Lifetime Of Motors Research Articles

Diagnostics and predictive maintenance of industrial electric motors

Automatic continuous or periodic control is the most promising method of diagnosing electric motors in productionnowadays. Itis aimed at predicting breakdowns and the remaining useful lifetimeof motors. However, research in this arearemains purely theoretical and eitherfocuses on very narrow problemsor providestoo superficial overview.Consequently,manual control devices orpartially automated devices are mainlyusedin practice[1]. In view of this, there is great interest in the development of a software method for predictive maintenance of electric motors. In this research recurrent neural networks with long short-term memory layers (LSTM-layers)are investigated due to their abilityto effectively model sequential data and learn complex dependencies [2].

Detection of Broken Bars in Induction Motors Using Histogram Analysis of Current Signals

The lifetime of induction motors can be significantly extended by installing diagnostic systems for monitoring their operating conditions. In particular, detecting broken bar failures in motors is important for avoiding the risk of short circuits or other accidents with serious consequences. In the literature, many approaches have been proposed for motor fault detection; however, additional generalized methods based on local and statistical analysis could provide a low-complexity and feasible solution in this field of research. The proposed work presents a methodology for detecting one or two broken rotor bars using the sums and differences histograms (SDH) and machine learning classifiers in this context. From the SDH computed in one phase of the motor’s current, nine texture features are calculated for different displacements. Then, all features are used to train two classifiers and to find the best displacements for faults and health identification in the induction motors. A final experimental evaluation considering the best displacements shows an accuracy of 98.16% for the homogeneity feature and a few signal samples used in a decision tree classifier. Additionally, a polynomial regression curve validates the use of 50 samples to obtain an accuracy of 88.15%, whereas the highest performance is achieved for 250 samples.

Calculation of Parasitic Capacitance to Analyze Shaft Voltage of Electric Motor with Direct-Oil-Cooling System

In modern electric vehicles, electrical failure has become a critical problem that reduces the lifetime of traction motors. Moreover, traction motors with high-voltage and high-speed systems for a high power density have been aggravating the shaft voltage problems. This study identifies that direct-oil-cooling systems exacerbate this problem. To address this, an analytical method for calculating parasitic capacitance is proposed to determine the effects of cooling oil in a traction motor with a direct-oil-cooling system. Capacitance equivalent circuits are configured based on whether the slot is submerged in the cooling oil. In addition, an electric field decomposition method is applied to analyze the distortion of the electric field by the structure of the conduction parts in the motor. The results indicate that the parasitic capacitances of the traction motor are increased by the influence of the cooling oil resulting in an increase in the shaft voltage.

EVALUATION OF FAULTS IN THE SQUIRREL CAGE THREE-PHASE INDUCTION MOTORS

Induction motors have played a central role in the techno-economic development of modern industries and electric power generation. However, the presence of recurring failures hinders a cost-effective performance and leads to catastrophic damage. Therefore, the present study proposed an assessment to investigate the influence of two types of failures in induction motors, namely failure due to broken bars in the rotor and defects in the connection between the rotor bars and the end ring. Accordingly, a three-phase induction motor was evaluated under different failure conditions that modified the operational torque and rotational speed. The results indicated that both types of failures magnify both the core and copper power losses by up to 13.3 % and 8 %, respectively, compared to the healthy condition. On the other hand, an efficiency reductionbetween 1.94 % to 3.41 % is an indication of failure progression. Finally, the appearance of harmonics 3 and 7, and the intensified magnitude of harmonic 5, represent a clear sign of failure occurrence related to rotor barsand defects in the connection to the end ring. In conclusion, the proposed methodology proved to be an adequate tool to predict failure appearance, which has a direct impact on extending the lifetime of induction motors.

Life Interval Prediction for Aging Solid-Propellant Rocket Motors with Uncertain Chemical Parameters

Predictions of the remaining lifetime of aging solid-propellant rocket motors are affected by the uncertainties of various chemical parameters in the reaction. This paper proposes a nonprobabilistic interval method for evaluating the life bounds of aging solid-propellant rocket motors. In this method, chemical uncertainties in the aging process are represented by uncertain-but-bounded initial parameters, and the uncertainties arising in aging solid-propellant rocket motors are described by an interval model. A sparse regression Legendre inclusion function is then employed to establish an interval model for aging solid-propellant rocket motors, which can be directly solved in deterministic form using the finite element method. Finally, in conjunction with the deterministic solutions, the sparse regression Legendre interval algorithm is employed to obtain the bounds of the storage life related to the uncertain interval parameters. The effectiveness of the proposed method is verified by considering an uncertain storage life prediction problem under the accelerated thermoaging process with constant temperature conditions. The proposed method provides a reliable tool for predicting the storage life of aging solid-propellant rocket motors.

Certain performance investigation on hybrid TiO2/Al2O3/MoS2 nanofiller coated 3[formula omitted] induction motor: A Taguchi and RSM based approach

The generation of heat is one of the main problems in the induction motor because it directly affects the performance, efficiency, speed fluctuations, and lifetime of motors. These entities mainly due to improper insulation of the electrical motors and this will avoid by using proper enamel filled nanofiller insulation. In this paper, a novel hybrid TiO2/Al2O3/MoS2based enamel insulation for a 3 phases squirrel cage induction motor was proposed to improve the thermal and electrical properties by using Taguchi and RSM in experimentally. To find an optimal combination of hybrid material TiO2/Al2O3/MoS2, the four different levels of 0.02, 0.04, 0.08 and 0.1 volume percentage with L16 orthogonal array was proposed. Design matrix, ANOVA, S/N ratio, main effect plot, normal probability plot, and surface plot were measured to analyze the optimum combination of the nanofiller to reduce the heat generation problem in an induction motor. ANOVA result shows the TiO2 has a significant effect on the thermal withstanding capacity of the induction motor due to its insulation property compared to Al2O3 and MoS2. A comparison result reveals the hybrid nanocoated induction has better thermal withstanding capacity in the range of 9%–12% compared to normal enamel filled induction motor. This article also analyzes the efficiency and electromagnetic interference of the hybrid nanocoated induction motor.

Moving Toward a Reliability-Oriented Design Approach of Low-Voltage Electrical Machines by Including Insulation Thermal Aging Considerations

Electrical machines (EMs) are required to consistently perform their intended mission over a specified timeframe. The move toward transportation electrification made the EMs' reliability an even stringent and predominant requirement, since a failure might cause severe economic losses, as well as endanger human lives. Traditionally, the design procedure of motors conceived for safety-critical applications mainly relies on over-engineering approaches. However, a paradigm shift is recently taking place and physics of failure approaches/methodologies are employed to meet the reliability figures, while delivering an optimal design. This article proposes and outlines a reliability-oriented design for low-voltage EMs. Thermal accelerated aging tests are preliminarily carried out on custom-built specimens. Once the aging trend of the turn-to-turn insulation system is assessed, the thermal endurance graph at several percentile values is determined and lifetime models are developed, for both constant and variable temperature operations. Finally, these models are used to predict the turn-to-turn insulation lifetime of motors meant for aerospace and automotive applications.

A Torque Vectoring Optimal Control Strategy for Combined Vehicle Dynamics Performance Enhancement and Electric Motor Ageing Minimisation

In this paper we propose a control architecture that combines velocity, sideslip angle and yaw rate regulation with motor temperature regulation on a electric vehicle with four independent electric motors. The linear controller incorporates both the vehicle dynamics and the electric motor dynamics by combining a four-wheel vehicle model with a motor degradation model. It is found that the resulting controller not only enhances the vehicle stability of the vehicle, but also extends the lifetime of motors by regulating their temperatures.

LIFETIME OF AUXILIARY MACHINES OF AC ELECTRIC TRAINS

Purpose. In this paper it is necessary to analyze increase the efficiency of auxiliary machines of AC electric trains, series ER 9M during operating under the real conditions. Methodology. An engineering method to determine the relative reduction of the lifetime of asynchronous motors, selected with a certain design factor of power reserve, under normal operating conditions and with decrease of the electric power supply quality in auxiliary circuits of rolling stock, which takes place in real operation in sections of Ukrzaliznytsia was proposed. Findings. As a result of a study, conducted by the author it was found that long-term operation of asynchronous motors, selected with a sufficient reserve of power k з = 1,6, when the supply voltage unbalance is 16 … 20% leads to a reduction of their lifetime on 9,5…33,2%, depending on the type of motors. It proves that the choice of auxiliary machines with a large margin of power is not a rational way to increase the efficiency of auxiliary machines of electric trains, series ER9M. Recommendations were suggested for the introductions of symmetry-balancing and protective devices based on modern microprocessor and microcontroller hardware components. They make impossible operation of auxiliary machines during a low level of electric energy quality in onboard electric circuits of AC electric train in general, and on the trains, series ER9M in particular. Originality. The issues of the analytical study of the energy supply quality effect on the lifetime of auxiliary machines of AC electric trains, series ER9M through the determination of the relative reduction of the lifetime of auxiliary machines, depending on the general overheating temperature were highlighted firstly. The effect of safety factor for motor capacity on the average overheating and on the heating process of electrical machines on the whole was taken into consideration. Practical value. Obtained results allow forming critical opinion about the existing protection of auxiliary machines of AC electric train and develop recommendations for the implementation of complex organizational and technical measures to improve operability of auxiliary machines of AC electric trains, series ER 9M.

Advanced Motor Monitoring and Diagnostics

Modern motor protection relays are capable of long term failure monitoring and diagnostics based on information collected by a powerful data acquisition system. This includes predicting life time of motors. This paper presents an advanced algorithm capable of performing such tasks. It is applicable to different types of rotating electric machines depending on their design. The components are: stator turn fault detection and rotor bar fault detection. Detection methods are based on calculating the cross coupled impedance and analyzing the current frequency signature of the motor. The presentation includes a theoretical background, simulated results and testing results performed on a particular physical model.

Life Prediction of DC Motor using Time Series Analysis based on Accelerated Degradation Testing

This study presents a method of life prediction for DC motor using time series modeling procedure based on DC motor accelerated degradation testing data. DC motor accelerated degradation data are treated as time series and stochastic process are utilized to describe the degradation process for life prediction. An accelerated degradation test is processed for DC motor until they failed and the accelerated degradation data are collected for life prediction. A comparison between the predicted lifetime and the real lifetime of DC motors is processed and the results show that the life prediction of DC motors using time series analysis is effective.

속도 프로파일 기반의 가감속제어를 통한 DC 모터의 토크제어

본 논문에서는 자동물류운반시스템(AGV)에 사용되는 가감속 제어를 위한 속도 프로파일 기반의 가감속 위치제어를 DC 모터 실험을 통한 토크변화에 대해서 고찰한다. 속도 프로파일을 이용한 모터의 가감속 제어는 모터에 걸리는 부하를 줄임으로써 시스템의 무리한 구동을 방지하고 수명을 연장 시키는 장점을 가지고 있다. 체계적인 설계 구조를 갖는 상태 피드백 제어기를 이용하여 속도 프로파일을 이용한 가감속 제어 기반의 DC 모터의 위치제어와 단순 위치제어를 모의실험을 통하여 비교함으로써 토크 크기를 비교 관찰한다. 또한 CEM-IP-01의 카트 위치 제어 실험을 통하여 이를 검증한다. This paper presents torque control of DC motor using the velocity profile based acceleration/deceleration controller for automatic guided vehicles (AGVs). This technique has some advantage; to reduce the damage of motors and to extend the life time of motors. First, we generate velocity profiles for three cases and design the state feedback controller using the generated velocity profile as a reference. The state feedback controller has servo system for solving regulation problem. For the verification, we apply the proposed method to control a cart position and shows some simulation result.

Prolongation of the Active Lifetime of a Biomolecular Motor for in Vitro Motility Assay by Using an Inert Atmosphere

Over the last few decades, the in vitro motility assay has been performed to probe the biophysical and chemo-mechanical properties as well as the self-organization process of biomolecular motor systems such as actin-myosin and microtubule-kinesin. However, aggression of the reactive oxygen species (ROS) and concomitant termination of the activity of biomolecular motors during investigation remains a drawback of this assay. Despite enzymatic protection that makes use of a combination of glucose, glucose oxidase, and catalase, the active lifetime of biomolecular motors is found to be only a few hours and this short lifetime restricts further study on those systems. We have solved this problem by using a newly developed system of the in vitro motility assay that is conducted in an inert nitrogen gas atmosphere free of ROS. Using microtubule-kinesin as a model system we have shown that our system has prolonged the active lifetime of the biomolecular motor until several days and even a week by protecting it from oxidative damage.

Design and characterization of MEMS micromotor supported on low friction liquid bearing

This paper examines the performance of rotating microdevices incorporating a liquid bearing to couple a rotating element to a fixed substrate. Liquid bearing technology promises to significantly improve the durability and lifetime of micromechanical motors. Here, the fluid is confined between the rotor and stator using surface patterning of a hydrophobic layer. Magnetic actuation of 10mm diameter silicon rotor is used to characterize the liquid bearing motor at rotation rates up to 1800rpm. Bearings with fluid thickness from 20 to 200μm are characterized. A minimum torque of 0.15μN-m is required to initiate rotation. At rotation rates above 720rpm, the rotor wobble is less than ±1mrad and the bearing exhibits viscous friction with a drag coefficient of 1.2×10−3μN-m/rpm. The drag performance of the disk-type liquid bearing using H2O as the fluid is approximately 15 times lower than that demonstrated in a micro-ball bearing supported rotor.

Improving the performances of ultrasonic motors using intermittent contact scheme

Most ultrasonic motors operate in intermittent contact scheme. Their stators drive the rotors (or sliders) when the stators contact the rotors, and the rotors (or sliders) move under an inertia force when the stators and the rotors are separated. The duty cycle of the contact and the “flight” manages motors’ output performance. To obtain a large output force or output velocity, this paper proposes a concept using the alternative work of a multistator or the multi-driving end of a single stator. The method can avoid larger noise, poor efficiency, and lifetime of motors. A novel linear ultrasonic motor using the alternative work of the multi-driving end of a single stator was fabricated and investigated experimentally. The traveling speed without load of the slider is 88 mm/s, and the maximum load is 0.32 N.

Mechatronical Design Studies on Small Brushless Motors

Brushless DC‐ and AC‐permanent‐magnet motors controlled by powerful micro‐controller electronics have opened up a significant share of the small motor market in the last years. Based on the mechanical low cost construction of single‐phase motor the paper presents electronic drive concepts to improve the performance and for special applications also the lifetime of brushless motors. The tangential and radial forces acting on the rotor are controlled by special phase current curves to reduce the torque ripple and to avoid expendable machinery parts like ball or sliding bearings.

Contact mechanics of piezoelectric ultrasonic motors

Piezoelectric ultrasonic motors are driven by tangential stresses in the interface between stator and rotor. These stresses are generated by the elliptical motion of the material points of the stator or rotor surface and depend on frictional processes in the contact area. The contact mechanics of piezoelectric ultrasonic motors determines the operational characteristics, like rotational speed and torque or transmitted mechanical power and efficiency. Wear properties and lifetime of piezoelectric ultrasonic motors are also determined by contact mechanics. The goal of the present paper is to summarize the state of the art in the understanding of some fundamental processes governing the contact mechanics of piezoelectric ultrasonic motors. After a short introduction, a survey of publications devoted to the subject will be given. Then, an attempt will be made to classify the mechanical models, which were developed in order to explain the contact mechanics of piezoelectric ultrasonic motors, according to the physical effects which have been taken into account in their derivation. Some results concerning the choice of proper contact materials, wear and lifetime of ultrasonic motors will be addressed in a separate section. Finally a summary and outlook will be given and open questions for future research will be formulated.