Abstract
In this paper, the optimization of the power and control stages of a previously proposed topology for an off-line LED electronic driver is presented. The full system avoids the use of electrolytic capacitors at the D C link, therefore increasing the lifespan and reliability of the driver. As a consequence of having a relatively small capacitance, the D C link operates with a large Low-Frequency ( L F ) voltage ripple. This work presents a design optimization for the power and control stages of a current-fed bidirectional buck converter, operating as the LED current control stage. As this block processes only the A C power arising from the L F voltage ripple, it can increase the system efficiency against the typical two-stage solution. In the original proposal, the main drawback was the high inductor losses due to the resulting large inductor currents and large inductance value. The proposed optimization ensures an enhanced design of the inductor while keeping a constant current through the LEDs. A new optimization methodology is proposed and the theoretical results have been validated in a built prototype for a 40 W LED lamp.
Highlights
LED lighting systems are gaining more importance as they provide a tool for a more rational use of electrical energy on household, public lighting systems, transportation, commercial applications, etc. [1,2]
The built LED driver is intended for a lamp with the specifications given in Section 6 and DC voltage source HP6812A, in order to control the average and ripple values of the DC link voltage
LEDs has been deeply analyzed, and a new design methodology for optimizing the converter size has been proposed. This methodology has been validated both by simulations and experimentally. The advantages of this improved methodology are mainly two: first, the optimization of the inductor design which implies that the resulting inductor value can be built in an ETD34 core, and secondly, the dynamics of the controller are improved allowing for comparably faster performance which implies that the proposed series scheme is suitable for LF Pulse Width Modulation (PW M) dimming control
Summary
LED lighting systems are gaining more importance as they provide a tool for a more rational use of electrical energy on household, public lighting systems, transportation, commercial applications, etc. [1,2]. LED lighting systems are gaining more importance as they provide a tool for a more rational use of electrical energy on household, public lighting systems, transportation, commercial applications, etc. One of the major power electronic development fields is related to the enhancement of efficient high-performance electronic lighting systems for LED lamps. Simple, passive, or cost-effective solutions can be used to deal with the DC behavior of the LED lamp [3]. [4] presents a linear regulator integrated with an LED lamp that provides an optimal solution in terms of power density for single LED applications. Linear regulators are not recommended when the application requires a high number of LEDs (as the overall efficiency of the system turns more critical) or when high-performance control schemes are needed.
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