Research On The Broken Rotor Bars Fault Diagnosing Instrument Using Dual-processor

The three phase squirrel cage induction motors are widely used in industry, because of its robustness, simplicity and cost-saving. In spite of these qualities, stresses of various natures and the high frequency of starting can produce faults in different parts of the motor. Broken bars and end rings are the mostly observed faults of the motor cage. How to prevent the serious fault and reduce the cost of maintenance is of great significance in both security and economy.In this thesis, the fault analysis principles of rotor winding and commonly used diagnostic methods have been introduced. The shortcomings of these methods are also presented in the thesis. To meet the needs of non-invasive on-line broken rotor bars fault diagnosing instrument, the motor current spectrum analysis (MCSA) is adopted in this study. Moreover, key points of Fourier Transform are discussed. The Host and slave hardware structures are employed in the broken rotor bars fault diagnosing instrument by using DSP and MCU, respectively. It has many advantages. Furthermore, arithmetic based on DSP is also accomplished in soft development.The characteristics of the Fourier Transform based on the stable running and its modified methods are summarized. At the same time, the shortcomings of these methods are also proposed. In order to resolve these problems, the principle of Park's Vectors approach and the advanced Park's Vectors approach are discussed particularly in this thesis. Then, the calculating equations of the influences of the imbalance three phase current to the diagnosis had been deduced. The numerical simulation and the experiments of this Park's vector approach are also carried out .Comparison tests on a normal motor and a fault one verify the validity of the developed instrument on the fault diagnoses.