A Coupled L-LC Filter for Interleaved Buck Converter Ripple Cancellation

A novel interleaved buck converter with the coupled
L-LC
filter (IBC-C
LLC
) is introduced to ensure low output ripple in a wide output range. Conventional interleaved buck converters have been extensively used due to their high-current output and quick response. However, its output ripple in various duty cycles is not acceptable in many modern applications. The low ripple of IBC-C
LLC
is guaranteed regardless of the duty cycle by using coupled winding and small passive components. For the IBC-C
LLC
, a multiphase decoupled equivalent circuit is derived with dual aims: to establish a frequency domain model for transient response analysis, and to deduce a single-phase ripple equivalent circuit for ripple calculation and parameters optimization. A laboratory prototype is developed to validate the effectiveness of IBC-C
LLC
, which has 90% ripple cancellation and less energy storage.