小波变换在电机性能测试中的应用研究

【作者】 陈暾；

【导师】 黄进；

【作者基本信息】 浙江大学 ， 电机与电器， 2003， 硕士

【摘要】 本论文主要关注小波分析在电机性能自动测试系统中的应用，针对传统电机测试系统以及信号处理技术在电机测试领域中应用的不足，以直流电机为例，提出了将时频分析、小波包变换以及基于小波脊的瞬时频率提取方法应用到电机测试领域的新思路；较系统地总结了时频分析和小波变换的基本理论，深入探讨了基于小波脊线和小波曲线的瞬时频率提取，并成功开发了基于正交小波包分析和基于小波脊线的瞬时频率提取的无转矩转速传感器的直流电机快速测试系统。 在分析了现有的各种电机性能自动测试系统的基础上，本论文讨论了基于PC机和数字化测试仪的电机性能自动测试系统，提出了基于PC机和数据采集卡的电机性能自动测试系统。论文中介绍了一种无转矩转速传感器直流电机快速测试系统，在硬件上，本系统由WB电流传感器与PCI-1202数据采集卡共同完成电枢电流数据采集功能，论文详细讨论了WB电流传感器，外围驱动电路，PCI-1202数据采集卡及其与PC机的接口及其编程等等与软硬件有关的问题。该系统可以作为基于PC机与数据采集卡的自动测试系统的一个很好的例子，它充分利用了PC机丰富的计算资源与快速的运算速度，在间接法测试中具有独到的优势。 论文较系统全面地介绍了小波分析理论，提出了利用正交小波包变换进行时频分析，直接从小波包分解系数中提取电机电枢电流中高频分量变化规律的方法，从而实现了一种无转矩转速传感器电机的快速测试方法。系统地研究了基于多分辨分析的离散正交小波变换和小波包变换的快速算法及其编程实现。并深入探讨了小波分析在电机测试领域的其他应用，包括小波去噪和小波滤波等。 论文从时频分析的基本理论出发，在渐进信号小波分析的基础上，研究了渐进信号小波变换的渐进估计方法，提出了利用小波脊线来提取信号频率随时间连续变化规律(即瞬时频率)的方法。并通过提取直流电机起动过程电流信号的瞬时频率有效地研制了一套无转矩转速传感器直流电机的快速测试系统。仿真和试验结果表明，本系统不仅有较快的测试速度，而且具有相当的精度，再加上其无需转矩转速传感器的优点，特别适用于一些不适合安装转矩转速等非电量传感器和需要进行快速测试的场合。类似的方法和原理经过适当的改进，同样也可以适用于交流电机测试系统。更多还原

【Abstract】 This paper focuses on the applications of wavelet analysis theory in the domain of motor test. Taking DC motor test as an example, a creative idea of applications of some advanced signal processing tools, such as time-frequency analysis, wavelet, and instantaneous frequency (IF) evaluation, in motor testing field is presented. The paper systematically summarizes basic theories of time-frequency analysis and wavelet transform based on which an in-depth research of effective IF evaluation based on wavelet ridge and wavelet curve is carried out. In the end a fast T-n characteristic testing system with neither torque nor speed sensor is successfully developed.After carefully comparing various existing motor performance testing systems and PCs and digital instruments based automatic testing systems, an effective testing system with PC and data acquisition card is proposed. The fast T-n characteristic testing system with neither torque nor speed sensor implemented in the paper is an excellent example of this new type. In the hardware level, the system acquires motor armature current by WB current sensor and PCI-1202 card. Hence WB current sensor, peripheral driving circuits, PC-1202 card and its interfaces are respectively discussed in detail in the paper. As a perfect example of the new pattern testing system previously mentioned, the system has distinct advantages because it fully exploits abundant resources and rapid speed of PCs.This paper synoptically and comprehensively introduces basic theory of wavelet analysis. Due to the distinct superiority of wavelet transform (WT) and wavelet packet transform (WPT) in time-frequency analysis of non-stationary signals, instantaneous frequency law can be obtained directly from amplitude of WPT coefficients. Thus an indirect T-n characteristic testing method can be implemented with satisfying precision. The paper also studies fast arithmetic and programming of discrete time quadrature WT and WPT and takes a deep look into their additional applications in motor testing, including denoising, filtering and so on.Starting from basic theory of time-frequency analysis and wavelet analysis of asymptotic signals, this paper investigates several IF law extraction methods and presents an especially effective one using wavelet ridge. This method can rapidly extract speed law from starting current of DC motor with fairly good precision, and thus the torque-speed characteristic can be acquired. Simulations and experiment results show that this system is provided with high speed and satisfactory precision besides getting rid of both torque and speed sensors. Therefore it is particularly fit for those occasions for which torque and speed sensors are difficult to amount. Indeed similar method can be generalized to AC motor performance testing after properly adaptation.更多还原