Maicol F. de Melo

High-power-factor street lighting system to supply LEDs without energy consumption during the peak load time

This paper presents two topologies for street lighting system with high power factor (HPF) based on light emitting diodes (LEDs). The main characteristic of this work is to develop a circuit that supplies the LEDs by an alternative source (battery) during the peak load time (PLT). The peak load time is considered as the period in which the demand for power from the mains is maximum, and therefore the generation of the power plants and transmission lines must be able to meet this demand. In this work, a bidirectional flyback converter with two outputs is used to supply the LEDs from the mains and also to charge the battery. One topology uses an auxiliary winding to supply the LEDs from the battery. The other uses the same primary winding to supply the LEDs from the battery or from the mains. The flyback converter is composed of a single core for both topologies. Besides, a buck converter is used as Power Factor Correction (PFC) stage. The integration of these converters is performed in order to reduce the number of components and consequently, the volume and cost of the circuit. The converters were implemented and experimental results are shown in order to validate the design methodology, and to compare both topologies.

Bidirectional Grid-Tie Flyback Converter Applied to Distributed Power Generation and Street Lighting Integrated System

This paper presents a multifunctional bidirectional converter applied to street lighting and photovoltaic (PV) microgeneration systems. The proposed converter works as an electronic driver supplying a street lighting luminaire based on light emitting diodes (LEDs) at night, from ac single-phase mains with high power factor and reduced harmonic distortion. During daylight hours, the converter injects the produced energy by a PV panel to the grid, working as a grid-tie inverter. The proposed topology is based on the integration of two flyback converters, one for each half-cycle of the grid voltage, avoiding the usual diode bridge rectifier for LED lamps drives, thus providing a bidirectional power flow. A prototype of the proposed electronic stage has been designed, built, and tested, in order to validate the system. Finally, experimental results are presented. In rectifier mode, an efficiency of 86% was achieved, whereas an efficiency of 89% was obtained in inverter mode.

Street lighting system based on integrated buck-flyback converter to supply LEDs without energy consumption during the peak load time

This paper presents a street lighting system with high power factor based on light emitting diodes (LEDs). The use of LEDs allows energy saving, high luminous efficacy and high useful life to the proposed system. However, the main characteristic of this work is to develop a circuit that supplies the LEDs by an alternative source (battery) during the peak load time. The peak load time is considered as the period in which the demand for power from the mains is maximum, and therefore the generation of the power plants and transmission lines must be able to meet this demand. In this work, a bidirectional flyback converter with two outputs is used to supply the LEDs by mains and still charge the battery. To supply the LEDs by battery, the same converter is used. Besides, a buck converter is used as Power Factor Correction stage. The integration of these converters is performed in order to reduce the number of components and consequently, the volume and cost of the circuit. The complete circuit was implemented and experimental results are shown in order to validate the design methodology.

Bidirectional Flyback converter connected to the grid and applied to a distributed microgeneration and street lighting system

This paper presents a multifunctional bidirectional converter. The proposed converter works as a grid-tied inverter, injecting power coming from a PV subsystem to the AC mains in the daytime hours, but also supplies energy to a LED-based street lighting system at night. The topology is based on the integration of two Flyback converters thus allowing the desired bidirectional energy flux. Each Flyback has a different polarity, making energy flowing in both directions possible. A prototype was built in order to prove the feasibility of the proposed topology and experimental results are shown below. In rectifier mode, an efficiency of 86% was achieved while a 88.9% in inverter mode.

Hybrid system of distributed power generation and street lighting based on LEDs: Grid connection

This work proposes an electronic driver for street lighting systems integrated to renewable energy. In recent lighting applications, the use of micro renewable generators in lighting points makes necessary the use of special electronics to handle the bidirectional energy flow in the ballast. The proposed input stage is a topology based on the integration of two flyback converters with different polarities, in order to avoid the use of the input diode bridge rectifying stage, allowing the converter operate with bidirectional energy flow. Thus, this system has two distinct operation modes. The rectifier mode is responsible to supply a street lighting system based on LEDs from de utility grid during the night, and the inverter mode must deliver energy into the power grid provided by a solar panel during the day. This work focuses in the inverter stage, which comprises a boost converter, responsible for the Maximum Power Point Tracking (MPPT), and a flyback inverter. The present topology is an alternative to standard bidirectional input stages, as it can be used to deliver energy into the power grid, due the avoidance of the input diode bridge.

Corrections to “LED Driver Based on Input Current Shaper Without Electrolytic Capacitor”

In the above titled paper (DOI: 10.1109/TIE.2017.2652365), Figure 16 is incorrectly inserted two times, one in Figure 15 and another in Figure 16. The correct Figure 15 is the one uploaded in this letter.

Design space for LED systems considering photoelectrothermal aspects

The knowledge of the interrelationships among the photometrical, electrical and thermal (photoelectrothermal) parameters is extremely important to design lighting systems based on light-emitting diodes (LEDs). This paper proposes a novel methodology based on the luminous flux estimation of LEDs considering a photoelectrothermal design space. The main contribution of the proposed methodology is the use of only LED datasheet information, which avoids experimental tests to obtain the LED data. This methodology provides 3D and 2D space designs, which helps to identify the luminous efficacy, heatsink thermal resistance and junction temperature of the system without requiring experimental tests or simulations with high computational cost. Thus, the designer can define the minimum system requirements and design the system with emphasis in the desired features. The proposed design methodology has been verified experimentally using three different scenarios, presenting satisfactory results.

Fast dynamics current control of DCM flyback as PFC front converter for lighting applications

Most common Power Factor Correction (PFC) solutions for low power applications, when galvanic isolation is required, involve the use of discontinuous conduction mode (DCM) dc to dc topologies. The control is generally based on fixed duty ratio operation, or at best, on a classic low-bandwidth duty-ratio control. Considering public lighting systems, in which a high number of low power converters are connected into a single power line, the transient response of the full system is critical for keeping the power line balanced without affecting the rest of the grid. Furthermore, at each ballast, the second stage needs also to operate independently upon such variations. This paper proposes a simple high bandwidth control technique for a PFC Flyback converter acting as front converter of a LED lighting system, that also reduces the harmonic content of the AC line current. The control scheme is discussed and implemented, and experimental results are presented.