Phase-shift controlled multi-output series resonant LED driver with independent current control

Abstract

Automotive LED headlamp systems require high-efficiency multi-output drivers capable of independently regulating high-beam and low-beam currents under wide input-voltage variations. Conventional single-inductor multiple-output and multi-stage resonant LED drivers often suffer from cross-regulation, hard-switching losses, increased component count, and limited independent dimming capability, thereby reducing overall efficiency and system reliability in electric vehicle (EV) environments. To address these limitations, this paper proposes a non-isolated dual-output full-bridge series-loaded resonant converter (FBSLRC) employing a reduced six-switch configuration for automotive lighting applications. The proposed topology enables independent current regulation of two LED loads through phase-shift modulation (PSM) without the need for additional magnetic components or auxiliary balancing circuitry. Owing to the lagging resonant tank current characteristics, wide-range zero-voltage switching (ZVS) is achieved for all primary switches, thereby minimizing switching losses and device stress. Steady-state analysis, soft-switching conditions, and power loss characteristics of the proposed converter are analytically derived. A 54-W experimental prototype is developed to validate the feasibility of the topology under dynamic input and load conditions. Experimental results demonstrate precise independent current tracking, improved dimming performance, reduced switch count, and a peak efficiency of 93.1 %, indicating the suitability of the proposed converter for compact and energy-efficient EV lighting systems.