Research On Variable-frequency Motor Automatic Testing System

With the development of power electronics technology, the maturity and improvement of AC variable speed technology continually; people use induction motor as the mode of locomotive power, which have taken the place of DC motor. It also emerges variable-frequency motor used for variable-frequency system specially. Compared with common induction motor, variable-frequency motor apply higher insulation grade and temperature-rise design. By special magnetic field design, it further limits higher harmonic, for which fulfils design index of broadband, efficiencies and low noise. At the same time, it makes higher demand on test system of variable-frequency motor.This thesis introduces an automatic testing system for variable-frequency motor. The system adopts Sinamics S120 as drive unit, which can make exact speed and torque adjustment; LCU is completed by PLC of Siemens S7-300 system, which achieves the control on relay set, and it can operate automatically. Upper monitor (PC monitor equipped with SIMATIC Manager,SCOUT,STEP7 and LabVIEW software) can monitor the whole testing process and process the test data, finally print and finish performance curve. As applying virtual instrument, it not only save the cost of instrument, but also increase the integrating degree and the capability of anti-jamming of the whole system, and promote the accuracy of the test.In this thesis, firstly, it introduces the application of variable-frequency motor and status of motor automatic test system; it is also compared with hardware structure of other system, which analyzes the advantages and disadvantages. Secondly, it introduces the system hardware components and function for every part. According to the characteristics of variable-frequency motor and combining national and occupation standard, it analyzes the automatic test of variable-frequency motor. Based on these features, design a set of testing method for variable-frequency motor. Thirdly, it introduces the design and compiling of system software, the testing process algorithm of automated testing, handling of testing data, fit of testing data, the drawing of motor performance curve, input and output of data and so on. Finally, it gives some advice on further consummation of system and makes prospect on the development of motor automatic test system.