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Thermal Management Master-class

Thermal Management Master-class. Dr Andy E Young andrew.young@litecool.co.uk. Overview. Why is thermal design so important? What are the challenges and solutions? What factors effect.. Performance? Reliability? Cost? Where are the common mistakes made?.

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Thermal Management Master-class

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  1. Thermal ManagementMaster-class Dr Andy E Young andrew.young@litecool.co.uk

  2. Overview • Why is thermal design so important? • What are the challenges and solutions? • What factors effect.. • Performance? • Reliability? • Cost? • Where are the common mistakes made? Let’s start with some questions for you..

  3. Question to the audience When you design a luminaire do you.. • Set the current and live with the lumens? • Drive the LED harder and live with consequences? Where is your ‘weakest link’ in thermal performance? • Package • Module • Luminaire body Are you confident your thermal performanceis as good as it could be? Why is thermal performance so important?..

  4. Why is thermal design so important? • Electrical current generateslightand heat • Cooler means morelightis generated • Maximum light needs both • High current • Low • This is a vicious-circle! Future Light Solutions, ULT2.0 tutorial  What are the challenges?..

  5. What are the challenges? • High current and low appear to be mutually exclusive • Complicatedinteractions • The data provided is incomplete, and • Where available it isoften for lab conditionseg.  What are the solutions?..

  6. What are the solutions? • Brute force • Over-engineered heat-sinks, etc. • Build-in active technology eg. fans • Apply thermal management technology • Close the loop in performance evaluation • Address root causes • For real-world conditions • Good thermal design can.. Build in the right technology, in the right place convert a vicious-circle into a virtuous-circle!  What factors affect performance?..

  7. What factors affect performance? • Goal: find design for and • is dependent on and • Denotes from LED package datasheet • Denotes from luminaire type • Denotes from thermal design Missing value! How to determine these values?

  8. What factors affect performance?Missing data • Related to the thermodynamic efficiency of the LED, referred to as the wall-plug efficiency • Hard to find, Often guessed at eg. 80% • Can be.. Measured, or Calculated Photopicsensitivity Normalised Plank function

  9. What factors affect performance?Luminaire type • The numbersscale thesignificanceof the variousthermal resistances Digital Lumens

  10. What factors affect performance?From thermal design • Conventional wisdom tells us thin layers are less resistive • All thermal resistances are composed of two effects..

  11. Exploiting the virtuous circle • Same .. • Lower and • Achieved by thermal design of package and module 

  12. What factors affect reliability? • Indicated by • Strongly dependent on and

  13. What factors effect.. Cost • Luminaire cost • Good thermal design can reduce cost if done well • $8 on down-light • $30 on a high-bay • Life cost • Indicated by E and L70 • Strongly dependent on Tj

  14. Common errors • Taking data on face value • Thinking in 1D • Component-by-component design • Neglecting interfaces • Not using TIMwell • Thermal tolerance stack-up • Assuming it is all about the heat-sink • Treating a luminaire body as a heat capacitor • And then adding long fins • Giving me less than a 5 on the feedback 

  15. Thank you fromThermally efficientLED Modulesandrew.young@litecool.co.uk

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