Study On Multirate Motor Test Signal Acquisition System

Motor test plays an important role in motor manufacture and also in daily life. Usually, a variety of performance parameters should be collected for testing motor quality. At present, the multi-channel signal acquisition system is used widely in the multiplexing A/D which can only work in uniform sampling rate. The sampling frequency must be set by the highest frequency signal in order to unavoidably cause a lot of redundant data in other channels, and make data transmission, storage and processing in trouble. Therefore, it has important theory significance and the practice value to study the multi-channel and multi sampling rate motor test signal acquisition system which is based on virtual instruments for the evaluation of motor performance and the optimization of test accuracy.Combining school motor test platform of laboratory construction project and aiming at the characteristics of motor test signals which is so many and different. Then the Motor performance automatic testing can be realized. The main research contents of the thesis are as follows:Firstly, according to the requirements of asynchronous motor Y2-80M1-4performance test and from the view of physical quantity collecting demand, the corresponding hardware equipments are selected. Combining with the advanced test technology, computer data acquisition technology, Friendly operation interface of electrical testing signal acquisition system is built by computer data acquisition technology and virtual instrument platform. Then the functions that motor parameter testing and recording, real-time curve display and data storage are realized.Secondly, from analysis of motor test parameters sampling results, we need to judge the test signal which is under-sampled or over sampling. Multiple sampling rate conversion principle is deeply researched around the adverse phenomenon of undersampling or oversampling. Then the method of interpolation and decimation is put forward for eliminating the aliasing phenomenon and reducing the data redundancy which are caused by undersampling and over-sampling. Thirdly, aiming at the difficulty of the mirroring and aliasing which may be generated in interpolation and decimation operation, a digital filter which is anti-imaging or anti-aliasing is designed. Also a second-order IIR compensating CIC filter is presented based on the study and comparison of several filter performance. Then the signal sampling rate conversion of each channel is realized.Finally, using the mixed of many software programming thinking, the Lab VIEW and MATLAB commands are builded by the ActiveX control structures. Then using the MATLAB nodes of LabVIEW programming function, the filter program with MATLAB can be called quickly. The sampling rate was successfully converted by avoiding the complex hardware circuit, also the multi-channel and multi sampling rate real-time acquisition is effectively realized.