In recent years, with the emergence of LED lamps, revolutionary changes have taken place in the field of lighting. In retail stores in Europe and the United States, ancient incandescent light bulbs have been hard to find, and even banned sales. In the alternative lighting market, low-power compact fluorescent lamps (CFL) are now facing new competitors. LED technology is constantly improving, and LED lamps are increasingly powerful in terms of brightness and power. These characteristics, combined with its unique high energy efficiency, make LED luminaires ideal for lighting. Generally incandescent bulbs can produce 10 lumens per watt, and LED manufacturers claim that LED lamps can reach up to 100 lumens per watt. However, the limitations of form factor and maximum operating temperature make it difficult for LEDs to realize their full potential. At present, the best performance LED replacement lamps can achieve 50-60 lumens per watt. Therefore, LED lamps are indistinguishable from CFL lamps in terms of efficiency standards (Note: The efficiency range of CFL lamps is 60-70 lumens per watt, and the improvement potential is limited). Ecological issues have also received increasing public attention. As people's awareness of environmental issues such as global warming and climate change continues to increase, the concept of saving resources and energy is becoming the focus of many marketing strategies. The reduction in automobile fuel consumption and the prohibition of incandescent lamps in the past 10 years are a good example of this trend. Many governments around the world have set a timetable for the elimination of incandescent lamps. There are also some public policies that provide loose tax support or other financial assistance for energy-saving and environmentally friendly "eco" products. The inherent advantages of LEDs are very in line with the public's eager expectations for safe, energy-saving and environmentally friendly lighting solutions. LED has many other advantages, such as higher dimming ability, longer life and smaller size, which opens the door to convenience in terms of shape, color, life and cost. Replacing traditional lighting sources (fluorescent lamps, CFL energy-saving lamps, halogen lamps, or other incandescent lamps) with LED lighting solutions that are compatible in mechanical, optical, electrical, and thermal aspects is an ongoing industrial change. The business, office and residential lighting markets call for high-quality LED improved lamps. Although cost issues are still the main obstacle to these solutions, but also need to pay attention to the following technical issues: • Electrical compatibility with existing infrastructure, especially when using standard in-wall dimmers. • The shape must adopt screw type • The heat dissipation of LED must be solved 1.1 Dimmer compatibility At present, the control equipment for lighting fixtures in homes, hotels and offices are designed and installed for incandescent lamps. The best way to provide a dimming function is to use a "commercial phase cut" dimmer. This dimmer was developed in principle for powering incandescent lamps. From an electrical point of view, an incandescent lamp can be regarded as a resistive load. The electrical equivalent load of electronic lighting sources (such as CFL energy-saving lamps or LED lamps) is no longer a purely resistive load. This makes a big difference in the way the dimmer works. Improper use of the load will cause the system to malfunction, and may cause very uncomfortable flicker, or even damage the lamp or dimmer. This may cause user dissatisfaction, thereby delaying the adoption of LED solutions. Currently, dimmers are still expensive and difficult to install. Therefore, the introduction of high-quality solutions compatible with existing dimmers has become a necessity to honor the promise of LED lighting promotion. Although there are different types of phase-cut dimmers, the working principle is basically the same (that is, part of the power supply sine wave is cut off in each cycle). This can be achieved by a switch. When the switch is turned on, the power is delivered to the load (bulb). When the switch is open, no power is supplied. By adjusting the on-time of the switch, the total energy supplied to the load can be adjusted. There are two types of dimmers: the leading edge phase-cut type and the trailing edge phase-cut type. see picture 1. • The leading-edge phase-cut dimmer is to cut the phase at the beginning of the power supply half cycle. After a period of time corresponding to the dimming position, the switch is turned on to supply power to the load until the end of the half cycle. After the zero point, repeat the same operation. See Figure 1 and Figure 2. • The trailing-edge phase-cut dimmer means that the switch is turned on at the beginning of the half cycle, and is turned off after a period of time corresponding to the dimming position, and the off state is maintained until the end of the half cycle. After the zero point, repeat the same operation. See Figure 3 and Figure 4. Figure 1. Leading edge-dimmer maximum position Figure 2. Leading edge-dimmer minimum position Figure 3. Rear edge type-dimmer maximum position Figure 4. Trailing edge type-dimmer minimum position To complete the phase cut, two main technologies are used: TRIAC (triac) switch or transistor switch. TRIAC dimmers are mostly phase-cut dimmers. The transistor switch can be either a leading-edge phase-cut dimmer or a trailing-edge phase-cut dimmer. The problem with TRIAC dimmers is that they need to meet special conditions to work properly: TRIAC can be turned on by triggering the gate, and once triggered, a minimum current is still needed to maintain it in a conducting state. This trigger current is called "latch current", and in order to keep TRIAC on, the current must be loaded for a period of time. Once the device is latched, there must be a continuous current supply. This current is called "hold current". If this current is disconnected or weakened, TRIAC will be turned off. In order to be compatible with dimmers, LED lamps must absorb the holding current required by the dimmer. For example, if a 6W LED lamp (approximately equivalent to a 40W incandescent bulb) is to be used with a dimmer with a minimum load of 10W, some additional circuitry is required to provide sufficient holding current. In this case, the lamp efficiency will be reduced, but it is still highly efficient compared to 40W. Without this circuit, the LED light will not work properly. Different dimmers have different holding currents. Therefore, the greater the additional loss, the better the compatibility with the dimmer. The design difficulty of dimmable applications lies in finding the best trade-off between luminaire efficiency and dimmer compatibility. NXP ’s SSL2101 (and its derivative product SSL2102) has two integrated bleed switches controlled by the IC. With an external resistor, two different bleed currents can be set. The IC provides greater flexibility in current selection and optimizes dimmer compatibility. In SSL2103 (the controller-only version of SSL2101), the integrated bleeder switch is removed, but it can be replaced with a low-cost external bipolar switch (still driven by the IC), optionally providing a higher bleeder current. At the same time, this version also removes the built-in MOSFET used for converter operation, but external corrections can be made to form a solution that meets specific regulation requirements. Solar Security Light,Solar Led Flood Lights,Outdoor Solar Security Lights,300W Solar Flood Lights Jiangmen Biaosheng Solar Energy Technology Co., Ltd. , https://www.bsprosolar.com
