Design Of A High Efficiency And Low Standby Power Consumption Secondary-side Regulation AC-DC Flyback Converter

In recent years,due to the rapid development of electronic technology and the improvement of living standards,the consumer electronic product market continues to be hot,and the global market has an increasing demand for switching power supplies,especially flyback converters.In addition,with the increasing shortage of energy sources and the significant increase in public awareness of environmental protection,green power has great potential for development.For the sake of the demand of the orientation market,a flyback converter chip with high efficiency and low standby power consumption urgently needs to be designed.Aiming at the above-mentioned requirements,two aspects of improving the conversion efficiency of the power supply and reducing its standby power consumption are designed and studied in this paper.For the flyback converter,the traditional method of improving the conversion efficiency has a complicated circuit structure and high cost,which can only improve the conversion efficiency under a specific load,which is not conducive to actual production.The six main losses of the secondary-side feedback flyback converter system are summarized and analyzed in this paper.It is found that the switching frequency and the peak current of the primary side of the system are the main factors affecting the system losses.According to the analysis results,in order to reduce the loss and improve the conversion efficiency of the system,the switching frequency regulation circuit and the peak current regulation circuit are designed to adjust the switching frequency of the system and the peak current of the primary side with the load.At light load,the system reduces the switching frequency and switching loss.At heavy load,the system limits the magnitude of the peak current of the primary side,reduces the conduction loss,and improves the average efficiency of the system.In addition,the burst mode is applied in this paper to reduce the standby power consumption of the system.Through the control of the feedback voltage,the system can work intermittently,which reduces the static power consumption of the system in the standby mode.The control IC for the proposed high efficiency and low standby power converter has fabricated in HHNEC BCD 350 nm GE process and the performance is verified by a 12 V / 1A prototype.The test results show that the maximum standby power consumption of the system is 65 m W under the AC input voltage of 90～265V.When the constant voltage output is 12 V,the constant voltage output accuracy of the system is ±1.3%,the linear adjustment rate is ±0.6%,and the load adjustment rate is ±0.7%.The maximum conversion efficiency under heavy load is 86.48%,the minimum conversion efficiency under light load is 82.66%,and the average conversion efficiency is higher than 85%.Therefore,the flyback converter designed in this paper has the characteristics of high efficiency and low standby power consumption,and it has a good application prospect in the market of low and medium power flyback converters.