Double Bus Provider Asymmetrical Half Bridge Converter With a Resonant DCX-Derived Auxiliary Circuit to Supply a LED-Based VLC Postregulator

The wide and settled use of Light-Emitting Diodes (LEDs) in lighting has made Visible Light Communication (VLC) an interesting option. Given the way LEDs are driven in VLC, the Two-Input Buck converter fits perfectly as a post regulator for VLC-LED lamps. Its main drawback is that it needs two input voltages with specific requirements tied to the VLC feature. One needs to be regulated according to the LEDs knee voltage thermal drift, while the other needs to be constant. With the objectives of avoiding complex circuits with cross regulation and using two converters performing the bus provider, the present work proposes a converter with two outputs that meet those voltage requirements. This converter is the integration of an Asymmetrical Half Bridge converter and a resonant unregulated Half Bridge converter. This integration is achieved thanks to the primary side similarity of both converters and the integration of both transformers, achieving a solution with fewer components. In addition, one output can be fully regulated by a standard control variable while the other remains naturally constant and independent. This greatly simplifies the control stage, avoiding cross regulation while fully complying with the application requirements. This work presents the circuit concept and how it relates to the intended application. The principle of operation will be explained and used to define the operational region where the topology meets the application requirements. To validate the proposed topology, a 45-W prototype is built and tested, archiving the output voltage requirements and an overall efficiency near 94%.