小功率开关电源传导干扰的分析

针对便携式小功率开关电源领域中,由于受体积和成本压力限制而无法增加电磁兼容专用滤波器,导致电源电磁兼容性较差的问题,首先分析了开关电源机理和传导干扰信号的种类和来源;然后对"整流滤波电路设计、高频变压器和钳位二极管选型、线路板布局"等方面问题进行了研究,得出了在不增加额外电路的情况下,将传导干扰抑制在标准限值范围的改进措施;最后对一5 W的小功率开关电源产品进行整改,将其传导干扰强度降低11 dBuV并通过认证。研究结果表明,该措施对抑制小功率开关电源的传导干扰信号是有效的。

Study on conduction disturbance of the low-powered switching power supply

The portable low-power switching power supply is not made use of the filters which are designed specially for electromagnetic compatbility since the power supply＇s small size and low cost,so the power supply is pulled in poor electromagnetic compatibility situations.Aiming at these problems,it was firstly analyzed that the general principle of switching power supply and the signal sources of conducted interference.Then,the research was done in the rectifier filter circuit,the model of high-frequency transformer and clamping diodes and the circuit board layout.Based on the research,the corrective measures were provided to suppress conducted signal without adding additional circuitry,so that the strength of conducted interference signal can be limited under the standard.At last,an example was shown about one product of 5 W switching power supply.The signal intensity was reduced by 11 dBuV and the certificates was gotten.The results indicate that the measures are effective to restrain conducted interference signal of low-power switching power supply.