Research On Measurement Method Of Torque Ripple Of Low-speed Permanent Magnent Torque Motor

Permanent magnet torque motor with its characteristics of high torque density,fast response, without intermediate gear，is getting more and more widely used inthe field of precision mechanical transmission system such as CNC machine toolsand elevator traction. However, due to the load is directly connected to thepermanent magnet torque motor, the torque ripple generated by its own will bedelivered directly to the load, and then there is an impact on the control system,reducing its control accuracy. Thus, accurate measurement of torque ripple hasbecome a prerequisite for precision control on the system.In this paper, a research on the measurement for the permanent magnet torqueripple has been conveyed, main contents are as follows.Firstly, Summed up and compared the current torque ripple measurementmethod, did analysis of the generating mechanism on the torque ripple of permanentmagnetic torque motor, including cogging torque ripple, the torque ripple caused bythe mechanical factors of manufacturing and assembly process and theelectromagnetic factors. The generating mechanisms on the torque ripple generatedby sine wave drive and square wave drive are studied and compared. Thenelaborated on the principles of strain gauge torque sensor, which is the core of thesystem.Secondly， as the balanced direct measurement method is proposed, theprinciple features are shown, the effect between the system and the different numberof harmonics is studied. And a measurement system based on given indicators isdesigned, including the selection of the various parts as well as part of the design ofmechanical transmission. Then did the research on the dynamics of the system,system theoretical error and improvements are given.Thirdly, the dynamic equations of the measurement system used by lumpedparameter is established, a virtual prototyping system of the test method is built byusing the ADAMS software. Some components of the system are flexible by theANSYS software which are needed to consider the strain effects, did Analysis of themodal and vibration mode of components. Analysis of the impact on variousparameters on the accuracy of the system is also given, including the flywheel inertia and different speeds.At last, the experimental study of the measurement on torque ripple of theprototype is on, including the cogging torque test, the torque ripple test of differentdrive ways such as sine wave drive and square wave drive. The features of torqueripple by different drive ways is analyzed, and compared the trends in differentspeed, the test results and simulation results are analyzed and compared, showingthat error exists mainly due to friction, mechanical factors and so on.