CN-115358109-B - Maximum torque calculation method of ultrasonic motor based on finite element simulation analysis

CN115358109BCN 115358109 BCN115358109 BCN 115358109BCN-115358109-B

Abstract

The invention discloses a maximum torque calculation method of an ultrasonic motor based on finite element simulation analysis, which utilizes ANSYS Workbench finite element analysis software to calculate the time-dependent change condition of a stator and a rotor of a traveling wave ultrasonic motor by combining a piezoelectric module in a structure transient analysis module, and determines the maximum torque of the traveling wave rotating ultrasonic motor at the time of motor reversal by loading torque which is opposite to the motor rotation direction and gradually increases. The method is simple, can preliminarily determine the maximum torque of the traveling wave rotary ultrasonic motor, lays a foundation for the later-period structure optimization and experiment, and has good practical value.

Inventors

Lai dongyang
JIN JIAMEI
LIU RUI
WANG LIANG

Assignees

南京航空航天大学

Dates

Publication Date: 20260505
Application Date: 20220725

Claims (1)

1. The maximum torque calculation method of the ultrasonic motor based on finite element simulation analysis is characterized by comprising the following steps of: Step 1), determining geometric structures and material definitions of a stator and a rotor of an ultrasonic motor; Step 2), dividing grids, and establishing a finite element simulation model of the ultrasonic motor; step 3), constraint boundary conditions and contact boundary conditions are set for the finite element simulation model of the ultrasonic motor; step 4), setting material properties of piezoelectric material parts in the ultrasonic motor, and determining polarization directions, piezoelectric constants and dielectric constants of the piezoelectric material parts; Step 5), carrying out modal analysis on the ultrasonic motor, and determining the working modal frequency of the stator of the ultrasonic motor; Step 6), establishing a transient dynamics simulation analysis module, and setting the calculation time of each load step according to the working mode frequency of the ultrasonic motor stator; canceling the inhibition on a rotor and a friction plate, adding a structure transient module, determining the time of each load step according to the resonant frequency f obtained by modal analysis, wherein the time of one period is 1/f, and subdividing one period into 8 load steps, so that the calculation time of each load step is 1/8f seconds; step 7), defining sub-steps in load step setting, setting the number of sub-steps to be 5, namely dividing each load step into 5 sub-steps, and calculating the number of steps in each period to be 40 steps; Step 8), setting voltage load, namely setting voltage for the load step in each period by taking the load step as a reference, and performing periodic circulation to obtain a change curve of the rotation angle of the ultrasonic motor rotor along with time; Step 9), loading torque, taking the load step as a reference, not applying opposite torque before 0.005s, and starting to apply torque gradually increased to 1Nm after the motor enters steady speed to obtain an opposite torque curve; Step 10), judging according to a change curve of the rotation angle of the rotor of the ultrasonic motor along with time, wherein the ultrasonic motor is in a starting working state at the moment when the slope of the curve is negative, and the maximum torque of the motor is the maximum torque when the slope of the curve starts to be positive; step 11), obtaining the reverse torque reverse rotation time of the motor applied to the motor at the trough of the change curve of the rotation angle of the motor rotor along with time, and determining the torque, namely the maximum torque of the motor, on the reverse torque curve according to the reverse rotation time.

Description

Maximum torque calculation method of ultrasonic motor based on finite element simulation analysis Technical Field The invention designs a traveling wave rotary ultrasonic motor, in particular to a maximum torque calculation method of an ultrasonic motor based on finite element simulation analysis. Background Aerospace is one of the most challenging high-technology fields with wide portability in the world, china is also accelerating the construction pace of the aerospace in China, and the application depth and breadth of the space are continuously expanded. The spacecraft is a carrier for space application, and various high-precision long-life space mechanisms such as a laser pointing mechanism (CPA), a Control Moment Gyro (CMG), a laser scanning three-dimensional imaging mechanism (LVDS), a space mechanical arm, an antenna driving mechanism (GDA) and the like are widely arranged on various spacecrafts so as to meet the requirements of different applications on accurate control, accurate observation, accurate and stable operation. The realization of the light weight and the rapid precise stable movement performance of the space institution becomes the basic capability for supporting the urgent promotion of the construction of the aerospace country in China. The motor is a driving source for the movement of various space mechanisms, and plays a vital role in the comprehensive performance of the space mechanisms. Unlike electromagnetic motor with space mechanism, the ultrasonic motor produces controllable microscopic vibration via piezoelectric ceramic exciting stator and converts the microscopic vibration into macroscopic rotation via stator and rotor friction. Based on the working principle, the ultrasonic motor can fully show the advantages of light weight, large torque, quick response, self locking and the like in the strict volume and weight constraint range of the space mechanism, and can better realize the system weight reduction and remarkably improve the response characteristic when applied to the space mechanism. Therefore, in order to meet the typical working condition requirements of high precision, long service life, ultra low speed, large speed ratio and reciprocating swing of the space mechanism, particularly, for the space mechanism, the load capacity of the ultrasonic motor is the most important capacity, so that the maximum torque of the ultrasonic motor is necessary to be studied. Disclosure of Invention The invention aims to solve the technical problem of providing a maximum torque calculation method of an ultrasonic motor based on finite element simulation analysis aiming at the defects related to the background technology. The technical scheme adopted for solving the technical problems is as follows: The maximum torque calculation method of the ultrasonic motor based on finite element simulation analysis comprises the following steps: Step 1), determining geometric structures and material definitions of a stator and a rotor of an ultrasonic motor; Step 2), dividing grids, and establishing a finite element simulation model of the ultrasonic motor; step 3), setting constraint boundary conditions and contact boundary conditions for the finite element simulation model of the ultrasonic motor by the root; step 4), setting material properties of piezoelectric material parts in the ultrasonic motor, and determining polarization directions, piezoelectric constants and dielectric constants of the piezoelectric material parts; Step 5), carrying out modal analysis on the ultrasonic motor, and determining the working modal frequency of the stator of the ultrasonic motor; Step 6), establishing a transient dynamics simulation analysis module, and setting the calculation time of each load step according to the working mode frequency of the ultrasonic motor stator; Step 7), defining sub-steps in the load step setting; Step 8), setting voltage load, namely setting voltage for the load step in each period by taking the load step as a reference, and performing periodic circulation to obtain a change curve of the rotation angle of the ultrasonic motor rotor along with time; Step 9), loading torque, taking the load step as a reference, not applying opposite torque before 0.005s, and starting to apply torque gradually increased to 1Nm after the motor enters steady speed to obtain an opposite torque curve; Step 10), judging according to a change curve of the rotation angle of the ultrasonic motor rotor along with time, wherein the ultrasonic motor is in a starting working state at the moment when the slope of the curve is negative, and the maximum torque of electrons is the maximum torque when the slope of the curve starts to be positive; step 11), obtaining the reverse torque reverse rotation time of the motor applied to the motor at the trough of the change curve of the rotation angle of the motor rotor along with time, and determining the torque, namely the maximum torque of the motor, on the reverse torque