Development of a Smart LED Lighting System

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Development of a Smart LED Lighting System: Rapid Prototyping Scenario
Giovanni Calisse, Gionata Cimini, Luigi Colombo, Alessandro Freddi, Gianluca Ippoliti, Andrea Monteriu and Matteo Pirro
Dipartimento di Ingegneria dell'Informazione, Universita Politecnica delle Marche Via Brecce Bianche 12, 60131, Ancona, Italy Email: { g.cimini.aJreddi.gianluca.ippoliti.a.monteriu.m.pirro } @univpm.it
equipment to draw a sinusoidal current and thus is a required feature for a good quality power converter system which needs to meet stringent specifications on efficiency, harmonic distortion and voltage regulation. Several performance analysis of DC-DC and AC-DC converters have been reported in [1]­ [3]. In particular, for the AC-DC stage considered in this paper, an interesting feedback control methodology has been developed with the aim to modify the closed loop energy dissipation and potential energy properties of nonlinear passive systems [4] and references therein. Passive systems are a class of dynamical systems in which the energy exchanged with the environment plays a central role. In passive systems the rate at which the energy flows into the system is not less than the increase in storage. The purpose of this approach, known as Passivity Based Controller (PBC) design [4] is to render the closed-loop system passive with respect to a desired storage function. Passivity-based method has clear advantages in terms of considering the system physical structure in the control design procedure [4]-[8]. A very important challenge in complex systems (such as the developed lighting system) is to ensure that services are functional and available despite faults. Fault diagnosis and prognosis capabilities, however, are rarely integrated in lighting control systems, even if they are necessary to ensure the proper functioning and reliability of the system [9]. A Fault Diagnosis and Prognosis (FDP) supervision module has been developed to detect and isolate faults on the LED lamp. Hardware redundancy, signal-based and model-based approaches [10], [II] all concur to increase the reliability of the lighting system, improve performances and to reduce its maintenance costs. Finally a fault tolerant control law ensures visual comfort in case of LED faults by means of current feedback. Therefore, a LED lighting system can be quite complex and involves ditlerent functional stages: the more complex are sys­ tems and the more advanced are the control techniques, since more knowledge is required, especially as regards hardware and software design theory and information about the handling development tools. Moreover the control algorithm needs more time and cost to be developed, even because the probabil­ ity of occurring errors increases. Beside these complexities, developing physical prototypes can be very expensive. Two common approaches to tackle these problems are simulation
Abstract-The goal of this work is the development of a LED driver system for industrial and domestic use , which integrates an AC-DC PFC interleaved boost converter, a resonant DC-DC LLC high efficiency converter, a low-level LED control and a fault detection component. Efficient energy use and harmonics reduction are the main goals to be achieved. AC-DC power stage has been designed to operate in interleaved mode and several control techniques have been tested to increase performances; a linear control has been implemented for the resonant converter; low-level LED control includes a fault detection capabilities. The approaches of simulation and rapid prototyping have been deeply exploited in this work to make faster design and test phases for each individual functional block and to minimize errors. The behaviour of the LED control component has been also compared with a real prototype.
I.
INTRODUCTION
In recent years, high power LED equipment has been applied more and more widely in lighting, viewing and other applications due to the developing of the LED industry. At the same time, requirements of the LED driver are becoming more demanding: small volume, high efficiency, stability and high Power Factor (PF). LED driver is an integral part of the LED application systems: its technical performance alfects the use and development of the LED devices directly. On the other hand, efficient energy use is the goal of etlorts to reduce the required amount of energy to provide products and services. Moreover, strict harmonic reduction requirements have been imposed by regulatory agencies (IEC 1000-3-2 and EN 610003-2). LED technology closely affects and impacts both of these aspects. In fact, in high power applications, the PFC LED driver uses a two-stage topology: the first stage is an AC-DC PFC converter such as a buck, a boost or a buck-boost and improves the power quality; while the second stage is usually a quasi half bridge series resonant converter and provides necessary constant voltage for LED load using a diode bridge rectifier and a bulk capacitor after the high frequency transformer. Because of the necessity of high power density, the convert­ ers used are Switched-Mode Power Supplies (SMPS) always operating at high switching frequencies with high efficiency and smaller passive components' size; the resonant converters are attractive due to their good efficiency, low harmonics, EMI and switching noise at very high switching frequency. Indeed, the implementation of a PFC technique forces the