Analysis And Optimization Of Voltage Sag Tolerance Characteristics Of Typical Built-in Switching Power Supply Equipment

Switching power supply is a kind of power supply that maintains steady output voltage by controlling the opening and closing time ratio of power electronic devices.This type of power supply has benefits of high integration,light weight,high efficiency and low power consumption,so it is widely used as the working power supply or control power supply of household and industrial electronic equipment.However,due to its sensibility to voltage sag,it is easy to cause the abnormal operation of its power supply equipment,which may lead to huge economic losses.Therefore,based on PLECS platform,this paper conducted a thorough study on the optimization of voltage sag tolerance characteristics of typical built-in switching power supply electrical equipment.Taking a certain type of LED electronic display provided by one of the equipment suppliers of Beijing Winter Olympics venues as an example,Chroma power 61860(voltage sag generator),IPQ-1 multi-channel power quality analyzer and HIOKl storage recorder(data acquisition system)are used.Based on the improved closure method,the influence of key voltage sag characteristics such as transient voltage sag value,duration,initial point and phase jump on the voltage sag tolerance characteristics of the identical equipment was tested.The quasi-rectangular distribution law of voltage sag tolerance characteristic curve is calculated,and the relevance between the above characteristics and the amplitude and waveform of voltage sag tolerance characteristic curve is elaborated.Based on the internal hardware topology of LED electronic display and the above test results,the relationship between switching power supply voltage sag characteristics and LED operating condition was determined,and the residual voltage(temporary sag value)and duration were identified as the key factors affecting the voltage sag characteristics.Aiming at the problems of complicated implementation and unclear switching power supply structure in existing internal optimization strategies,taking full-bridge switching power supply as an example,the voltage sag sensitive mechanism is firstly elaborated,and the voltage sag tolerance evaluation mechanism is proposed.The parameter optimization scheme of adjusting the switching tube width duty ratio by changing the turns ratio of high-frequency transformer is tried to be adopted.Then,based on the simulation on PLECS platform,the accuracy and feasibility of the tolerance evaluation mechanism and the improved tolerance parameter optimization scheme were verified.Combined with the actual statistical data of voltage sag characteristics of typical power grids,the practicability of the parameter optimization scheme was further verified.Finally,combined with the LED electronic display,the optimization process of the voltage sag tolerance characteristic was given,and the voltage sag tolerance characteristic curve of the LED electronic display before and after the internal optimization was compared,which confirmed the effectiveness of the internal optimization strategy of the switching power supply in alleviating the voltage sag effect of the internal switching power supply equipment.In view of the problems such as the difficulty in transforming the grid line,the time consuming and the power consuming in debugging and maintenance,and the high cost of governance in the external governance of the existing equipment,the optimization strategy of external voltage sag characteristic based on PFC inverter is proposed.The typical topology of PFC inverter and the internal mechanism of reducing the influence of voltage sag are described,and the parameter configuration procedure of PFC inverter is given.Secondly,the PLECS platform was used for simulation to verify the feasibility of the external optimization strategy for voltage sag tolerance characteristics of switching power supply.Then combined with the LED electronic display,the design of internal and external optimization strategy to optimize the voltage sag tolerance characteristics and the simulation verification of tolerance characteristics optimization are shown.Finally,referring to the actual statistical data of typical grid voltage sag characteristics,the effectiveness and practicability of internal,external and internal optimization strategies for voltage sag tolerance characteristics of electrical equipment of built-in switching power supply are expounded.