Reliability-Oriented Optimization of the LC Filter in a Buck DC-DC Converter

Lifetime is an important performance factor in the reliable operation of power converters. However, the state-of-the-art LC filter design of a buck dc-dc converter is limited to the specifications of voltage and current ripples and constrains in power density and cost without reliability considerations. This paper proposes a method to optimize the design of the LC filters from a reliability perspective, besides other considerations. An enhanced model is derived to quantify the lifetime of the capacitor in the filter considering the electrothermal stress on it. Furthermore, the influence of different design aspects such as the value of capacitance, the value of inductance, and the type of the capacitor have been discussed, focusing on their impacts on the key design objectives, which are the cutoff frequency, lifetime, and volume. Based on the analysis, an optimized design is proposed among different parameter sets. A 1-k W converter prototype is applied to verify the theoretical analysis and simulation.