Studies On The Testing System Of AC Electrical Dynamometer Based On Wavelet Theory

Nowadays, due to the rapid development of domestic automotive industry and the policy of environment protection, higher-level test technologies are required for the engine test. AC electrical dynamometer is an important device for engine test with easy-controlled testing conditions, easy-collected and managed parameters as well as high measuring precision. Based on these considentions, this thesis focuses on the testing system design of AC electrical dynamometer based on the wavelet analysis.In this thesis, after illustrating the operating principle and the relationships of the main torques of electrical dynamometer, the author examine the factors which has the possibilities to cause the errors in the electrical dynamometer torques, furthermore the methods to correct the errors are put forward. The technology of electrical circuit design are applied to establish the hardware platform for testing system of electrical dynamometer with the accuracy and real-time ability as the main design objectives. The design methods and concrete circuit diagrams are presented to detect the torque, rotation speed, current, temperature, etc. Finally, the software of the electrical dynamometer control system is realized by utilizing Lab VIEW and VC++.In allusion to the hard working environment of testing system, detailed analysis on the various disturbances, which are likely to emerge in the course of testing are given, meanwhile the related measures for disturbance rejection are proposed. Base on the realization of testing system hardware and design for hardware disturbance rejection, the author studies how to extract the real torques signals which reflect the practical working of engine from the disturbed and collected torques signals. The transaction of torques collecting signals by adopting wavelet transform to reduce noises is proposed and different methods applying wavelet for noises-reducing are also compared.Many experiment results show that the electrical dynamometer test and control system, based on wavelet analysis, possesses higher accuracy needed for engine test.