Mitigation Conducted Emission Strategy Based on Transfer Function from a DC-Fed Wireless Charging System for Electric Vehicles

Abstract

The large dv/dt and di/dt outputs of power devices in wireless charging system (WCS) in electric vehicles (EVs) always introduce conducted electromagnetic interference (EMI) emissions. This paper proposes a mitigation conducted emission strategy based on transfer function from a direct current fed (DC-fed) WCS for EVs. A complete test for the DC-fed WCS is set up to measure the conducted emission of DC power cables in a frequency range of 150 kHz-108 MHz. An equivalent circuit with high-frequency parasitic parameters for WCS for EV is built based on measurement results to obtain the characteristics of conducted emission from WCS. The transfer functions of differential mode (DM) interference and common mode (CM) interference were established. A judgment method of using transfer functions to determine the dominated interference mode responsible for EMI is proposed. From the comparison of simulation results between CM or DM and CM+DM interference, it can be seen that the CM interference is the dominated interference mode which causes the conducted EMI in WCS in EVs. A strategy of giving priority to the dominated interference mode is proposed for designing the CM interference filter. Finally, the conducted voltage experiment is performed to verify the mitigation conducted emission strategy. The conducted voltage of simulation and experiment is decreased respectively by 21.17 and 21.4 dBµV at resonance frequency 30 MHz. The conduced voltage at frequency range of 150 kHz-108 MHz can be mitigated to below the limit level-3 of CISPR25 standard (GB/T 18655-2010) by adding the CM interference filters.

Research on Magnetic Field Distribution and Characteristics of a 3.7 kW Wireless Charging System for Electric Vehicles under Offset

“…The inductor of the LC filter needs to not make the output current deteriorate. The inductor L o and capacitor C o can be selected according to the following formula [2]:…”

“…One is to study the magnetic field distribution of WCS working on normal conditions. When the coupling coils are aligned, characteristics of electromagnetic fields distribution around the coupling coils are studied [2][3][4]. Magnetic field under different charging modes like the constant current and constant voltage charging operations are compared [5].…”

A Parametric Conducted Emission Modeling Method of a Switching Model Power Supply (SMPS) Chip by a Developed Vector Fitting Algorithm

“…For the conducted emission modeling of SMPS, the earlier research starts from the physical parameters of the device and constructs the CE model [4][5][6][7]. However, this method requires detailed information of the device, the modeling process is complicated, and the established model has poor precision.…”

High Efficiency and Power Tracking Method for Wireless Charging System Based on Phase-Shift Control

“…An exhaustive theoretical discussion on this topic is given for example in . The authors usually build their mathematical models based on the equivalent electrical circuit method using linear equations with lumped electrical parameters, but only few of them consider also the parasitic effects (e.g., [12][13][14][15][16]). Another frequently proposed approach is to describe the system behaviour while using electromagnetic field calculated through the finite element analysis [28][29][30][31][32][33][34][35][36][37][38][39][40].…”