Steady state characterization of current ripple in DCM interleaved power converters

Power converters that operate in Discontinuous Conduction Mode (DCM) are able to reduce switching losses, when compared to Continuous Conduction Mode (CCM) operation. This reduction is mainly due to zero current commutation and the reduction of the reverse recovery losses. However, DCM operation in high power converters is limited due to the increment in current ripple, which increases losses and volume in the differential mode (DM) filter. Multiphase DCM power converters can reduce total ripple by dividing total current among N phases and interleaving its ripples. Nevertheless, magnitude of ripple reduction as a function of the system parameters has not yet been completely determined. This information would be an important performance indicator and a useful tool for aiding in the design of key converter features, such as the number of phases and DM filter design, in order to meet total ripple, losses or electromagnetic interference specifications. In this sense, this paper proposes a methodology for the steady state characterization of input and output ripple in both buck and boost converters operating in DCM. Experimental tests on a 4-phase buck converter validate the proposal.