DC-Link Capacitors for Twice-Line Frequency Power Decoupling: Design-Oriented Figures-of-Merit with Empirical Application

The conventional dc-link aluminum electrolytic capacitor bank simply, efficiently, and cost-effectively decouples the instantaneous power mismatch inherent to all single-phase ac-dc power converters. However, the practical realization of the capacitor bank remains largely qualitative and dependent on the opaque performance capabilities of the capacitor technology. This work presents an exhaustive survey of commercial aluminum electrolytic capacitors and defines both quantitative and justly comparative device-level figures-of-merit (FOM). By configuring the relative voltage ripple ratio specification $\alpha$ of the dc bus, these device FOM enable the determination of minimal dclink capacitor volume, cost, and/or mass. Graphical illustration demonstrates that the set of commercially available yet viable components diminishes as specification $\alpha$ increases; the realized dc-link capacitor bank volume and cost will grow appreciably for $\alpha >$ 10% and $\alpha >$ 5%, respectively.