an important role in restraining conducted EMI of the power electronic system. The characteristics of the high permittivity material, under the operating voltage in circuits, are very important. In this paper, a system is proposed to measure the impedance of a capacitor in the high DC voltage condition. According to the different discharge time constants of capacitors, the system is divided into two modes. In addition, the CaCu3Ti4O12 ceramic has been measured by the system, as well as the high-frequency models of resistors, conductors and capacitors are established. The parasitic parameters of the models are extracted by an analytical approach, which are used on the data processing. A test verifies the measure system.