Effect of Electrode Loss Morphology and Thickness on Electric Field Distribution in Self-Healing Metallized Film Capacitors

Due to the wound structure of metallized film capacitors (MFC), it is difficult to obtain the physical field distribution characteristics of the metallized electrode after self-healing breakdown in experiments. To address this, this study uses the finite element method to simulate and analyze the local electric field of MFC. Based on the morphology of the holes formed after the self-healing breakdown of the electrode, holes with similar shapes were set on the electrode in the geometric model to analyze the physical field distribution characteristics of the electrode loss area. The results show that the self-healing breakdown point of the metallized film forms a potential difference, and the field strength is significantly higher than in other areas. For regularly shaped electrode loss holes, the current density and power density are mainly concentrated at the upper/lower edges of the hole, whereas for irregularly shaped electrode loss holes, the current density and power density are mainly concentrated at the tops of the branches. Irregularly lost electrodes may subsequently develop along branch-like structures. Furthermore, the current density and power density in the electrode loss area increase as the electrode thickness decreases. Statistical analysis shows that the self-healing breakdown hole area on metallized films is mostly between $0-1 \text{mm}^{2}$, while the electrode loss area is mostly between $\mathbf{0 - 1 0 ~ m m} \mathbf{~ 2}^{\mathbf{2}}$.