In addition to higher blocking voltages of wide bandgap (WBG) power modules, their volume has been targeted to be several times smaller than that of Si-based modules. This translates into higher electric stress within the module and, in turn, a higher risk for unacceptable partial discharge (PD) activities, leading to aging and degradation of both the ceramic substrate and the silicone gel. Due to the small dimensions of power module geometry, in the mm- or μm (for protrusions)-range, and due to its extremely non-uniform electric held geometry, conventional high-voltage testing electrode geometries cannot simulate real conditions. On the other hand, university-based laboratories often cannot provide manufacturing/factory conditions for testing samples and for high-quality materials. Thus, it is difficult to determine the efficacy of electric held control methods through experiments. In these situations, numerical electric held calculation is the only feasible way to evaluate different electrical insulation designs. To this end, the infinite-element method (FEM) models of the electrical insulation system used in WBG power modules are developed in COMSOL Multiphysics. It is shown that the current geometrical techniques alone cannot address the high-electric held issue within high-density WBG modules. To address this issue, for the first time, nonlinear held-dependent conductivity (FDC) materials applied to high-electric stress regions in combination with a recently introduced geometrical technique known as the protruding substrate is proposed. In this regard, the nonlinear FDC layer is characterized and various designs to reduce the electric held are evaluated. Moreover, the effect of the operating frequency on the performance of the solution mentioned above will be studied.

中文翻译：

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非线性场相关电导率层与突出衬底耦合的特性，以解决高压高密度宽带隙功率模块中的高电场问题

除了宽带隙（WBG）电源模块具有更高的阻断电压外，其体积的目标是要比基于Si的模块小几倍。这将导致模块内更高的电应力，进而导致发生不可接受的局部放电（PD）活动的更高风险，从而导致陶瓷基板和硅凝胶的老化和降解。由于功率模块的几何尺寸较小，在毫米或微米（用于突起）范围内，并且由于其极不均匀的电保持几何形状，常规的高压测试电极几何形状无法模拟实际条件。另一方面，基于大学的实验室通常无法提供用于测试样品和高质量材料的制造/工厂条件。从而，通过实验很难确定电动控制方法的功效。在这种情况下，数值电保持计算是评估不同电绝缘设计的唯一可行方法。为此，在COMSOL Multiphysics中开发了WBG电源模块中使用的电气绝缘系统的无限元方法（FEM）模型。结果表明，仅当前的几何技术无法解决高密度WBG模块内的高电保持问题。为了解决这个问题，首次提出了将非线性保持依赖性电导率（FDC）材料应用于高电应力区域，并结合最近引入的称为凸出基板的几何技术。在这方面，表征了非线性FDC层并评估了减少电保持的各种设计。此外，将研究工作频率对上述解决方案性能的影响。