A novel design method for half-bridge converters with high-order actively-damped filters

This paper presents a novel structured design method for actively-damped, lossless, LC-ladder filters of general order. The method builds on the theory of ladder network synthesis and on a control algorithm actively emulating the termination of a ladder network. Given a desired reference transfer function, a normalized ladder network is synthesized and scaled to meet the physical requirements. As such, it simultaneously tackles the design and sizing of the filter, and the active damping of filter resonances. The associated digital-control architecture is also elaborated. The method is applied to designing a 3
^rd
-order LCL filter, of which the experimental results show properly damped responses. Moreover, the design of a 5
^th
-order LCLCL filter is introduced and the result is promising for the applications requiring high bandwidth and/or high attenuation.