CCM Operation of a Single-Stage Boost-Flyback Converter with Active-Clamp for LED Driver Applications

Due to the ever-expanding use of light emitting diodes (LED) lamps and the necessity of constant current to operate properly, a drive circuit is required for these types of lamps. Also, power factor correction (PFC) to eliminate harmonics, is required and must be included in these types of drivers based on the existing standards. Soft switching can effectively reduce the switching losses and electromagnetic noise. Consequently, high switching frequency operation is possible which reduces the converter weight and size, effectively and high power density is achieved. In this paper, continuous conduction mode (CCM) operation of a single-stage boost-flyback converter with active-clamp for LED driver applications is introduced. Its CCM operation leads to low input current ripple which reduces the input filter volume effectively. Also, low voltage and current stresses on the components are obtained. As a result, the converter can be used for high power applications compared with previously proposed discontinuous conduction mode (DCM) operation. Theory, simulation as well as practical results are presented below.