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电子工程2019年16期

低共模噪声隔离DC-DC 变换器的设计
潘成飞,游勇,陈红亮
(广州致远电子有限公司,广东 广州 510660)

摘  要:数据采集系统中通常采用隔离开关电源给浮置测量电路供电,然而对于被测信号接地的情况,变压器初次级间的噪声对测量电路而言是一个共模干扰源,影响测量精度。为提高测量精度,对初次级间共模噪声产生的机理、共模噪声在测量回路中形成干扰的原因进行分析,得到降低共模噪声的思路。最后设计一款隔离电源,使用平衡对称指数规律变化的波形驱动变压器,以降低驱动电压和漏感电动势的dV/dt,采用全桥驱动和全波整流的对称拓扑并结合单层绕组抵消初次级间感应电动势产生的泄漏电流。试验表明采取这些措施后共模噪声远低于常规不控制变压器dV/dt 的方波驱动方案。


关键词:开关电源;共模噪声;驱动波形;漏感电动势



中图分类号:TM46         文献标识码:A         文章编号:2096-4706(2019)16-0022-04


Design of Low Common Mode Noise Isolation DC-DC Converter

PAN Chengfei,YOU Yong,CHEN Hongliang

(Guangzhou Zhiyuan Electronics Co.,Ltd.,Guangzhou 510660,China)

Abstract:The isolation switch power supply is usually used in the data acquisition system to supply power to the floating measurement circuit. However,when the measured signal is grounded,the noise between the primary stages of the transformer is a common mode interference source to the measurement circuit,affecting the measurement accuracy. In order to improve the measurement accuracy,this paper analyzes the mechanism of common mode noise in the first stage and the reason of common mode noise in the measurement loop,and obtains the idea of reducing common mode noise. Finally,an isolated power supply is designed,which uses the waveform of balanced symmetric exponential law to drive the transformer,so as to reduce the driving voltage and the dV/dt of the leakage induced electromotive force. The symmetric topology of full bridge drive and full wave rectification is adopted,and the single-layer winding is combined to offset the leakage current generated by the initial induced electromotive force between stages. The results show that the common mode noise is much lower than that of the conventional square wave drive scheme without controlling transformer dV/dt.

Keywords:switching power supply;common mode noise;drive waveform;leakage electromotive force


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作者简介:潘成飞(1987.06-),男,汉族,广东肇庆人,技术经理,本科,研究方向:精密测量仪器。