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Recently, a new type of lighting source, deep ultraviolet light-emitting diode (LED), has appeared in the markets of space purification and surface sterilization. In this paper, a new type of electronic lighting driver for supplying a deep-ultraviolet LED sterilization lamp is proposed and developed. The main circuit combines a buck converter and a flyback converter into a single-stage single-switch buck-flyback AC-DC power converter with power factor correction. In addition, the proposed electronic lighting driver leverages a wide bandgap SiC Schottky diode as the output diode to lower the power diode losses and recycles the energy stored in the leakage inductance of the transformer in order to improve the circuit efficiency. The magnetizing inductor inside the presented AC-DC power converter is designed to operate in discontinuous conduction mode (DCM), which naturally enables power factor correction (PFC). A single-stage prototype driver with a power rating of 3.6 W (90 V/40 mA) was developed and implemented for providing a deep ultraviolet LED disinfection and sterilization lamp. Experimental results show that the measured power factor (PF) is greater than 0.9 and the measured total harmonic distortion (THD) of the input current is less than 18% at an input utility voltage of 110 V. Furthermore, the measured output voltage ripple factor is less than 1% and the output current ripple factor is less than 4%. In addition, the proposed single-stage electronic lighting driver for supplying a deep ultraviolet LED disinfection and sterilization lamp achieves high circuit efficiency (greater than 90%), low circuit component count, and low circuit cost. [ABSTRACT FROM AUTHOR]

A novel ac/dc LED driver with power factor correction and soft-switching functions is proposed. The circuit topology mainly consists of two modified single-ended primary inductance converters (SEPIC) with interleaved operation. The first half stage of SEPIC operates like a boost converter and the second half stage operates like a buck–boost converter. Each boost converter is designed to operate in discontinuous current mode (DCM) to function as a power factor corrector (PFC). The two buck–boost converters that share a commonly coupled inductor are designed to operate at near boundary conduction mode (BCM). Without using any active clamping circuit, auxiliary switch or snubber circuit, the active switches can achieve zero-voltage switching on, and all diodes achieve zero-current switching off. First, operation modes in steady state are analyzed, and the mathematical equations for design component parameters are derived. Finally, a prototype circuit of 180 W rated power was built and tested. Experimental results show satisfactory performance of the proposed circuit. [ABSTRACT FROM AUTHOR]

This paper presents a single-stage driver with soft-switching and interleaved power-factor correction (PFC) features suitable for light-emitting diode (LED) energy-saving streetlight applications. The proposed LED streetlight driver integrates an interleaved buck-boost PFC converter with coupled inductors and a half-bridge LLC resonant converter into a single-stage power-conversion circuit with reduced voltage stress on the DC-linked capacitor and power switches, and it is suitable for operating at high utility-line voltages. Furthermore, coupled inductors in the interleaved buck-boost PFC converter are operated in discontinuous-conduction mode (DCM) for accomplishing PFC, and the half-bridge LLC resonant converter features zero-voltage switching (ZVS) to reduce switching losses of power switches, and zero-current switching (ZCS) to decrease conduction losses of power diodes. Operational modes and design considerations for the proposed LED streetlight driver are introduced. Finally, a 144 W (36V/4A)-rated LED prototype driver is successfully developed and implemented for supplying a streetlight module and operating with a utility-line input voltage of 220 V. High power factor, low output-voltage ripple factor, low output-current ripple factor, and high efficiency are achieved in the proposed LED streetlight driver. [ABSTRACT FROM AUTHOR]