Development and trend of LED intelligent control technology
1 Introduction to LED Intelligent Control Technology
1.1 Research content
LED intelligent control technology is connected to the control system through the network, using the smart client to regulate the lighting, changing the lighting to meet the scene comfort scene settings, and deploying a more comfortable, safe, energy-saving, healthy and suitable light environment. LED is the most suitable light source for adjustment control in current light sources. Healthy intelligent lighting is a new trend in the development of the lighting industry.
The intelligent control lighting system utilizes advanced electromagnetic voltage regulation and electronic sensing devices to monitor and track the power supply in real time with the public lighting G-BUS system intelligence as the platform, automatically and smoothly adjust the voltage and current amplitude of the circuit, and improve the imbalance in the lighting circuit. The additional power consumption caused by the load increases the line power factor and reduces the operating temperature of the lamps and lines to optimize the power supply.
The current prevailing lighting control systems are based on fieldbus (FCS) technology and can be divided into closed and open categories according to the openness of the protocol. The closed protocols are Bus and Dynet; the open protocols are EIB, DALI, X-10 and HBS.
(1) Bus bus protocol, using a pair of twisted pairs (both bus device working power and bus device information), bus devices can communicate directly, without the need to pass the central controller, support linear, star or tree Structure but does not support ring structure.
(2) Dynet bus protocol, using two pairs of twisted pairs (one pair of twisted pairs provide DC12V bus device working power, another pair of twisted pair for transmitting bus device information), based on RS485 four-wire transmission protocol, only Support for linear structures.
(3) EIB (European Installing Bus) bus protocol, the dominant building and home automation standard in Europe. In 1999, EIB entered China.
(4) DALI (Digital Addressable Lighting Interface) protocol, an abbreviation for Digital Addressable Lighting Interface, which defines the communication between the control device and the device controller. The DALI protocol has certain advantages in the field of intelligent control lighting because of its practicability, easy expansion, low system development difficulty and low development cost.
(5) X-10 has adopted the power line carrier technology and achieved great commercial success in North America. Products that use this protocol do not require wiring, and ease of use and low price are their biggest highlights.
(6) HBS is a home network protocol introduced by Japanese companies.
1.2 Technical principles and functional elements
1.2.1 Technical principles
Ambient light detection allows the light to be dimmed when other sources have provided sufficient illumination. In addition, the color of the RGB illumination system can be adjusted by detecting the color of the ambient light. The communication function allows remote control and connects the lighting devices into a central network. Energy measurement accurately calculates the power consumed and provides system insight for predictive maintenance. All of these featuresâ€”environmental light detection, communication, and energy measurementâ€”will further save energy and reduce operating costs.
Ambient light sensors (ALS) detect nearby light levels, and these functional devices become the "eyes" of LED lighting systems and are key to energy savings. When the room is already bright enough, the lighting is completely unnecessary, and the system can dim or completely turn off the lights, reducing power consumption and extending the life of the lights. Key features of the ALS include lumens of the lamp, power consumption monitoring, and IR and UV filtering. These sensors must be quietly running in the system and do not consume excessive power to disrupt the system's energy savings. Good ALS consumes less than 1Î¼A, and the lumen detection range must reach the typical lumen range of 0.1lx-100 000lx for outdoor environments, which is generally sufficient for most applications. Considering system reliability, it may be necessary to adopt a slightly larger range. IR and UV filtering eliminates the spectrum of invisible light in real systems.
1.2.2 Functional Elements
(1) Intelligent LED light detection function
Ambient light sensors must avoid the illumination of the light itself to avoid the effects of ambient light measurements. In this design, the ALS is located on a separate board in the shadow of the body of the illuminator. This design allows the ALS to turn off the illuminator when ambient light is detected above a preset value. RGB sensors can even add more â€œfeaturesâ€ to lighting applications. Similar to Figure 1, an LED lighting system with RGB and ALS dynamically adjusts the color output of the lamp to meet specific application needs, such as stage lighting or commercial displays.
Figure 1: ALS installation in the shadow of the main body of the light to avoid the sensor reading its own light intensity
(2) LED intelligent communication
By illuminating the lights, the lights can be turned on, off and dimmed via the network, which reduces energy consumption. Communication also provides fast feedback on power outages, maintenance, and contingency, which will save overall system maintenance costs. Wireless and wired communications work well in different environments, depending on network size and topology. Wireless is more suitable for small indoor and large outdoor applications, which require continuous line of sight, available frequency bands, and sufficient transmission power. Power line communication (PLC) is the use of existing power lines to achieve communication, PLC is very suitable for large municipal lighting systems, tunnels, indoor parking lots and other environments that cannot use natural light due to physical location or building walls. Reliability is the key to all communication references, and there is no benefit if the communication fails.
In wireless applications, the signal transmission method may be WiFi, ZigBee or others, often belonging to, but not limited to, standard protocols for industrial, scientific, and medical (ISM) radio frequencies. Limiting power consumption provides network flexibility, which is critical if the endpoint uses a battery. Figure 2 shows a unique application where the light switch is equipped with an energy harvesting radio frequency (RF) transceiver. The system collects the energy used to activate the switch, produces a dc voltage that can be used, and supports radio communication (1 GHz RF) for the luminaire. The switch can be placed anywhere in the room as long as the signal can cover the light source. No need to connect the lighting switch, the application design is more flexible and the lighting control is more reliable.
Figure 2: Building automation application lighting switch with transceiver to control LED lighting
The PLC lighting control method utilizes the existing power supply line as a high price option. Since the communication is realized by the well-maintained existing power supply line, the PLC avoids many troubles such as shared communication frequency, performance in bad weather, and network maintenance. Its range, speed and reliability are the keys to designing a PLC.
The noise of the power line greatly affects the reliability of the system communication. G3-PLC communication is a new PLC standard based on OFDM, which can realize reliable communication of power lines. The standard supports speeds up to 300kbps, mesh networking, and reliable modes in noisy environments, making it ideal for LED control networks. The lighting network based on OFDM and PLC control is similar to the existing G3-PLC.
Figure 3: Example of a municipal street light network using PLC
Figure 3 shows the NyxHemeraTechnologies PLC unit for road lighting, which saves 25% in power and maintenance costs by 30%. The large facility system supports up to 1022 ç› lights with a communication distance of up to 3km.
(3) Intelligent LED lighting energy measurement function
Intelligent LED lighting also requires power calculation capabilities, from smart meters to voltage controllers to electric car chargers. Each smart grid device has a power measurement function that provides accurate power usage information to power companies and users in real time. Most lighting fixtures that send back power consumption provide detailed information about the building and municipal lighting environment, ensuring that utility bills are consistent with the user's actual power consumption. Respond to user needs in a timely and accurate manner by dimming or turning off the lights when not in use. In addition, the power consumption fluctuations of a particular illuminator indicate that system maintenance, maintenance, or replacement is required. There is no doubt that many lights are in hard-to-reach areas, and optimized maintenance saves money. To generate useful data in the smart grid, the energy measurement design must maintain high precision measurements over a wide range of currents. Not only that, limiting or eliminating calibration time also reduces overall system cost. Figure 4 shows a flexible LED lighting design with energy measurement, and the energy measurement chip also provides system dimming and DALI interface.
Figure 4: Complete intelligent LED lighting system with energy measurement
Non-intelligent LED lighting is currently installed in many cities, which offers tremendous opportunities for integrated modules that improve the performance of LED lighting. To be scalable, these systems need to be connected to a smart lighting system, and if the cost and capacity of the LEDs are constant, simply replace the relatively new and more efficient LEDs. Simple interfaces such as DALI allow for future additions to ALS, communication and energy measurement functions.
1.3 Technical characteristics
(1) Intelligent: A control system with intelligent features such as information collection, transmission, logic analysis, intelligent analysis reasoning and feedback control.
(2) It can be connected to various sensors to automatically control the light.
(3) Time control: In some occasions, the brightness can be adjusted with the commute or demand time.
(4) System integration: It is a modern control system integrating computer technology, computer network communication technology, automatic control technology, microelectronic technology, database technology and system integration technology.
(5) System networking: use the above control means for integrated control or networking with the building intelligent control system to achieve system networking.
(6) The system can control continuous dimming or switching of any loop.
(7) Convenient to use: Since various control information can be displayed in a graphical form, the control is convenient, the display is intuitive, and the lighting effect can be flexibly changed by using a programming method.
(8) Scene control: Multiple different scenes can be set in advance, and multiple conversion modes can be faded in or out during scene switching.
(9) Mobile sensor: The infrared detection of the human body achieves the control of the light. If a person comes to light, the person goes out of the light (dark).
(10) Bright illuminance sensor: For some occasions, the indoor light can be adjusted according to the intensity of outdoor light, such as the constant illumination control of the school classroom.
(11) Infrared remote control: The handheld infrared remote control can be used to control the light.
(12) The control of the light can be achieved by the movement detection of sound, light, heat, human and animal.
(13) Networking: Traditional lighting control is mostly an independent, local or local system. It does not need to use a dedicated network for connection, and intelligent lighting control can be a wide range of control systems, including hardware technology and software technology. Computer network communication technology is supported to perform the necessary control information exchange and communication.
2 Application status of LED intelligent control technology
LED lighting makes the world more energy efficient, and intelligent lighting combined with LED light communication and control is more convenient and controllable. LED lights can transmit information and commands by transmitting network signals, control signals, and modulated signals. In addition to connecting to the network, LED lights can also act as commanders for a variety of household appliances.
The entire intelligent control system can be monitored through a computer network, such as understanding the current working status of each lighting circuit, setting and modifying the scene, controlling the entire system when an emergency occurs, and issuing a fault report. It can be connected to the control system of the building's BA system, fire protection system or security system through the gateway interface and serial interface. The LT-net intelligent lighting control system usually consists of dimming module, switching power module, scene control panel, sensor, programmer. Components such as programming sockets and PC monitoring, and various modules with independent control functions are connected to the computer data line to form an independent lighting control system to realize various intelligent management and control of the lighting system.
In terms of hardware, ZigBee wireless technology, combined with GPRS (or 3G/4G) technology, enables close-range operation, long-distance GPRS control or a combination of far and near communication modes, which can be thousands of miles away. . In terms of software, it is highly integrated in scalable functions, basic requirements (lamp switch), expansion requirements (current, voltage, power factor detection) and innovative requirements (single lamp control, multi-lamp linkage, dimming color adjustment). Meets lighting needs while expanding more features for a better user experience.
2.1 Application category
Intelligent control lighting technology can ensure the best illumination power of the lamp under the premise of ensuring the normal operation of the lamp, which can reduce the illumination glare, make the light emitted by the lamp softer and the illumination distribution more uniform, and save energy 20%-40 %. Intelligent control lighting technology is adaptable, can be used in lighting and hybrid circuits, and can work continuously and stably under various harsh grid environments and complex load conditions, and will effectively extend lamp life and reduce maintenance costs.
2.1.1 point (light) control type
Point (light) control refers to a system or equipment that can directly control a certain lamp. The early lighting control system, home lighting control system and ordinary indoor lighting basically adopt point (light) control mode. The lamp control can be accomplished using only a few electrical switches, wires and combinations. It is the most widely used and basic lighting control and the basic unit of the lighting control system.
2.1.2 Area Control Type
The area control lighting system refers to a system that can complete lighting control within a certain area. It is characterized by direct or indirect control of all the lamps in the entire area according to different functional requirements. Since the lighting control system is basically designed according to the circuit capacity, that is, separately controlled according to each circuit, it is also called a road (line) controlled lighting system.
In general, the road (line) controlled lighting system is composed of a control host, a control signal input unit, a control signal output unit, and a communication control unit. Mainly used in road lighting control, lighting in plaza and public places, large buildings, urban landmark buildings, public events and bridge lighting control applications.
2.1.3 Network Control Type
The network-controlled lighting system uses a computer network technology to network lighting devices in many local or small areas, thereby implementing a unified control lighting control system by a control center. In the lighting control center, the computer control system performs unified control and management on the lighting equipment in the control area. The network control type lighting system generally consists of hardware control system (server, computer workstation, network control switching equipment) and lighting control software (database , control applications, etc.) two major components. The control signal transmission system completes the transmission of the control signal and the feedback signal in the lighting network control system, thereby completing the control of the lighting device in the control area.
The network control switching device actually controls the lighting control system (device) of several small areas of a certain control area. The area lighting control system (device) is a subsystem of the entire networked control system, which can be used as an independent Used by the control system, it can also be used as a terminal device of the networked control system.
Through the entire lighting control system to complete the control of each lamp, the lamp control device is installed on each lamp, and can communicate with the lighting control center through the remote control signal transmission unit, thereby completing the relevant control of each lamp (such as On/off, dimming control, and the monitoring status of each lamp can be monitored through the lighting control center to complete the control of each lamp.