中文摘要：

负载调整率是直流电源的一个重要参数,负载调整率的高低决定了整个系统的性能。研究了LM2577升压芯片的内部结构及性能参数,在此基础上,提出了两种提高其负载调整率的新方法：（1）在LM2577反馈脚接入可程控数字电位器,代替原固定电阻,用AD采样输出电压的变化,通过反馈算法调节数字电位器的阻值,保持输出电压稳定,进而提高其负载调整率;（2）在LM2577反馈脚接入加法器,加法器的输入端分别由输出电压分压端和受单片机控制的DA提供,单片机通过采样输出电压来调整DA的输出,进而实现输出电压的稳定,提高负载调整率。为了缩短调整时间,提高控制效率,软件部分采用了PID控制算法。经测试,在5 V输入、600 m A负载条件下,设定输出为7 V,方法 1和方法 2升压电路的负载调整率从1.043%分别提升到0.700%及0.042%;而设定输出为12 V时,负载调整率从0.658%均提升到0.008%。同时,方法 2的输出电压纹波在10 m V以内。

英文摘要：

As one of the most important parameters of direct current（DC） power supply,load regulation determines the performance of whole system.The internal structure as well as performance parameters of LM2577 boost converter was investigated and two new methods of improving its load regulation were proposed based on this investigation.One method（method 1） was to replace the resistor by connecting a programmable potentiometer to the feedback pin of LM2577 and sample the variation of output voltage using an AD converter.The potentiometer was adjusted under the control of feedback algorithm to keep the output voltage stable,thus the load regulation was enhanced.In the other method（method 2）,an adder was connected to the feedback pin of LM2577 to stabilize the output voltage of DC power supply and increase the load regulation.A voltage divider made up of resistors divided the output voltage and provided the divided voltage to one input of the adder.The other adder input came from DA converter controlled by microcontroller.To reduce the adjust time and increase the efficiency,PID algorithm was applied in the software part of the system.12-bit AD（ADS1115）,12-bit DA（TLV 5638） and 10-bit programmable potentiometer（AD5293） were used to test the methods above under the condition of 5 V input voltage and 600 m A load current.When output is set to 7 V,the load regulation is improved from 1.043% to 0.700% and 0.042% by applying the first and second method,respectively.When output voltage equals 12 V,the improvement is from0.658% to 0.008%.Meanwhile,the method 2 suppresses output voltage ripple to be less than 10 m V.