What are the six categories of LED power supply according to the circuit structure?
1. Step-down of conventional transformer:
The advantage of this kind of power supply is that it is small in size, but the disadvantage is that it is heavy in weight and the power supply efficiency is also very low, generally 45%~60%. Because the reliability is not high, it is generally rarely used.
2. Capacitor step-down:
This type of LED power supply is easily affected by grid voltage fluctuations, and the power supply efficiency is low. It is not suitable for LEDs to be used when flashing, because the circuit reduces the voltage through capacitors. When flashing is used, due to the effect of charging and discharging, the instantaneous current through the LED Very large, easy to damage the chip.
3. Step-down of electronic transformer:
The disadvantage of this power supply structure is that the conversion efficiency is low, the voltage range is narrow, generally 180~240V, and the ripple interference is large.
4. Resistance drop:
This power supply method has low power efficiency and low system reliability. Because the circuit is stepped down by a resistor, it is greatly disturbed by the change of the grid voltage, and it is not easy to make a regulated power supply, and the step-down resistor itself consumes a large part of the energy.
5. RCC step-down switching power supply:
The advantages of this method of LED power supply are that the voltage regulation range is relatively wide and the power supply efficiency is relatively high. The main disadvantages are that the switching frequency is not easy to control, the load voltage ripple coefficient is large, and the load adaptability is poor in abnormal conditions.
6. PWM control switching power supply:
At present, the LED power supply designed by PWM control method is ideal, because the output voltage or current of this switching power supply is very stable. The power conversion efficiency is extremely high, generally as high as 80%~90%, and the output voltage and current are very stable. The LED power supply in this way is mainly composed of four parts: the input rectifier and filter part, the output rectifier and filter part, the PWM voltage regulation control part, and the switching energy conversion part. Moreover, this circuit has perfect protection measures and belongs to high reliability power supply.
