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This paper describes a Very High Frequency (VHF) converter made with three Class-E inverters and a single Class-DE rectifier. The converter is designed for the US mains (120 V, 60 Hz) and can deliver 9 W to a 60 V LED. The converter has a switching frequency of 37 MHz and achieves an efficiency of 89.4%. With VHF converters the power density can be improved and the converter described in this paper...
A new switching mode technique based on input current calculation has been proposed for accurate control of input current in single stage AC-DC converter. The input current shape is precisely managed to a desired pattern by calculating averaged switching current without a compensation method and a fine tuning sequence. This switching mode scheme provides sinusoidal input current with excellent power...
LED lighting is becoming more attractive and popular due to its high efficiency, long lifetime, instant brightness and ability to dim. But LEDs are powered by DC, which requires a rectifier to allow it to run off the AC utility grid. These converters must have small form factors and operate in high ambient temperatures due to the close proximity of the LED light. Gallium Nitride (GaN) based switched...
Light-Emitting Diodes (LEDs) has become a very promising alternative lighting source with the advantages of longer lifetime and higher efficiency than traditional ones. The lifetime prediction of LEDs is important to guide the LED system designers to fulfill the design specifications and to benchmark the cost-competitiveness of different lighting technologies. The existing lifetime data released by...
This paper presents a single phase, two-stage electrolytic-free offline LED driver that utilizes a hybrid film-ceramic stacked switched capacitor (SSC) energy buffer (EB) in place of limited-life electrolytic capacitors for twice-line-frequency energy buffering. The proposed LED driver comprises a front-end power factor correction (PFC) stage, followed by an isolated dc-dc conversion stage, with an...
It is well-known that the power transfer efficiency and the power transmitted over a wireless inductive link are significantly affected by the strength of the magnetic coupling and the spatial displacement between the transmitting and receiving coils. Misalignment between the transmitting and receiving coils is practically unavoidable. In order to control and regulate the receiver-side power, on-the-spot...
This paper presents Thick Printed Copper (TPC) as substrate technology for High Brightness LEDs, which features a strongly improved reliability combined with a significant cost advantage over incumbent technologies for High Brightness LED substrates. The advantages of TPC over Direct Bonded Copper (DBC) and Direct Plated Copper (DPC) substrates will be demonstrated by thermal shock test results and...
Control scheme for TRIAC dimming high PF single-stage LED driver with adaptive bleeder circuit and nonlinear current reference is studied in this paper. The target of the control scheme is to achieve high efficiency and high compatibility to different kinds of TRIAC dimmers. The control scheme includes adaptive bleeder circuit control, operation modes control, non-linear current reference and output...
This paper introduces a high power density step-up converter for LED applications, based on a hybrid serial-output (HSO) architecture [1], which is suitable for on-chip implementation. In this system, the output voltage is formed by stacking the output of a switched-capacitor (SC) converter on top of a boost converter output. The high power density SC converter processes around a half of the power...
Conventional AC/DC LED drivers require a large energy storage capacitor at the output to provide a constant current to the LEDs. In order to minimize the size and cost of the driver circuit, electrolytic capacitors are conventionally used due to its high energy density and low cost. However, electrolytic capacitors are sensitive to operating temperature and have much shorter lifetime than the LED...
This work presents a driver for High-Brightness Light-Emitting Diodes (HB-LED) in three-phase grids, which complies with IEC 1000-3-2 Class C requirements, achieves high Power Factor (PF), low Total Harmonic Distortion (THD), as well as, the capability to achieve full dimming while disposing of the bulk capacitor and having galvanic isolation. The HB-LED driver is based on the use of six four-port...
This paper presents a novel LED drive system based on matrix rectifier. Matrix rectifier is applied to the LED drive system for the first time as to our knowledge. The novel LED drive system is composed of two stages. The first stage is the matrix rectifier, and the second stage is the multi-port two-transistor forward converters (TTFC) that share a leg. The space vector modulation strategy of matrix...
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