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From Measurements to Standardized Multi-Domain Compact Models of LEDs

Periodic Reporting for period 3 - DELPHI4LED (From Measurements to Standardized Multi-Domain Compact Models of LEDs)

Reporting period: 2018-06-01 to 2019-09-30

The goal of the project is to develop a standardized method to create multi-domain (thermal-electrical-optical) LED compact models from testing data.

The key objectives are:
• Define set of LED model equations that can be implemented into a FEM/CFD tool, for the purpose of self-consistent multi-domain simulation of LEDs thermal, electrical and light output characteristics.
• Provide interfacing between measurement tools, modelling tools and simulation tools to allow the application of the compact LED models.
• Prove the benefits of the use of compact models in the development process to reduce development times, cost and prepare for the digital revolution.

See Led characterization and Compact Model creation

Relevance and Impact
The European lighting industry faces a couple of key challenges due to the introduction of LED:
• On the market side, it is necessary to speed up development time, improve quality of current LED products and enable towards value-added activities in order to gain competitive advantage.
• On the development side, LED lighting has different challenges than conventional lighting applications. New characterisation procedures have to be defined as well as new standardization in order to boost LED adoption.
This will lead to an industry standard in the lighting industry.

Achievement of this project is expected to boost time to market of LED products cut by 1/3, cut development cost by 50%, reduce Cost of Non-quality by 25%.
The European lighting industry is offered a unique competitive advantage, necessary to catch the 30-40% speed of growth of its LED market and tape into potential new markets.
Delphi4LED provides first mover advantage to the European LED ecosystem in providing tools and methods for integration into Digital Manufacturing chain. Thus ensuring a long term competitive advantage.

Technical Innovation
In order to achieve a good design of LED systems, a modular, multi-domain based modelling approach is needed – this way allowing the freedom for LED component integrators to use such models in any kind of luminaire designs.
In order to overcome those key challenges, seamless integration of the LED in the product development chain is necessary. For that a communication bridge, in the form of standardization, has to be established between the semiconductor industry (LED
supplier) and the Lighting industry (LED component integrators).

In order to achieve this, the following tools have to be provided:
• Generic, multi-domain model of LED chips
• Compact thermal model of the LED chips’ environment
• Modeling interface towards the luminaire
General Results
- All requirements specification defined: end-users, LED parameters, LED samples, modeling methodologies, simulation benchmarks, project demonstrators.
- Experience gained from all the measurements done by all the partners.
- A lot of work done for the preparation of the Round-Robin, 6 labs involved (+1 external). No information was available in literature for such RR.
- Established the framework for chip level multi-domain Spice-like modeling and package and luminaire level compact thermal modeling.
- CIE Technical committee TC 2-84 launchedm- 2 presentations held at Jeju (Jp) and Eindhoven (NL) meetings and 1 workshop held in Eindhoven
- “European Task force” specific discussions
- Participation at Lighthouse Industry 4.E
- Presentation at JEDEC (March2017, March2018)
- Website
- Create awareness to the public
- 14 publications in IEEE conferences and journals; 17 materials for outreach activities to the general public and 5 project demonstrators defined

- Requirements specification for creating LED Multi-domain compact models in Delphi4LED
- Identification of end-user and their requirements
- Output parameters and accuracy requirements from Delphi4LED partners
- Methodology of selecting representative LEDs for measurements (Round Robin and characterization), simulation, and demonstrators addressing aspects like e.g. #LED chip, different LED architecture, CCT, power ranges, applications, etc.
- Definition of LED simulation benchmark problems
- Identified methodologies to generate compact models based on:
- Measurements (Spice-like models)
- 3D FVM and RC-network optimization
- Mathematical model order reduction
- Defined project demonstrators

- Huge amount of samples selected, purchased, mounted and aged for the measurements
- More than 1000 measurements done
- JEDEC and CIE define different standards for LED testing: JEDEC focusing on Rth and CIE on optical properties which means two different methods of Tj setting
- Comparison and evaluation of the 2 methods is still in progress
- Many findings already: e.g. K-factor calibration, options to speed up measurements, etc

- Modular approach to compact modelling of LED based systems
- Multi-domain on chip level only
- Same techniques for package, module/luminaire level thermal compact modeling
- Improvement of chip level Spice-like LED multi-domain model
- Sources of inaccuracies identified
- Proposals for mitigation:
-Modified topology and model equations
- Minimal number of data points for parameter extraction suggested

- Awareness raised outside the consortium with positive reactions
- Contacts established with international standardisation bodies
- Challenge is that we cannot ensure the outcome of the voting within the standardization bodies
- In order to fully exploit the landing of the outcome of the project, follow up is required.
- We are already identifying the way forward to ensure the positive landing after this 3 year project. Further actions might be required to answer new identified questions gathered from feedbacks (CIE, JEDEC, EU Task Force).

- Project website running,
- All following dissemination are available on our website:
10 IEEE publications
4 journal publications
2 education materials: Cooling of electronics magazine, contribution to the yearly book of the Hungarian lighting association
10 press releases in Finland, Hungary, France
4 exhibitions: Tiger meeting at Philips, Cluster Lumiere, ILIAD
ECSEL flyer
- 5 demonstrators defined

- Methodology for selecting and tracking (every 3 months new LEDs will be on the market) representative LEDs for measurements (Round Robin and characterization), simulation, and demonstrators addressing aspects like e.g. #LED chip, different LED architecture, CCT, power ranges, applications, etc.
- First of a kind Round Robin between 6 labs partners + 1 external reference lab.
- Initiated and launched new standardisation technical committee CIE TC2-84

Expected results till the end of the project
- Demonstrator and workflow comparing old and new way of working
- Proposal for data reporting for standardisation bodies
- Characterisation procedure in place

Potential impact
- Time to market reduction
- Optimized product