变压器耦合式直流固体继电器传导发射分析与抑制

在采用变压器耦合作为隔离电路的固体继电器中，变压器工作在自激振荡状态，通过磁芯将高频信号传递到变压器次级。这使得变压器成为对外传导发射的主要干扰源，严重时会影响到其他电子设备的正常工作。文中以某型号变压器耦合式直流固体继电器为研究对象，首先根据GJB1515A 中CE102(10kHz-10MHz 电源线传导发射要求)的规定，试验测量得到输入端电源线对外传导发射。首先，将传导发射分为差模干扰和共模干扰两种形式，并分析了传导发射的干扰源和主要传播通道。其次，在建立考虑铁心损耗和绕组铜损的变压器高频模型的基础上，利用ANSOFT Q3D 和Orcad Pspice 仿真软件得到该固体继电器用于传导发射分析的等效电路模型。仿真结果与试验结果相吻合，均表明该继电器输入端电源线对外传导发射超出国军标的要求。为抑制传导发射，文中提出在固体继电器输入端串入EMI 滤波器的优化方案。试验结果显示，优化后输入端电源线对外传导发射低于国军标的规定，提高了变压器耦合式固体继电器的电磁兼容性能。

Analysis and Suppression of Conducted Electromagnetic Interferenceof DC SSR with Transformer Isolation

In this paper, the conducted EMI (Electromagnetic Interference) of a DC SSR (Solid State Relay) in whichtransformer isolation circuit was adopted was investigated at working frequency and higher harmonic. The origin and propagationpath of the conducted EMI was analyzed by dividing it into common mode EMI and differential mode EMI. The equivalent circuit ofdual-winding transformer of iron-core was proposed considering leakage inductance, iron loss in core and cupreous loss in winding.The conducted EMI model of the DC SSR was built by Orcad Pspice and Ansoft Q3D to predict EMI in the input port which wasprescribed in GJB 1515A-CE102. The results of both simulation and experiment showed that the conducted EMI exceeded the limitof CE102. In order to improve EMC of SSR, an EMI filter was proposed to reduce the conducted EMI which was useful validated byexperiment.