Motor Torque Frequency Characteristics Based On Load Motor Behavior Model Test System Research

The motor dynamic torque is generally measured with a torque sensor,but the angle of the torque sensor strain gauge is easy to change,and it is easy to be deformed after long-term use,resulting in a large error in the motor dynamic torque measurement result,and the long-term stable measurement of the motor torque frequency characteristic cannot be performed.To this end,this paper proposes a scheme for measuring the torque-frequency characteristics of the torque sensor behavior model.This scheme uses the brushless DC motor as the load motor and uses linear regression to establish the behavior of the relationship between the current,speed and torque of the load motor.The model is used to measure the torque,and the rotation speed is measured by counting the number of changes of the Hall signal output by the load motor.A system for measuring the motor torque frequency characteristics based on the load motor behavior model is designed to achieve long-term stable measurement of the motor torque frequency characteristics.The test system mainly includes the following parts:main controller module,load motor drive module,current detection module,communication module and power supply module.In this paper,the least square method is used to solve the optimal parameters of the model,so as to obtain the plane equation of the three-dimensional behavior model.After the expression of the behavior model is determined,the current and speed of the load motor are input,and the torque of the motor can be directly and accurately calculated through the behavior model.The system uses ARM+ FPGA as the main controller to improve the real-time and reliability of the system.ARM is mainly used to control the motor,receive and process data,and communicate with the host computer;FPGA is mainly used to detect the position of the load motor rotor and commutation control of the load motor.Through the MODBUS communication protocol,the communication between the main controller and the host computer is completed,the parameter design and debugging of the system through the host computer are realized,and the parameters such as the current,speed,and torque of the motor measured by the system are displayed on the host computer in real time.Taking the 750W permanent magnet synchronous motor as the test object,the system was tested using this method and the torque frequency measurement method using torque sensors,and the results based on the behavior model were basically consistent with the torque frequency measurement method using torque sensors.The maximum relative error of the system when measuring the motor speed is 0.119%,the maximum relative error when measuring the motor torque is 1.58%,the repeatability error is 0.083%,and the nonlinear error is 0.79%.It shows that this method can replace the torque sensor to thoroughly achieve the long-term stable measurement of the dynamic torque frequency characteristics of the motor,and has more advantages in terms of volume,cost,structure,operation and maintenance.