The Relation Between The Mechanical Failures And The Current Of Motors

Wind power generation technology,which is one of the most concerned clean electricity resources,has been playing significant role of changing the energy structure and the future of global environment.Sometimes there may be faults happening when a wind farm is running and they might have adverse effect on the generating efficiency.Therefore,the monitoring and diagnosis is necessary to wind power generators.Vibration-based technology to detect faults has been widely and practically used,but it has some disadvantages such as high hardware cost,limited installation position for sensors.Besides,the detecting system is costly to maintain because of the bad working condition where noise-signal ratio is low.Stator current detection is a new diagnosis technology which costs less,more easy to install and more proper to nowadays elaborate management tendency in wind farm than previous diagnosis technologies and it is gaining world-wide attention.This article introduced the main types of motor faults diagnosis technique and their development in china and other countries in the world.Then the article introduced the basic principles and development of stator current detection and the applications on different kinds of motor faults.This article also studied the mechanism of rolling bearing failure and the time and position variation of air gap flux,given formulas of the fault characteristic frequency and made preparation for the fault characteristic frequency of the stator current.Based on the Electro mechanics and Electromagnetic theory,this article studied the mechanism of bearing fault and air gap eccentricity and the parameter change inside the motor.Eventually the fault characteristic frequency of the stator current in the condition of both bearing fault and air gap eccentricity appeared was obtained.Ansoft Maxwell is a software on finite element analysis,used to model the motor and simulate the condition in bearing fault and air gap eccentricity,with the engineering electromagnetic modeling software Ansys Simplorer.By modeling faults,the theory and formulas was verified.