Abstract:
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.