The development of an online method for the early detection of a stator turn insulation deterioration is the objective of the research at hand. A high percentage of motor breakdowns is related to the failure of the stator insulation system. Since most of the stator insulation failures originate in the breakdown of the turn-to-turn insulation, the research in this realm is of great significance. Despite the progress that has been made in the field of stator turn fault detection methods, the most popular and the best known ones are still limited to the detection of solid turn faults. The time span between a solid turn fault and the breakdown of the primary insulation system can be as short as a few seconds. Therefore, it is desirable to develop a method capable of detecting the deterioration of the turn insulation as early as possible and prior to the development of a solid turn fault. The different stresses that cause the aging of the insulation and eventually lead to failure are described as well as the various patterns of an insulation failure. A comprehensive literature survey shows the methods presently used for the monitoring of the turn insulation. Up to now no well-tested and reliable online method that can find the deterioration of the turn insulation is available. The most commonly used turn insulation test is the surge test, which, however, is performed only when the motor is out of service and disconnected from the supply. So far no research at all has been conducted on the application of an online surge test. The research at hand examines the applicability of the surge test to an operating machine. Various topologies of online surge testing are examined with regard to their practicability and their limitations. The most practical configuration is chosen for further analysis, implementation and development. Moreover, practical challenges are presented by the non-idealities of the induction machine like the eccentricity of the rotor and the rotor slotting, and have to be taken into account. Two solutions to eliminate the influence of the rotor position on the surge waveform are presented. Even though the basic concepts of online surge testing can be validated experimentally by a machine with a solid turn fault, it is preferable to use a machine with a deteriorated turn insulation. Therefore, a method, which does not require complex and expensive hardware, to experimentally emulate the turn insulation breakdown is implemented. The concepts at any stage of the work are supported by simulations and experimental results. In addition, the theory of surge testing is further developed by giving new definitions of the test's sensitivity, i.e., the frequency sensitivity and the error area ratio (EAR) sensitivity.

Orientador: João Mauricio Rosario / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-22T16:01:59Z (GMT). No. of bitstreams: 1 Hervella_Cassio_M.pdf: 6637417 bytes, checksum: a9b3d4d37dcc1eba14ccf5bd3013af19 (MD5) Previous issue date: 1997 / Resumo: Neste trabalho foi projetado, desenvolvido e implementado um sistema de controle programável flexível, para aplicação principal no controle de manipuladores e robôs industriais. Como método de abordagem global de um problema de controle automático, podemos dividí-lo em quatro partes principais, a primeira sendo a medição, aquisição e tratamento das grandezas a controlar, a segunda sendo o algoritmo de controle e o sistema de acionamento, a terceira sendo a automatização via programação e simulação de trajetórias e tarefas, e finalmente, a quarta parte sendo a interface homem-máquina. Sendo assim, subdividiu-se o sistema de controle desenvolvido em quatro módulos principais, sendo eles, o módulo de Monitoramento e Supervisão, o módulo de Controle e Acionamento, o módulo de Programação e Simulação e o módulo de Interface com o Usuário; por sua vez, estes módulos são compostos por vários sub-sistemas modulares, que foram projetados, desenvolvidos e testados separadamente, para que fossem flexíveis e confiáveis, tendo sido integrados em seguida, de várias maneiras, de modo a atender às características específicas de cada aplicação. Dentre os sistemas desenvolvidos, temos, por exemplo, interfaces de interface de entrada e saída de dados digitais, interfaces de supervisão de posição, interfaces de acionamento de potência, interfaces de decodificação de sinais de encoders; programas de testes para as interfaces desenvolvidas, programa de interface gráfica para utilização pelo usuário, e outros. Numa aplicação típica, no controle de um robô industrial, podemos ter diversos tipos de atuadores, sensores, mecanismos e arquiteturas do sistema mecânico a controlar, assim, com a substituição de alguns módulos, obtêm-se uma integração flexível que atende as necessidades de cada caso, sem que seja necessário um sistema de controle completamente novo, tomando a automação mais simples, eficiente e rápida. Por exemplo, na automação de um robô, podem ser necessários dois computadores, para que as cargas de processamento de dados de controle e a carga de processamento da interface gráfica com o usuário possam ser divididas entre estes; porém, numa aplicação, como o posicionamento de uma câmera de vídeo, a simplicidade do sistema mecânico, permite a utilização de um único computador, ou mesmo, uma interface dedicada, sendo mantida toda a estrutura global do sistema de controle / Abstract: In this work, it has been designed, developed and implemented a programmable flexible control system, for main application in the control of manipulators and industrial robots. As a global approaxing method for an automatic control problem, we can divide it in four main parts, the first beeing the measument, aquisition and treatment of the variables to control, the second beeing the control algorithm and the actioning system, the third beeing the automation throw programming and simulating of jobs and trajectories, and finally,the fourth beeing the man-machineinterface. Thus, we divided the developed control system in four main modules, which are, the Monitoring and Supervising module, the Actioning and Control module, the Simutation and Programming module and the User's Interface; which are compound by various modular subsystems, that were designed, developed and tested separately, so that they would be dependable and flexible, beeing then integrated, in many ways, to full-fill the specific caracteristics of each application. Within the developed systems, we have, for example, digital data input and output interface boards, position supervising boards, power driving boards, encoder sinal decodifying boards; test programs for the developed boards, graphics interface program to be utilized by the user, and others. In a tipical application, in controlling an industrial robot, we can have many diferent types of actuators, sensors, mechanisms and architectures of the mechanical system to control, thus, by substituting a few modules we can obtain a flexible integration that answers to the needs of each case, without the need of a completely new control system, making the automation more simple,eficient and fast. As an example, in the automation of a robot, may be neccessary two computers, so that the data processing loads of control and the user's graphics interface processing load can be divided between these, but, in an application, like a vídeo camera positioning, the simplicity of the mechanical system, enables the use of only one computer, or even, a dedicated board, beeing keept the global structure of the control system / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

In this thesis, we develop several novel degradation models based on techniques from functional data analysis. These models are suitable for characterizing different types of sensor-based degradation signals, whether they are censored at a certain fixed time point or truncated at the failure threshold. Our proposed models can also be easily extended to accommodate for the effects of environmental conditions on degradation processes. Unlike many existing degradation models that rely on the existence of a historical sample of complete degradation signals, our modeling framework is well-suited for modeling complete as well as incomplete (sparse and fragmented) degradation signals. We utilize these models to predict and continuously update, in real time, the residual life distributions of partially degraded components. We assess and compare the performance of our proposed models and existing benchmark models by using simulated signals and real world data sets. The results indicate that our models can provide a better characterization of the degradation signals and a more accurate prediction of a system's lifetime under different signal scenarios. Another major advantage of our models is their robustness to the model mis-specification, which is especially important for applications with incomplete degradation signals (sparse or fragmented).

Brushless Direct Current (BLDC) motors are one of the motor types rapidly gaining popularity. BLDC motors are being increasingly used in critical high performance industries such as appliances, automotive, aerospace, consumer, medical, industrial automation equipment and instrumentation. Fault detection and condition monitoring of BLDC machines is therefore assuming a new importance. The objective of this research is to advance the field of rotor and load fault diagnosis in BLDC machines operating in a variety of operating conditions ranging from constant speed to continuous transient operation. This objective is addressed as three parts in this research. The first part experimentally characterizes the effects of rotor faults in the stator current and voltage of the BLDC motor. This helps in better understanding the behavior of rotor defects in BLDC motors. The second part develops methods to detect faults in loads coupled to BLDC motors by monitoring the stator current. As most BLDC applications involve non-stationary operating conditions, the diagnosis of rotor faults in non-stationary conditions forms the third and most important part of this research. Several signal processing techniques are reviewed to analyze non-stationary signals. Three new algorithms are proposed that can track and detect rotor faults in non-stationary or transient current signals.

This dissertation proposes several simple, robust, and non-intrusive condition monitoring methods for induction motors fed by closed-loop inverters and claw-pole generators with built-in rectifiers. While the flexible energy forms synthesized by power electronic converters greatly enhance the performance and expand the operating region of induction motors and claw-pole generators, they also significantly alter the fault behavior of these electric machines and complicate the fault detection and protection. In this dissertation, special characteristics of the connected closed-loop inverter and rectifier have been thoroughly analyzed, with particular interest in their impact on fault behaviors of the induction motor and the claw-pole generator. Based on the findings obtained from the theoretical and experimental analysis, several sensorless thermal, mechanical, and insulation monitoring methods are proposed by smartly utilizing special features and capabilities of the connected power electronic converter. A simple and sensitive stator turn-fault detector is proposed for induction motors fed by closed-loop inverter. In addition, a stator thermal monitoring method based on active DC current injection and direct voltage estimation is also proposed to prevent the closed-loop controlled induction motors from thermally overloading. The performance of both methods is demonstrated by extensive experimental results. Methods to detect serpentine belt slip, serpentine belt defect, rotor eccentricity have been proposed for claw-pole generators using only the available electric sensor information. Methods to detect and protect stator turn faults in claw-pole generators are also presented in this dissertation. Lastly, a novel method to detect the generalized bearing roughness fault is proposed. All the proposed condition monitoring techniques have been validated by experimental results.

Induction motors are reliable and widely used in industrialised nations. However induction motors, like any other machine, will eventually fail. If the failure is not anticipated, it can result in a significant revenue loss. Therefore, there is a strong need to develop an efficient maintenance program. The most cost-effective solution is condition-based maintenance. An effective condition-based maintenance program requires an on-line condition monitoring system that can diagnose the condition of an induction motor in order to determine the types of faults and their severity while the motor is under a normal operating condition. The work in this thesis investigates the detection of stator and rotor faults (i.e. shorted turn faults, eccentricity faults, and broken rotor bar faults) using three types of sensor signals (i.e. current, leakage flux, and vibration) under different loading conditions. The work is based on an extensive series of sensor measurements taken using a number of nominally identical healthy machines (2.2 kW) and custom-modified machines (2.2 kW) with configurable stator and rotor fault settings. The thesis starts by investigating the estimation of rotor speed and rotor slot number. These two parameters are important in determining the fault frequency components that are used for detecting the stator and rotor faults. The rotor speed investigation compares four different estimation methods from the three different sensor signal types. It is found that the speed estimation techniques based on the eccentricity harmonics and the rotor frequency in the stator current, the axial leakage flux, and the motor vibration sensor signals can detect the rotor speed very accurately even when the load is as low as 2%. Similarly, this thesis proposes three different rotor slot number estimation techniques from the three different types of sensors and demonstrates that all three techniques can estimate the rotor slot number accurately. In addition, it is shown that the reliability of the estimation techniques can be increased significantly when the three techniques are combined. The shorted turn investigation in this thesis examines and compares potential shorted turn features in the three sensor signal types under five different fault severities and ten different loading conditions. The useful shorted turn features are identified in the thesis, and then examined against variations between the healthy machines in order to determine the loads and the fault severities in which the feature can reliably detect the faults. The results show that the feature based on the EPVA (extended Park’s vector approach) is the best method. This feature can detect turn to turn faults with a severity of 3.5% or greater at loads greater than 20% and phase to phase turn faults with a severity of 1.7% or greater under all loading conditions. However, estimating the fault severity is generally found to be difficult. The thesis also examines the feasibility of detecting static eccentricity faults using the different types of sensor signals under ten different loading conditions. The thesis compares potential eccentricity features under nine different fault severities. The useful features are identified and then combined through weighted linear combination (WLC) in order to produce a better eccentricity fault indicator. The indicator begins to show significant magnitude variation when the fault severity is greater than or equal to 25% and the load is greater than or equal to 25%. The experimental results show that detecting the static eccentricity faults is possible but estimating the fault severity may be difficult. Furthermore, the effects of misalignment faults on the useful eccentricity features are investigated. In this thesis, the analysis of broken rotor bar faults is performed under motor starting and rundown operation. The starting analysis introduces a new approach to detect broken rotor bar faults that utilises the wavelet transform of the envelope of the starting current waveform. The results of the wavelet transform are then processed in order to develop a normalised parameter, called the wavelet indicator. It is found that the wavelet indicator can detect a single broken bar under all loading conditions during motor starting operation. The indicator also increases its magnitude as the severity of the fault increases. On the other hand, the rundown analysis proposes several broken rotor bar fault detection techniques which utilise the induced voltage in the stator windings and the stator magnetic flux linkage after supply disconnection. The experimental results show that detecting the faults during rundown is generally difficult. However, the wavelet approach, which is based on monitoring changes in the motor torque for a given slip, seems to give the best result. / Thesis (Ph.D.) -- University of Adelaide, School of Electrical and Electronic Engineering, 2008