Modeling of Common-Mode Noise Equivalent Circuit for Solid-State Transformer based on ISOP Configuration

This paper discusses common-mode noise of a solid-state transformer (SST) based on input-series output-parallel (ISOP) configuration. The ISOP configuration has a complex common-mode current path because of the increased parasitic component of the switching devices. The power factor correction (PFC) part in the SST is modeled with a common-mode equivalent circuit in order to measure the characteristics of the common-mode current. The leakage current between the simulation and the experimental result is compared in order to evaluate the common-mode equivalent model. The maximum spectrum values of the leakage current in the simulation and the experimental result are $67.2 \mathrm{~dB} \mu \mathrm{A}$ and $63.6 \mathrm{~dB} \mu \mathrm{A}$ at the 4.5 MHz band. This means that the frequency 4.5MHz is the resonant frequency between the parasitic capacitor and the parasitic inductor of the switching devices. The experimental results of the leakage current envelope curve almost agree with the simulation results. Thus, the proposed common equivalent model is valid in order to evaluate the common mode current based on CISPR 16.