The Research on Interference Analysis and Suppression Methods of Pressure Transmission in Electric Propulsion System

As an advanced space propulsion system, electric propulsion generates thrust by ionizing and accelerating a gaseous propellant, commonly xenon or krypton, which serves as the working medium. The precise and stable supply of the working gas is a critical factor in ensuring the stable and standardized performance of the electric thruster, as it directly influences parameters such as specific impulse, thrust level, and overall system efficiency. Among various control parameters, the pressure of the working gas is particularly important for accurate flow rate regulation in electric propulsion systems, requiring both high stability and measurement accuracy to maintain optimal thruster operation.During system operation, however, common-mode interference originating from high-frequency switching circuits, power converters, or other electronic subsystems can adversely affect the performance of the pressure sensor. Such interference may lead to measurement deviations, signal instability, or even sensor malfunction, thereby compromising the reliability of the propulsion system. This paper systematically analyzes the origins and propagation paths of common-mode interference affecting the pressure sensor within the electric propulsion system. The interference mechanism is investigated through both theoretical modeling and experimental observation, taking into account factors such as electromagnetic coupling, ground loop effects, and power supply fluctuations.To mitigate these adverse effects, interference suppression methods are proposed and evaluated. These include the installation of common-mode capacitors between the input side of the power control unit and the pressure sensor, as well as between the input side of the pressure sensor and the system housing. Additionally, capacitors are applied across the positive and negative differential signal acquisition lines of the pressure sensor to enhance noise immunity. These measures are designed to attenuate high-frequency common-mode noise and improve signal integrity.Experimental validation was conducted under typical operating conditions. The results indicate that when common-mode capacitors with values of 0.01 μF and 22 μF were applied, the maximum pressure deviation observed among three identical pressure sensors was limited to 0.00149 MPa. This outcome demonstrates the effectiveness of the proposed method in suppressing common-mode interference in the pressure sensing circuit of electric propulsion systems. The approach has subsequently been implemented in related engineering products, contributing to enhanced measurement accuracy and operational reliability.