Analysis of the rapid development of AC-driven LED light source technology

As the fourth-generation lighting fixtures of green, energy-saving, energy-saving and long-life, LED light sources have sprung up, attracted wide attention and are rapidly developing in full swing. The current LED light source is a semiconductor device that operates at a low voltage (VF=2→3.6V) and a large current (IF=200→1500mA), and must provide a suitable DC current to emit light normally. The technology of direct current (DC) driving LED light source has become more and more mature. Since the power supply used in our daily lighting is high voltage AC (AC100~220V), we must use the buck technology to get lower voltage. The commonly used transformer is the transformer. Or the switching power supply is stepped down, and then the alternating current (AC) is converted into direct current (DC), and then converted into a direct current constant current source to promote the LED light source to emit light. Therefore, the system application scheme of DC-driven LED light source must be: transformer + rectification (or switching power supply) + constant current source (Figure 1). LED lamps must have a certain amount of space to house this module, but for E27 standard screw luminaires, the space is very limited and difficult to place. Whether it is via transformer + rectification or switching power supply step-down, the system will have a certain amount of loss. When DCLED is switched between AC and DC, about 15% to 30% of the power is lost, and the system efficiency is difficult to achieve more than 90%. If the LED light source can be directly driven by AC (AC), the system application scheme will be greatly simplified, and the system efficiency will easily reach 90% or more.

Figure 1 System application scheme for DC drive LED light source

Seoul Semiconductor Co., Ltd., today's Seoul Semiconductor , invented ACLEDs that can be directly driven by AC in 2005, followed by III-NTechnology in the United States. 3N technology develops GaN substrates based on MOCVD growth technology. Lighting and sensor applications reduce costs and increase productivity. Provides 6-inch production technology for large and small silicon LEDs. 3N invented the single-chip AC light-emitting diode (ACLED), which has established a comprehensive patent portfolio to protect and improve technology, firmly establishing its proprietary position, and is the premier large-scale commercial production of AC LED products. In 2008, the "Industrial Technology Research Institute" of Taiwan Province of China also completed AC LED products that can be industrially produced and have practical application system solutions. It can be directly plugged into AC110V AC voltage of 60Hz or higher to make AC light, which is used for indication. Lamps, neon lights, and low wattage lights can effectively solve the shortcomings of existing LEDs that cannot be directly used under AC sources, resulting in higher product application costs. Taiwan Industrial Technology Institute's OnChipACLED (on-chip ACLED) won the 2008 R&D100Award Award, which is known as the American Industry Innovation Oscar. Nowadays, only the United States, South Korea and Taiwan have this technology in the world. The Taiwan Industrial Technology Research Institute has developed the process technology of white, blue and green ACLED, which is not only synchronized with the international market, but also one of the world leaders.

Advantages of ACLED lamps

Compared with incandescent lamps, halogen lamps, fluorescent fluorescent lamps, fluorescent energy-saving lamps, and DC LED lamps, ACLED lamps are more energy-efficient, longer-lived, and more energy-efficient. ACLED illumination eliminates the need for costly AC/DC converters and constant current sources. The performance comparison between AC LED and existing lighting fixtures is shown in Table 1.

Table 1 AC LED and existing lighting fixture performance comparison