Inter-turn Short Circuit Fault Research Articles

Performance Analysis of Squirrel-Cage Induction Motors Under Broken Rotor Bar and Stator Inter-Turn Fault Conditions Using Analytical Modeling

Stator winding inter-turn (SWI) short-circuit fault and broken rotor bar (BRB) fault are two common faulty modes of the squirrel cage induction motors (SCIMs). These faults have various impacts on the motor performance and may be rooted in each other; therefore, they may be presented at the same time in an SCIM. This paper proposes an exact analytical model for the SCIMs, which is able to include the SWI and BRB faults presenting simultaneously or individually with variable severities. Multiple coupled circuit modeling is applied to achieve such analytical model. The magnetic saturation effect is included in the model by applying appropriate air gap function and the rotor bars skew effect is taken into account by using 2-D winding function theory. Simulation results as well as the corresponding experimental results approve the presence of the same harmonics in the stator line currents due to the proposed faults. However, more detailed study gives solution for discrimination of the faults. The attained analytical model can be applied to examine the performance of the related fault diagnosis methods and to design novel fault diagnosis techniques including the model-based ones.

Online Slight Inter-Turn Short-Circuit Fault Diagnosis Using the Distortion Ratio of Load Current in a Low-Voltage Induction Motor

Online Slight Inter-Turn Short-Circuit Fault Diagnosis Using the Distortion Ratio of Load Current in a Low-Voltage Induction Motor

A Proposed Technique for Discrimination between Saturation Phenomenon and Short-Circuit Faults in Induction Motor

This paper proposes a new technique of discrimination between the two signatures related to the magnetic saturation phenomenon (MSP) and the inter-turn short-circuit (ITSC) fault in a three-phase induction motor (IM). This technique is based on the exploitation of the amplitude and the phase angle of a new harmonic characterizing both phenomenons obtained from the characteristics of the Hilbert transform. In addition, and in order to simplify the interpretation and analysis of the various modes of operation covered in this paper, a new graphical tool based on a triangular representation is proposed. This graphical representation depending on the position and the orientation of the triangle makes it possible to display in a simple and clear manner the existence of the ITSC fault and its discrimination with respect to the MSP phenomenon. To assess the performance of this new technique, some simulation works are performed on signals obtained from a mathematical model of the IM based on the calculation of the inductances by the modified winding function approach (MWFA).

Research on current imbalance law of bus - bar caused by inter - turn short circuit of dry-type air - core reactor

Dry-type Air-core Reactor is widely used in power system. It is an important reactive power compensation equipment in power system. In recent years, the dry air reactor has suffered a number of failures in operation. The failure occurred most frequently in the dry-type air-core reactor and we cannot detect the inter-turn short circuit faults in neither single wire winding nor multiple wire windings. The research and protection of reactor faults is almost in the blank at present. This paper presents the method of collecting the unbalanced current between bus-bars to detect the winding inter-turn short circuit faults. The numerical simulation of short circuit model between different windings of the reactor is carried out. Current-differential analyzed on the unbalanced current data of experiment are used to determine whether an inter-turn short circuit occurs. The results indicated that the closer the short-circuit is to the end of the reactor, the greater the unbalance current is. The changes of collecting current between bus-bars are much larger than the total current. Short-circuit current redistribution only occurs between two windings after the short circuit. The circuit in other windings is almost unchanged.

Multifield Calculation and Analysis of Excitation Winding Interturn Short Circuit Fault in Turbo-Generator

Excitation winding interturn short circuit (EWISC) is a common fault in turbo-generators. Once the fault occurs, if not handled in time, it will result in significant security risks to the power system. Using the multifield characteristics of fault generators for a comprehensive diagnosis can make the diagnostic results more accurate and credible. In this paper, taking a TA-1100-78 type, two pole pairs turbo-generator as the research object, the two-dimensional finite element electromagnetic model of stator/rotor and the three-dimensional finite element heat transfer model of rotor were established. The electromagnetic field, temperature field, and stress field of the generator were simulated and analyzed. At the same time, the air gap magnetic field, three-dimensional temperature field, and stress field distribution of the rotor were calculated for EWISC faults in different fault degrees and positions. The results showed that the EWISC fault weakened the air gap magnetic field and caused unbalanced electromagnetic distribution. At the same time, it caused a distortion of the rotor temperature field, resulting in an unbalanced distribution of the temperature field. The stress field was affected by the distortion of temperature field, and the local thermal stress increased but did not exceed the yield limit of the material. Restorable elastic deformation occurred when the rotor was heated, which caused the thermal bending of the rotor. The method adopted in this paper can provide a reference for the calculation of multiphysical field after a generator fault. It is also pointed out that the thermal unbalance influence should not be neglected in the study of generator vibration characteristics.

Discrete and Parametric Fault Diagnosis of an Inverter-Driven Brushless DC Motor Using a Hybrid Formalism

This paper presents a diagnosis approach for inter-turn short circuit faults and open circuit switch faults in a brushless direct current (BLDC) motor driven by a three-phase voltage source inverter taking into account their hybrid behaviour. The diagnosis method consists of a discrete faults diagnosis module and a continuous faults diagnosis module combined by means of a hybrid automaton. The discrete diagnoser constitutes the discrete part of the hybrid automaton. It is designed based on a discrete presentation of the system taking into consideration the nominal and faulty states. On the other hand, continuous fault diagnosis is achieved by a hybrid sliding mode observer based on the Super Twisting algorithm. A Lyapunov based approach is used to address the convergence analysis problem of the hybrid observer. The performance of the proposed approach in detection and isolation of discrete and parametric faults is demonstrated by numerical simulations.

Diagnosis of Inter-Turn Short Circuit of Synchronous Generator Rotor Winding Based on Volterra Kernel Identification

The inter-turn short circuit is a common fault in the synchronous generator. This fault is not easily detected at early stage. However, with the development of the fault, it will pose a threat to the safe operation of the generator. To detect the inter-turn short circuit of rotor winding, the feasibility of identifying the stator branch characteristics of synchronous generator during inter-turn short circuit was analyzed. In this paper, an on-line fault identification method based on Volterra kernel identification is presented. This method uses the stator branch voltage and stator unbalance branch current collected from the generator as input and output signals of the series model. Recursive batch least squares method is applied to calculate the three kernels of Volterra series. When the generator is in normal state or fault state, the Volterra kernel will change accordingly. Through the identification of the time-domain kernel of the nonlinear transfer model, the inter-turn short circuit fault of the synchronous generator is diagnosed. The correctness and effectiveness of this method is verified by using the data of fault experimental synchronous generator.

Fault Detection of Stator Inter-Turn Short-Circuit in PMSM on Stator Current and Vibration Signal

The stator inter-turn short circuit fault is one of the most common and key faults in permanent magnet synchronous motor (PMSM). This paper introduces a time–frequency method for inter-turn fault detection in stator winding of PMSM using improved wavelet packet transform. Both stator current signal and vibration signal are used for the detection of short circuit faults. Two different experimental data from a three-phase PMSM were processed and analyzed by this time–frequency method in LabVIEW. The feasibility of this approach is shown by the experimental test.

Analysis of the Impact of Stator Interturn Short-Circuit Faults on Induction Machines Driven by Direct Torque Control

This paper addresses the analysis of three-phase squirrel-cage induction machine (IM) with interturn short-circuit (ITSC) fault and its influence on direct torque control (DTC). The particularities of the DTC such as its behavior, its standard heuristic derivation, and its nature of been a nonlinear hysteresis-based predictive controller are exploited, thus allowing the improvement and development of alternative explanations to the phenomena. The understanding of DTC and the development of the current state–space model of the asymmetric IM, presented here for first time in the literature, enables the analytical treatment of the research topic and the discovery of several DTC reactions to the fault. The ITSC impact on DTC and its reaction leads to the following twofold characterizations: first, unobservable and visible effects, and second, compensation and tolerant reactions. For purposes of simulation, a plug-and-play configurable circuit-block for the asymmetric IM was developed based on Norton's equivalent circuit. Simulation and experimental results demonstrate the assertiveness of the developed analyses and theoretical findings, which allows future research in online fault diagnostics and condition monitoring of inverter-fed IM with this type of fault.

Unknown Input Observer-Based Fault Diagnosis in Induction Machine: Theory and Experiment

This paper presents an observer-based approach to diagnosis and detect inter-turn short-circuit fault in induction machine based on residual generation. Residual signals are generated by taking measured three-phase stator currents and those reconstructed by unknown input observer. By comparing these residuals to a predefined threshold, such fault can be detected and fault signatures are obtained. These signatures are used to develop a faulty phase isolation algorithm. The ability to detect the fault and isolate the faulty phase is tested by simulation and validated using experimental test bench with real-time interface based on the dSpace environment.

Study on the Influence of Inter Turn Short Circuit Fault on Permanent Magnet Synchronous Motor Output Performance

When the inter turn short circuit (ITSC) fault occurs, the value of the short circuit ring loop current is large. A pulsating magnetic field generated by the loop current has a great influence on the motor inside magnetic field. The motor internal magnetic field is obviously distorted, and the motor output performance is limited. In order to study the influence of the fault on the permanent magnet synchronous motor (PMSM) output performance, first, a PMSM fault model is established based on the FEM. The influence of the fault on the motor electromagnetic field is studied. The motor magnetic field is decoupled and the armature magnetic field harmonic content is obtained by using the Fourier decomposition theory. Second, by using the Maxwell energy method, the output torque, radial force density and electromagnetic force are analyzed. The influence mechanism of the ITSC fault on the torque ripple and the electromagnetic force is revealed. Finally, the prototype test platform is built to study the ITSC fault, and the simulation results are compared with the experimental data. The correctness of simulation research is verified. The conclusions obtained are of the great significance for the PMSM fault analysis.

On-line diagnosis of inter-turn short circuit fault for DC brushed motor

Extensive research effort has been made in fault diagnosis of motors and related components such as winding and ball bearing. In this paper, a new concept of inter-turn short circuit fault for DC brushed motors is proposed to include the short circuit ratio and short circuit resistance. A first-principle model is derived for motors with inter-turn short circuit fault. A statistical model based on Hidden Markov Model is developed for fault diagnosis purpose. This new method not only allows detection of motor winding short circuit fault, it can also provide estimation of the fault severity, as indicated by estimation of the short circuit ratio and the short circuit resistance. The estimated fault severity can be used for making appropriate decisions in response to the fault condition. The feasibility of the proposed methodology is studied for inter-turn short circuit of DC brushed motors using simulation in MATLAB/Simulink environment. In addition, it is shown that the proposed methodology is reliable with the presence of small random noise in the system parameters and measurement.

On-Line Detection of Coil Inter-Turn Short Circuit Faults in Dual-Redundancy Permanent Magnet Synchronous Motors

In the aerospace and military fields, with high reliability requirements, the dual-redundancy permanent magnet synchronous motor (DRPMSM) with weak thermal coupling and no electromagnetic coupling is needed. A common fault in the DRPMSM is the inter-turn short circuit fault (ISCF). However, research on how to diagnose ISCF and the set of faulty windings in the DRPMSM is lacking. In this paper, the structure of the DRPMSM is analyzed and mathematical models of the motor under normal and faulty conditions are established. Then an on-line ISCF detection scheme, which depends on the running modes of the DRPMSM and the average values for the difference of the d-axis voltages between two sets of windings in the latest 20 sampling periods, is proposed. The main contributions of this paper are to analyze the calculation for the inductance of each part of the stator windings and propose the on-line diagnosis method of the ISCF under various operating conditions. The simulation and experimental results show that the proposed method can quickly and effectively diagnose ISCF and determine the set of faulty windings of the DRPMSM.

Research on fault diagnosis of asymmetric stator winding for doubly-fed induction generators

Magnetic field distribution, negative-sequence stator current, stator phase-angle difference between phase currents, and instantaneous rotor power were studied by theoretical analysis, modeling and simulation, experiment after stator winding fault in doubly-fed induction generators. Firstly, On the basis of analyzing the variation of magnetic field and stator current after stator winding inter-turn short circuit fault based on the finite element method, the variation of negative-sequence stator current and stator phase-angle difference between phase current were analyzed and studied. Grid model of doubly-fed induction generator was established in PSCAD, and through signal analysis it’s found that the sensitivity and reliability of instantaneous rotor power spectrum are not only much better than those of current spectrum, voltage spectrum, but also better than those of negative-sequence component of stator current in slight fault diagnosis of stator winding. Finally, the experimental platform of stator winding fault for doubly-fed induction generator was built in the dynamic model laboratory of Hohai University, which further verified the reliability and superiority of instantaneous rotor power spectrum. So the synthetic diagnosis of stator winding fault for doubly-fed induction generator based on instantaneous rotor power with negative-sequence stator current and phase-angle difference between phase current is proposed.

Research on inter‐turn short circuit of armature windings in the multiphase synchronous generator–rectifier system

The multiphase synchronous generator–rectifier system could provide an ideal DC power source for more electric aircraft (MEA). When the inter-turn short-circuit fault occurs in phase windings of the generator, a large short-circuit current would be introduced inside the armature windings, which could cause severe damages to the system for overheat in the windings and irons as well as huge electromagnetic forces on the end coils. To improve the reliability of the MEA, this study researches on the inter-turn fault of the multiphase generator–rectifier system, including the theoretical analysis, numerical simulation and experimental verification. A 12-phase system is taken for example, and a multi-loop mathematical model is built up to calculate all voltages and currents in the multiphase synchronous generator–rectifier system with armature inter-turn fault. Many factors are thoroughly considered in the model, including the location and short-turns of fault, space harmonics of air-gap magnetic field and the changing circuit topology of the system. The mathematical model is verified by fault experiment results. Moreover, the electric characteristics of the fault are summarised, which could provide a quantitative basis for early detection of the inter-turn faults in the multiphase generator–rectifier system.

A Hierarchical Approach for the Recognition of Induction Machine Failures

Due to its sturdiness, low cost and ease of implementation, the induction machine is one of the most common electrical motors used in industry. However, this machine still concedes failures leading to unplanned shutdowns, sources of significant financial losses. For this reason, induction machine failure diagnosis has become an ordinary task, where some ameliorations have to be achieved in order to improve the efficiency of maintenance programs by minimizing the number and the time period of unexpected shutdowns. In this paper, we address the recognition of inter-turn short circuit (ITSC) in the stator windings and broken rotor bars (BRBs) in the three-phase squirrel cage induction machine by proposing a new approach. This approach relies on the three-phase current analysis method to extract features and a new hierarchical recognition algorithm based on an ensemble of three different classifiers. In addition, the present work studies the failures recognition of the induction machine operating with a torque and speed control. The proposed approach is a major advanced for the induction machine diagnosis research because it recognizes correctly (detects, localizes and estimates the degree of severity) ITSC and (detects and estimates) BRB faults with an accuracy of 93.36% and with a great robustness compared to a classical machine learning algorithm.

Minimization of the Electromagnetic Torque Ripple Caused by the Coils Inter-Turn Short Circuit Fault in Dual-Redundancy Permanent Magnet Synchronous Motors

With the development of electric vehicles and More-Electric/All-Electric aircraft, high reliability is required in motor servo systems. The redundancy technique is one of the most effective methods to improve the reliability of motor servo systems. In this paper, the structure of dual-redundancy permanent magnet synchronous motor (DRPMSM) with weak thermal coupling and no electromagnetic coupling is analyzed and the mathematical model of this motor is established. However, there is little research on how to suppress the torque ripple caused by short-circuited coils in the DRPMSM. The main contribution of this paper is to present the advantages of DRPMSM and to find a way to suppress the torque ripple caused by the short circuit fault in DRPMSM. In order to improve operation quality and enhance the reliability of DRPMSM after a short circuit occurs, the torque ripple caused by the coils inter-turn short circuit fault in DRPMSM is analyzed in detail. Then, a control method for suppressing the electromagnetic torque ripple of a short-circuited coil is proposed for the first time by using an improved adaptive proportional resonant (PR) controller and a proportional integral (PI) controller in parallel. PR control is a method of controlling alternating components without steady-state error, and it can be used to suppress torque ripple. DRPMSM adopts speed and current double closed-loop control strategies. An improved adaptive PR controller and a PI controller are employed in parallel for the speed loop, while traditional PI control is adopted in current loop. From the simulation and experimental results, the torque ripple is reduced from 45.4 to 5.6% when the torque ripple suppression strategy proposed in this paper is adopted, in the case that the speed is 600 r/min. The torque ripple suppression strategy based on the PR controller can quickly and effectively suppress the torque ripple caused by the short-circuited coils, which makes the motor speed more stable.

Short-Circuit Fault Tolerant Control of a Wind Turbine Driven Induction Generator Based on Sliding Mode Observers

The installed energy production capacity of wind turbines is growing intensely on a global scale, making the reliability of wind turbine subsystems of greater significance. However, many faults like Inter-Turn Short-Circuit (ITSC) may affect the turbine generator and quickly lead to a decline in supplied power quality. In this framework, this paper proposes a Sliding Mode Observer (SMO)-based Fault Tolerant Control (FTC) scheme for Induction Generator (IG)-based variable-speed grid-connected wind turbines. First, the dynamic models of the wind turbine subsystems were developed. The control schemes were elaborated based on the Maximum Power Point Tracking (MPPT) method and Indirect Rotor Flux Oriented Control (IRFOC) method. The grid control was also established by regulating the active and reactive powers. The performance of the wind turbine system and the stability of injected power to the grid were hence analyzed under both healthy and faulty conditions. The robust developed SMO-based Fault Detection and Isolation (FDI) scheme was proved to be fast and efficient for ITSC detection and localization.Afterwards, SMO were involved in scheming the FTC technique. Accordingly, simulation results assert the efficacy of the proposed ITSC FTC method for variable-speed wind turbines with faulty IG in protecting the subsystems from damage and ensuring continuous connection of the wind turbine to the grid during ITSC faults, hence maintaining power quality.

Hybrid Electric Vehicle Fault Tolerant Control

This paper investigates the supervisory-level, fault tolerant control of a 2004 Prius powertrain. The fault considered is an interturn short circuit (ITSC) fault in the traction drive (a surface mount permanent magnet synchronous machine (SPMSM) for which its rotor is part of the vehicle's driveline). ITSC faults arise from electrical insulation failures in the stator windings where part of a phase winding remains functional while the remaining decoupled windings form a self-contained loop. Because the permanent magnets on the rotor (driveline) shaft are able to induce very large eddy currents in this self-contained loop if its rotational velocity is left unchecked, the maximum allowable driveline speed, and consequently, vehicle speed, must be reduced to avoid exceeding the drive's operational thermal limits. A method for detecting these ITSC faults and the induced eddy current in an SPMSM using a moving horizon observer (MHO) is reviewed. These parameters then determine which previously computed, fault-level-dependent SPMSM input–output power efficiency map and maximum safe operating speed is utilized by the supervisory-level controller. The fault tolerant control is demonstrated by simulating a Prius over a 40 s drive velocity profile with fault levels of 0.5%, 1%, 2%, and 5% detected at the midpoint of the profile. For comparison, the Prius is also simulated without a traction motor fault. Results show that the control reduces vehicle velocity upon detection of a fault to an appropriate safe value.

A Model-Based Strategy for Interturn Short-Circuit Fault Diagnosis in PMSM

A model-based method for interturn short-circuit fault detection and isolation in permanent magnet synchronous machines (PMSMs) is proposed in this paper. The fault detection is realized based on a residual current vector (RCV) generated by the difference between the measured stator currents and the stator currents estimated by a state observer. In order to avoid false alarms due to possible undesired perturbations, the sequence decomposition of the RCV is performed by employing different reference-frames. Thus, the proposed RCV allows the correct detection of interturn short-circuit faults and quantification of the fault severity in any faulty stator-phase winding. Moreover, since the back-EMF generated by the magnets is proportional to the rotor shaft speed, the electrical angular speed is estimated through the stator voltages measurement, without using a speed sensor. Simulation results from the three-phase PMSM dynamic model that allows considering the interturn short-circuit fault in any stator phase-windings are presented. The proposed method is validated using a three-phase PMSM prototype with modified stator windings. The robustness and the reliability of the proposal was tested for several interturn fault conditions under transient conditions including different disturbances.