LED street light power is the world's highest efficiency switching power supply up to 95%, high power factor up to 0.99, high reliability and long life, in line with IP67 waterproof rating. It is applied to high-power lamps such as street lamps and ramp lights. The aluminum casing of the product package has good heat dissipation effect. The choice of LED street light power supply (the type of LED street light power supply) is crucial for the normal operation of the electronic control system of the mechanical equipment. When choosing LED street light power (LED street light power knowledge), the factors and points we have to consider are also multifaceted. So, in the selection process of LED street light power, we have to consider those aspects? Let us step by step to understand the LED street light power supply.
LED street light power principle
The LED switching power supply has a circuit to control the switching tube for high-speed switching and cut-off. The conversion of direct current into high-frequency alternating current to transform the converter to produce the required one or more sets of voltages! The reason for converting to high-frequency alternating current is that the efficiency of high-frequency alternating current in the transformer circuit is higher than that of the commercial power 50Hz or 60Hz. Therefore, the switching power supply transformer can be made small in size, and it will not be very hot when the switching power supply is working. The product price is lower than the power frequency DC regulated power supply. If you do not change 50Hz or 60Hz into high frequency, then switching power supply does not make any sense. The switching power supply can be roughly divided into two types: isolated and non-isolated. The isolated type must have a switching power converter, and the isolated power supply converter does not necessarily have to be isolated. Switching power supply has the advantages of small size, light weight, and high efficiency compared with traditional DC power supply.
LED street light power classification
1, according to the driving method can be divided into two categories
1.1 Constant current
a. The current output from the constant current drive circuit is constant, and the output DC voltage varies within a certain range according to the magnitude of the load resistance. The load resistance is small, the output voltage is low, and the load resistance is larger. The higher the voltage;
b. The constant current circuit is not afraid of load short circuit, but it is forbidden to completely open the load.
c. Constant current drive circuit driving LED is ideal, but relatively high price.
d, should pay attention to the maximum withstand current and voltage value used, which limits the number of LEDs used;
1.2 voltage regulator
a. When the parameters in the voltage regulator circuit are determined, the output voltage is fixed, and the output current changes as the load increases or decreases;
b. The voltage regulator circuit is not afraid of the load open circuit, but it is forbidden to completely short the load.
c. Drive the LED with a voltage-stabilized driving circuit, and each string needs to be added with a suitable resistor to make each string of LEDs display brightness average;
d. The brightness will be affected by the rectified voltage change.
2, according to the circuit structure
2.1 Resistor and capacitor step-down mode
By the capacitor step-down, when the flashing is used, due to the action of charging and discharging, the instantaneous current passing through the LED is extremely large, and the chip is easily damaged. It is susceptible to grid voltage fluctuations, low power efficiency and low reliability.
2.2 resistance step-down mode
Through the resistor step-down, the interference from the grid voltage change is large, it is not easy to make a regulated power supply, and the step-down resistor consumes a large part of the energy. Therefore, the power supply mode has low power efficiency and the system reliability is low. .
2.3 conventional transformer step-down mode
The power supply is small in size, heavy in weight, and low in power efficiency, generally only 45% to 60%, so it is rarely used and reliability is not high.
2.4 Electronic transformer step-down mode
The power supply efficiency is low, the voltage range is not wide, generally 180~240V, and the ripple interference is large.
2.5 RCC Buck Mode Switching Power Supply
The voltage regulation range is relatively wide, and the power supply efficiency is relatively high. Generally, it can be 70%~80%, and the application is also wide. Since the oscillation frequency of this control mode is discontinuous, the switching frequency is not easy to control, the load voltage ripple coefficient is relatively large, and the abnormal load adaptability is poor.
2.6 PWM control mode switching power supply
It is mainly composed of four parts, input rectification and filtering part, output rectification and filtering part, PWM voltage regulation control part and switching energy conversion part. The basic working principle of PWM switching regulator is that in the case of input voltage, internal parameters and external load changes, the control circuit performs closed-loop feedback by the difference between the control signal and the reference signal to adjust the pulse width of the main circuit switching device. The output voltage or current of the switching power supply is stabilized (ie, the corresponding regulated power supply or constant current power supply). The power supply efficiency is extremely high, generally 80%~90%, and the output voltage and current are stable. Generally, such circuits have perfect protection measures and are highly reliable power supplies.
LED street light power supply selection points
The first point. Select the appropriate control mode LED street light power supply according to the load characteristics.
Nowadays, there are many kinds of LED street lamp power supplies sold on the market, and the functions are also increasingly powerful. The performance of LED street lamp power supply has become the decisive factor of the speed control performance. In addition to the "innate" conditions of the LED street lamp power supply manufacturing process, It is also very important to control the way LED street light power is used. The following table summarizes the performance characteristics of various LED street light power control methods in recent years.
In summary, the asynchronous motor variable frequency control uses different control methods to obtain the speed regulation characteristics of different performance characteristics.
Second point. Select the protective structure of the LED street light power supply according to the installation environment.
The protection structure of the LED street lamp power supply should be adapted to the installation environment. This should consider environmental temperature, humidity, dust, pH, corrosive gas and other factors, which is related to the long-term, safe and reliable operation of the LED street lamp power supply.
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