| The permanent magnet servo motor has many advantages, such as high power factor, simple structure, small size, low loss, etc., so permanent magnet motors has become the mainstream of servo motor in the current. But there are some flaws affecting its performance, including cogging. Cogging phenomenon is inevitable due to the physical structure.,even in the case of permanent magnet motor is not energized, it will also exist. Cogging can cause torque fluctuation, reduced control accuracy, especially at the situation of low speed control. Therefore, the measurement to cogging of permanent magnet servo motor is meaningful.The purpose of this paper is:Through the new test system to measure a large number of motors, find the regular pattern of cogging and proposed the criteria of motor assembly based on measurement result of cogging. The experimental results were analysis by MATLAB.This article focuses on the following work:1. Study the cogging generating mechanism, based on energy method to derive the mathematical expressions of torque ripple caused by cogging.2. Come up with innovative measurement solutions. And do the cogging measured for 78 different models, different batches of the servo motor and using MATLAB for data processing. Analysis comprehensively the performance differences of those motors from the time domain and frequency domain. Propose a new cogging evaluation.3. Analysis the constituents of motor waveform, study performance differences between different batches and its influencing factors. Study the frequency domain components that reacted motor assembly quality. And draw the correspondence between the frequency domain and time domain index between the components. In the result, propose the diagnostic criteria of motor assembly quality based on the experimental results of the cogging test. |
