Design And Vibration And Noise Analysis On Drive Motor Used In Bionic Fish Tail

Due to the significant progress of the bionics and the robitics,biomimetic robotic fishs is favored by more and more researchers.Bionic robotic fish has been applied in many fields,and the impetus of bionic fishs to military development is immeasurable.The permanent magnet synchronous motors are chosen as the driving mechanism of bionic fishs tail in this thesis.Because it has the advantages of high efficiency,high mechanical strength and strong servo capability.However,the vibration and noise are unavoidable when the motors are running,which reduces the invisibility of the bionic fishs when performing special military tasks.Therefore,this thesis studies the vibration and noise of the bionic fishtail drive motors.First of all,the permanent magnet synchronous motors are selected as the bionic fishtail drive motors.The technical parameters and operating environment of the motors are integrated to estimate the electromagnetic loading.Besides,one of the important data of the motors,its main imensions must be calculated.To select the rotor structure of the motors successfully and calculate the number of pole slots of the motors,three aspects should be studied.It involves winding coefficient,vibration and noise and slot torque.To verify the design of the near pole groove bionic fish tail permanent magnet synchronous motors can meet the design requirements by means of the research of no-load and load magnetic field distribution.Analyze the output torque performance of the motors and verify that the motor meets the performance requirements.Next,solve the expression of radial electromagnetic force of permanent magnet synchronous motors,and analyze the order and frequency of radial electromagnetic force.The variation of radial electromagnetic force in space and time is simulated and analyzed to verify that it conforms to the theoretical analysis results.To decrease the amplitude of radial electromagnetic force,the distribution law of radial electromagnetic force on the stator tooth top of the motors are explored.According to this distribution law,the segmented cutting structure of the stator tooth top is used to weaken the amplitude of radial electromagnetic force,and the appropriate cutting depth is selected.Simulation results show that this structure has a capability.This ability is to reduce the radial electromagnetic force to the size required by the equipment.And,it ensure that the torque output performance of the motors are not greatly weakened.Finally,the vibration and noise suppression of the motors with sectional cutting structure of stator tooth top are further verified.Simulation and analysis of vibration mode and natural frequency of motor stator mode,when the difference between natural frequence and electromagnetic frequence is large,the resonance phenomenon does not occur.The radial electromagnetic force obtained by electromagnetic analysis is coupled to the stator tooth of the three-dimensional model of the motor,vibration acceleration and velocity to be calculated at the housing.The noise sound pressure level must load the vibration velocity of the housing into the noise domain of the motors.Two factors,vibration acceleration and noise sound pressure level,are crucial.Because these two factors can be used to determine whether the noise is reduced.Meanwhile,considering that the bionic fish drive motor runs in the sea and the noise transmission medium is seawater,which is conducive to noise increase.Therefore,it is necessary to study the noise boost level in a specific environment by placing the motor in seawater.