First of all, let's talk about what is LED drive power? It can convert the power supply into a specific voltage and current to drive the voltage converter of the LED light. Under normal circumstances: the input of the LED drive power includes high-voltage power frequency AC (ie mains), low-voltage DC, high-voltage DC, low-voltage high-frequency AC (Such as the output of an electronic transformer) and so on. The output of the LED driving power supply is mostly a constant current source that can change the voltage with the change of the forward voltage drop of the LED.

　　The core components of the LED power supply include switching controllers, inductors, switching components (MOSfet), feedback resistors, input filter components, output filter components, and so on. According to the requirements of different occasions, there are also input overvoltage protection circuits, input undervoltage protection circuits, LED open circuit protection, overcurrent protection and other circuits.

　　Classified by driving method

　　(1) Constant current type

　　The output current of the constant current drive circuit is constant, but the output DC voltage varies within a certain range with the size of the load resistance. The smaller the load resistance, the lower the output voltage. The larger the load resistance, the output voltage is also Higher

　　Constant current circuit is not afraid of load short circuit, but it is strictly forbidden to open the load completely;

　　Constant current driving circuit to drive LED is more ideal, but relatively expensive;

　　It should be noted that the maximum withstand current and voltage values ​​used, which limit the number of LEDs used.

　　(2) Regulated

　　When the various parameters in the voltage regulator circuit are determined, the output voltage is fixed, but the output current changes with the increase or decrease of the load;

　　The voltage regulator circuit is not afraid of load opening, but it is strictly forbidden to short-circuit the load completely;

　　The LED is driven by a voltage-stabilized driving circuit, and each string needs to be added with a suitable resistance to make each string of LEDs show an average brightness;

　　The brightness will be affected by the rectified voltage changes.

　　Features of LED drive power

　　(1) High reliability

　　Especially like the driving power of LED street lights, it is inconvenient to maintain and costly to maintain when installed at high altitude.

　　(2) High efficiency

　　LED is an energy-saving product, and the efficiency of the driving power supply should be high. It is very important for the power supply installed in the luminaire to dissipate heat. The efficiency of the power supply is high, its power consumption is small, and the heat generated in the lamp is small, which reduces the temperature rise of the lamp. It is beneficial to delay the light decay of LED.

　　(3) High power factor

　　The power factor is the requirement of the grid on the load. Generally, there are no mandatory indicators for household appliances below 70 watts. Although the power factor of a single consumer with low power is lower, it has little effect on the power grid, but the large amount of lighting used at night and too concentrated similar loads will cause serious pollution to the grid. For LED drive power supplies of 30 watts to 40 watts, it is said that in the near future, there may be certain index requirements for power factors.

　　(4) Drive mode

　　There are two types currently in use: one is a constant voltage source for multiple constant current sources, and each constant current source individually supplies power to each LED. In this way, the combination is flexible, and the failure of one LED will not affect the work of other LEDs, but the cost will be slightly higher. The other is direct constant current power supply, which is the driving method adopted by "Zhongke Huibao", LED series or parallel operation. Its advantage is that the cost is a bit lower, but the flexibility is poor, and it must solve the problem of one LED failure without affecting the operation of other LEDs. These two forms coexist for a period of time. Multi-channel constant current output power supply mode will be better in terms of cost and performance. Maybe it is the mainstream direction in the future.

　　(5) Surge protection

　　The ability of LED to resist surge is relatively poor, especially the ability to resist reverse voltage. It is also important to strengthen protection in this area. Some LED lights are installed outdoors, such as LED street lights. Due to the onset of the grid load and the induction of lightning strikes, various surges will invade from the grid system, and some surges will cause damage to the LED. Therefore, it is analyzed that the drive power supply of "Zhongke Huibao" should have certain deficiencies in surge protection. As for the frequent replacement of power supplies and lamps, the LED drive power supply must have the ability to suppress the surge intrusion and protect the LED from damage.

　　(6) Protection function

　　In addition to the conventional protection functions of the power supply, it is best to add negative feedback of the LED temperature to the constant current output to prevent the LED temperature from being too high; it must meet the requirements of safety regulations and electromagnetic compatibility.

　　Advantages and disadvantages of overall constant current and constant current working methods

　　Compared with the overall constant current, although the channel-by-channel constant current has more disadvantages, the cost is also higher. But it can really protect the LED and extend the life of the LED, so the constant current is the future trend.