Yiguang Technology

According to the latest statistics from the US Department of Energy (DOE), over four billion incandescent bulbs currently in use in American households are dimmable using thyristors. According to the latest forecast from Philips Lighting, LED lighting will occupy up to 50% of the consumer market in 2015.

Controllable silicon dimming has great advantages and huge market demand:

1. Easy to install. At present, incandescent and halogen lamps on the market can be easily replaced with LED lamps without changing the wiring.

2. Dimmers are inexpensive and have a high usage rate.

3. There are many brands of dimmers, which are easy to purchase and have a good market foundation.

4. The energy-saving effect is significant.

5. The dimming effect meets people's habitual needs.

6. Controllable silicon dimming has formed an alliance with incandescent and halogen lamps, occupying a large market share in dimming.

1、 What are the problems with existing thyristor dimming LED lighting

All compatible thyristor dimming LED drivers available in the market:

1. The overall efficiency is very low. 10% -15% lower than constant current LED driver;

2. The fever is very high. More than 50% lower than the driving life of constant current LED;

3. Cannot generate high power, usually less than 20W. Due to low efficiency, high heat generation, and high THD; And many dimmers have a power of over 400W.

4. Dimming curve difference. The dimming range varies greatly among dimmers of different powers and brands;

5. The total harmonic distortion (THD) is significant. The THD value is 100% -400% of that of a constant current LED driver;

6. The compatibility with the dimmer is poor. Flashing, jumping, and slowing down are common issues, and achieving 70% compatibility is already very good;

7. The electromagnetic compatibility (EMC) is very poor. Generally unable to meet FCC and EN55015 requirements;

8. High cost. 20% -100% higher than similar constant current LED drivers;

2、 What is the ideal thyristor dimming LED lighting

1. High efficiency. Higher than or equal to the same type of constant current LED driver;

2. Low fever. The lifespan of the same type of constant current LED driver is greater than or equal to 50000 to 100000 hours;

3. It can achieve power greater than 25W, up to 50W or even 100W. Making thyristor dimming widely used in LED lighting;

4. Deep dimming. The adaptability of dimming range for dimmers of different powers and brands conforms to people's habits;

5. Total harmonic distortion (THD) is better than or equal to incandescent dimming;

6. Good compatibility. Achieve over 99% without issues such as flickering, jumping, slowing down, or difficulty starting;

7. Electromagnetic compatibility (EMC) fully meets common standards such as FCC and EN55015;

8. Reasonable or lower cost. Consistent with the low cost of thyristor dimmers, it is equal to or lower than similar constant current LED drivers;

This type of thyristor dimming LED driver meets people's expectations for dimming products and can be widely used.

In today's rapidly developing LED lighting industry, thyristor dimming products will not disappear from the market. There will be at least 10-20 years of transition time, and a large market demand urgently requires the emergence of ideal thyristor dimming LED drivers.

3、 Yiguang Technology's innovative technology products

Shenzhen Yiguang Technology Company has developed a new type of thyristor dimming LED driving technology with ultra-high efficiency, low harmonic distortion (THD), flicker free (Flicker free), and micro flicker free (Shimmer).

This technology also has the characteristics of deep dimming (1-100%), no buzzing sound, fast low light intensity start, fast dimming without flicker, and MTBF greater than 600000 hours.

This new technology product also has the characteristic of low cost. Meanwhile, this technology makes it easy to control the EMC of thyristor dimming LED lighting.

Due to the adoption of new control technology, the compatibility of the dimmer is significantly better than existing technical solutions, reaching almost 100% compatibility.

By applying this innovative technology, low-cost single-stage PFC technology (Signal stage) can be developed, as well as PFC+PWM two-stage flicker free technology.

The maximum power of commonly used thyristor dimming LED lighting in the market is less than 40W. Due to the high efficiency of this technology, the power output of thyristor dimming products can range from 5W to 100W, or even higher. The controllable silicon dimming LED driver that can achieve the highest power in the world.

Yiguang Technology has collaborated with a well-known semiconductor company in the United States to develop a specialized IC suitable for this technology, making the peripheral circuit simple, using less than 60 parts, and making single-sided PCB design easy.

This innovative technology overcomes a series of disadvantages caused by the use of controllable silicon dimming in LED lighting, making cheap controllable silicon dimming LED lighting have new and abundant market application prospects.

The following table compares the performance of Yiguang Technology's innovative technology products with common similar products in the market

4、 Analysis of Innovative Technologies

Below, analyze and describe the characteristics of this product from several aspects: high efficiency, low THD, flicker free, deep dimming, fast dimming, compatibility, and EMC.

1. Ultra high efficiency and high-power dimming

At present, although multiple multinational chip companies have launched chips and solutions that are compatible with existing thyristor dimming, the Bleeder circuit set up to solve the problem of thyristor stable operation results in significant loss of efficiency and heat generation. In order to limit the peak current of AC and prevent the thyristor from turning off incorrectly, a series power resistor is required to limit the current. All of these will result in very low overall efficiency, severe heat generation, especially for high-power applications. Generally, it is not possible to make thyristor dimming LED drivers larger than 25W.

Due to the presence of these stable circuits, the efficiency will not exceed 80%, and even without the use of a dimmer, these circuits are still working. The iWATT scheme uses MCU detection to improve efficiency when working without a dimmer, but still has low efficiency when working with a dimmer. At the same time, there are also issues of high THD and severe IC heating, which cannot be balanced.

The innovative thyristor dimming technology of Yiguang Technology, including no discharge circuit and infinite current circuit, is intelligently controlled by a dedicated IC to ensure stable operation of the thyristor. It effectively transfers the current required for stable operation of the thyristor to the output LED, greatly improving efficiency. And the efficiency index is higher than that of PSR constant current single-stage PFC.

Yiguang Technology has developed a series of products including 12W, 20W, 30W, 40W, 50W, 75W, and 96W using this new technology. The 12W product has a working efficiency of up to 89% without a dimmer, and up to 87% with a dimmer, making it the most efficient product on the market currently.

Due to its high efficiency, this technology can achieve high-power applications. At present, Yiguang Technology has achieved 75W thyristor dimming LED driver products. The working efficiency without dimmer is as high as 89%, and the working efficiency with dimmer is as high as 87%, making it the only technology product with the highest efficiency and maximum power in the global market.

Due to its high efficiency, this technology can achieve high-power applications. At present, Yiguang Technology has achieved 96W thyristor dimming LED driver products. The working efficiency without dimmer is as high as 89%, and the working efficiency with dimmer is as high as 87%, making it the only technology product with the highest efficiency and maximum power in the global market.

Figure 1 shows a comparison of typical efficiency curves for 20W dimming products.

From the above figure, it can be seen that Yiguang Technology's 20W new technology thyristor dimming product has a maximum efficiency of 89%, including thyristor dimming. Even in low dimming, it still maintains a high efficiency.

However, the maximum efficiency of other controllable silicon dimming products is only 78%, and the smaller the dimming, the more efficiency decreases.

2. Low harmonic technology (THD), flicker free (Flicker), and flicker free (Shimmer)

Low harmonic is an important requirement in the American Energy Star and DLC standards.

The quality of the AC current waveform can accurately reflect the technical performance of the thyristor dimming LED driver.

Below is a typical AC current waveform of a widely used thyristor dimming LED product in the market:

Figure 2: TRIAC Dimming AC Current Waveform (Leading Edge)   ELV Dimming AC Current Waveform (Trailing Edge)

From the waveform of this AC current, it can be seen that the TRIAC dimming has severe overshoot of the turn-on current and produces severe current ringing, which easily fails to meet the holding current (Latch) condition of the thyristor and leads to unstable turn-on. And during low-temperature operation, the holding current (Latch) and holding current (Hold) of the thyristor increase, making it more prone to unstable turn-on and premature turn off phenomena, resulting in flickering of dimming. Due to different brands and powers of thyristors, their holding current (Latch) and holding current (Hold) are also different, and this technology product has low compatibility with dimmers.

Under such AC current conditions, THD performance is poor. So, a large number of thyristor dimming products work on the same power grid, which is severely polluted, causing interference and unstable operation of other electrical appliances. At the same time, products with this technology have a high peak AC current (5 times the normal peak current), which can easily damage the thyristor dimmer.

Another typical AC current waveform of thyristor dimming LED products widely used in the market:

Figure 3: TRIAC Dimming AC Current Waveform (Leading Edge)  ELV Dimming AC Current Waveform (Trailing Edge)

From this AC current waveform, it appears as a short-term peak turn-on, with high current and short duration, and severely insufficient and incomplete turn-on phase.

Although the holding current (Latch) condition of the thyristor is ensured to maintain normal turn-on in each cycle, it cannot maintain full phase conduction, resulting in low overall efficiency and high peak current, which is acceptable for low-power applications. However, low efficiency and higher peak current are completely unacceptable for high-power operation.

The THD performance of this dimming technology is very poor, and its widespread application causes significant pollution to the power grid. High peak currents can easily damage the dimmer.

Due to incomplete phase turn-on, small current turn-on is prone to asymmetry, resulting in low light intensity flashes (Shimmer) or slow light intensity changes.

The following is the AC current waveform of Yiguang Technology's new technology dimming:

Figure 4: TRIAC Dimming AC Current Waveform (Leading Edge)  ELV Dimming AC Current Waveform (Trailing Edge)

From the AC current waveform, it can be seen that the current overshoot of Yiguang Technology's new technology products is very small, the phase turn-on is sufficient and complete, the THD can reach the minimum value of thyristor dimming products, and there is no current ringing. The waveform of the dimming AC current is almost identical to that of incandescent lamps.

Under this current waveform, the thyristor opens and conducts stably, without flickering or micro flickering, and has the best dimming effect.

The thyristor dimming product using this technology has a very small peak current, minimal pollution to the power grid, and the dimmer works reliably and is not easily damaged.

3. Deep dimming technology

Deep dimming technology has always been a challenge in thyristor dimming products.

Due to the differences in power and brand of thyristor dimmers, there are significant differences in the maximum and minimum turn-on phases of dimming. Moreover, these differences can lead to significant differences in maximum and minimum dimming for products that rely on phase angle dimming. The consistency of thyristor dimming in LED lighting product applications is often poor, with maximum dimming less than 85% and minimum dimming greater than 30%, resulting in poor dimming effects.

In response to the above situation, Yiguang Technology uses MCU processing technology. When the phase is fully turned on at 180 degrees, the maximum output is used for phases greater than 140 degrees, and logarithmic compensation is used for dimming phases less than 40 degrees. This ensures that different dimmers have the characteristic of deep dimming.

The following figure shows a typical dimming curve of a product using this compensation technology.

The following figure describes the effect of using common dimming curves with common Lutron and Leviton dimmers.

The dimming range using the Leviton dimmer is 1% to 100%, while the dimming range using the Lutron dimmer is 1.7% to 49%. Obviously, this dimming effect is unacceptable.

The following figure describes the effect of using common Lutron and Leviton dimmers on the deep dimming curve with the new technology of Yiguang Technology.

The dimming range using a Leviton dimmer is 2% to 98%, while using a Lutron dimmer is 7% to 95%. Obviously, this dimming effect is good.

4. Rapid dimming flicker free technology

Fast dimming is common in practical use. The commonly used thyristor dimming technology, as shown in Figures 2 and 3, requires balancing the 15Hz bandwidth of PFC and handling the holding current (Latch) and holding current (Hold) of the thyristor to ensure the stability of dimming. The system response speed is generally less than 10Hz. Therefore, during rapid dimming, significant overshoot will occur, and the holding current (Latch) and holding current (Hold) of the thyristor cannot be maintained, resulting in flickering instability and even instability that cannot be stabilized.

The new technology of Yiguang Technology uses MCU control technology with phase preset and fast response. The system response speed is greater than 20Hz, and flexible transformation control is adopted to ensure that the current output during fast dimming is stable and does not produce overshoot and flicker.

5. Compatibility

Due to the adoption of new control technology, the stable working conditions of the latch current, latch time, and hold current of the thyristor can be met at any time, whether it is the maximum conduction angle, the maximum 90 ° conduction angle of the impulse current, or the minimum conduction angle. Even when using a high-power 700W dimmer for low-power LED lighting less than 3W, it can still meet the requirements. So, its thyristor compatibility is much better than the current thyristor dimming solutions of world-renowned brands, and it can be almost 100% compatible.

6. EMC technology

The application of any new technology must meet the corresponding product standards.

Another main feature of the thyristor dimming technology innovatively developed by Yiguang Technology is its easy to meet EMC requirements.

The thyristor dimmer essentially only operates stably with a resistive load and a minimum load greater than the specified value. Due to the fact that the thyristor dimmer is driven by a rectifier filter circuit, it exhibits capacitive behavior, resulting in discontinuous current flowing through the thyristor dimmer and causing it to fail to operate stably.

At present, the controllable silicon dimming solutions of world-renowned brands use various technical means to simulate resistive characteristics, and adopt discharge circuits and current limiting circuits to meet the stable working conditions of controllable silicon. In order to reduce the sacrifice of efficiency, it is necessary to avoid using or reduce X capacitors as much as possible, which will inevitably make it difficult for products to pass through EMC conduction and radiation. Products with less than 10W can barely pass through EMC by increasing common mode and differential mode inductance, but products with more than 20W are difficult to pass through EMC due to high power and interference.

And this innovative technology of Yiguang Technology completely breaks away from traditional thinking, with no discharge circuit and infinite current circuit. Through intelligent control of dedicated IC, it effectively transfers the current that the thyristor needs to work stably to the output LED, still ensuring the stable operation of the thyristor. Not only does it greatly improve efficiency, but it also allows the addition of X capacitors to improve EMC without sacrificing efficiency. This revolutionary innovative technology has achieved the goal of solving EMC problems without sacrificing efficiency at all. The LED driver with thyristor dimming has truly achieved ideal and practical implementation.

Yiguang Technology has completed the productization of high-power 40W, 50W, and 96W thyristor dimming LED drivers, fully meeting the requirements of FCC and EN55015.

5、 Message

Due to its traditional dimming technology, thyristor dimming has the advantages of low cost, easy installation and use, and ease of purchase. And it has long formed an alliance with incandescent and halogen lamps, occupying a large market share in dimming. In the original market where incandescent and halogen lamps are being phased out, it is not possible to immediately exit the thyristor dimming market, which has led to a 5-10 year or even longer historical stage for the replacement and compatibility market of thyristor dimming LED.

After a year of research, Yiguang Technology has truly solved multiple technical bottlenecks in thyristor dimming LED driving, making thyristor dimming LED lighting practical and idealized. People no longer criticize the many shortcomings of thyristor dimming LED lighting, but fully enjoy the affordability and convenience brought by controllable thyristor dimming.

This new technology product, due to the use of dedicated ICs, requires fewer parts, has high reliability, and MTBF greater than 600000 hours. Products below 50W only use single-sided PCB design, which is cost-effective and matches the low cost of thyristor dimming. The designed LED lamps have significant cost advantages.