Research On Electromagnetic Design And Performance Analysis Of Flywheel Motor

Reaction flywheel system is the actuator of attitude adjustment for satellite and other spacecraft.The characteristics of the system requires small size,light weight,high precision,strong reliability with long life.Flywheel motor is the key component of spacecraft attitude control system.Its performance directly affects the control accuracy,stability,operation efficiency and loss of spacecraft.The conventional flywheel motor has the poor quality of air gap flux density waveform and back EMF waveform,large loss and large torque ripple.Based on the conventional flywheel motor,this thesis proposes a double-circle magnetic steel flywheel motor and the electromagnetic design and optimization of the motor is carried out,which improves the air gap magnetic flux waveform,torque ripple and increases the output torque and reduces the losses of motor.Then,a double-layer Halbach flywheel motor was proposed,and the electromagnetic design and optimization were carried out to further improve the performance of the motor.The specific research work is as follows:(1)The structure and working principle of flywheel motor are analyzed.The electromagnetic design of conventional flywheel motor is carried out by equivalent magnetic circuit method,and the motor is analyzed by finite element software.(2)Based on the structure of conventional flywheel motor,the structure of doublecircle magnet flywheel motor is designed.The electromagnetic design and analysis of double-circle magnet flywheel motor are carried out by using finite element software,including the design of rotor,stator and permanent magnet.Finally,the specific size of the motor is determined.(3)The performance of the double-circle magnet flywheel motor and conventional flywheel motor are analyzed.The air gap magnetic density waveform,back EMF waveform and electromagnetic torque of the conventional flywheel motor and the double circle magnets flywheel motor are analyzed by finite element software.The analysis results show that the air gap magnetic density waveform of the double circle magnets flywheel motor is 26.6% higher than that of the conventional flywheel motor,and the torque ripple is reduced by 18%.It is beneficial to improve the control precision and stability of the reaction flywheel system.Then,the motor loss of the conventional flywheel motor and the double-circle magnets flywheel motor is analyzed and compared.The results show that the loss of the double-circle magnets flywheel motor is smaller.(4)Based on the double-circle magnet flywheel motor,a double-layer Halbach flywheel motor is proposed.The structure of the motor and the number of blocks of the Halbach magnetic pole are determined.The analytical calculation method and the finite element method are used to calculate the air gap magnetic density waveform.The motor is then analyzed by finite element software and the pole-arc coefficient of the motor is optimized.Compared with the double-circle magnet flywheel motor,the results show that the double-layer Halbach flywheel motor has smaller torque ripple and smaller loss than the double-circle magnet flywheel motor.The performance of motor has been further improved.