LED driver has been widely used in many industrials includes the lighting business and you must be upset about lots of LED driver fail

Basically, the main function of the LED driver is to convert the input AC voltage source into a current source whose output voltage can vary with the forward voltage drop of the LED.

As a key component in LED lighting, the quality of the LED driver directly affects the reliability and stability of the overall. Based on LED driver and other related technologies and customer application experience, this paper analyzes the failures of lamp design and application:

1. The range of variation of the LED lamp bead is not considered, resulting in low efficiency of the lamp and even unstable operation.

The LED lamp load end is generally composed of a number of LED strings in parallel, and working voltage is Vo=Vf*Ns, where represents the number of LEDs connected in series. The of the LED fluctuates with temperature. In general, at a constant current, becomes low at high temperatures, and becomes at low temperatures. Therefore, the operating voltage of the LED lamp at high temperature corresponds to and the load voltage of the LED lamp at low temperature corresponds to VoH. When selecting an LED driver, consider that the driver output voltage range is greater than VoL~VoH.

If the maximum output voltage of the selected LED driver is lower than VoH, the maximum power of the may not reach the actual power required at low temperature. If the minimum voltage of the selected LED driver is higher than the driver output may exceed the working range at high temperature. Unstable, the lamp will flash and so on.

As shown in Figure 1, the red curve shows the power derating curve of the LED driver’s load as a function of ambient temperature at 120Vac input. When the ambient temperature is below 50 °C, the drive allows 100% full load. When the ambient temperature is up to 70 °C, the drive can only to 60% load. When the ambient temperature changes between 50-70 °C, the drive load will follow. The temperature rises and decreases linearly.

The blue curve shows the power derating curve of the LED driver’s load as a function of ambient temperature when 230Vac or 277Vac is input. The principle is similar.

As shown in Figure 2, the blue curve shows the curve of the LED driver’s output power as a function of input voltage at an ambient temperature of 55 °C. When the input voltage is 140Vac, the load of the driver allows 100% full load, and the input voltage is lowered. If the output power is constant, the input current will rise, resulting in increased input loss, reduced efficiency, and increased device temperature. Individual temperature points will be May exceed the standard and may even cause device failure.

Therefore, as shown in Figure 2, when the input voltage is less than 140Vac, the output load of the driver is required to decrease linearly as the input voltage decreases. After understanding the above curve and the corresponding requirements, when selecting the LED driver, it should be considered and selected according to the actual ambient temperature and input voltage, and the margin should be appropriately set. the LED, avoid introducing some indicators that do not conform to the principle of working characteristics, and avoid the indicators far exceeding the actual demand, and avoid excessive-quality and waste of cost.

3, do not understand the working characteristics of LED

Some customers have requested that the input power of the lamp be a fixed value, fixed by 5% error, and the output current can only be adjusted to the specified power for each lamp. Due to the different working environment temperatures and lighting times, the power of each lamp will vary greatly.

Customers make such requests, despite their marketing and business factor considerations. However, the volt-ampere characteristics of the LED determine that the LED driver is a constant current source, and its output voltage varies with the LED load series voltage Vo. The input power varies with Vo when the overall efficiency of the driver is substantially constant.

At the same time, the overall efficiency of the LED driver will increase after thermal balance. Under the same output power, the input power will decrease compared to the startup time.

Therefore, when the LED driver application needs to formulate the requirements, it should first understand the working characteristics of the LED, avoid introducing some indicators that do not conform to the principle of working characteristics, and avoid the indicators far exceeding the actual demand, and avoid excessive-quality and waste of cost.

4, failure in the test

There have been customers who have purchased many brands of LED drivers, but all samples failed during the test. Later, after on-site analysis, the customer used the self-internal voltage regulator to directly test the power supply of the LED driver. After power-on, the regulator was gradually adjusted from 0Vac to the rated operating voltage of the LED driver.

Such a test operation makes it easy for the LED driver to start and load at a small input voltage, which causes the input current to be much larger than the rated value, and the internal input related devices such as fuses, rectifier bridges, The thermistor or the like fails due to excessive current or overheating, causing the drive to fail.

Therefore, the correct test method is to adjust the voltage regulator to the rated operating voltage range of the LED driver and then connect the driver to the power-on test.

Of course, technically improving the design can also avoid the failure caused by such test misoperation: setting the startup voltage limiting circuit and the input Undervoltage protection circuit at the input of the driver. When the input does not reach the startup voltage set by the driver, the driver does not work; when the input voltage drops to the input under-voltage protection point, the driver enters the protection state.

Therefore, even if the self-recommended regulator is used in the customer test, the drive has self-protection function and will not be invalid. However, customers must carefully understand whether the LED driver products purchased have this protection function before testing (taking into account the actual application environment of the LED driver, most LED drivers do not have this protection function).

5, different loads, different test results

When the LED driver is tested with an LED lamp, the result is normal. When the test is carried out with an electronic load, the result may be abnormal. Usually, this phenomenon has the following reasons:

(1) The output voltage or power of the output of the driver exceeds the working range of the electronic load meter. (especially in CV mode, the maximum test power should not exceed 70% of the maximum load power, otherwise, the load may be over-power protected during loading, causing the drive to not work or load.)

(2) The characteristics of the electronic load meter used are not suitable for measuring the constant current source. The load voltage position jump occurs, causing the drive to not work or load.

(3) Because the input of the electronic load meter will have a large internal capacitance, the test is equivalent to connecting a large capacitor in parallel with the output of the driver, which may cause unstable current sampling of the driver.

Because the LED driver is designed to meet the operating characteristics of LED luminaires, the closest test to actual and real-world applications should be to use LED bead as the load, string on the ammeter and voltmeter to test.

6. The following conditions that often occur can cause damage to the LED driver:

(1) The AC is connected to the DC output of the driver, causing the drive to fail;

(2) The AC is connected to the input or output of the DC/DC driver, causing the drive to fail;

(3) The constant current output terminal is connected with the modulating light, causing the driver to fail;

(4) The phase line is connected to the ground line, resulting in no output of the driver and charging of the outer casing;

7, the phase line is wrong

Generally, the outdoor engineering application is a 3-phase four-wire system. Take the national standard as an example. The rated working voltage between each phase line and the neutral line is 220Vac, and the voltage between the phase line and the phase line is 380Vac. If the construction worker connects the input of the drive to the two-phase lines, the power input to the LED driver exceeds the standard and the product fails.

As shown in the figure above, V1 represents the first phase voltage, V2 represents the second phase voltage, and R1 and R2 represent the LED drivers normally installed in the line. When the neutral line (N) on the line is disconnected, the drivers R1 and R2 on the two branches are connected to the 380Vac voltage in series. Because of the difference in input internal resistance, when one of the drivers is charged to start, the internal resistance becomes small, and the voltage may be mostly applied to the other driver, causing its overvoltage damage to fail.

Therefore, it is recommended that the switch or circuit breaker be broken together on the same distribution branch, and not only the neutral line can be disconnected. Do not place the distribution fuse on the neutral line. Avoid contact with the neutral line on the line.

8, the grid fluctuation range is beyond the reasonable range

When the wiring of the same transformer grid branch is too long and there is large power equipment in the branch when the large equipment starts and stops, the grid voltage will fluctuate drastically, and even the grid will be unstable. When the instantaneous voltage of the power grid exceeds 310Vac, the drive may be damaged (even if there is a lightning protection device, because the lightning protection device is dealing with pulse spikes of several tens of uS level, and the power grid fluctuation may reach several tens of mS or even several hundred mS).

Therefore, special attention should be paid to the large-scale electric machinery on the street lighting branch network. It is best to monitor the fluctuation range of the power grid or the power supply of the separate grid transformer.

9, the line frequently trips

The lights on the same branch are connected too much, resulting in overloading of the load on one phase and uneven distribution of power between the phases, causing the line to trip frequently.

10, drive cooling

When the drive is installed in a non-ventilated environment, the drive housing should be in contact with the lamp housing as much as possible. If possible, apply thermal grease or thermal pad on the contact surface of the housing and the lamp housing to improve the heat dissipation performance of the driver, thus ensuring the driver’s life and reliability.

In summary, the LED driver has many details to be aware of in practical applications. Many problems need to be analyzed and adjusted in advance to avoid unnecessary failures and losses!

ARCATA ELECTRONICS INC

Shanghai Arcata Electronics Inc., formed in mid of 2005, specializes in electronics manufacturing services (EMS). It located in QingPu Liantang Industrial Park. By Feb of 2006, Arcata had established itself as a newly and professional company with sophisticated manufacturing facility, and has been producing high quality electronic products.

CHANGZHOU HIPOWER ELECTRONIC TECHNOLOGY CO LTD

Hipower-tek is a leading edge LED manufacturing company, specializing in the development and production of high end commercial and industrial lighting products. Since the establishment in 2012, our company’s performance has improved rapidly year by year.And also, we have become a recognized technologic-leading company in LED industry.

Hipower-Tek have self-developed various specifications and wide input voltage range LED drivers. Our products possess features such as high efficiency, superior reliability and long durability. Our professional R&D team guarantees the advancement and diversity of our technology. We have expanded our products to PLC dimming control, emergency power supply, led retrofit kit etc.

Hipower-Tek always holds the concept that constant innovation, satisfying service and good credibility mark the excellence of a company, so we intend to provide you the best solution, customized service and quick respond.

The talented crew, advanced technology and scientific management contributes to Hipower-Tek ‘s rapid development, along with our pragmatic and aggressive entrepreneurship comprise the core competence of our company.

We may not have a glory history,.but we believe that with our ideas and incredible products we will be making history in the near future

DONGGUAN BECKY ELECTRONICS TECH CO LTD

Dongguan Becky Power, established in 2008 with registered capitals of 10 million RMB and 10,000 square-meter factory areas, is a high quality switching power supply and LED lighting driver supplier integrating part design, developing and manufacturing. As a National High-tech Company of 500 employees, Becky’s products are extensively applied on audios, LED lighting devices and household appliances etc..

Ever since its foundation, Becky has been insisted on the philosophy of “Client First, Excellent Quality, Professional Innovations & United Cooperation”, operates in strict accordance with the ISO quality system and environmental protection system, and passed the ISO9001:2008 assurance system in 2009. All Becky’s products meet ROHS+REACH restrictions. Becky believes innovation triggers company development, and has developed various independent patented technologies through years of self-research & developments. Embraced by the experienced R&D team as well as management team, the Company is capable of designing fashion and novel products as well as saving energy. With “V”as the energy saving principle, Becky has achieved UL, FCC, GS, CE-LVD, CB, EMC, RCM, 3C, PSE approvals all over the world,and gained trust and recognition of inland& overseas customers.

We adhere to the quality policy of “market-oriented, overall participation, continuous improvement, innovation and full customer satisfaction”, and are committed to providing cost-effective products and solution, continuously improving product quality, presenting a full range of choices for customers.

EPTRONICS INC

EPtronics, Inc. is a leading innovator, designer and manufacturer of LED power supplies. We develop and continuously grow our line of LED drivers based on field applications and input from customers including many leaders in the LED lighting industries.

As one of the few power conversion companies in the world with an exclusively dedicated focus in LED illumination power supplies, we take full advantage of our experience and resource in lighting power supply application as to offer products with exceptional performance. For the last few years EPtronics has made significant investment for being able to offer products with advanced technology, high performance, reliability and a variety of selections for fast evolving and growing LED applications. With multiple design centers led by our U.S. design team and supported by our own cost effective factories that specialize in power supply manufacture, we are able to offer the greatest value for innovative and flexible models.

With world-wide headquarters in Los Angeles, our sale and design team are just a phone call away from offering you off-the-shelf LED drivers with the regulatory approvals that allow them to drop into your designs. If one of our current models is not perfect for your application, we can modify them or produce a unique LED driver to fit your needs.Visit our product page to select the driver that fits your needs, or let our sales team find the perfect LED driver for your desired application.

…EPtronics LED drivers, designed with customer’s end product in mind.

Inventronics (Hangzhou) Inc

Established in 2007, Inventronics is one of the world’s top LED driver manufacturers specializing in building innovative, highly reliable and long-life products that are certified compliant to all major international safety and performance standards. We design our own drivers at our headquarters in Hangzhou, China and have specialized teams that focus on low, mid and high-power designs as well as teams for network controls and accessory products. Our drivers are manufactured within our Science and Technology Park in Tonglu, China. We encourage factory visits for a first-hand experience of our commitment to quality.

We provide superior products, exceptional technical support, and best-in-class customer service. We also seek to create value for our customers by working to extend and increase the return on investment for solid-state lighting systems.

Inventronics sole focus on LED drivers and accessories enable us to stay at the forefront of technologies to better empower the next generation of LED luminaires. This includes:

• An in-house R&D team with over 160 employees
• 241 patents
• Broad portfolio suitable for nearly any application Customer solutions
• 2 safety labs (UL and TUV Rheinland) for expedited product release
• Exceptional product development and design qualification processes
• In-house production line with a monthly capacity of 1 million units
• Extensive product testing
• On-going reliability testing

MW MCWONG INTERNATIONAL INC

For over 30 years, McWong International, Inc. has been bridging the best of East and West in order to achieve for our valued customers an unparalleled mix of quality, service and innovation. A California corporation, McWong has grown to become a leader in the design and manufacture of high quality lighting control equipment and related electrical components. Our teams on both sides of the Pacific take great pride in the fact that the majority of our growth comes from organic nurturing of business with long-term, world-class customers. Reliable, competitive products paired with committed customer service year in and year out have enabled sustained growth over three decades.

Today, the pace of technological change has quickened and competition continues to intensify. We are meeting these challenges through heightened investment in capable individuals, promising technologies and advanced manufacturing facilities. McWong’s disciplined approach to quality management, customer service, and cost control ensures that we are well-poised to accelerate our pace of growth as we partner with our stakeholders to achieve a brighter, more sustainable, more successful future.

Shenzhen Angui Technology Co Ltd

Shenzhen Angui Technology Co., Ltd. (AGT for short) is a professinal high technology enterprise engaged in LED power supply, custom-made power supply and magnetic components research, development, production and sales.
With the development of five years, we have formed LED tube driver, LED panel light power supply and LED down light power supply three big series of products. Our Annual production capacity is 3 million units, 80% of these products exported to the countries and regions all over the world, including America, Germany, Russia, Britain, Spain, Japan etc. The products have passed UL、GS、VDE、TUV、3C、FCC、CE,etc.

AGT takes the quality, efficiency, innovation, service as our business philosophy,provides high performance, reliable product as a fundamental, continuous innovation as the backing, fast and efficient way to serve the customers. With “Concentration only for you” as the purpose of enterprise,use professional technology,focused attitude and dedicated spirit, we provide world class LED green products as our own highest pursue.

SHENZHEN BILLDA TECHNOLOGY CO LTD

Shenzhen BillDa technology Co.,Ltd. founded in 2009, It is an enterprise that has passed ISO9001 quality management system

certificationis, BillDa is a high technology enterprise and professional emergency LED driver R&D manufacturer. Our factory has automatic numerical control equipment with high-speed chip placement, reflow soldering, automtic wave soldering, ultrasonic plastic welding and advanced ROHS test equipments. The company has 60 patents on emergency power supply, utility model patents and appearance patents. Our products include LED dimmable drivers, LED emergency drivers, intelligent controllers etc. All products are UL, FCC CE, TUV, CB, CCC, ROHS certified to meet different.

We insist on high technology, excellent quality and superior service as the orientated, providing high-quality LED drivers
and LED emergency driver and best service to our customers, Shenzhen Billda will build a world-class brand.

Shenzhen Fahold Electronics Co Ltd

Shenzhen Fahold Electronics Co.,Ltd.was established in 2010, a factory which integrating the LED Drivers design, R&D and manufacture, passed the ISO9001 quality management system certification. It covering an area of 5000 squre meters, existing staff of 180 workers which including 25 Researchers, 20 quality controls. The production capacity of Fahold are 5 million units per year.

Products passed UL, TUV, SGS, SAA ,CB,CE,ROHS Ceritification.

Products applicable to street light, industrial and mining light, linear light, tri-proof light, flood light , panel light and so on.

Markets are in North America, Europe, Australia, South Korea and other countries.

Quality first, Management excellence; Keep Continually improving, Strive for perfection.

Shenzhen Wei Peng Shiji Technology Co Ltd

Shenzhen Wei Peng Shiji Technology Co.,Ltd (WeledPower) is a national high-tech enterprise specializing in LED Drivers. WeledPower was founded in 2008 and now has become a global to led driver solution supplier, an iconic enterprise in power supply industry in China, a well-known brand in Shenzhen, a famous trademark enterprise in Guangdong Province as well. There are 400 workers, 10,000m2 office and production area, independent and standard LED driver Test Lab in WeledPower. As a professional LED Driver manufacturer and power solution supplier, WeledPower has been focusing on the upmarket LED Drivers and led emergency drivers for 10 years. With the joint efforts of all WeledPower’s people and the recognition and support of nearly one thousand clients, our production capacity have broken through 1,000,000pcs I month.

Shenzhen Xiezhen Electronics Co Ltd

Shenzhen Xiezhen electronics co.,ltd.,founded in 2009,is spercialized in the R&D,productio adn sales of switching power supply,With over 15-year experience in desiga and manufacture of communication power supplies,industrial power supply and LEDdriver,there are more than 200kinds of power supplies in xiezhen production line,in cluding LED driver,intelligent controller,industrial power supply etc.

There are more than 100 R&D staff withmore than 7-year experience developing LED drivver.Xiezhen knows well how to process sophisticated custonized LED driver for customers in 10 working days.There are more than 600 staff in our shenzhen and hunan factories.Xiezhen meets customers requirements on short lead time.There are more than 100QC staff to guarantee the defective rate.

Xiezhen keeps in mind than quality first and customer oriented.Under the operation with ISO 9001:2008.Many of our products gains CE,PSE,UL,TUV-MARK,CB,SAA,GS,SGS,CCC,ROHS.Xie zhen pffers customers great sales

and after-sales experience to finalinze .