LED lighting design early why thermal simulation? The benefits of thermal simulation, consideration and accuracy

In recent years, LED lighting market showing explosive growth, which is driven by many factors, including green legislation and environmental problems are the most important factors. LED than the traditional light source (incandescent lamp) much more efficient, more environmentally friendly than the fluorescent lamp, mercury, and can adjust the color and brightness. Therefore, LED is widely used, can be used for professional, industrial and consumer applications. However, the design of solid-state lighting products is a complex multi discipline problems. Here, we will focus on the challenges and how to heat, thermal simulation development team that is reliable, consistent with the size and performance of the product (Figure 1).

Simulation of A lamp and 1. hot finished map (source: Future Facilities Limited)

In fact, the service life of the LED lamp (usually 25000-50000 hours in between) can not be fully realized, the performance of solid-state lighting products sometimes degraded over time. The performance (quality and quantity, light output and service life, maintain color and other parameters) is closely related with the temperature in the lamp or replacement lamps. For a given environment, heat and temperature of lamps design how to effectively dissipate internally generated is directly related to the.

Design challenges

Two other related factors also affect the long-term reliability of LED lighting: LED driver for electrolytic capacitor energy storage circuit of aluminum, and the market demand driven lighting manufacturers to create more compact lamps.

In addition to mechanical and electrical components such as fan, aluminum electrolytic capacitor will limit the use of life in many electronic circuits. The capacitor is an electrochemical device, during normal operation, the wet electrolyte gradually for the re formation of alumina dielectric layer. The capacitor will eventually dry, and cause disastrous consequences. At high temperature, this process will be accelerated.

In professional applications, such as entertainment lighting, lighting device requires smaller, so transportation and operation easier, in the use of less obtrusive. In the transformation of the application, from the street to the home downlight, will need to maintain the size and shape of the old definition of lighting technology in. In the directional lighting situations, usually including installed electronic driver circuit and LED transmitter module and the lens in the lamp.

Fit drive circuit

LED drive circuit needs to be converted to low voltage AC grid DC voltage to drive the LED, and to ensure the effective way to achieve the maximum output. Although the efficiency is very high, the LED chip will generate heat; drive circuit components, especially the power transistor will generate heat. If all the heating components placed in a narrow space, to meet the physical design constraints, so heat will soon, the highest 100 degrees C even more than LED node can withstand.

LED lighting designer's challenge is how all these things are put in the available space, at the same time to ensure that the product of internal and external key point to maintain the temperature within acceptable limits. At this time, the thermal simulation can play a role, especially in the whole design process. Figure 2 shows the chip module paradigm has good heat dissipation in the thermal simulation.

Figure 2. thermal simulation shows that the chip module shows the characteristics of good thermal management. (source: Future Facilities Limited)

The benefits of thermal simulation

In the past, most of the design and development work is based on the use of "rule of thumb" from the angle of thermal calculation of a specific component, printed circuit board (PCB) or the complete assembly. The design and development process of any electronic products are iterative, so the calculation must be repeated throughout the product development process. At each stage, need to correct design errors, and may even miss hot. Each change will increase the project time and cost, increase the risk of losing the opportunity in the market.

Moreover, the accuracy of this method is relatively poor, the designers had to design excessive heat management. For example, this may mean greater use of fins, increase the size and cost of the finished product, may even mean fan used in without fan case, greatly reduce the MTBF of finished products "(MTBF). Even more frightening is that after the production of finished products, hot issues, and warranty claims, product replacement, brand reputation etc..

Therefore, thermal management enables engineers to design smaller, more economical, better performance and longer service life of the product. Thermal simulation iterative design make faster, you can try a variety of thermal management options, and ultimately shorten the time to market.

Simulation in the development process

In the design process, the more early thermal simulation, the more can reduce the need for major design change risk to overcome the potential problems of the heat. In the project, electronic, mechanical and thermal engineers need to work together to ensure that in the design process considering the thermal simulation results, and fully realize the effects of the change on the thermal performance of the design. Figure 3 describes the interaction between different disciplines with team members.

Figure 3. for thermal simulation value, the engineers need to work together. (source: Future Facilities Limited)

In the beginning, a very simple conceptual model including all electronic components expressed as a centralized heat block can be used to determine whether it is possible to make the lighting cooling in the specification limits (Figure 4). The total power consumption and product size, the size of the radiator and the fan airflow (if used) represents the stage for all available information.

Figure 4. (source: Future Facilities Limited)