High-power LED area lighting challenge driving power such as street and parking lot lighting

As people's awareness of energy conservation and environmental protection is increasing, the industry is paying more and more attention to the impact of energy consumption on the environment. Among various energy consumption pathways, it is estimated that up to 20% to 22% of electrical energy is used for illumination. Increasing the energy efficiency of lighting applications and even further reducing their energy consumption will help reduce carbon dioxide emissions and create a greener world. Therefore, energy-efficient lighting is becoming a focus of competition in the industry.

From the application field, lighting covers different categories such as residential lighting, industrial lighting , street lighting and restaurant, retail and service lighting. In terms of power level, in addition to low-power lighting, it also includes high-power area lighting. Typical applications such as bollards, wall wash, wall pack, tunnel lighting, street lights, parking field lighting and public safety, industrial and retail lighting, outdoor lighting, and low overhead light (low bay), high Bay (high bay), freezer / refrigerator and a parking garage and other indoor lighting.

There are many challenges in high-power area lighting, such as the possibility that the luminaire may be difficult to access, the safety problem may occur when the light source fails, and there are many extreme environmental conditions in the outdoor. In addition, it is worth noting that existing light sources (such as metal halide lamps (MHL), high pressure sodium lamps (HPS), linear fluorescent lamps (LFL), and compact fluorescent lamps (CFL)) are used in high-power area lighting. There are many limitations, such as the poor color rendering of high-pressure sodium lamps (CRI is about 22), the typical lamp loss of metal halide lamps is higher (40%) and the time from start-up to illumination to full brightness may take up to 10 minutes. Linear fluorescent lamps have poor cold temperature performance, and compact fluorescent lamps also have slower startup speeds.

On the other hand, as high-brightness white light-emitting diodes ( LEDs ) continue to improve in terms of performance and cost, they are increasingly used for high-power area lighting and offer advantages not found in traditional light sources, such as emitting light per lumen. It consumes less power, has better direction control, better color quality, is environmentally friendly, and can be more easily controlled by turning it on and off, allowing automatic detection of ambient light to change brightness; in addition, LED reliability is better. Helps reduce maintenance costs and total cost of ownership.

LED area lighting application requirements

The main function of the LED driver is to flow at a lower limit of various conditions and to protect the LED from surges and other fault conditions, as well as to provide a level of safety against vibration and ignition (electrical and/or mechanical). For regional lighting applications, outdoor environments present temperature challenges to LED drivers and may require AC input voltages higher than the standard voltage of 277 Vac, 347 Vac, or even 480 Vac.

LED drivers for regional lighting applications may also need to meet certain regulatory standards for power factor or harmonic content. For example, the European Union's International Electrotechnical Union (IEC) IEC61000-3-2 standard requires harmonic content of lighting devices (class C) with a power exceeding 25 W, equivalent to a total harmonic distortion (THD) of less than 35%; However, compliance with IEC61000-3-2 Class C harmonic content requirements does not necessarily mean that the power factor (PF) is higher than 0.9. In some markets (such as the US), PF is generally required to be above 0.9 and THD is below 20%.

Many regional lighting applications are outdoors and may withstand a variety of stringent temperature conditions, which can affect overall service life. While the overall system design has a significant impact on service life, it is important to use an energy-efficient LED driver with less internal heat and lower losses, and to thermally isolate the driver from the LED heat source in the design to enhance system reliability.

Figure 1: Example of a smart dual brightness level LED street lighting.

The control of LED lighting can also become more intelligent. Traditional street lights come from the main control with a timer or ambient light sensor. The use of power line communication (PLC) or wireless control technology can provide highly flexible LED area lighting control, such as time-based light output level centralized control, vehicle flow sensor based illumination level control, and control based on detection of people and vehicle activity. Downtown lighting, taking care of walking cars and street lighting. LED smart control technology saves power and does not compromise safety. Typical applications include smart dual-brightness lighting, such as parks, gas station ceilings, parking lots, stairs, and refrigerator cabinet lighting that support lighting levels that adjust brightness levels as needed. LEDs can be turned on and off instantly, allowing for easy adjustment of lighting levels based on motion or activity in these applications, such as providing 20%-40% brightness levels when no activity is detected and 100% when activity is detected Brightness lighting. This will save a lot of extra power consumption.