The high frequency of LED switching power supply is the direction of its development. High frequency makes the switching power supply miniaturized, and makes the switching power supply enter a wider application field, especially in the field of high and new technology, which promotes the miniaturization and convenience of high and new technology products. In addition, the development and application of switching power supply is of great significance in saving energy, saving resources and protecting the environment. The main electronic devices used in LED switching power supply are LED diode, IGBT and MOSFET. SCR has a small number of applications in switching power supply input rectifier circuit and soft start circuit. GTR drive is difficult and switching frequency is low, so it is gradually replaced by IGBT and MOSFET. There are three conditions for LED switching power supply: 1. The switch is that the power electronic device works in the switching state rather than in the linear state.
2. High frequency: power electronic devices work at high frequency rather than near power frequency
3. DC: the switching power supply outputs DC instead of AC LED switching power supply, which is controlled by the circuit to turn on and off the switch tube at high speed. It is to convert DC into high frequency AC to convert the converter into voltage conversion, so that it produces one or more sets of voltage needed!
The efficiency of high frequency AC in transformer circuit is higher than that of municipal power 50Hz or 60Hz, so the switching power supply transformer can achieve very small volume, it will not be very hot when the switching power supply works, and the product price is lower than the power frequency DC voltage stabilizing power supply. If 50Hz or 60Hz is not converted into high frequency power supply, then the switching power supply will not have any significance. Switching power supply can be divided into isolation and non-isolation. There must be switching power converter in isolation type, but there may not be switching power converter that is not isolated. Compared with the traditional DC power supply, switching power supply has the advantages of small size, light weight, high efficiency and so on. The control of LED switching power supply has been controlled by analog control and analog-to-digital hybrid control, and has entered the full digital control stage. All-digital control is a development trend and has been applied in many power conversion devices. The advantage of all-digital control is that the digital signal can be calibrated with smaller quantity and the chip price is lower than the mixed analog-to-digital signal; the current detection error can be accurately digital corrected and the voltage detection can be more accurate; and the fast and flexible control design can be realized. Electromagnetic compatibility
LED switching power supply electromagnetic compatibility: the electromagnetic compatibility (EMC) problem of high frequency LED switching power supply has its particularity. The di/dt and dv/dt produced by power semiconductor devices in the switching process will cause strong conduction electromagnetic interference and harmonic interference, as well as strong electromagnetic field (usually near-field) radiation. Not only seriously pollutes the surrounding electromagnetic environment, causes electromagnetic interference to the nearby electrical equipment, but also may endanger the safety of nearby operators. At the same time, the internal control circuit of power electronic circuit (such as switching converter) must also be able to withstand the interference of EMI caused by switching action and electromagnetic noise in the application site. CAD of LED switching power supply system, including main circuit and control circuit design, device selection, parameter optimization, magnetic design, thermal design, EMI design and printed circuit board design, reliability prediction, computer aided synthesis and optimization design, etc. The CAD of LED switching power supply system is carried out with the expert system based on simulation. Scope of use
LED switching power supply is widely used in LED display screen (monochromatic door screen, full color screen), LED lighting (LED lamps, LED street lamps), LED lighting (guardrail tube, wall washing lamp, advertising light box) to provide power supply for all kinds of constant voltage and constant current products, low voltage current safety, green, health.
Then how to quickly test the input and output parameters of the switching power supply without load, if it is simpler, the input voltage, current, power factor, frequency input voltage, current and power parameters of the switching power supply can be measured by adding electronic load to the power meter.
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If you want to know the more detailed parameters of this drive, you can use a special LED drive power supply integrated tester, in addition to the above functions can also test voltage and current harmonics. Initial phase, peak phase, termination phase, ripple voltage and current, energy efficiency coefficient. Some drive standby power is unstable, but also can test its average power and the displacement factor DF which is concerned about in the previous period.
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If you also want to test the photoelectric color of lamps, luminous angle, EMI European ERP energy efficiency and other content. Zhongxiang instrument provides lighting testing laboratory, including THD harmonic analysis (IEC61000-3-2 harmonic IEC61000-3-3 flicker) + new European instruction ErP stroboscopic (SVMPstLM+DF displacement factor) + IES distribution curve + integral sphere spectral energy efficiency (new European standard energy efficiency grade) + EMI electromagnetic compatibility test + EMS lightning surge test + electrostatic test + safety gauge comprehensive test (voltage, grounding, insulation, leakage).
March 10, 2023
