Design and Benchmark of Capacitive DC Links for the Hold-up Time Application

Capacitive DC links are widely used in power electronic systems to balance the instantaneous power difference between the input source and output load. The conventional capacitive DC link, which uses passive capacitors, encounters challenges in lifetime and power density. Recently, novel active DC links implemented by power electronic circuits are proposed for low voltage ripple requirement application, which can achieve lower energy storage, high power density and longer lifetime. However, the existing design of active DC links can not be extended to the applications with hold-up time requirement directly, due to it does not take the energy storage into account. This paper proposes the design methods for two typical active DC links with the energy storage constraint, so as to achieve specified hold-up time requirement. Moreover, benchmarking between passive and typical active DC links are investigated in terms of cost and volume. The results serve as guideline to select and design capacitive DC links to achieve specified hold-up time requirement.