Robustness Assessment of the EMI Filter in a Three-Level Inverter

The increasing demand for high-power-density power electronics converters requires they operate in higher and higher switching frequency. The silicon carbide (SiC) device is becoming more and more popular due to its superior characteristics compared with the silicon device. However, its fast switching capability also induces severe electromagnetic interference (EMI) issues. An EMI filter with a suitable design margin is essential to conform to the EMI standards and enable a safe operating environment for other electronic devices. Excessive design margin can increase the converter's size and cost, while an insufficient margin can affect the long-term robustness of the EMI filter and may result in a system-level failure. This paper presents a robustness assessment of an EMI filter for a SiC-based three-level active neutral-point-clamped inverter taking into account component degradations. The mission profile, including multiple degradation-critical stressors, is adopted to analyze the real field application's operating scenario. The parameter shifting of film capacitors and nanocrystalline core chokes during the aging is obtained, considering the parameter variation of the models and devices. Finally, experimental results and robustness analysis of the studied filter are presented and used as feedback to determine a suitable filter design margin for doing a robust design.