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

A novel interleaved Buck converter with the coupled L-LC filter (IBC-CLLC) is introduced to ensure low output ripple in a wide output range. Conventional interleaved Buck converters (IBC) 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-CLLC is guaranteed regardless of the duty cycle by using coupled winding and small passive components. For the IBC-CLLC, a multi-phase 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-CLLC, which has 90% ripple cancellation and less energy storage.