Development of White LED Down Light for Indoor Lighting

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lighting resulted in a vast selection of integrated circuit devices to provide controlled ... called solid state lighting (SSL) is a new light source concept which offers ...
Development of White LED Down Light for Indoor Lighting Rajendran Sinnadurai 1, M.K.A. Ahamed Khan 2, Mohaamed Azri3, Vikneswaran4 Electrical Division, Faculty of Engineering University Selangor, Bestari Jaya Campus, Batang Bejuntai, Selangor Darul Ehsan, Malaysia 1 [email protected] , [email protected], 3mohaamed_azri@hotmail, [email protected]

Abstract— The rapid improvement in LED technology with relatively low power consumption and long lifetime, provides greater potential for general lighting applications ranging from traffic signal, signboard, message displays, instrumentation signals, cars lamp and others. The exponential growth of LED lighting resulted in a vast selection of integrated circuit devices to provide controlled white LEDs. No longer acceptable to an energy-conscious world, switched-mode LED drivers have long since replaced power-hungry linear current sources as the standard. In many instances, real-time changes in LED output intensity are required and commonly referred to as dimming control. The driver can automatically switch to Pulse Width Modulation (PWM) according to dimming input signals. The study presents the potential of LED for indoor applications and demonstrates a white LED lamp module to replace the compact fluorescent lamp (CFL) and to reduce the energy consumption. Furthermore, a prototype of LED lamp module was fabricated to demonstrate the feasibility of such a lighting device, where the LED lamp module is compared to (CFL). Several techniques are used to provide dimming control to switched-mode WLED drivers. Experimental results are presented here to verify the performance of the driver connected to white LED lamp module. From the outcome of this study, the white LED driver circuit lamp module is much more efficient and has a great potential for indoor application.

LEDs are being widely used in industrial applications, including public and commercial signage, signaling, and automotive sector. Recently developed WLEDs bring significant benefits over conventional light sources and are becoming a suitable lighting source for general illumination. WLEDs are safe, reliable, physically robust, energy efficient, cost effective and environmentally friendly. A single ‘0.1 Watt’ WLED offers enough light to allow reading in the dark [1]. There is no question that SSL powered by renewable energy is an ideal solution to the remote non-electrified communities. SSL has a huge potential to improve the quality of life of the 2 billion people currently without access to a safe, healthy and affordable light [1, 2]. Figure 1 shows, the directional nature of LED light which enables much higher fixture efficiencies than is possible with Omni-directional light sources. Figure 2 shows the variation of the beam angle of the Cree XLamp, XR-E LED to the light output pattern of the target fixture. The beam angle of the bare LED is similar enough to the target fixture that no secondary optic is required. Therefore, there is no optical loss due to secondary optics for the example luminaire [3-4].

Keywords- LED lamp module, Compact Fluorescent Lamp (CFL), and Pulse Width Modulation (PWM).

I.

INTRODUCTION

LED technology for lighting applications has the potential for wide-scale use and large energy savings. During the last hundred years, electric lighting sources have gone through a series of technology transition that from early carbon filament lamps to the ever present tungsten filament incandescent lamps to the use of plasma discharge sources such as the fluorescent lamp or pressure sodium vapour (PSV). LED lighting also called solid state lighting (SSL) is a new light source concept which offers different operating characteristics to the market. The term Solid State Lighting (SSL) is used to describe of the use of White Light Emitting Diodes (WLED) for illumination purposes. Prior to the employment of semiconductors, almost every active electronic circuit used fragile vacuum tubes [1]. Therefore the title ‘solid state’ is derived from the use of solid pieces of semiconductor material in the construction of LEDs, the source of illumination.

Figure 1: Comparison of CFL & LED Coefficient of Utilization

2 cm

1 cm

Figure 3: The mounted CREE X Lamp LEDs with variable distance.

Figure 2: Light Output vs. Angle for CFL Fixture & XLamp XR-E LED

II.

1.5 cm

CREE X LAMP MODULE DESIGN

It is important to use the minimum flux listed for the LED order code and not the typical number on the data sheet. Most LED companies sell to minimum flux ranges. By designing against this minimum number, ensuring that all luminaires made with that LED order code meet the target requirements. The luminaire will use two type of LEDs that is CREE XLamp XR-E LEDs at 5000K CCT with minimum luminous flux of 100 @ 350mA and 5mm white LEDs @ 20mA. Lumens per LED have to consider the ± percentage tolerance, from the data sheet, it shows that CREE LEDs have ± 7 % of flux + tolerance .The lumens per LED are 100ℓm × 0.93 = 93ℓm per LEDs. The number of white LED required can be computed by using the equation 1. (1)

Figure 4: The PCB board diagram for CREE X Lamp Module

CREE X Lamp module used 8 LED’s in a series circuit to minimize the currents that needs to be supplied or used by the LED module circuit. To determine the exact space between each LED’s, view angle of the LED’s is considered first. For the CREE-X Lamp XR-E LED’s (cool white); the view angle is 90º. An experiment needs to be done, where two LED’s are mounted in a PCB board with different distances of 1 cm, 1.5 cm, and 2 cm. Figure 3 shows the mounted LED’S with different ranges. Then, the PCB boards are placed in a down light reflector and installed at a height of 3 meters while readings are taken on the floor for each 5º from the centre point of two LED’s.

After completion the hardware design for the LED lamp module, the next step will be the comparison, where the brightness of the LED lamp module will be compared with the common 11 W of compact fluorescent lamp (CFL) and it will be measured using a Lux meter. Both the LED lamps module and CFL are installed at the height of 3 meter and the readings are taken on the floor surface for each five degrees from the centered point of the lamp as shown Figure 5. For both LED lamp module, the reading of lumen are been taken using the diffuser and without the diffuser. The CREE XLamp module was tested and measured the minimum current in order to achieve the same amount of lumens produced by the CFL lamp.

From the experiment, the 1 cm distance between LED had been chosen for LED Lamp module this because 1 cm distance shows the best output of performance compared to 1.5 cm distance and 2 cm distance. In a round shape module lamp, it is not possible to put all the LED’s at an exact distance of 1 cm. If this occurs, it will affect the equality of the round shape PCB board. That’s why four of the LED’s have 1 cm distance and other four are placed between 2.5 cm. Figure 4 shows the PCB board diagram of CREE X Lamp module.

The range of taking measurement is shown in the Figure 6 and the relevant formula used is shown in equation 2. Where S is the height of the lamp module installed on the ceiling and the T is the position of the Lux meter to measure the brightness. Whereas by using the equation 2, the angle θ can be determined.

will supply 5V to PNP to allow Vcc fully connected intensity in ‘HIGH’ mode. The SW4 works in the versa of SW3 when it is pressed. Whereby the intensity of WLED is decreased to 3 stage ‘MEDIUM’,’LOW’ and ‘OFF’. The Figure 7 illustrates the PIC chip interfaced with input and output of the driver circuit.

Figure 5: View of the room used for measurement.

Figure 7: WLED driver circuit

IV.

Figure 6: Position of taking measurement.

θ = tan-1 (T/S)

(2) III.

WLED DRIVER CIRCUIT

A driver circuit is powered by 24 V DC current and the voltage is regulated to 5 V to connect to PIC 16F877A. The push button 1 (SW1) is connected to the pin 1 of the PIC. Pin 1 of the PIC act as the reset button and its uses low triggering signal to reset. The push button 2 (SW2) is connected to the pin 2 of the PIC. The SW2 act as selector and it transmits an ‘active high’ signal. When SW2 is pressed once, the PIC will trigger WLED set 2 and displays ‘LAMP 2’ in the LCD display. This means the WLED set 2 is in the standby mode. This action is repeated to activate WLED set 3, WLED set 4, and WLED set 1 by pressing the SW2 twice, thrice and simultaneously. Initially, when power supply is ‘ON’ all the WLED sets are in ‘OFF’ mode. When SW3 is pressed once, the PIC will supply less than 5V to trigger the selected WLED set in ‘LOW’ mode. When the SW3 is pressed twice, the PIC will supply LOW