Reliability Analysis And Fault-tolerant Design Of The Reaction Flywheel

Attitude controlling is one of the most important function of satellite system.As a kind of actuator used for controlling the attitude. The performance andreliability of Reaction Flywheel have great impact on the performance and life-spanof the satellite. Therefore, the studies of reliability of flywheel have importantsignificance for the reliability of entire satellites. This paper focus on studying thereliability and fault-tolerant approach about the new high-speed，light and smallreaction flywheels successfully developed by our group. The contents are as follows:1.Firstly, this paper explains the theory, mechanical structure and mathematicalmodels of Reaction Flywheels systematically. From the flywheel mechanicalstructure and control circuits, the reliability of its various components are estimatedusing these reliability prediction methods, locate the weaknesses of reliability offlywheel. According to the operating environment in the whole experiment, thispaper establishes a fault tree and failure mode analysis of the cause of failure. Inaccordance with the flywheel failure mode, some fault-tolerant design methods weremade with some simulation and experimental verification of the correctness of theproposed fault-tolerant design approach.2.According to the fault mode of the reaction flywheel, redundancy MOSFET inthe drive-axle circuit is designed, and adding a dead-zone in control methods isapplied. Take the flywheel actual using environment into consideration, a CAN busprotocol for communication is worked out. In the protocol, author designed sometreatments about these failures flywheel may encounter when in operation. Faultmode of the Hall signal is studied, and the algorithm flow chart for the fault-tolerantcontrol of the Hall sensor is designed after discussing the qualification of flywheel control system.3.To test the flywheel performance and the feasibility of fault-tolerant method, adesign based on DSP flywheel control circuit board was made. A PC program usingMicrosoft’s MFC class library with serial communication in real-time renderingflywheel speed, bus voltage and bus current was programmed. Flywheel speed andbus current curves were measured using dual loop PID controller and controlledunder the conditions of Hall sensor fault, and compared to the results under thegeneral condition, verify feasibility of the fault-tolerant method.Flywheel reliability analysis and fault-tolerant approach are supplements ofsuccessfully developed flywheel system, have certainly importance.