AC Powering High Power Chip On Board LED Array

LEDs for lighting application are conventionally powered by Direct Current (DC) sources with DC-DC converters or Alternating Current (AC) sources with AC-DC converters. DC-DC converters and AC-DC converters are well understood but have disadvantages of driver cost, size, electrical circuits complexity and reliability. With the development of LEDs technology and enhancement of LEDs dies reliability, the reliability of the converters is becoming the bottleneck of the lighting system. Direct AC powering LEDs without AC-DC converters have advantages of higher efficiency, enhanced reliability, reduced cost and ready to replace existing lighting fixture due to the elimination of AC-DC converter. In the first part of this work, existing AC LED technologies including design concept, challenges and products are reviewed. Advanced analysis on AC and DC lighting efficiency and LED light output under different AC regulation modes are performed. In the second part of this work, a novel high power AC LED system solution for lighting application is described in the dissertation. The novel high power AC LED system solution includes a novel reconfigurable COB (Chip On Board) LED array packaging with flexible electrical connection and a novel dynamic load configuration powering method. The new powering method is specially designed for COB LED array and leverage the unique load nature of multiple discrete LEDs. The LEDs electrical connection is dynamically configured with supply voltage variation. It both enables LEDs module working under different supply voltage standard with high efficiency and protects LEDs from supply voltage variation. The control circuits enhance both AC LEDs reliability and light output stability. The combination of the packaging and powering method provides a low cost, high efficiency and high reliability solution for high power LED lighting application and leads to a new way of high power AC LEDs system design for LED lighting application.