Design of a multi-cell, DCM PFC rectifier for a 1mm thick, 200W off-line power supply — The power sheet

For applications like LED lightning, flat screens, mobile electronics or smart surfaces converter systems with extreme aspect ratios are increasingly under investigation. Many of these systems include an AC-DC rectifier as mains interface with an input voltage of 230Vac and an output voltage of 400Vdc. In this study the design of an ultra-flat 200W PFC rectifier with a thickness of 1mm and a footprint similar to an A4 paper is presented. Due to the low profile components have to be integrated in the PCB which results in several limitations for the design of the devices. Designs for integrated inductors and transformers are discussed and the state of the art of integrated capacitors is presented. The integration of active switches is particularly important since the heat transfer has to be performed through the PCB. The paper shows that a distributed topology with soft switching is advantageous to meet the limitations of the components. This leads to distributed losses as well as to smaller inductances since the transmitted power is divided.