A Nonisolated Wide Input Series Resonant Converter for Automotive LED Lighting System

In this article, a reconfigurable nonisolated buck-boost (BB) integrated full-bridge series resonant converter (FBSRC) based light emitting diode (LED) driver is proposed for wide input voltage automotive lighting applications. The proposed LED driver is derived by the integration of BB operation with FBSRC. It can be reconfigured into three different resonant converter topologies such as BB integrated FBSRC, BB integrated half-bridge series resonant converter (BB-HBSRC), and conventional HBSRC and, hence, produces three levels of voltage gains. By transformation from one topology to other based on the input voltage range and with asymmetrical pulsewidth modulation control, it can operate for wide input voltage range while maintaining the soft switching. The main advantages of the proposed configuration are smooth transformation into three different topologies without any additional switching devices, no topological transitions within a switching cycle in steady state, use of simple proportional-integral controller, soft switching, and wider voltage gain with buck/boost operation. In addition, dimming control is also achieved using pulsewidth modulation technique. Detailed theoretical analysis of the proposed converter is presented. To verify the analysis and performance, a prototype of 22.7 W, 22.5 V LED driver is designed, simulated, and tested for a wide input voltage range of 18 to 120 V.