1. Project basis 1.1. Project purpose and significance With the widespread use of high-power LEDs in lighting decoration and lighting, high-power LED drivers are becoming more and more important. Using high-voltage AC to drive high-power LEDs needs to solve the problems of voltage reduction and constant current, and the reliability of the entire LED driver. In the field of LED green lighting, energy saving must be reflected, and high efficiency and power factors must be achieved. Under normal use, the life span of the LED is very long. To make the entire lamp life long, the life span of the entire LED driver should be considered in the circuit design. In the field of LED lighting, to reflect the characteristics of energy saving and long life, it is very important to choose LED drivers. Without good driver matching, the advantages of LED lighting cannot be realized. 1.2. Current status and trends of technology development at home and abroad At present, the development of foreign AC LED drive power supplies is relatively mature, featuring high reliability, high efficiency, high power factor, and long life. The only disadvantage is that the price is very high, which is 3 to 4 times more expensive than the general driving power supply, which increases the overall cost of LED lamps and is difficult to apply on a large scale. Most of the domestic LED manufacturers use outsourcing of power supplies, and there are very few that actually develop and produce LED drive power by themselves. Most of these manufacturers want to invest a small amount of money and recover them immediately, and they can make a profit. This determines that they are unwilling to make long-term investments, just like power supplies, they don't want to spend money on custom-made models. It is this rapid assembly that has led to the root cause of the endless quality problems of the current LED lamps. At present, the domestic manufacturers that develop LED driver power supplies are mainly professional manufacturers of power supplies, and they only produce a few general specifications and models, and they can’t match thousands of LED lamps. Naturally, all aspects of performance are not up to the design. Claim. 1.3. Analysis of the industrialization prospect of the project The power supply is the main component of the LED lamps, and it must be used together with the LED lamps. However, the successful research and development of the project has greatly improved the overall quality of LED lamps, thereby enhancing the competitiveness of the products. Therefore, the industrialization prospect of the project should be the prospect of LED lamps, and the development prospect of LED lamps is agreed by the whole world. It will be the "third generation" revolutionary light source after incandescent lamps and fluorescent lamps, and the prospects are very bright. 2. Research and development content, methods, technical route 2.1. Main research content 1) Design according to the working characteristics of LED lights to improve the reliability of LED lights. Many engineers believe that the 350mA LED must have a constant current of 350mA, and the 700mA LED must be equipped with a 700mA driver. Actually this kind of view is wrong. In high-power LED applications, the current that the LED can withstand has a certain relationship with temperature. In our design, considering that the lamp body may reach 50 degrees, the 3W LED driver is designed to be about 600mA. In addition, in practical applications, the surge voltage of the power grid may exist. Especially in the thunderstorm season, the surge voltage of lightning will be conducted through the wires. When designing the power supply and LED lamps, consider adding a surge generator to the entire product to avoid certain damage when abnormal. 2) Improve the power factor of the power supply. The power factor is the cosine of the phase angle between the voltage and current waveforms applied to the load (if the phase angle difference between the voltage waveform and the current waveform is φ, then cosφ is the power factor of the power supply). One of the results of the phase difference between the voltage and current waveforms applied to the load is a reduction in power supply efficiency, that is, more power is required to generate the required power. The result is another and more serious consequence, that is, the difference in voltage and current waveforms produces too many high-order harmonics. A large number of high-order harmonics are fed back to the main input line (grid), causing the grid to be polluted by high-order harmonics and become a hidden danger of vicious accidents. At the same time, such high-order harmonics will also disturb the sensitive low-voltage circuits in the control system. As the concept of energy saving gains popularity, the development of high-power LEDs has become more mature, and the indicator of “power factor” has also been raised by the LED power drive industry. The actual power in an AC system is equal to the power multiplied by the power factor. At present, almost all power supplies have power factor indicators. The power factor of traditional energy-saving lamps in my country is 0.5, while the power factor of the driver developed by our company is greater than 0.90. 3) Improve the efficiency of the power supply. The power consumption of the driving power supply includes the fixed loss caused by the parasitic resistance of semiconductor switches, magnetic components and wiring, and the switching loss during switching operations. For the fixed loss, since it mainly depends on the characteristics of the component itself, it needs to be suppressed by the improvement of component technology. In terms of magnetic components, there has been a long history of research on low-loss winding methods that take into account the skin effect and the adjacent wire effect. In order to reduce the switching loss caused by the switching surge caused by the leakage inductance of the transformer, new circuit technologies such as a snubber circuit with a surge energy regeneration function have been developed. The following are circuit and system methods to improve the efficiency of switching power supplies: Method 1: ZVS (Zero Voltage Switching), ZCS (Zero Current Switching), etc. use resonant switching to reduce switching losses. Method 2: Use Edge Resonance represented by an active clamp circuit to reduce switching loss. Method 3: Reduce the fixed loss by extending the on-time of the switching element to suppress the peak current. Method 4: In low-voltage and high-current situations, improve the synchronous rectifier circuit to reduce the fixed loss. Method 5: Use the parallel structure of the converter to reduce the fixed loss. 4) Extend the service life of the power supply. Everyone knows that LEDs are semiconductor materials, and under certain conditions, their life span can reach 100,000 hours. If the entire LED lamp has to last such a long time, the structure of the entire power supply must be changed. Traditional power supplies have high-voltage electrolytic capacitors at the input end. The longest life of good high-voltage capacitors is less than 10,000 hours, and the normal ones are 4000 hours and 6000 hours. In the field of LED lighting, if you consider the traditional power supply method, it is obvious that its life will be very short. We consider this factor in the design, and use metal capacitors in the design. Because there is no electrolyte in the metal capacitors, the entire capacitor life is up to 50,000 hours. With this change, our new generation of LED drivers can reach at least 30,000 hours. So as to meet the needs of the entire LED lamp. 2.2. The key technology to be solved The reliability of the power supply is mainly affected by temperature. Excessive temperature reduces the life of the electrolytic capacitor inside the power supply, which will cause the power supply to fail quickly. It can be said that the electrolytic capacitor is the bottleneck restricting the life of the LED power supply. But the longest life of a good high-voltage capacitor is less than 10,000 hours, and the normal ones are 4000 hours and 6000 hours. If you consider the traditional power supply in the field of LED lighting, obviously its life span will be very short. Therefore, how to extend the life of the capacitor through a new design is the key technology of the LED drive power supply. 2.3. The proposed method, technical route, process flow and step-by-step implementation plan to improve the overall quality of LED lights, the key is to extend the life of the LED drive power supply, and the life of the power supply has a great relationship with the temperature. So the key lies in how to reduce the heat generation and thermal management of the power supply. We plan to take the following steps to reduce the heating of the power supply: 1) Reduce the temperature rise of the LED chip. Because most of the current LED lamps adopt an integrated design, the heat of the power supply will be transferred from the chip in addition to self-heating. Therefore, the temperature of the power supply can be reduced indirectly by reducing the temperature rise of the LED chip. 2) Improve the efficiency of the power supply. The main reason for the heat generation of the power supply itself is that its own components consume a certain amount of power, and improving the efficiency of the power supply can reduce the consumption of these powers, thereby reducing the heat generation of the power supply. 3) Optimize the layout design of the circuit, which is conducive to the diffusion of heat. 4) Use metal capacitors to replace electrolytic capacitors. 2.4. Project features and innovation breakthrough points 1) Design innovation We have subverted the traditional power supply design thinking, and adopted the design of non-electrolytic capacitors in the design, completely eliminating the bottleneck restricting the life of the power supply, and greatly extending the service life of the power supply. Through this change, our new generation of LED drivers can reach at least 30,000 hours, thus meeting the overall lifespan requirements of LED lamps. 2) Technological innovation Our LED driver is a pulsed constant current power supply, and the frequency and duty cycle of the current pulse can be adjusted. Due to the pulse power supply, the LED is in an intermittent working condition, and the temperature rise of the LED lamp is relatively slow, which prolongs the service life of the high-power LED. In addition, the driver works at high frequency, making full use of the afterglow effect of the phosphor in the LED, not only does not light flicker, but also further improves the luminous efficiency of the LED. 3) Circuit innovation The conversion efficiency is an important technical indicator of the driver. It determines the power utilization rate of the product. The advantage of the LED light source is energy saving and high efficiency. To give full play to its performance, its driver should also have high efficiency performance. The low efficiency of LED lighting affects the performance of the entire product, which will also make the development and promotion of LED lighting products meaningless. The power factor of electrical appliances determines the impact of electrical appliances on the power grid, the loss of power grid lines, and the requirements for power supply equipment on the power grid. The drive developed by our company can reach a maximum conversion efficiency of 94%, while achieving a power factor greater than 0.9; while other similar products on the market cannot achieve either of these two indicators, or can not achieve both indicators at the same time. 2.5. The technical, economic indicators and social and economic benefits expected to be achieved after the completion of the project will drive and enhance the industry. After the completion of the project, the current LED lamps will have a strong heart and greatly extend the overall service life of the LED lamps. Give full play to the advantages of LED lights in energy saving, environmental protection and long life. It is of great significance to promote the development of LED lighting technology and speed up the popularization of LED lights. The LED lamp itself has very good economic and social benefits, but if the quality of the driver itself is not good enough, the economic and social benefits of the LED itself will be greatly reduced, and even huge waste will be caused. For example, the general life of an LED chip is 50,000 hours. If the life of the driver is only 10,000 hours, the overall life of the lamp is only 10,000 hours. The service life of energy-saving lamps is almost the same, but the price is several times that of energy-saving lamps. Such a result is difficult to accept. This is invisibly a huge waste, completely contrary to the original intention of advocating green energy saving and environmental protection. Although the LED driving power supply itself will not bring huge economic and social benefits, it maintains the original economic and social benefits of the LED itself. In a sense, it is equivalent to creating these benefits.