1. Hella Lighting Finland Oy, Finland
Multiphysics Simulation Story: Keeping LEDs Cool Gets More Manageable Through Simulation
Univ. of Turku, Finland
Philips, Netherlands
Hella Lighting Finland Oy, Finland
Helvar Oy Ab, Finland
Aulis Tuominen1, Mika Maaspuro1, Toni Lopez2, Sami Yllikäinen3, and Raimo Laitinen4
1 Univ. of Turku
2 Philips
3 Hella Lighting Finland Oy
4 Helvar Oy Ab

2. The Challenge
Light emitting diode (LED) light sources offer many benefits over incandescent lighting
Longer life spans
High luminous efficiency
Environmentally friendly
The biggest drawback is that LEDs require careful temperature regulation
LEDs must operate at the lowest possible temperature
New materials may offer solutions, but manufacturers must wait for samples to be able to test them
LED light bulbs offer a long-lasting and environmentally friendly option in lighting.

3. The Solution
The LED junction, the small active area where light generation takes place, is kept cool by a heat sink
Efficient conducting materials such as aluminum are expensive
Using less expensive materials, the geometrical dimension and shape of the heat sink become more important
Modeling allows for parameters to be easily altered for optimization
Newer materials, such as nanomaterials, can be analyzed before those materials are made available for testing
Top, 3D geometry of the LED lighting device composed of an internal LED module, a heat sink, and a cap. Bottom, Simulation results of the air domain inside the cap show temperature variations.

4. The Simulation
Using a 3D geometry of a LED lighting device, conduct an electrothermal analyses of high-power LEDs
Predicts self-heating, current crowding, forward voltage and other LED performance indicators
Experiments with physical prototypes validated the simulation results
The next step will be modeling the driver of the LED
Analyzing electromagnetic interference and electromagnetic compatibility
LED driver module simulation results where power dissipation in each component has been resolved by SPICE circuit simulation.