According to the power grid rules and the characteristics of LED driver power requirements, LED driver power supply selection and design to take into account the following points:

1. High reliability Especially like LED street lamp drive power, installed at high altitude, waterproof aluminum shell drive power, good quality is not easy to be bad, reduce the number of maintenance.

2. High-efficiency LED is energy-saving products, higher efficiency of the drive power. It is especially important for the power supply to install the LED driver power supply within the luminaire. Because the luminous efficiency of LED drops with the increase of LED temperature, LED's heat dissipation is very important. The high efficiency of the power supply, its power consumption is small, the heat in the lamp is small, it reduces the temperature rise of the lamp. To delay the decline of the LED light. Statistics show that the temperature rise of electronic components for each 2 ℃, the reliability decreased by 10%; temperature rise of 50 ℃ life expectancy is only 25 ℃ when the temperature rise of 1/6. In addition to electrical stress, temperature is the most important factor affecting equipment reliability. This requires technical measures to limit the temperature rise of the chassis and components, which is the thermal design. Thermal design principles, one is to reduce the heat, that is, choose better control methods and technologies, such as phase-shifting control technology, synchronous rectification technology, the other is the selection of low-power devices, reducing the number of heating devices, increase Coarse printed line width, improve power efficiency. The second is to strengthen the heat, that is, the use of conduction, radiation, convection heat transfer technology, which includes the radiator design, air-cooled (natural convection and forced air cooling) design, liquid (water, oil) design, thermoelectric cooling design, Design and so on.

Forced air-cooled heat dissipation more than ten times larger than the natural cooling, but to increase the fan, fan power, interlocking, etc., in the design according to the actual situation to choose the cooling method.

3. High power factor Power factor is the power grid requirements of the load. General 70 watts of electrical appliances, there is no mandatory indicator. Although the low power of a single electric appliance power factor has little effect on the power grid, but everyone lights, similar load is too concentrated, the power grid will have more serious pollution. For 30 watts ~ 40 watts of LED driver power supply, it is said that in the near future, there may be some indicators of the power factor requirements. Harmonic current of switching power supply pollutes the power grid and interferes with other common network equipment. It may also cause the neutral current of three-phase four-wire system to be too large, which may cause an accident. One solution to the problem is to use a switching power supply with power factor correction technology.

4. There are two ways to drive the current pass: One is a constant voltage source for multiple constant current source, each of the individual constant current LED power supply. This way, flexible combination, all the way LED failure, does not affect the work of other LED, but the cost will be slightly higher. The other is a direct current power supply, LED series or parallel operation. It has the advantage of low cost, but poor flexibility, but also to solve a LED failure, does not affect the operation of other LED problems. Both forms co-exist over time. Multi-channel constant current output power supply, the cost and performance will be better. Probably the mainstream direction in the future.

5. Surge Protection Power Surge Suppression module has two kinds:

(1) Power-on inrush current suppression module with limited current resistance; (2) Power-on inrush current suppression module with unlimited current resistance;

LED anti-surge ability is relatively poor, especially anti-reverse voltage capability. It is also important to strengthen the protection in this area. Some LED lights are installed outdoors, such as LED street lights. Due to the rejection of the grid load and the lightning strike, various surges will invade from the grid system, and some of the surge may cause the LED to be damaged. Therefore, the LED driver power supply must have the intrusion of surge suppression, LED protection is not damaged.

6. Protection function In addition to the normal power protection, it is best to add a negative feedback LED temperature in the constant current output to prevent the LED temperature is too high.

7. Protection Lighting installation type, power supply structure to be waterproof, moisture-proof, the shell should be resistant to light.

8. Drive power to match the life of the LED.

9. To comply with safety regulations and electromagnetic compatibility requirements.

Electromagnetic compatibility (EMC) design techniques

Switching power supply more use of pulse width modulation (PWM) technology, the pulse waveform is rectangular, the rising edge and falling edge contains a large number of harmonic components, while the other output rectifier reverse recovery will produce electromagnetic interference (EMI), which is the impact The disadvantage of reliability, which makes the system has become an important issue of electromagnetic compatibility. There are three necessary conditions for creating electromagnetic interference: sources of interference, transmission media, sensitive receiving units, and EMC designs that destroy one of these three conditions.

For switching power supply, the main source of interference suppression, interference sources focus on the switching circuit and the output rectifier circuit. Techniques used include filtering techniques, layout and routing technology, shielding technology, grounding technology, sealing technology and other technologies.

With the increasingly wide range of LED applications, LED driver power performance will be more and more suitable for LED requirements.