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With the continuous development of modern society, industry, equipment increasingly large-scale, integrated, high-speed, automated and intelligent. Real-time monitoring of the health of some of the key equipment to ensure its normal operation, the mechanical system status monitoring and fault diagnosis of continuous development. The basic task is to monitor the running state of the machinery and equipment, diagnosis and to determine the mechanical equipment failure and provides effective troubleshooting measures to guide the management and maintenance of equipment. Gear failure form is relatively complex, and a variety of fault forms, and is widely used in vehicles, machine tools, aviation, marine, and other fields, has important practical significance and important for real-time detection of gear transmission system operating status . Gear fault monitoring and diagnosis, the gear vibration signal contains rich information about the failure, thus the vibration test is the basic means of collecting the fault signal. However, in practical applications, since the sensor mounting difficult and inconvenient factors, want to get a good vibration signal is not easy. In recent years, the motor speed sensor technology development, motor current gear transmission system monitoring and fault diagnosis has become a new hot spot. We can easily get the motor phase current value, and the sensor is very easy to install. Load induction motor current signal can reflect good dynamic characteristics, different current values, we can predict the dynamic characteristics of the external load, which provides a reliable basis for fault diagnosis system. This article, in any coordinate system (d, q), the establishment of the induction motor drive gear transmission system the joint loading small signal model, and gives an expression of the system transfer function, theoretically, the motor current The voltage signal may reflect the dynamics of the system, thereby laying the foundation for the use of the motor current signal for fault diagnosis. Since a variety of failure modes of the gear, so the performance of the gear of the vibration signal is very complex, such as a gear broken tooth, tooth root, cracks, etc., the influence of the vibration signal are changed with time, the performance of the non-stationary characteristics, the traditional Fourier spectrum not meet the requirements analysis, fault signal analysis is efficient when frequency analysis, this paper will adopt flexible wavelet analysis techniques. Need to be overcome before the application of wavelet technology, the the wavelet decomposition increasing frequency and boundary effects. For the increased frequency of the phenomenon, the use of the the detail signal summation method to solve the increasing frequency decomposition; segmented symmetric extension method for boundary effects. The simulation results proved the feasibility of the two methods, which we apply wavelet decomposition to provide a strong support to deal with non-stationary signals. Finally, let's drive induction motor on the basis of joint loading small signal model of the gear transmission, the use of the motor operating status of the VC program simulation. A simulation result of the different external loads described in the arbitrary coordinate system (d, q) of the motor current signal can be well reflected in the dynamic characteristics of the external load; simulation result of the spectral analysis is also totally reflects the frequency characteristics of the external load, i.e. The current signal contains information that can reflect the external load. Then, using wavelet analysis of individual current signals measured in the experiment, to make a diagnosis of system failure.
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