Research On Key Technology Of Attitude Control Flywheel System For Small Satellites Application

Flywheel is the main implementing component of satellite attitude control system. High precision, low power consumption, small size and high reliability have been the main goals during the development of flywheel technology. The research of this paper is carried out under the background of the attitude control flywheel systems for small satellites application. The key technologies including the design of structure and the permanent magnet brushless DC motor(BLDCM) as well as the optimization method for flywheel system are investigated. The main contents are as follows:(1) The driving motor is the core part of the flywheel system and its accuracy of the electromagnetic design has great effect on the overall performance of the system. As the driving motor has large radial dimension and small axial length, the coupled field-circuit method is adopted to determine the parameters including the air-gap length, the equivalent calculating polar arc factor, the leakage magnetic coefficient and the armature winding parameters, laying foundation for electromagnetic design.(2) The power consumption of the flywheel system can be reduced by improving the efficiency of the driven motor. A method realizing the inverse electromagnetic design for the permanent magnet BLDCM is proposed, which meets the low power consumption and high efficiency demands of the motor. Based on this method, a rim-driven flywheel system is designed and the key elements affecting the motor’s performance are investigated, such as the permanent magnets’ magnetizing models, the pole pairs and the axial air-gap. High design accuracy of the method is manifested in simulation and the maximum design error is about 10.7%.(3) To optimize the system’s performance, the multidisciplinary optimization techniques are applied to the multi-objective optimization of the flywheel body after considering the mechanical properties, which involve the mass, volume and air-gap flux density, and the motor’s electromagnetic performance. To improve the flywheel system’s reliability, the structural strength and stiffness, mode distribution and random excitation responses are analyzed based on the finite element analysis(FEA), and the results show that the structure can meet the engineering requirements after optimization.(4) Traditional flywheel systems usually has large axial size and relaxed structure, leading to lower function density. To improve integration and technical portability, a flywheel system based on an axial flux motor and a PCB winding stator is proposed. The mathematic model of the PCB winding is established to predict the main parameters of motor’s performances. A wave form PCB winding is designed to eliminate the anti-torque’s effect on the performance of flywheel system and the power consumption. The eddy current in the winding conductors is analyzed and the intersected track as well as ordinary disc type winding are used to reduce the losses.(5) The flywheel system prototypes are fabricated for the engineering application and their power consumption performances are investigated. And the prototypes’ performances in high temperature, thermal vacuum and random vibration environment are tested to ensure the reliability and safety.The works in this essay closely tracks the modern engineering applications, which are significant for both the theoretical research and engineering application in the miniaturization and lightweight design and low power consumption design of attitude control flywheel systems for small satellites application.