Sustainable Lighting Technology:
From Devices to Systems
《可持續》照明技術 : 從 模 塊 到 系 統
Project number: T22-715/12-N
Project period: September 2012 – August 2017
Collaborating institutions: The University of Hong Kong and the Hong Kong Polytechnic University
| Project Coordinator (PC) | HUI Shu Yuen Ron Chair Professor |
Dept. Electrical & Electronic Engineering, HKU |
| Co-Principal Investigator(s) | CHOI Hoi Wai Anthony Associate Professor |
Dept. Electrical & Electronic Engineering, HKU |
| TSE Chi Kong Michael Chair Professor |
Dept. of Electronic & Information Engineering, PolyU | |
| WAFFENSCHMIDT Eberhard Chair Professor |
Cologne University of Applied Sciences, Germany (formerly with Philips Solid State Lighting - until 2011) |
|
| Co-Investigator(s) | LEE Chi Kwan Assistant Professor |
Dept. Electrical & Electronic Engineering, HKU |
| TAN Siew Chong Associate Professor |
Dept. Electrical & Electronic Engineering, HKU | |
| WONG Siu Chung Associate Professor |
Dept. of Electronic & Information Engineering, PolyU | |
| LAI Yuk-Ming Associate Professor |
Dept. of Electronic & Information Engineering, PolyU |
Introduction
Passive LED Installation in Heshan City (2015), China
Lighting systems consume about 20% of global electrical power and their control circuits have been identified as one of the major sources of electronic waste. With the recent revolution of LED technology, new LED devices with much improved luminous efficiency and lifetime are now commercially available. They are also expected to replace energy-inefficient incandescent lamps and mercury-based fluorescent lamps in the future. LED technology actually involves several technical aspects, including (i) LED Devices, (ii) LED Drivers, (iii) Power Control and (iv) Thermal Design of Lighting Fixtures. While LED technology has successfully found applications in decorative, signaling, display and signage applications, it is still not widespread in public lighting applications. With continuous progress in LED “devices”, recent creditable research highlights that the actual bottlenecks of LED technology in public lighting lie in the “system” aspects. The lifetime of an LED “system”, for example, is limited not by the lifetime of the LED “devices” (typically 80,000 hours), but by the that of the electrolytic capacitors (typically 8,000 hours) in conventional LED drivers. The bottleneck of the “System” aspects of LED technology has been severe enough that led to a special industrial session by LED manufacturers in the IEEE Applied Power Electronics Conference to address the systems reliability issues in February 2012.
This proposal is related to the “sustainability” of lighting systems (used in buildings and cities’ large-scale infrastructures such as road lighting) that consume 20% of electricity globally. Sustainable Lighting Technology proposed here deviates from the traditional Energy-Star concept which focuses only on energy saving. It stresses a new principle that includes:
- energy saving,
- long product lifetime and
- recyclability of product materials.
It highlights the important point that “energy-saving technology is not necessarily environmentally-friendly if it generates lots of harmful electronic waste within a short product lifetime”.
This project involved a new investigation into a new General LED System Theory for “multiple non-identical” Solid-State LED devices. By linking LED “device” theory to “system” theory, novel LED systems with not only high energy efficiency and luminous efficacy, but also lifetime exceeding 10 years and over 80% product materials recyclable will be studied and developed. The project focused on an “integrated system approach” that covers (i) new white LED device structures and manufacturing processes, (ii) novel passive and active LED drivers and control techniques including both power and color control, (iii) current balancing techniques, (iv) novel device geometrically-staggered distribution and thermal designs, so that future LED systems can meet the 3 sustainability criteria.
This project has led to both theoretical & practical breakthroughs. The outcomes of this proposal included (1) a novel Generalized LED System Theory for “multiple non-identical” LED devices, (2) new LED device structure with improved thermal management, (3) the generalization and classification of LED driver topologies with long lifetime, (4) a new design methodology & tool for optimization of a new generation of highly efficient and sustainable lighting systems, and (5) practical realization of the new “Sustainable Lighting” principle that can replace traditional “Energy-Star” concept with the aim of drastically reducing electronic waste worldwide. Besides over 30 top-tier journal papers, we have transferred several patented and patent-pending technologies to industry, which has already installed the sustainable lighting products in China and Hong Kong. The sustainable LED lighting systems developed under this TRS project have been awarded (i) The Prize of Patent Office Of Cooperation Council for THE ARAB STATES OF THE GULF – GCCPO and (ii) Gold Medal with Special Recognition in the 46th Geneva International Exhibition of Inventions.