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A systematic procedure to determine the parameters of a previously proposed low- to high-frequency induction motor model is presented. An analysis of the high-frequency behavior with regard to the impact of magnetic core selection, parasitic interturn and winding-to-frame capacitors, and skin effects of windings is investigated in greater detail for the proposed universal model of an induction motor. The model is universal in the sense that it is derived by extending the low-frequency standard T-equivalent circuit (IEEE Standard 112) to include high-frequency effects under both common- and differential-mode domains and can be used for transient reflected-wave studies and electromagnetic interference emissions in motor drive systems. A test-based method and an analytical approach, which are useful in application and design stages, respectively, are presented to determine the frequency characteristics of the induction motor. Findings of the investigation were verified experimentally with results presented in this paper. Index Terms--Electromagnetic interference (EMI), high-frequency model, induction motor, reflected wave, transient overvoltage.

A three-phase induction motor model that depicts the motor behavior over a wide range of frequencies from 10 Hz to 10 MHz is presented in this paper. The model is universal in the sense that common-mode, differential-mode, and bearing circuit models are combined into one three-phase equivalent circuit model. The proposed model is basically an extension of the low-frequency IEEE Standard 112 circuit model. The proposed model was experimentally simulated and verified with results presented. Index Terms--Bearing current, common mode (CM), differential mode (DM), electromagnetic interference (EMI), high-frequency model, induction motor, pulsewidth-modulated (PWM) voltage source inverter, reflected wave, transient overvoltage.

A robust interturn fault diagnostic approach based on the concept of magnetic field pendulous oscillation, which occurs in induction motors under faulty conditions, is introduced in this paper. This approach enables one to distinguish and classify an unbalanced voltage power supply and machine manufacturing/construction imperfections from an interturn fault. The experimental results for the two case studies of a set of 5-hp and 2-hp induction motors verify the validity of the proposed approach. Moreover, it can be concluded from the experimental results that if the circulating current level in the shorted loop increases beyond the phase current level, an interturn fault can be easily detected using the proposed approach even in the presence of the existence of motor manufacturing imperfection effects. Index Terms--Broken-bar, condition monitoring, induction motor, interturn short circuit, stator fault, transient modeling.

The effects of load level on the ability to diagnose broken bar faults in squirrel-cage induction motors are studied in this paper. The pendulous oscillation of the rotor magnetic field orientation is implemented as a fault signature for rotor fault diagnostic purposes at steady-state operations. Moreover, the effects of load level on the low-side band component of the stator current spectrum, and associated diagnostic difficulties in this approach particularly in the presence of motor operation from pulsewidth-modulation drives, are reported as well. These investigations were performed through testing 2-hp and 5-hp induction motors over a wide range of load levels and control drives. The results of these tests and investigations demonstrate the efficacy of the pendulous oscillation signature as a diagnostic means that can be used for a wide range of motor operating conditions. Index Terms--Broken bar diagnosis, induction motor fault detection, pendulous oscillation, rotor magnetic field orientation, swing angle.

A new technique based on rotor magnetic field space vector orientation is presented to diagnose broken-bar faults in induction machines operating at steady state. In this technique, stator currents and voltages are used as inputs to compute and subsequently observe the rotor magnetic field orientation, which has a more significant 'swing-like' pendulous oscillation in case of broken-bar faults than in healthy operation. It will be shown here that the range of this 'pendulous oscillation' is a function of the number of broken bars. Also in this technique, it was found that an inter-turn shorted stator-winding fault, which exhibits similar pendulous oscillation, could be distinguished from rotor broken-bar faults through the use of a variance index. In order to validate this method, experimental evidence is given here for several broken-bar cases in a 2-hp three-phase two-pole squirrel-cage induction machine. Index Terms--Fault diagnosis, induction machines, rotor magnetic field space vector, swing-like pendulous oscillation.