Pre-sizing of magnetic actuators and sensors for space applications

This dissertation has been written following a full-time 6-month internship in Thales Alenia Space Cannes. It is divided in 5 main parts. The first part of the thesis introduces the fundamental concepts for the study of magnetism. Mainly Maxwell’s equations, an introduction to material science of magnetic materials as well as a presentation of FEM for magnetism from a structural engineering point of view is done. Part II serves as a rapid overview of the code developed during my internship that will be used in parts III and V. It is based on J.P Yonnet’s equations for permanent magnets. Part II doesn’t aim to re-explain all of J.P Yonnet’s theory, but merely to give some insight for the reader on the model used during the essay. In particular, it explains how force maps from random magnetization direction magnets can be obtained from Yonnet’s model. Part III is dedicated to the pre-sizing process of 3 concepts of a magnetic actuator for an on-orbit servicing solution. It is composed of a magnetic sizing process description as well as a dynamic model (Simulink) explanation for the study of the docking of satellites with the actuators. Three main actuators have been sized: a simple identical permanent magnet solution, a solution coupled with iron and coils as well as an innovative passive self-separating permanent magnet-based solution. Methods used include FEM, Matlab simulations and non-linear global optimization methods. Part IV focuses on the pre-sizing of a magnetic sensor for a Solar Array Drive Mechanism. It was mainly conducted in TAS’s clean room in Cannes on a test bench the company possesses. The study aims to validate the pre-sizing phase of this device from the processing of results given by the laboratory’s oscilloscope, as well as the study of different magnetic shields for the sensor. FEM simulations on CST studio have also been conducted for correlation purposes. Part V presents a rapid feasibility analysis of a novel magnetic bearing solution for a self-levitating optical payload actuation system. It establishes the fundamental relationships between parameters to be able to conduct an in-depth sizing of the mechanism down the line.