LED Driver Power Supply Classification Method

LED driver power supply: It can convert the power supply into a specific voltage and current to drive the voltage converter of LED lighting. Generally, the input of LED driver power supply includes high-voltage AC (i.e. mains), low-voltage DC, high-voltage DC, low-voltage high-frequency AC (such as the output of electronic transformers), etc. The output of LED driver power supply is mostly a constant current source that can change the voltage with the change of LED forward voltage drop value.
The core components of LED power supply include switch controllers, inductors, MOSFETs, feedback resistors, input filtering devices, output filtering devices, and so on. According to the requirements of different occasions, there should also be input overvoltage protection circuit, input undervoltage protection circuit, LED open circuit protection, overcurrent protection circuit, etc.
Classified by Drive Method 01
Constant current type
The output current of a constant current drive circuit is constant, while the output DC voltage varies within a certain range with the size of the load resistance. When the load resistance is small, the output voltage is low, and the larger the load resistance, the higher the output voltage;
A constant current circuit is not afraid of load short circuits, but it is strictly prohibited to completely open the load;
The constant current drive circuit is ideal for driving LEDs, but relatively expensive;
Attention should be paid to the maximum withstand current and voltage values used, which limit the number of LEDs used.
Stable voltage type
After the various parameters in the voltage stabilizing circuit are determined, the output voltage is fixed, while the output current changes with the increase or decrease of the load;
The voltage stabilizing circuit is not afraid of open circuit of the load, but it is strictly prohibited to have a complete short circuit of the load;
Drive the LED with a voltage stabilizing driving circuit, and add appropriate resistors to each string in order to make the brightness of each LED display average;
The brightness will be affected by the voltage changes caused by rectification.
Characteristics of LED driver power supply
(1) High reliability
Especially like the driving power supply of LED street lights, installed at high altitude, maintenance is inconvenient and the cost of maintenance is also high.
(2) High efficiency
LED is an energy-saving product, and the efficiency of the driving power supply needs to be high. The heat dissipation of the junction installed in the lighting fixture is very important for the power supply. The power supply has high efficiency, low power consumption, and generates less heat inside the lamp, which reduces the temperature rise of the lamp. It is beneficial for delaying the light decay of LEDs.
(3) High power factor
Power factor is the requirement of the power grid for the load. Generally, household appliances below 70 watts do not have mandatory indicators. Although the power factor of individual appliances with low power has little impact on the power grid, using a large amount of lighting at night and concentrating similar loads can cause serious pollution to the power grid. For LED driver power supplies ranging from 30 watts to 40 watts, it is said that in the near future, there may be certain requirements for power factors.
(4) Driving method
There are two types currently in use: one is a constant voltage source that supplies multiple constant current sources, with each constant current source supplying separate power to each LED. This method is flexible in combination, and if one LED fails, it will not affect the operation of other LEDs, but the cost will be slightly higher. Another type is direct constant current power supply, which is the driving method adopted by Zhongke Huibao. The LED operates in series or parallel. Its advantage is lower cost, but poor flexibility, and it also needs to solve the problem of one LED failure without affecting the operation of other LEDs. These two forms coexist for a period of time. The multi-channel constant current output power supply method will be better in terms of cost and performance. Perhaps it is the mainstream direction in the future.
(5) Surge protection
The ability of LED to withstand surges is relatively poor, especially in terms of resistance to reverse voltage. Strengthening protection in this area is also important. Some LED lights are installed outdoors, such as LED street lights. Due to the load shedding of the power grid and the induction of lightning strikes, various surges may invade the power grid system, some of which can cause damage to the LED. Therefore, the analysis shows that the driving power supply of Zhongke Huibao should have certain deficiencies in surge protection. As for frequent replacement of power supply and lighting fixtures, the LED driving power supply should have the ability to suppress surge intrusion and protect the LED from damage.
(6) Protection function
In addition to conventional protection functions, it is best to add LED temperature negative feedback in the constant current output of the power supply to prevent excessive LED temperature; To comply with safety regulations and electromagnetic compatibility requirements.
Advantages and disadvantages of overall constant current and path by path constant current working methods
Compared to the overall constant current, although there are more drawbacks and higher costs, the path by path constant current is also relatively high. But it can truly protect LEDs and extend their lifespan, so constant current is the future trend.