Mechanism for electro-magnetic interference in an aircraft's electric braking system and its suppression method

This paper deals with the problem that the signals of the force sensor of an aircraft's electric braking system are superimposed with high-amplitude interference. The analysis of the electric braking system shows that the three-phase current of its motor and the pulse width modulation (PWM) wave output by the electro-mechanical actuator controller (EMAC) are the primary sources of interference and that the coupling interference between cable lines is the main cause of the interference of signals of the force sensor. The mathematical model of coupling interference between cable lines is established, according to which the transmission cable is designed and the line coupling was reduced by using electromagnetic shielding, line twisting and effective grounding. A passive electromagnetic interference (EMI) filter is designed for the output end of the EMAC. Through these improvements, the interference superimposed on the force sensor is greatly reduced. The paper also improves the electromagnetic compatibility of the electric braking system and ensures that the braking force servo system works normally.