Series input modular architecture for driving multiple LEDs

This paper introduces a modular power converter architecture based on series input connected converter cells with independent outputs that each drive a small series string of LEDs. The approach provides the benefits of operating from a high bus voltage while using low voltage cells that independently regulate LED currents for improved light uniformity and LED failure mitigation. Stability of the series converter string and independent regulation of the floating LED output currents are achieved using a two-loop controller that relies on chain control communications between cells to share system information. Experimental verification of input bus voltage sharing and independent cell current regulation is provided using a prototype of the proposed system with four series buck-boost converter cells, where each cell drives four 700 mA LEDs.