一种原边反馈反激变换器负载调整率优化技术

A Method for Improving Load Regulation of Primary-Side Feedback Flyback Converter

原边反馈控制技术中,后级输出阻抗产生的压降使采样精度降低,产生负载调整率差的问题,分析指出该误差仅与输出电流大小有关。现提出一种简单的结构,通过计算磁芯复位时长,将输出电流引起的误差信号转换成对应的电平值并引入电压环,对输出电压进行补偿,改善了变换器的负载调整率。实验结果表明:在一款输出12V/0.125A的原边反馈式反激变换器中,输入电压为28V时,使用该补偿电路后,负载调整率从3%降低到0.5%,达到了预期要求。

In primary-side feedback flyback converter,the voltage drop of the second-side output impedance affects the accuracy of sampling.And an analysis shows this error is only related to output current.In order to improve the load regulation,a concise compensation method is proposed in this paper.By calculating the magnetic reset time,the error signal is conversed to a capacitor voltage.Then the voltage is imported into the feedback loop to compensate the output voltage.The experiment is verified on a 12 V/0.125 Aprimary-side feedback flyback converter.When the input voltage is 28 V,load regulation decreases from 3%to 0.5%after using the proposed method,which reaches the desired requirement.