Modeling and Design of Active Filter for EMI Cancellation in High Voltage Power Supply of Motor Controller for Electric Vehicle

The rapid switching of IGBT and other power semiconductor devices in the drive motor controller of electric vehicles generates transient voltage and transient current, resulting in conducted and radiated emissions of high-voltage lines exceeding the limits specified in the CISPR 25-2021 standard. In order to solve the problems of poor electro -magnetic interference suppression and large volume in the low-frequency range of passive EMI filters (PEF), as well as poor high-frequency interference suppression in active filters, an active EMI filter (AEF) suitable for high-voltage power supply of electric vehicle motor controllers was designed. A high-frequency circuit model of the proposed high-precision AEF was established, and a prototype of the AEF was designed. The insertion loss of AEF is greater than 35.2dB from 100kHz to 100MHz, with a maximum of 39.3dB. Compared with PEF with the same insertion loss, the proposed HEF reduces its volume by approximately 50%. When the motor operates under load, the conduction voltage of the motor controller meets the requirements of level 3 of CISPR25-2021.