What are the LED power supply classification?
First, LED power by drive can be divided into two categories:
A. Regulated:
1, the regulator circuit to determine the parameters, the output is a fixed voltage, the output current changes with the load changes
2, although the regulator circuit is not afraid of load open, but the load is strictly prohibited short circuit
3, after the rectifier voltage changes will affect the brightness of LED
4, to make each string to stabilize the circuit to drive LED display brightness uniformity, need to add the appropriate resistance can
B. constant flow:
1, constant current drive circuit driver LED is ideal, the disadvantage is that the price is higher
2, although the constant current circuit is not afraid of load short circuit, but the load is strictly prohibited open
3, constant current drive circuit output current is constant, and the output of the DC voltage with the load resistance of the size of the different changes in a certain range
4, to limit the number of LED use, because it has the maximum withstand current and voltage
Second, LED power according to the circuit structure can be divided into six categories:
1, the conventional transformer buck:
The advantages of this power supply is small, the inadequacies of the weight is heavy, power efficiency is very low, generally 45% to 60%, because the reliability is not high, so generally rarely used.
2, the capacitor buck:
This way the LED power supply is susceptible to fluctuations in the grid voltage, power efficiency is low, should not be used in flashing LED, because the circuit through the capacitor buck, flashing use, due to the role of charge and discharge, through the LED instantaneous current Great, easy to damage the chip.
3, electronic transformer buck:
This power structure is the lack of conversion efficiency is low, the voltage range is narrow, generally 180 ~ 240V, ripple interference.
4, resistance step-down:
This power supply is very low power efficiency, and the system is also relatively low reliability. Because the circuit through the resistance step by step, by the power grid voltage changes in the interference is not easy to make a regulated power supply, and buck resistance itself also consume a lot of energy.
5, RCC step-down switching power supply:
This way the advantages of LED power supply is a wide range of voltage regulator, power efficiency is relatively high, generally in 70% to 80%, wider application. Disadvantages are mainly switching frequency is not easy to control, load voltage ripple coefficient is large, abnormal load adaptability is poor.
6, PWM control switching power supply:
At present, the PWM control mode design of the LED power supply is ideal, because the switching power supply output voltage or current are very stable. Power conversion efficiency is extremely high, generally can be as high as 80% to 90%, and the output voltage, current is very stable. This way the LED power supply is mainly composed of four parts are: input rectifier filter part, output rectifier filter part, PWM regulator control part, switch energy conversion part. And this circuit has a sound protection measures, are high reliability power supply.
LED drive power nine performance characteristics
According to the power grid rules and LED drive power characteristics of the requirements, in the selection and design of LED drive power to take into account the following nine performance characteristics:
1. High reliability, especially as LED lights drive power, installed at high altitude, maintenance is not convenient, maintenance costs are also large.
2. High efficiency LED is energy efficient products, drive power efficiency is higher. It is especially important for the power supply to be installed in the fixture. Because LED luminous efficiency with the LED temperature increases and decreased, so the LED heat is very important. Power efficiency is high, its power consumption is small, the heat in the lamp is small, it will reduce the temperature rise of the lamp. To delay the LED light failure beneficial.
3. High power factor power factor is the load on the grid requirements. Generally less than 70 watts of electrical appliances, there is no mandatory indicators. Although the power is not a single power factor lower power factor on the power grid is not big, but at night we light, similar load is too concentrated, will produce more serious pollution of the grid. For 30 watts to 40 watts of LED drive power, it is said that in the near future, may have a certain degree of power factor requirements.
4. There are two ways to drive now: one is a constant pressure source for multiple constant current sources, each constant current source to each LED power supply. This way, the combination of flexible, 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 constant current power supply, LED series or parallel operation. Its advantage is a little lower cost, but the flexibility is poor, but also to solve a LED failure, does not affect the other LED operation problems. These two forms coexist for a period of time. Multi-channel constant current output power supply, in terms of cost and performance will be better. Perhaps the future direction of the mainstream.
5. Surge protection LED anti-surge capability is relatively poor, especially anti-reverse voltage capability. It is also important to strengthen this protection. Some LED lights installed in the outdoors, such as LED lights. Due to the load of the grid load and lightning induction, from the grid system will invade a variety of surges, and some waves will lead to LED damage. So the LED drive power to suppress the surge of intrusion, the protection of the LED is not damaged capacity.
6. Protection function In addition to the conventional protection function, it is best to increase the LED temperature in the constant current output negative feedback to prevent the LED temperature is too high.
7. Protection aspects of lighting outside the installation type, the power structure to waterproof, moisture, the shell to light.
8. The life of the drive power supply is compatible with the life of the LED.
9. To meet the requirements of safety and electromagnetic compatibility.
With the growing popularity of LED, LED drive power performance will be more and more suitable for LED requirements.