Efficiency analysis on DCM interleaved boost power converters

One of the main challenges in power converters for photovoltaic (PV) energy conversion is their efficiency. In this sense, discontinuous conduction mode (DCM) is able to improve efficiency, mainly due to zero current commutation and the reduction of the reverse recovery losses. Furthermore, interleaved DCM power converters are able to extend this operating mode to higher power applications, due to the reduction on the differential mode (DM) filter requirements, by dividing total current among N phases and interleaving its ripples. One additional requirement is that high efficiency must be maintained over the entire operating range. For this purpose, the number of active phases can be dynamically adjusted as a function of load power. Even though this technique, known as phase shedding, has been used in continuous conductiond mode (CCM) and boundary conduction mode (BCM), it has not yet been implemented for DCM. In this paper, the criterion for establishing the efficiency boundaries as a function of the number of phases in DCM is presented. In this criterion, the losses in semiconductor devices and passive components as a function of N are considered. Furthermore losses in the input and output DM filters are taken into account, considering the total ripple reduction achieved with the interleaved operation.