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LED Lighting System

LED Lighting System. Team 18. Jonathan Chambers Hyungrae Cha SeungJin Nam. Objectives. Create an LED lighting system to replace incandescent and fluorescent lights typically found in a home

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LED Lighting System

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  1. LED Lighting System Team 18 Jonathan Chambers Hyungrae Cha SeungJin Nam

  2. Objectives • Create an LED lighting system to replace incandescent and fluorescent lights typically found in a home • Occupancy sensor to turn on lights when a person enters a room and turn off the lights when they leave • Light sensor to detect ambient light level and adjust intensity of LEDs accordingly • User has option of switching between automatic and manual intensity adjustment

  3. Outline • Motion Detector • Automatic/Manual Dimmer • Power Protection Circuit • LED Driver • LEDs

  4. Motion Detector • Leviton OSSNL-IDW Occupancy Sensor

  5. Automatic/Manual Dimmer

  6. Triac Dimmer Triac

  7. Automatic Dimmer Schematic PR1: CdSPhotoresistor Sense light from 400-700 nm Dark Resistance: 150 kΩ Bright Resistance: 4 kΩ

  8. Automatic Dimmer Simulation

  9. Automatic Dimmer PCB

  10. Power Protection Circuit Bridge Retifier Low pass Filter (LC) TVS Common mode Filter Thermistor Terminal Block

  11. Power Protection Circuit

  12. Power Protection Circuit Actual VBR output Expected VBR output Actual VAC output Expected VAC output

  13. LED Driver Schematic

  14. LED Driver PCBs

  15. AC Line Sense Circuit

  16. Valley-Fill Circuit

  17. Buck Regulation Circuit

  18. Output Measurement at VBUCK Expected Result: Actual measurement :

  19. LEDs • 10x Cree cool white XLamp XP-E LEDs • Minimum 114 lumens each at 350mA • Driven at a maximum current of 500mA

  20. LED Output Characteristics • 10x LEDs driven at 500 mA • Power Consumption 500 mA * 3.3 V * 10 = 16.5 W • Lumen Output 114 lumens at 350 mA 114 * 1.4 * 10 = 1596 lumens • Efficiency at 500 mA 1596/16.5 = 96.7 lumens/watt

  21. LEDs vs. Incandescent/Fluorescent Lights • Efficiency at light output of 1600 lumens http://www.energystar.gov/index.cfm?c=cfls.pr_cfls_lumens

  22. LED Driver Efficiency • Testing results obtained using Variac input set to 30 V. • Efficiency: (8.7/9.7)*100 = 89.7 %

  23. Performance Issues/Solutions • Issues • Flickering • Reason for Flickering – The output frequency of LM3445 Driver didn’t reach the minimum standard point which is 120 Hz because our rectifier didn’t work as the full rectifier. Normally, LEDs can turn on and off at high frequency with varying the total on time to achieve perceived dimming. Driver output frequency should be at least 120 Hertz (Hz) to avoid flickering.

  24. Performance Issues/Solutions • Issues • Delivering too much current to the LEDs • ( typically at the max power) • Reason for overflow current – Pin ISNS at LM3445 sets the • maximum LED current. However, our LM 3445 circuit didn’t work properly specially in ISNS pins. • Therefore, the ISNS didn’t control the constant maximum current to the LEDs.

  25. Performance Issues/Solutions • Solution for Flickering • replace the bridge rectifier with diodes in parallel to make the full wave rectifier and make test easier to find whether it provide constantly high frequency to the LM 3445 driver or not. • Solution for overflow current to the LEDs • - Based on the LM3445 working properly, then we can increase the value of the limiting current resistor R3 to decrease the maximum current.

  26. Summary • We experienced a flickering issue when dimming the LEDs and an overflow of current provided to the LEDs at the maximum dimmer setting. • Based on our objectives, we were able to successfully implement the motion detector, manual/automatic dimmers, and LEDs. • Our efficiency values measured were high, so we successfully created an LED lighting system that produces sufficient light with a small amount of power.

  27. Special Thanks • Cree for donating our LEDs • The parts shop for soldering help and components • The power lab for help testing our circuits • TDK, Coilcraft for donating inductors and capacitors • LM3445 Designer who gave some ideas for the LED driver.

  28. Questions ?

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