By Rudy Ramos, Mouser Electronics
As well as illuminating the spaces we live, work and relax in, modern LED lighting can form an integral part of truly smart buildings. These spaces contain sophisticated networks of systems that collect data, process it and then respond appropriately. The aim is simultaneous to increase the comfort of those using the building, and to reduce running costs by improving efficiency.
LED lighting can be a key facet of these new-generation buildings, particularly when you integrate it with other systems. Lets look briefly at what intelligent lighting systems enable, then explore the technologies typically used to link everything together and get maximum benefit from the overall smart building installation.
The art of the possible with intelligent lighting systems
The main aim of a connected intelligent LED lighting network is to tailor illumination appropriately for different parts of a building (as opposed to operating a one-size-fits-all approach). Smart lighting does this by monitoring input from sensors and adjusting itself accordingly. This is particularly valuable in locations such as offices, hospitals, warehouses and other industrial or multi-purpose spaces, where you do not necessarily want the same lighting throughout. In this way, you can configure your lighting in ways that could help improve employee mood, concentration, productivity and general well-being. You could, for example, align lighting patterns to fit in with the human circadian cycle, or tweak the output depending on how much natural light is coming in through the windows.
Now take this a step further: imagine a building with automated heating, ventilation and air conditioning (HVAC) system that adjusts the temperature of different spaces for optimal human comfort, machine performance and to optimize efficiency. By linking an intelligent LED lighting network to the HVAC system, you could set up your illumination in such a way that contributes to the same goals.
The technology behind LED smart lighting networks
Underpinning many intelligent LED light networks is Power over Ethernet (PoE) technology, bringing Internet-of-Things (IoT)-style low-voltage cabled power and connectivity to light fittings. Your light fittings effectively become things in your buildings IoT network. PoE is straightforward to set up and widely available, thanks to the success of IP-based platforms over recent years. It also means you only have to install one set of infrastructure, and it is cheaper than copper cable.
A typical intelligent lighting network using PoE requires some components: PoE gateways, LED light fixtures, LED lights, LED smart drivers, LED cable harnesses, sensors, wireless switches and dimmers. The image below shows how these elements fit together.
The PoE gateway
Central to an intelligent LED lighting network is the gateway, which links the light fixtures, switches and sensors with the computers and other equipment used to manage them. The gateway powers the individual fixtures and controls the lighting, which can include dimming, color adjustments and collecting or responding to sensor data. Such gateways can deliver up to 60W of power if you need greater wattage, perhaps for high-bay lights, you will still require AC line voltage. In these cases, you can control your devices using a wireless line voltage relay.
The IP industry standards derived from the Advanced Telecommunications Computing Architecture (AdvancedTCA or just ATCA) call for 48 VDC. As a result, many PoE gateways are set up for either unregulated 48 VDC, constant-voltage 24 VDC or 48 VDC, or constant current.
You can also get wireless PoE gateways, which conform to the IEEE 802 standards, running at 902 MHz in North America and 868 MHz in Europe. These gateways have a typical range of around 15m, and enable two-way communication with multiple devices, without needing to worry about interference with another kit.
The light fixtures
The second component of the smart network is the LED light fixture. These enable you to control the LED light they are the difference between creating a low-energy system by simply replacing traditional bulbs with LED ones and creating a truly intelligent, human-centric, responsive lighting system, using smart fixtures.
Then there are the LED bulbs themselves. With manufacturers investing significantly in their development, the amount of light output (lumens) per watt is increasing, while the cost per lumen is dropping. Moreover, when it comes to choosing lights for your system, you have plenty of choices.
Lumileds has its LUXEON MX LED Module, a high-power, multi-die emitter. This is a cost-effective option for outdoor or high-bay applications, with efficacy as high as 150 lumens per watt in a 12 VDC configuration, thereby producing up to 1200 lumens at 85C
OSRAM Opto Semiconductors range includes the DURIS E 2835 LED, offering a wide viewing angle and excellent efficacy, all from a small (2.8 x 3.5 mm) plastic leaded chip carrier (PLCC) package. You can get these surface-mount LEDs with a correlated color temperature (CCT) of 2700-6500 K.
Surge-protectors, connectors and drivers
A system may also contain other elements, such as surge-protectors, connectors and LED drivers.
An example surge-protector is the PLED6N Open LED Protector from Littelfuse. This gives you a switching electronic shunt path if an LED in a string fails and becomes an open circuit. At just 1.1 mm tall, it can be used with 1W-rated LEDs with a nominal 350 mA current at 3 VDC (1W).
Regarding connectors, two options are the Molex Lite-TrapTM and Mini Lite-TrapTM SMT Wire-to-Board Connector System, Push-Button Type. Both are ideal for use with thin LED lighting modules, thanks to their low profile heights (as little as 2.65 mm), high wire-retention forces, easy wire removal and low wire insertion force. In particular, the thin profile helps prevent shadowing.
In the LED drivers space, the Texas Instruments TPS92515/TPS92515-Q1 2A LED drivers gives you monolithic switching regulators in a small package that includes a low-resistance N-Channel MOSFET. Their target use case is very bright LED lighting that requires high bandwidth, efficiency, pulse-width modulation (PWM) and/or analog dimming.
Global MOSFET leader Infineon also offers the CoolMOS CE, which is a popular choice for LED drivers and tubes, thanks to its ease-of-use, efficiency, electromagnetic interference (EMI) performance and attractive price point. You can use these in LLC, PFC, buck and flyback topologies.
Intelligent LED drivers
An intelligent LED driver can listen to instructions coming via the PoE gateway from the lighting or broader smart building network, and consequently deliver appropriate power and control signals to the LED engine. Smart drivers are currently available in either a single- or dual-channel configuration, able to drive LED fixtures with constant currents at 12-42 VDC, with a 45 W top output power. You can connect up to eight drivers to a single PoE gateway by daisy-chaining them together.
LED cable harnesses have not yet become the standard way to deliver power and data connectivity to smart LED drivers. In the meantime, Molexs Micro-Fit 3.0 Interconnect System enables you to create your high-contact-density power or signal connector. Despite the compact 3 mm pitch, you still get many of the features found on larger connectors. This system can convey currents of up to 5 A.
Next, there are the sensors. These can be wired or wireless and may be part of the LED light fixture, or standalone devices linked to (and potentially powered by) the PoE gateway.
Among the most common sensors are wireless ambient light detectors. They report back to the central control system, enabling it to adjust lights in real time.
Sensors are also often used to monitor temperature, air quality, humidity, motion, proximity, color temperature and other factors.
Wireless switches and dimmers
Lastly, you have got your switches and dimmers. While this may sound counter-intuitive when you have a smart system that can be controlled centrally or from a mobile device, wall switches remain a convenient means of control. Moreover, incorporating new switches neednt mean lots of rewiring: like with the sensors, there are self-powered options available. Here, the act of someone pressing the switch can generate enough energy to send the appropriate signals wirelessly to the PoE gateway. Moreover, as well as lighting, this type of switch can be used to control other elements of your smart building, such as heating and air conditioning.
LED lighting: a central part of tomorrows smart buildings
The intelligent, connected lighting systems being used in smart buildings demand a variety of technologies, from gateways and wireless switches to smart drivers and fixtures. By blending the right components, building designers can make smart lighting an integral part of their connected control systems, thereby making the spaces both more comfortable and more efficient.