Torsional Vibration Testing And Suppression Method Research For Electric Drive System

Electric traction system(ETS)is a system that uses electromotor as prime mover and hauls a mechanical load via a transmission during production.It has a wide range of applications in industries like aviation,chemical production,textile,and other industries.An operating ETS tends to experience torsional vibration and thereby generates noise if there is an imbalance between the driving torque on the prime mover and the resistance torque on the mechanical load.Moreover,the torsional vibration can shorten the service lives of the prime mover's rotor and the transmission.Therefore,there is a need for new ways to control torsional vibration in ETS.To this end,research can be done to find approaches to directly measuring ETS's torsional vibration and to reveal the causes of torsional vibration,pattern of variation,and mechanisms by which related parameters affect it.Such research is considered to be of both scientific and engineering value.The kinematics equations for ETS imply that one manifestation of ETS's torsional vibration is angular acceleration fluctuation.In view of this,this study proposed a method that allows direct,real-time and objective detection of angular acceleration,on the basis of the principles of electromagnetic induction,and illustrated the measurement principle.The validity of this principle was verified through simulation using a finite element model.After that,an angular acceleration sensor with a new structure was designed based on the method proposed,and a sensor prototype was built.As the accuracy of angular acceleration measurement depends heavily on the accuracy of calibration,an angular acceleration calibration method was presented.The calibration principles were explained.An angular acceleration excitation system was developed.The sensor was then calibrated using the calibration method and a prototype of this device.In the calibration test,the sensor's performance indicators were obtained and the sources of errors in the excitation device were analyzed.Later,torsional vibration testing was performed on two types of ETS using the aforementioned angular acceleration sensor.The testing results revealed what caused the systems' torsional vibration and how it varied and was influenced by related parameters.Based on the findings,an approach to suppressing the torsional vibration was proposed.The research content is outlined below:1.A mathematical model was created for an ETS with a single-phase capacitor-run motor based on the operating principle of motors of this type.Torsional vibration in the ETS was examined when it operated under the following conditions: no load,a varying load,and varying capacitance.An analysis suggests that the system's torsional vibration was attributed primarily to variations in the ellipticity of RMF of the stator.By use of equivalent circuits and phasor diagrams,the patterns of variation in the system's torsional vibration under different operating conditions were revealed and the mechanisms by which load and capacitance influenced RMF ellipticity were determined.Based on the results,a method was proposed for reducing torsional vibration in ETS with single-phase capacitor-run motor.In this method,the ellipticity of stator's RMF can be improved through reasonable load matching and variable capacitor matching,thereby suppressing the system's torsional vibration.2.This section presents the principles of shaded-pole motors and a new method for calculating ellipticity of RMF of stators.The equivalent circuit of an ETS with a shaded-pole motor was constructed by calculating the magnetic potential produced by the stator using the double rotating field theory.Then mathematical expressions for air-gap RMF,rotor current and electromagnetic torque on the shaded-pole motor were inferred.The electromagnetic torque includes a component induced by double-frequency vibration,as indicated by its expression.Next,the ETS with a shaded-pole motor underwent a torsional vibration test and the test results confirmaforementioned theory.After an analysis of how this system 's torsional vibration arose and varied,a new method for controlling torsional vibration was put forward based on the principle of complementary superposition of peaks and dips.A composite shaded-pole motor with a new structure was developed;a prototype of it was made and then subject to torsional vibration testing.The experimental results show that the torsional vibration arising from the torque produced by the new shaded-pole motor's double-frequency vibration was greatly suppressed.The angular acceleration sensor developed in this study can be used to directly measure instantaneous torsional vibration and is easy to install.A sensor will be ready for use after it is mounted coaxially on a system under test.The proposed calibration method for the angular acceleration sensor enables users to determine angular acceleration directly from its source;compared to indirect calibration,this method can significantly reduce errors in the sensor.The methods proposed for controlling torsional vibration in motors mainly involve mechanism-based control and require no complex control algorithm or hardware circuit.More importantly,they are economical,practical and highly effective.