As long as the digital control flexibility allows the OEM to design a controller that can drive a variety of end products, improve design flexibility, in order to bring new intelligent lighting installations and differentiation.
With the lighting industry to LED highbay light technology, but also increase the need for more intelligent controller and driver requirements. Efficient operation of the LED family with the unit can be effectively suppressed the rising electricity costs. Many applications need to provide constant lighting quality, while supporting advanced control functions such as dimming, color temperature equilibrium, and precise blending and so on. Self-diagnosis can be applied to reduce the demand for technical personnel, thereby reducing maintenance costs, remote connectivity has become a routine requirement for these applications.
LED lighting applications in the smart fixed function may need to turn LED driver based on a microcontroller or programmable architecture. Dedicated power electronics microcontroller also be able to control lighting control and communication outside lighting power, enabling lighting applications with higher efficiency and more cost-effective. The conversion to digital control to enhance the flexibility, you can make lighting products to reach a new level of intelligence and differentiation.
Obtain intelligence platform
Lighting industry is rapidly exploit the many advantages of LED technology (see sidebar "LED advantages"). However, LED applications for the need to support the ability to have great differences.
Home Applications include bulb replacement, accent lighting and a small outdoor lighting. Typically, only a few light LED, generally a bunch to the two strings. For this market there is low pressure, generally not used to advanced control functions.
Business applications including fluorescent ballast, bulb replacement, and accent lighting. Only a few light LED, generally a bunch to the two strings. Although the focus on cost, but also pay attention to the energy market. Higher-end applications that require remote connectivity capabilities, as well as some controllers intelligence.
Entertainment applications, including high-end displays and mood lighting. Full control of light intensity and consistent color quality is a basic requirement, while also have remote access, and support for industry-standard protocols such as DALI (Digital Addressable Lighting Interface available) and DMX512.
Outdoor and infrastructure applications, including street lighting and lighting factories and large office buildings. Usually requires a lot of LED, must be supported by a lot of string lights; high brightness LED highbay light is also very common. These applications require remote connectivity capabilities, as well as a high level of control intelligence.
LED-based lighting system is the easiest to use an LED driver, which is usually a fixed-function device, it provides a straightforward, low-cost control methods. Generally, they have a good power efficiency, no software programming. Developers at best decision in selecting a drive or circuit board components when you need to do some specific numerical calculations.
Although the use of simple and clear, but a lot more advanced LED driver system lacks sufficient flexibility. To support a given application or multiple LED Type LED string structure, it may require a different solution. In fact, any changes in the system might need to change drives, such as the number of changes in the LED string, or a device changes the number of LED strings. Thus, a majority of lighting provided by the OEM may require specialized analog driver. If a large number of products, such a requirement would increase the OEM or the supplier's inventory kind of variety, may reduce economies of scale, or lead to higher equipment costs.
On the other hand, intelligent controller is to enable developers to create a more flexible lighting system. In the micro-controller system, code can be configured to support a variety of different types of LED, proprietary power level requirements, different string lengths, and different number of strings without having to make some major changes to the hardware. Systems can be designed to automatically detect the required number of LED driver. Programmable microcontroller system enables advanced features and even dimming and timing functions for more advanced lighting scene control and automatic illumination level.
Flexibility of digital control as long as the OEM to design a controller that can drive a variety of end products. Re-use control IP also can significantly reduce design effort. A flexible controller can reduce the need to inventory the number of devices through economies of scale and reduce the overall system cost.
Integration with the digital control
An intelligent LED lighting system's basic architecture consists of three main parts: power conversion, LED control and communications (Figure 1).
Power conversion stage for the LED provides the correct voltage and current. Start the AC / DC rectifier, and a PFC (Power Factor Correction) level, and then followed by one or more parallel DC / DC conversion stage. Energy-efficient power conversion requirements for these stages accurate and flexible control.
Each part of the main stage requires an intelligent controller, in order to maintain their efficiency and functionality. Fixed-function analog programs may require a separate PFC, DC / DC, LED, and the communication controller. And a dedicated micro-controller power electronics high degree of integration can be achieved, reducing the number of components of the power supply. In fact, the single microcontroller has enough performance, power-optimized peripherals and communication ports can provide a centralized programmable platform to coordinate control of an intelligent lighting system, all three level to deal with the power supply, LED lighting control and communication tasks.
Digital power control is also possible to make the dynamic system to achieve higher conversion efficiency. Although the LED efficiency than conventional light sources significantly improved, thereby correspondingly reducing the use and cost of electricity, but not all LED systems are the same. Digital power control can be done in the LED highbay light dimming systems, changing the color output, or adjust the light intensity output, allowing for higher efficiency power stage. Similarly, in the fixed lighting conditions, the micro controller can be more advanced power level designed to increase operating efficiency. This increase in efficiency is very attractive to the end user, can be two kinds of competition with each other when the LED system is a key point of difference.
Assuming an urban planning to replace 2,000 streetlights, is evaluating two models, the efficiency between 10% difference (Fig. 2). Systems for high efficiency, power input into the system is 178W, and the low efficiency of the system needs to get the same effect 200W 160W light output. This alone is the power supply itself, converted to annual energy cost savings of about 10% can have more, in this case is U.S. $ 33,726. Savings balance exceeds savings with LED systems.
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Benefits of Intelligent
For many applications (including commercial display and entertainment lighting), light quality is very important. At this time, the quality of which the output light intensity and color stability of the capacity. Affect LED performance has three main factors: making a difference, temperature and aging.
Different batches of the LED output may vary widely; using different batches of the same product line, but the LED devices may light quality is different, it is because there is making a difference. In a single device using the same batch of the LED, you can maintain the consistency of quality, if you can not do this, do different batches of LED devices adjacent to the installation, the luminous quality can generate appreciable (and non- acceptable) differences. With the intelligent controller, the system can compensate for any difference do the calibration. Since the completion of this work is the software, so if you need product consistency can be completed during the calibration of the device fabrication process.
As the ambient temperature changes, LED output will change. To compensate for this effect, the system needs to use a sensor to detect the ambient temperature. The microcontroller reads the sensor data, and accordingly adjust the LED driver dynamically calibrate the color and light intensity. Only periodic checks the temperature, so the work load is not high. This also allows the system to monitor the security situation themselves. For example, when LED temperature exceeds a predetermined threshold value, the illumination controller can reduce the light intensity, or turn off a particular LED string, and remotely notify the staff. Extreme heat can cause premature aging of LED to light output degradation. Ensure that the LED does not exceed a certain temperature, can extend its life.
LED aging will affect the light quality, resulting in a color change. For example, the red LED aging faster than the blue LED, a power output or PWM frequency to determine the resulting color drift over time. Intelligent controller can be taken into account aging, color correction curve, resulting in LED systems throughout the life cycle to maintain a consistent light.
Used for quality control of the same technology can also improve the safety and efficiency of luminescence intensity can be adjusted to suit the current ambient light, for example, in stormy weather, street lights may be turned on in advance, or when there is sufficient ambient light, can be lowered brightness to save energy. Traffic lights or special sensors on the street late at night can monitor the traffic situation, if traffic increases, the brightness can be improved street lighting.
In the warehouse, workers may use different space sporadically. Through the indoor inductive sensors being used to only part of the lighting. If at any time, only 50% of the area used in the workshop, the remaining lamp can be turned off to save energy consumption by half.
Also consider the example in Figure 2 lights. In the middle of the night, a lot of bright lights can be dimmed than full, as traffic declined. If there is communication between the motion sensor networks can be dynamically switch lights to meet traffic needs. In order to obtain greater efficiency, 178W shown in Figure 2 to close 25% of the input system of the light, corresponding to 25% of the energy saving, of $ 68,218 per year, calculated with the following formula number: 1,819,160 kWhr / years × 75% / night working hours = 1,364,370 kWhr / Year 1,364,370 kWh r / in × 0.15 美元 / kWhr = 204,656 dollars per year cost of $ 272,874 minus the initial annual cost of $ 204,656 the year after amendment fee = annual savings of $ 68,218 will save hundreds and power efficiency Smart Work savings numbers together, annual savings of $ 101,944, representing about 33% of the system.
Remote Connection
Remote connection is intelligent lighting system, a key performance. Intelligent devices can automatically manage their operation, improve efficiency and quality. But unless the device can communicate with the central controller, otherwise this smart must be well prepared in advance, and only a single device can obtain maximum efficiency.
Lighting systems by networking the various components, developers can coordinate the whole apparatus of the device operation. Doing so can achieve a completely new features, including remote dimming, remote shutdown and emergency control. The operator can adjust the position from a central control group throughout the illumination intensity of light, without the need to individually adjust each lamp.
For most functions, each part must not only receive information, but also be able to send back information to the operator. Thus, the street can do simple self-diagnosis to determine the LED burned out, or performance below a minimum quality threshold, and then inform the operator perform necessary maintenance. In this way, you do not need to do regular maintenance technicians to ensure that the equipment to work properly, the operator can remotely make checks only when a serious problem to a certain extent, he had sent technicians to go. This remote monitoring and long working life of LED combination can greatly reduce maintenance costs and increase operational safety, because you can immediately identify the fault.
Remote Control also enables other advanced features that work efficiency and cost has a significant impact, can dynamically control lighting, as well as the multiple networked lighting point to somewhere a control point, the control point may be related to the actual lighting distant location. For example, street lights may need to make adjustments in accordance with daylight saving time, then do not need to send technicians to each of the control box, the lighting system operator can modify all the lights in the system schedule. Operators can also be easily implemented temporary changes in the schedule, for example, in the late field provided after the end of the Games, road lighting, or to keep the factory busy season lighting. Remote control but also in the direct control of light emergency situations, thereby enhancing safety.
Commercial and industrial in intelligent lighting and a more useful function, which is to accurately track power situation. For example, in the past streetlights pay rate is fixed, and with intelligent lighting controller, municipal operator can track the actual power consumption, the data sent to a central point of control to ensure that the city does not exceed the actual payment of electricity bills amount.
The actual usage data recording allows the operator to precisely adjust their operational cost planning, maintenance resources and future investment. It can also achieve more advanced, proactive diagnostics. Dynamic high energy consumption or replace the lamp requires a lot of these problems if they can advance to inform the operator, you can push them before high operating and maintenance costs, to be addressed as soon as possible.
Connectivity is also the basis for many lighting systems, especially in entertainment applications. This market has been a lot of communication standards, including DALI, DMX512 and KNX, which device will support these protocols have a competitive advantage.
Powerline Communication
PLC (Power Line Communication) network device that allows for the operation of the device to the same power supply line, without the need for separate installation cable as the communication link, which is an important technology lighting applications. A full set of features that do not require the application of PLC, PLC-Lite is a flexible alternative to it at a lower data rate provides the simplicity and reduce protocol overhead. Developers can link a much lower cost to achieve each PLC-Lite, smaller than some of the more complex PLC variants such as G3 or PRIME (Power Line Smart reading performances of).
Because PLC-Lite is not a fixed standard, developers can take advantage of its flexibility to achieve optimal characteristics of a channel, which need to be addressed in order to improve the power line interference environment link robustness. PLC-Lite is ideal for low-cost but need to have a strong communication channel applications such as home networks single lamp or wall switch.
Developers can also use radio frequency technology to wirelessly connect various devices. Modular structure, the device can use any connection best suited to customer needs. Whether the link is the use of PLC or Wi-Fi, data through a standard I2C or SPI port is sent to the microcontroller.
Integration advantages
To reduce system cost, developers need a sufficient capacity of the micro controller, micro-controller can be achieved with a power level, LED highbay light control, sensor input and remote connectivity. Typically, a system controller integrates all design than the single-chip multi-MCU solution to lower prices.
However, there are some illumination system high voltage and low voltage, typically in the PFC and DC / DC isolation between there is a boundary (Figure 3). In this case, the use of two micro-controller may be easier, two microcontroller via I2C or SPI interface communication across the isolation boundary. If the design is non-isolated, then use the same only microcontrollers PFC and DC / DC converter function is relatively simple.
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When the LED design uses a single micro-controller, it is best to have a wide range of applications for high-performance architecture, which is designed for digital power control will be able to support a variety of power structures. Integrated micro controller preferably has the following features:
(1) Accuracy PWM generation, and duty cycle control, and precision dead zone, in order to achieve the power level more efficient and high-performance control. Advanced PWM provides a very accurate color output and generates dimming level capabilities. For example, by 16 PWM outputs, the microcontroller can independently control up to 16 individual LED strings.
(2) provide up to 4.6M samples / s sampling and conversion speed ADC. A / D module with PWM combination enables engineers to create a tight feedback loop system to changing working conditions and surroundings react quickly.
(3) built-in fail-safe mechanism to deal with overcurrent and overvoltage conditions. PWM fault tripping zone allows the system to unexpected system conditions, bypassing the CPU and use a pre-set state alternative PWM signal, thereby preventing damage to the system.
(4) I2C, SPI, UART, USB and CAN peripheral has been production-ready firmware drivers, to meet the connectivity needs of most LED applications.
Texas Instruments C2000Piccolo platform is designed for LED lighting integrated microcontroller example (Figure 4) .32-bit microcontroller core provides TMS320C28x device in digital signal processing, an arithmetic operation with optimized for interrupt-driven real-time control architecture, and can respond to change events programmable flexibility. TI's integrated CLA (control regulations tooth accelerator) is an independent core, without increasing the cost or overhead MCU only the second premise, to achieve the dual-core operation. CLA can be run independently C28xDSP, which is designed to perform highly efficient parallel processing.
Piccolo microcontroller will be a function of the lighting system is divided into core and CLA C28x core with a chip to achieve a complete smart LED controller. For example, CLA PLC algorithm can be used to run while C28x core is focused on the digital power conversion and control of the LED string. For applications requiring higher bandwidth or more advanced PLC application, there is a use for the Piccolo F2806x microcontrollers integrated Viterbi complex arithmetic unit (VCU). PLC algorithms specifically for the VCU made adjustments, compared with no VCU, PLC processing speed can make up to six times.
Many companies offer software and hardware developers to help engineers evaluate and design a variety of LED lighting applications, from small voltage auxiliary power supply system, until there is a remote connection function fully AC high voltage power supply system. TMDSIACLEDCOMKITacLED Lighting and Communications Developer's Kit to provide a complete platform to accelerate the AC-powered intelligent lighting product design, it has a high efficiency (about 90%), and fully supports remote access and lighting communications protocols.
More info you can visit: www.lead-lighting.com
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