End Of Motor Research Articles

A JOINT WEARABLE STRUCTURAL REINFORCING DEVICE FOR VIBRATION SUPPRESSION IN ROBOTIC MILLING

The structural vibration caused by poor rigidity is one of the main obstacles limiting the machining efficiency of robot milling. The existing vibration suppression strategies mainly focus on process parameter optimization, passive vibration absorption at the end and feedback control of joint motor. Although these strategies have certain vibration suppression effects, they cannot directly improve the structural rigidity of the robot. In this paper, a joint wearable structural reinforcing device (JWSRD) is proposed, which can achieve vibration suppression effect by improving the rigidity of the robot joints, fundamentally improve the processing ability of the robot, and ensure the processing stability. Firstly, the structure of the device is designed without affecting the processing flexibility. Secondly, the braking torque of the JWSRD is tested. Considering the feedback of joint braking torque, the vibration simulation model under harmonic excitation is derived. Finally, the offset mass experiments are carried out to verify the vibration suppression effect of the JWSRD. The results show that the JWSRD installed on the robot joint has the notable potential to enhance the structural rigidity, reduce the machining vibration and improve the machining efficiency.

Axle Temperature Monitoring and Neural Network Prediction Analysis for High-Speed Train under Operation

Predicting the axle temperature states of the high-speed train under operation in advance and evaluating working states of axle bearings is important for improving the safety of train operation and reducing accident risks. The method of monitoring the axle temperature of a train under operation, combined with the neural network prediction method, was applied. A total of 36 sensors were arranged at key positions such as the axle bearings of the train gearbox and the driving end of the traction motor. The positions of the sensors were symmetrical. Axle temperature measurements over 11 days with more than 38,000 km were obtained. The law of the change of the axle temperature in each section was obtained in different environments. The resultant data from the previous 10 days were used to train the neural network model, and a total of 800 samples were randomly selected from eight typical locations for the prediction of axle temperature over the following 3 min. In addition, the results predicted by the neural network method and the GM (1,1) method were compared. The results show that the predicted temperature of the trained neural network model is in good agreement with the experimental temperature, with higher precision than that of the GM (1,1) method, indicating that the proposed method is sufficiently accurate and can be a reliable tool for predicting axle temperature.

Research on heat transfer of submersible motor based on fluid network decoupling

A heat transfer model of submersible motor based on partition decoupling is proposed. Due to the special circulation system of the fluid in the submersible motor, the internal inner flow field represents a repeatability alone the axial direction. In addition, the relationship between the velocity and pressure of the internal fluid inside the gap, the inner cavity of the shaft and the oil splashing holes of the bearing are also determined, which can determine the boundary conditions of the end of the single motor Then the global motion fluid field is decomposed into local flow field, which simplifies the thermal model of the global fluid field of the submersible motor. Taking a submersible motor as an example, the temperature distribution of each component and the flow state of the internal motor are calculated, and the influence of the latter on the temperature field is analyzed. Finally, the validity of the method is verified by comparing the calculated results with the experimental data. The research results provide a theoretical basis for analyzing the global fluid field and thermal effect of other motors with special fluid structure.

A Novel FLC Based Closed-Loop V/f Control of Five-Level Inverter Fed Open-End Winding Induction Motor Drive

A fuzzy logic based closed-loop V/f control scheme for five-level inverter-fed open-end winding induction motor drive is proposed and experimentally validated in this paper. To the best of the authors’ knowledge, closed-loop V/f control for open-end winding induction motor has not been explored so far. The five-level inversion operation is achieved by feeding one end of the open-end winding induction motor by 3-phase, 3-level cascade inverter and other by 3-phase, 2-level inverter. To achieve the closed-loop V/f speed control, a fuzzy logic based auto tuned controller is designed. The controller is capable of reducing undesired sustained oscillations under different loading conditions. A hardware prototype model of the drive is developed to investigate the performance of the proposed controller for the full range of speed under light and high loading conditions.

Paraquat Exposure Increases Oxidative Stress Within the Dorsal Striatum of Male Mice With a Genetic Deficiency in One-carbon Metabolism.

Paraquat is an herbicide that is commonly used worldwide. Exposure to paraquat results in Parkinson's disease (PD)-like symptoms including dopaminergic cell loss. Nutrition has also been linked in the pathogenesis of PD, such as reduced levels of folic acid, a B-vitamin, and component of one-carbon metabolism. Within one-carbon metabolism, methylenetetrahydrofolate reductase (MTHFR) catalyzes the irreversible conversion of 5, 10-methylenetetrahydrofolate to 5-methyltetrahydrofolate. A polymorphism in MTHFR (677 C&→T) has been reported in 5%-15% of North American and European human populations. The MTHFR polymorphism is also prevalent in PD patients. The goal of this study was to investigate the impact of paraquat-induced PD-like pathology in the context of reduced levels of MTHFR. Three-month-old male Mthfr+/- mice, which model the MTHFR polymorphism observed in humans, were administered intraperitoneal injections of paraquat (10 mg/kg) or saline 6 times over 3 weeks. At the end of paraquat treatment, motor and memory function were assessed followed by collection of brain tissue for biochemical analysis. Mthfr+/- mice treated with paraquat showed impaired motor function. There was increased microglial activation within the substantia nigra (SN) of Mthfr+/- mice treated with paraquat. Additionally, all Mthfr+/- mice that were treated with paraquat showed increased oxidative stress within the dorsal striatum, but not the SN. The present results show that paraquat exposure increases PD-like pathology in mice deficient in one-carbon metabolism.

Mechanical Strength Improvement of Mud Motor’s Elastomer by Nano Clay and Prediction the Working Life via Strain Energy

In directional drilling, the most important thing that leads to pulling out the drill string is end of mud motor working life. Considering the working conditions of down hole mud motors; increasing the mechanical properties of their stator’s elastomer is crucial. Some attempts were done to increase the motor performance through geometrical changes but lack of material improvement is significant in previous studies. In this study, NBR/nanoclay composite samples were prepared through melt intercalation in an internal mixer and tested with regard to the temperature and drilling mud of down hole. Hardness, tear, fatigue and tensile test results of neat NBR elastomer and nanocomposite of NBR and different loading of nanoclay showed that the mechanical strength of new composites are considerably increased. With the help of strain energy method it was revealed that the life of NBR/nanoclay composite compared to neat NBR was enhanced. Therefore, increasing the working life and performance of the motor is achievable by using this nanocomposite. In the drilling industry, there is a direct relation between time and cost; therefore, increasing the working life of the motor leads to a considerable cost reduction in this expensive industry.

Responsiveness and minimal clinically important changes for the Tampa Scale of Kinesiophobia after lumbar fusion during cognitive behavioral rehabilitation.

The Tampa Scale of Kinesiophobia (TSK) is a commonly-used measure for the assessment of fear of movement beliefs in chronic complaints, but its responsiveness in subjects after lumbar fusion has been never reported. Evaluating the responsiveness and minimal clinically important differences (MCIDs) for the TSK and its subscales after lumbar fusion. Population-based cohort study. Secondary care rehabilitation hospital. In-patients undergoing rehabilitation after lumbar fusion. At the beginning and end of a four-week motor and cognitive-behavioral rehabilitation program, 180 patients completed the TSK. After the intervention, the global perceived effect (GPE) was analyzed to produce a dichotomous outcome (improved vs. stable). Responsiveness for the TSK and its subscales were calculated by distribution (effect size [ES], standardized response mean [SRM]) and anchor-based methods (receiver operating characteristics (ROC) curves; correlations between change scores of the TSK and its subscales and GPE). ROC curves were also used to compute MCID values. The ES ranged from 1.63 to 1.77 and the SRM from 1.25 to 1.39 for TSK and its subscales. The ROC analyses revealed a value of area under the curve (0.999 [95% CI: 0.978; 1.000], 0.998 [95% CI: 0.975; 1.000], 0.990 [95% CI: 0.962; 0.999] for the TSK, Harm and Activity Avoidance subscales, respectively). MCID values greater than 6 (95% CI: >5; >6), 4 (95% CI: >3; >5), and 2 (95% CI: >2; >2) were achieved for the TSK, Harm and Activity Avoidance subscales, respectively. Correlations between change scores of the TSK and its subscales and GPE were high (0.786-0.830). The TSK and its subscales were sensitive in detecting clinical changes in subjects undergoing rehabilitation after lumbar fusion. The obtained MCID values will help in the design of future randomized controlled trials and in the interpretation of the clinical impact of a rehabilitation program after lumbar fusion.

Role of Rho Kinase Inhibition in the Protective Effect of Fasudil and Simvastatin Against 3-Nitropropionic Acid-Induced Striatal Neurodegeneration and Mitochondrial Dysfunction in Rats.

3-Nitropropionic acid (3-NP)-induced neurotoxicity is an experimental model which mimics the pathology and motor abnormalities seen in Huntington's disease (HD) in human. The present investigation was directed to estimate the role of rho kinase (ROCK) inhibition in the possible protective effect of fasudil and simvastatin in 3-NP-induced striatal neurodegeneration in rats. Animals were injected s.c. with 3-NP (20mg/kg/day) for 1week with or without administration of fasudil (10mg/kg/day, p.o.) or simvastatin (20mg/kg/day, p.o.). At the end of experiment, motor and behavioral abnormalities were evaluated. Animals were then sacrificed for measurement of mitochondrial membrane potential as well as succinate dehydrogenase (SDH) and caspase-3 activities in striatum. Moreover, tumor necrosis factor-alpha (TNF-α) level and protein expressions of proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), ROCK, phosphorylated-Akt (p-Akt), endothelial and inducible nitric oxide synthase (eNOS and iNOS), Bax, and Bcl-2 were estimated. Finally, histological changes as demonstrated by striatum injury score, glial activation, and percentage of altered mitochondria were assessed. Both fasudil and simvastatin effectively inhibited 3-NP-induced behavioral, biochemical, and histological changes through inhibition of ROCK activity. However, fasudil provided more amelioration in histological changes, mitochondrial membrane potential and SDH activity in addition to p-Akt and PGC-1α protein expressions. The present study highlights a significant role of ROCK/p-Akt/eNOS pathway in the protective effects of fasudil and simvastatin on neurotoxicity and mitochondrial dysfunction induced by 3-NP in rats. Thus, specific inhibition of ROCK may be considered a promising new approach in the management of HD.

High Efficient Induction Motor Drives Using Triple Lift Converter

This paper proposes a high efficient advanced DC-DC converter by name Triple-Lift converter in the front end of Induction motor (IM) drives system. The conventional IM drives use PWM rectifier, boost converter, buck-boost converter, etc., in the front end which holds inadequacy in pump-up voltage and deprived output current. The Triple-Lift converter (TLC) implemented in the system employs voltage lift technique and produces the output voltage in arithmetic progression. The voltage source inverter (VSI) coupling IM derives a wide range of DC input (ripple free) from TLC which can be adopted for high rated motors with good efficiency. Simulation results using MATLAB show the effectiveness of the proposed converter arrangement for IM drives.

Coupled Electromagnetic and Thermal Design of Miniaturized Permanent Magnet Linear Motors for Sliding Door Applications

The design process for permanent magnet linear motors (PMLM) is similar to that used for their rotary counterparts. A number of electro-technical equations are used to get the best design for a specific application. Nevertheless, there are two issues that differ from the design of a standard rotary machine that must be considered. The first one is the intrinsic asymmetry of the magnetic circuit, which makes the flux distribution different from pole to pole. The second one is the particular geometry and constraints of the thermal circuit, which is crucial for the design of miniaturize linear motors. This paper presents an analytical method for computing the flux distribution in a surface-mounted PMLM. The method, based on the equivalent magnetic circuit method, considers the saturation of the material, the leakage at the end of the motor and the asymmetrical distribution of the magnetic flux. Additionally, an analytical lumped parameter thermal model for linear drives that gives results for both transient and steady-state temperatures is described. Validation of the models is performed by using Finite Element and Computer Fluid Dynamics software. Finally, both magnetic and thermal circuits have been used to design a miniaturized PMLM to drive a sliding door to experimentally verify its goodness

A Dual Inverter Fed Four-Level Open-End Winding Induction Motor Drive With a Nested Rectifier-Inverter

A four-level inverter drive could be obtained by feeding an open-end winding induction motor by two two-level inverters from either side with unequal dc-link voltages, which are in the ratio of 2:1. This inverter modulation scheme is capable of producing 64 space-vector combinations. Some of the space vector combinations could result in the overcharging of the dc-link capacitor corresponding to the inverter operating with the lower voltage. In this paper, a new power circuit topology is proposed, in which, a rectifier-inverter combination is nested within a conventional two-level inverter configuration. The output of the conventional two-level inverter feeds one end of the open-end winding induction motor, while the output of the nested rectifier-inverter combination feeds the other end. The total dc-link voltage needed in the proposed topology is only 77% of the one needed in the conventional multilevel inverters. Also, the problem of zero-sequence current, commonly encountered in open-end winding induction motor drives, is avoided by resorting to a decoupled space vector modulation PWM scheme, which eliminates the zero-sequence voltage of the dual-inverter system by forcing the sampled average of the zero sequence voltage of individual inverters to zero.

A Hybrid Active Filter for a Three-Phase 12-Pulse Diode Rectifier Used as the Front End of a Medium-Voltage Motor Drive

This paper describes a hybrid active filter intended for mitigating the line-side harmonic currents of a three-phase 12-pulse diode rectifier used as the front end of a medium-voltage high-power motor drive. This hybrid filter is characterized by series connection of a simple LC filter and a small-rated active filter. This circuit configuration brings low cost, small size, and light weight to the hybrid filter. A three-phase experimental system rated at 400 V and 15 kW is designed, constructed, and tested, which is a downscaled model of the medium-voltage motor drive system. In this experiment, the LC filter is tuned to the 11th-harmonic frequency, and the active filter is based on a three-level neutral-point-clamped pulsewidth modulation converter (NPC PWM) with a dc capacitor voltage as low as 28 V. This hybrid filter is connected on either first or fourth winding of a line-frequency transformer with a first Δ-winding voltage of 400 V in the primary, and a second Δ-winding voltage of 220 V, a third Y-winding voltage of 220 V, and a fourth Δ-winding voltage of 400 V in the secondary. Experimental results show that the hybrid filter performs satisfactory filtering in a range from no-load to full-load conditions.

Harmonic Filtering Performance of a Hybrid Active Filter for a Three-Phase 12-Pulse Diode Rectifier

This paper describes a hybrid active filter for harmonic-current compensation of a three-phase 12-pulse diode rectifier used as the front end of a medium-voltage motor drive system. This hybrid filter is characterized by the direct series connection of a simple LC filter and a small-rated active filter. This circuit configuration brings low cost, small size, and light weight to the hybrid filter. The authors design, construct, and test a three-phase experimental system rated at 400V and 15kW, which is a downscaled model of the medium-voltage motor drive system. In this experiment, the LC filter is tuned to the 11th harmonic frequency, and the active filter is based on a three-level diode-clamped PWM converter with a dc capacitor voltage as low as 28V. This hybrid filter is connected on either the first or fourth winding of a line-frequency transformer with a first Δ-winding voltage of 400V in the primary, and a second Δ-winding voltage of 220V, a third Y-winding voltage of 220V, and a fourth Δ-winding voltage of 400V in the secondary. Experimental results show that the hybrid filter performs satisfactory filtering in a range from the no-load to full-load conditions.

The Structural Basis for the Large Powerstroke of Myosin VI

Due to a unique addition to the lever arm-positioning region (converter), class VI myosins move in the opposite direction (toward the minus-end of actin filaments) compared to other characterized myosin classes. However, the large size of the myosin VI lever arm swing (powerstroke) cannot be explained by our current view of the structural transitions that occur within the myosin motor. We have solved the crystal structure of a fragment of the myosin VI motor in the structural state that represents the starting point for movement on actin; the pre-powerstroke state. Unexpectedly, the converter itself rearranges to achieve a conformation that has not been seen for other myosins. This results in a much larger powerstroke than is achievable without the converter rearrangement. Moreover, it provides a new mechanism that could be exploited to increase the powerstroke of yet to be characterized plus-end-directed myosin classes.

The unique insert at the end of the myosin VI motor is the sole determinant of directionality

Myosin VI moves toward the pointed (minus) end of actin filaments, the reverse direction of other myosin classes. The myosin VI structure demonstrates that a unique insert at the end of the motor repositions its lever arm and is at least in part responsible for the reversal of directionality. However, it has been proposed that there must be additional modifications within the motor that contribute to its large step size and to the reversal of directionality. To ascertain the inherent directionality of the motor core, we attached the myosin V lever arm to myosin VI, with and without the unique insert. If the insert was maintained, the motor moved toward the minus end of actin filaments, but if removed, movement was redirected toward the plus end. Single-molecule studies revealed that further adaptations within the motor increase the magnitude and variability of the plus-end directed converter movements, and unexpectedly provide the source of the highly variable myosin VI step size. Thus, the unique insert is necessary and sufficient to reverse an inherently plus-end directed myosin.

A Transformerless Hybrid Filter Using a Three-Level Diode-Clamped PWM Converter

This paper deals with a transformerless hybrid active filter integrated into a medium-voltage three-phase diode rectifier used as the front end of an adjustable-speed motor drive. The hybrid filter is formed by a single LC filter tuned to the 7th-harmonic frequency per phase and a small-rated active filter based on a three-phase three-level diode-clamped PWM converter. A three-phase downscaled system rated at 400V and 15kW is designed, constructed, and tested to verify the filtering performance of the hybrid filter. Experimental results show that the current THD (total harmonic distortion) gets less than 5%, and that the voltage-balancing control proposed in this paper works properly even in transient states.

축방향 누설자속 측정에 의한 유도전동기의 회전자 결함검출에 관한 연구

유도전동기에 대한 결함 검출의 도구로서 축방향 누설자속 측정 방법을 사용할 수 있는가를 평가하고 전동기고장 검출에 관한 진단 알고리즘을 개발하기위한 회전자에 관한 2번째 논문이다. 결함 검출을 위해 운전 중인 전동기의 끝단에 설치된 자속코일 센서로 누설자속 신호를 수집하며 전동기의 각종 결함을 검출하기 위해 시간과 주파수 영역에서 신호를 분석하였다. 센서 신호 형상이 전동기 각각의 결함에 대해 시간과 주파수 영역에서 해석하였다. 전동기의 회전자 관련 결함인 회전자봉 파손, 단락환 파손 및 회전자 편심이 축방향에서 측정된 고해상도의 스펙트럼으로부터 검출할 수 있는 방법을 확인하였다. 누설자속 스펙트럼으로부터 특정 주파수와 회전자봉 통과주파수의 측파대를 분석함으로서 회전자 결함을 검출하는 방법을 알았다. 또 유도전동기에 대하여 축방향 누설자속 측정을 위한 최적의 자속코일센서 및 측정시스템을 검증하고 회전자 결함을 검출하기 위한 방법을 개발하였다.

축방향 누설자속 측정에 의한 유도전동기의 고정자 결함검출에 관한 연구

본 논문은 유도 전동기에 대한 상태 모니터링 시스템의 도구로서 축방향 누설자속 측정 방법을 사용할 수 있는가를 평가하고 전동기에 대한 진단 알고리즘을 개발하는 것이다. 결함검출을 위해 전동기를 정지시키지 않고 전동기의 코일단에 설치된 자속코일로 누설자속 신호를 수집하여 전동기의 각종 결함을 검출하기 위해 시간과 주파수 영역으로 신호를 분석한다. 전동기 각각의 결함에 대해 시간과 주파수 영역에서 특정 신호 현상이 검출되었다. 전원전압 불평형과 고정자 권선의 선간 단락은 축방향에서 측정된 고해상도의 누설자속 스펙트럼으로부터 특정 측대파와 회전자봉 통과주파수의 측대파를 분석함으로서 결함을 검출할 수 있다. 주파수 영역에서의 스펙트럼이 모니터링 목적으로 더욱 유용하다는 결론을 얻었다.<br/> 본 논문에서는 유도 전동기의 축방향 누설자속 측정이 진단 방법으로서 적합한 도구임을 증명하고 결함을 검출하기 위한 알고리즘을 개발하였다.

Analysis of the reduction of detent force in a permanent magnet linear synchronous motor

The problem in improving the positioning precision of a permanent magnet linear synchronous motor (LSM) is the large detent force caused by the permanent magnet. The detent force is thought to arise from the difference of the position of a permanent magnet end and a tooth position. If one detent force is independent from the other, we can reduce the total detent force of the permanent magnet linear synchronous motor by the arrangement of a permanent magnet end and a tooth. This paper presents are improvement of the arrangement of the permanent magnet end of a linear synchronous motor in order to reduce the detent force by using numerical analysis.

Turbulent Flow Analysis of Erosive Burning of Cylindrical Composite Solid Propellants

An axisymmetric turbulent boundary layer was analyzed in order to investigate erosive burning in composite solid-propellant rocket motors. It was found that there is a strong interaction between the core flow acceleration and turbulence level in the boundary layer. The increase of turbulence near the surface of the propellant plays an important role in the erosive burning mechanism. Reducing the port diameter makes a rocket motor more sensitive to erosive burning. When the port diameter is uniform, the erosive burning rate increases toward the aft end of the rocket motor. This trend is less pronounced or even reversed when the port diameter is divergent.