Week 20

Progress:

4.1.3 Efficiency

LED light bulbs use only 2-17 Watts of electricity. LED bulbs used in fixtures inside the home save electricity, remain cool and save money on replacement costs since LED bulbs last so long. Small LED flashlight bulbs will extend battery life 10 to 15 times longer than with incandescent bulbs.

LEDs do not provide ultraviolet radiation and infrared radiation. The only loss for LED is the heat loss. Industry experts expect continued improvement in light output and cost effectiveness of LED lighting. LED manufacturers expect that LED efficacy will ultimately be achieving a goal of 150 to 200 lumens per watt in the future.

LEDs also have favorable operating characteristics where the light do not require any strike time which means it is instantly come on and off without effect of lifetimes.

Light Source	Loss in Radiation (%)	Heat Loss (%)
Incandescent Lamp	81-86	5-6
Fluorescent Lamp	30-32	44
HID (mercury)	62-65	16-22
LED	0-0.2	80-88

Table 4.1: Losses for different lighting devices

Week 19

* mid sem break *

Week 18

Progress:

4.1.2 Working Topology

            LEDs use solid state semiconductor technology similar to those used in modern microprocessors. The parts of an LED are two semiconductor materials layered on substrate and powered by a low direct-current voltage; electrons released from the negative n-type layer combine with holes from the positive p-type. When electron-hole pairs are combined, a photon of light is emitted from the active layer. The semiconductor is often called a chip. The chips can be packaged in a variety of optical refracting forms to enhance the light output. The most common type has been the bullet-shape (T-1) that encases the chip in a 5mm epoxy package. Current advances in chip packaging configurations now allow for improved directional control of the light output, better thermal management and overall flexibility in design of light fixtures.

Incandescent lamp creates light by heating a thin filament to a high temperature above 2500 °C and then turns the heat to the visible light. Hence, over 90% for the energy is transfer to the invisible infrared light or heat.

To let the fluorescent lamp and the halogen lamp glow up, the energy is used to produce ultraviolet light and then the electricity is passed across the tube through the mercury vapor to make the phosphor coating glow or fluorescent. Hence, the efficiency for the fluorescent lamp will be decreased during the process of the generation of the ultraviolet light and converting the ultraviolet light to the visible light.

                The working topology for LEDs is much simpler. The simplest topology is by using a current limit resistor to control the current passing through the LEDs. Developing the DC-DC converter with current regulation can make the power circuit more reliable.

Week 17

Progress:

4.1.1 Power Consumption

            LED light bulbs use about half the wattage of fluorescent lighting, about 9 watts of power versus 18 watts of power for a CFL light bulb. The highest efficiency of LEDs that are available in the market can reach up to 100lumen/LED and 150lumen/LED with forward voltage of 3.3V and forward current of 350mA produced by CREE and Philips respectively. With these characteristics, the energy consumption for LED lamp could be reduced by at least 50 percent compared to incandescent bulb and up to 50 percent if compared with the fluorescent lamp at the same level of luminous flux.

            According to Audi, the first car manufacture that uses LED as headlights, they stated that using LED as the low beams to produce equal amount of light that can draw less current than the traditional halogen or xenon bulbs. Typically, a high power high flux LED required only 4V 700mA LVDC supply. By using the Audi A8 as the example, they just used five LEDs for the low beams, which mean the power used is just around 14W. By comparing with the traditional D2s Xenon HID which needs 35W for the low beam lamp, hence it shows that using LED can save up to 60% power than the use of HID.

            In this research, a 9W LED bulb was compared with the 18W CFL and 36W fluorescent lamp. The bulbs were mounted on the power meter that shows the power consumption by these lamps. 

Week 16

Progress:

RESULT AND ANALYSIS

4.1 Characteristics of the LED lamp

LED lamps are used for both general and special purpose lighting. Where colored light is needed, LEDs naturally emitting many colors are available without filters. This improves the energy efficiently over a white light source that generates all colors of light then discards some of the visible energy in a filter.

White-light LED lamps have longer life expectancy and higher efficiency than most other lighting. LED sources are compact, which gives flexibility in designing lighting fixtures and good control over the distribution of light with small reflectors or lenses. Because of the small size of LEDS, control of the spatial distribution of illumination is extremely flexible and the light output and spatial distribution of a LED array can be controlled with no efficiency loss.

LED lamps have no glass tubes to break and their internal parts are rigidly supported, making them resistant to vibration and impact. With proper driver electronics design, an LED lamp can be made dimmable over a wide range, there is no minimum current needed to sustain lamp operation.

Week 15

First week of the new semester.

Progress:

Bought LED lamp 18W tube type for the experiment. Cost about RM68.

Week 14

Final Year Project Proposal and Progress Report Submission

Submitted the project proposal and progress report to the supervisor! Done with FYP 1 :)