Comprehensive understanding of LED driving power supply problems of LED lighting
The most critical parts of an LED lighting product are heat dissipation, drive power, and light source. At the same time, heat dissipation is particularly important. The heat dissipation effect directly affects the life quality of lighting products, and the life of the drive power itself. And the stability of the output current and voltage also has a great impact on the overall life quality of the product. The light source is the core part of the entire product. The drive power supply will be analyzed and explained below. LED drive power supply is also a supporting product. The quality of power supply on the market is uneven. The following provides some knowledge of LED drive power supply. 1. What is LED drive power The LED drive power supply converts the power supply into a specific voltage and current to drive the LED light-emitting voltage converter. Generally, the input of the LED drive power supply includes high-voltage power frequency AC (that is, commercial power), low-voltage DC, high-voltage DC, low-voltage high-frequency AC (such as the output of an electronic transformer), etc. The output of the LED drive power supply is mostly a constant current source that can change the voltage as the LED forward voltage drop changes. The core components of the LED power supply include switching controllers, inductors, switching components (MOSfet), feedback resistors, input filter components, output filter components, etc. According to the requirements of different occasions, there must be input overvoltage protection circuit, input undervoltage protection circuit, LED open circuit protection, overcurrent protection and other circuits. 2. Characteristics of LED drive power (1) High reliability The performance is especially like the driving power of LED street lamps. It is installed at high altitude, which is inconvenient for maintenance and the cost of maintenance is also large. (2) High efficiency LED is an energy-saving product, and the efficiency of the driving power supply is high. It is very important for the heat dissipation of the power supply installed in the lamp. 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 load requirement of the power grid. Generally, there is no mandatory index for electrical appliances under 70 watts. Although the power factor of a single consumer with low power is a little low, it has little effect on the power grid, but the amount of lighting used at night is large, and the similar loads are too concentrated, which will cause serious pollution to the power grid. For LED drive power 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 method There are currently two types of traffic: one is a constant voltage source for multiple constant current sources, and each constant current source supplies power to each LED individually. In this way, the combination is flexible, all the way LED failure, does not affect the work of other LEDs, but the cost will be slightly higher. The other is the direct constant current power supply, that is, "Zhongke Huibao" changed to the driving mode, LED series or parallel operation. Its advantage is that the cost is a bit lower, but the flexibility is poor, and it is necessary to solve the problem of a certain LED and not affect 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 resist surge is relatively poor, especially the ability to resist reverse voltage. It is also important to strengthen protection in this regard. Some LED lights are installed outdoors, such as LED street lights. Due to the induction of the grid load and the induction of lightning strikes, various surges will be invaded from the grid system, and some surges will cause damage to the LED. Therefore, the analysis of the "Zhongke Huibao" drive power supply should have some deficiencies in terms of surge protection. As for the frequent replacement of power supplies and lamps, the LED drive power supply must have the ability to suppress the intrusion of the surge and protect the LED from damage. (6) Protection function In addition to the conventional protection functions of the power supply, it is best to increase the LED temperature negative feedback in the constant current output to prevent the LED temperature from being too high; it must meet the requirements of safety regulations and electromagnetic compatibility. 3. Classification by driving method (1) The output current of the constant current type constant current drive circuit is constant, and the output DC voltage varies within a certain range with the size of the load resistance. The load resistance is small, the output voltage is low, and the load resistance The larger, the higher the output voltage; the constant current circuit is not afraid of the short circuit of the load, but it is strictly forbidden to completely open the load; the constant current drive circuit is ideal for driving LEDs, but the price is relatively high; pay attention to the maximum withstand current and Voltage value, it limits the number of LEDs used. (2) Voltage stabilizing type After the parameters in the voltage stabilizing circuit are determined, the output voltage is fixed, but the output current changes with the increase and decrease of the load; the voltage stabilizing circuit is not afraid of the load open circuit, but it is strictly prohibited to load completely Short circuit; drive the LED with a voltage-regulated drive circuit. Each string needs to be added with a suitable resistance to make each string of LED display brightness average; the brightness will be affected by the rectified voltage change. 4. The advantages and disadvantages of the overall constant current and channel-by-channel constant current working methods Compared with the overall constant current, the channel-by-channel constant current has more disadvantages and higher cost. But it can really protect the LED and extend the life of the LED, so the constant current is the future trend. 5. Insufficient LED power supply Reasons for the shortage of LED drive power: The technical personnel of the company producing LED lighting and related products do not have enough understanding of the switching power supply, and the power supply made can work normally, but some key evaluations and electromagnetic compatibility considerations are not enough, and there are still certain hidden dangers; most LED power supplies The production enterprises are transformed from ordinary switching power supplies to make LED power supplies, and their understanding of the characteristics and use of LEDs is not enough; there are almost no standards about LEDs at present, and most of them refer to the standards of switching power supplies and electronic rectifiers; most LEDs now The power supply is not unified, so most of the volume is relatively small. The purchase volume is small, the price is high, and the component suppliers are not very cooperative; the stability of the LED power supply: wide voltage input, high and low temperature operation, over temperature, over voltage protection and other issues have not been solved one by one; the first is The overall life of the drive circuit, especially the key components such as: the life of the capacitor at high temperature directly affects the life of the power supply; it is the LED driver that should challenge higher conversion efficiency, especially when driving high-power LEDs, because all The light output power is used as heat dissipation, the power conversion efficiency is too low, which affects the LED energy-saving effect. At present, in the applications with low power (1-5W), the proportion of the cost of the constant current drive power supply has been Close to 1/3, which is close to the cost of the light source, which has affected the market promotion to a certain extent
It is well known that wireless serial is a very reliable and efficient way to connect serial devices. RS232 serial port is ideal for point-to-point data communication which makes setting up a communication link quickly and easily.
GrandComm`s serial RS232 RF Radio Modem is a radio data transceiver which allow you to send and receive wireless data between two serial devices or computers with RS232 serial port.
The communication range for serial RS232 RF radio modem typically range from 1 kilometer to over 50 kilometers.
This industrial grade radio modem has an air data rates of 19200bps in 25kHz channel spacing and 9600bps in 12.5kHz.
RS232 Radio Modem,RS232 Data Radio Modem,RS232 RF Modem,Industrial RS232 Radio Modem Shenzhen PuFang Technology Co., Ltd. , https://www.hytelus.com