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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.

SUMMARYThis paper proposes a single-stage light-emitting diode (LED) driver that offers power-factor correction and digital pulse-width modulation (PWM) dimming capability for streetlight applications. The presented LED streetlight driver integrates an alternating current-direct current (AC-DC) converter with coupled inductors and a half-bridge-type LLC DC-DC resonant converter into a single-stage circuit topology. The sub-circuit of the AC-DC converter with coupled inductors is designed to be operated in discontinuous-conduction mode for achieving input-current shaping. Zero-voltage switching of two active power switches and zerocurrent switching of two output-rectifier diodes in the presented LED driver decrease the switching losses; thus, the circuit efficiency is increased. A prototype driver for powering a 144-W-rated LED streetlight module with input utility-line voltages ranging from 100 to 120 V is implemented and tested. The proposed streetlight driver features cost-effectiveness, high circuit efficiency, high power factor, low levels of inputcurrent harmonics, and a digital PWM dimming capability ranging from 20% to 100% output rated LED power, which is fulfilled by a micro-controller. Satisfying experimental results, including dimming tests, verify the feasibility of the proposed LED streetlight driver.

This paper presents a single-stage alternating current (AC)/direct current (DC) light-emitting diode (LED) tube lamp driver for energy-saving indoor lighting applications; this driver features power-factor corrections and soft switching, and also integrates a dual buck-boost converter with coupled inductors and a half-bridge series resonant converter cascaded with a bridge rectifier into a single-stage power-conversion topology. The features of the presented driver are high efficiency (>91%), satisfying power factor (PF > 0.96), low input-current total-harmonic distortion (THD < 10%), low output voltage ripple factor (<7.5%), low output current ripple factor (<8%), and zero-voltage switching (ZVS) obtained on both power switches. Operational principles are described in detail, and experimental results obtained from an 18 W-rated LED tube lamp for T8/T10 fluorescent lamp replacements with input utility-line voltages ranging from 100 V to 120 V have demonstrated the functionality of the presented driver suitable for indoor lighting applications.