EMI conducted emission for a vehicle DC wiper motor

DC wiper motor is an important component for vehicle, but it is also a serious EMI (electromagnetic interference) source. Aiming at this problem, an analysis of EMI source was done and an EMI conducted emission test along power lines for wiper motor was carried out according to standard CISPR25. Conducted voltage and common-mode current were measured and the test results verified the common-mode current was the EMI source of wiper motor. In order to suppress common-mode current, common-mode choke was designed and good suppression effect was obtained.