Reducing Energy Demand Using Solid-state Lighting. Presented by: Ray Kendall, P.E May 6, 2009

Transcription

1 Reducing Energy Demand Using Solid-state Lighting Presented by: Ray Kendall, P.E May 6, 2009

2 What is solid-state lighting? Solid-state lighting uses LEDs (light emitting diodes) LEDs use semiconductor technology to emit light when an electric current is applied Ongoing technological advances continue to enable improvements in LED performance and cost Conventional electric lighting uses mature technologies with limited long-term improvement potential Incandescent lighting Gas discharge lighting (including fluorescent)

3 Advantages of solid-state lighting Lower energy consumption due to higher efficiency than other lighting technologies Presently up to 25% efficient, compared to approximately 8% efficiency for incandescent and 21% efficiency for fluorescent lighting (1) Efficiency = (desired optical power out) (electrical power in) Improvements in technology are expected to improve future efficiency Better control of brightness, color and direction of emitted light can improve effective efficiency Longer operating life, resulting in lower maintenance cost Up to 50,000 hour operating life, compared to 1000 to 2000 hours for incandescent and 10,000 to 15,000 hours for fluorescent lamps (2) Environmentally friendly No mercury as in fluorescent lamps Inherently higher reliability and ruggedness than other lighting technologies

4 Where can solid-state lighting be used? Facility lighting Office and residential Complete facility conversions from fluorescent lighting have resulted in energy savings of 48% (3) Area lighting (parking lots, runways) Vehicle lighting Military and commercial ground vehicles Aircraft Ships Portable and hand-held lighting Sign and signal lighting

5 Applications of solid-state lighting General purpose illumination Warning and signal lights Collision avoidance Night vision (infrared)

6 Challenges for solid-state lighting implementation Higher initial cost to achieve given output brightness (price per lumen) Improvements in LED technology continue to lower costs Thermal management challenges LED output brightness and lifetime are reduced at higher temperatures Higher output spectrum efficiency results in less radiated heat Designs must provide means to remove excess heat Control electronics complexity Electronic controls are needed to provide uniform LED current with optimal efficiency

7 Solid-state lighting System design objectives Use state-of-the-art high brightness LED technology to provide the highest energy efficiency for the color of light needed Standardize LED packages to make designs easy to upgrade to improved LEDs as they become available in the future Optimize optical design to efficiently deliver required light intensity where it s needed Use lens or reflector optics if needed Use efficient LED-driver electronics with switching power conversion technology Use efficient thermal design to optimize removal of waste heat

8 Solid-state lighting design case study LED selection Design goals: Infrared (IR) source for visibility using military night vision devices High visibility for collision avoidance during lights-out missions Rugged package for simple, cost effective design implementation Selected off-the-shelf IR LED (4) Rugged, environmentally-tolerant package with good thermal dissipation Highest available optical power output Optimized optical output spectrum All optical output is in IR band of interest, maximizing efficiency Virtually no optical output in visible band Very wide optical emission angle

9 Solid-state lighting design case study LED-driver electronics - design 1 Design goals: Operate on vehicle with wide DC power input (18 36 VDC) Provide accurate current control to LEDs Minimize power losses (maximize efficiency) in electronics First design used linear current regulation Operates by dissipating power in series with LEDs to regulate LED current Simple implementation Regulates LED current Disadvantages: Inefficient: series element dissipates power as waste heat to limit LED current Requires input voltage to be higher than LED voltage

10 Solid-state lighting design case study LED-driver electronics - design 2 Improved design used switching current regulation Operates by switching and averaging power to LEDs to regulate LED current Uses integrated circuit (IC) switching power controller designed for LED-driver applications Regulates LED current Very efficient Low power loss Dissipates very little heat Can operate with a wider input voltage range Disadvantages: Requires more electronic parts Creates more electrical noise (EMI) that must be filtered

11 Solid-state lighting design case study Planned upgrades Implement designs with red, green, and white LEDs Potential applications include aircraft position and anti-collision lights Optical output and emission angles must be considered to determine LED quantity and orientation to ensure needed coverage and brightness Surface mount LEDs require careful thermal packaging design and environmental protection Implement brightness control Preferred method of brightness control uses Pulse Width Modulation (PWM) PWM adjusts perceived brightness by adjusting on-off times at a high rate PWM gives the widest dimming range with maximum efficiency Many switching power controllers include PWM capability

12 QUESTIONS?

13 References 1. Cary Eskow, Avnet LightSpeed, Light Matters 2. Wikipedia, 3. Mike Malloy and Paul Scheidt, Cree, Inc., Photonics Tech Briefs, October Opto Diode Corp., INTUITIVE Contact Information Ray Kendall, P.E. Principal Electronic Engineer x121 Tonya Maurice Director of Corporate Relations x107