The electronic devices used in LED switching power supply are mainly LED diode, IGBT and MOSFET. SCR has a few applications in switching power supply input rectifier circuit and soft start circuit. GTR is difficult to drive and the switching frequency is low. It is gradually replaced by IGBT and MOSFET.
Principle and characteristics
Three conditions of LED switching power supply
1. Switch: power electronic devices work in the switching state rather than the linear state
2. High frequency: power electronic devices work at high frequency rather than low frequency close to power frequency
3. DC: the output of switching power supply is DC rather than AC
Led switching power supply has a circuit to control the switch tube for high-speed channel on and off. It is to convert DC into high-frequency AC to transform the converter to produce one or more groups of voltages required! The principle of converting high-frequency AC into high-frequency AC is that the efficiency of high-frequency AC in transformer circuit is higher than that of commercial power 50Hz or 60Hz. Therefore, the switching power supply transformer can be small in size, will not be very hot when the switching power supply works, and the product price is lower than that of power frequency DC regulated power supply. If 50Hz or 60Hz is not changed into high-frequency power, the switching power supply has no meaning. Switching power supply can be divided into isolation and non isolation. If it is isolated, there must be switching power converter, while if it is not isolated, there may not be switching power converter. Compared with traditional DC power supply, switching power supply has the advantages of small volume, light weight and high efficiency.
Detection points of LED switching power supply
Output voltage ripple detection;
Efficiency detection of switching power supply;
If the power factor is required, the power factor shall also be tested;
Input voltage regulation rate detection and full load power supply temperature detection to prevent the sudden change of input power supply from affecting the circuit.
