A Dummy-Variable Model for Humidity-Influenced DC Film Capacitors Lifetime Estimation

Film capacitors are used in power electronic converters due to their higher reliability compared to aluminum electrolytic capacitors. Humidity is one of the critical factors affecting the aging of film capacitors. However, the existing methodologies for the lifetime estimation of film capacitors rarely consider humidity. Besides, sometimes it is hard to obtain a large amount of data in the accelerated aging test of the device. To solve these problems, this article proposes a lifetime estimation methodology that requires fewer data and testing time. In the proposed methodology, humidity dummy variables are introduced into the degradation model based on the multivariate linear regression (MLR) algorithm. The impact of introduced dummy variables with different structures on the degradation model is studied and the effect of the proposed lifetime estimation method is verified. The results show that the proposed scheme achieves a comparable performance and can be valid in reality.