Analysis and design of the integrated double buck-boost converter operating in full DCM for LED lighting applications

In this paper the integrated double buck-boost (IDBB) converter operating with both stages in discontinuous conduction mode (DCM) is analyzed. The converter is intended to supply high voltage LED lamps from the mains, typically in street lighting applications. A high input power factor is assured by operating the first stage in DCM, thus verifying harmonic injection standards. In this case, the second stage is also operated in DCM as an option to the continuous conduction mode (CCM) that has been studied in a previous paper. The behavior of the converter with both stages in DCM is compared with that of the converter operation with the second stage in CCM. It is demonstrated that with both converters operating in DCM the filter capacitances are reduced even further, allowing for the use of long-life non-electrolytic capacitors. A laboratory prototype to supply a 70W LED lamp with nominal voltage of 200V from a 230V/50Hz mains maintaining the same design conditions as in the previous work is presented. A comparison of both prototypes is also carried out.