Motor Terminals Research Articles

A Novel Bearing Condition Monitoring Method in Induction Motors Based on Instantaneous Frequency of Motor Voltage

Bearing failures are the most frequent faults in induction motors. By utilizing an efficient bearing condition monitoring (BCM) method, unscheduled breakdowns and unnecessary costs caused by bearing failures can be eliminated. The methods proposed in the literature for this purpose are mainly based on measuring and analyzing vibration and current. This paper proposes a novel BCM method based on “instantaneous frequency of motor voltage.” Simulation and experimental results show that defective bearings cause to increase the amount of non-Gaussianity in this signal. In this paper, it is shown the global kurtosis of the proposed signal is able to detect bearing defects at an early stage. In contrast, for both vibration and current signals, it is preferable to applying the kurtosis locally in different frequency bands. The electrical signals are acquired from the motor terminals and motor control center of an oil pump station. Results approve the merits and effectiveness of the proposed method for industrial applications.

Altered terminal Schwann cell morphology precedes denervation in SOD1 mice

In mice that express SOD1 mutations found in human motor neuron disease, degeneration begins in the periphery for reasons that remain unknown. At the neuromuscular junction (NMJ), terminal Schwann cells (TSCs) have an intimate relationship with motor terminals and are believed to help maintain the integrity of the motor terminal. Recent evidence indicates that TSCs in some SOD1 mice exhibit abnormal functional properties, but other aspects of possible TSC involvement remain unknown. In this study, an analysis of TSC morphology and number was performed in relation to NMJ innervation status in mice which express the G93A SOD1 mutation. At P30, all NMJs of the fast medial gastrocnemius (MG) muscle were fully innervated by a single motor axon but 50% of NMJs lacked TSC cell bodies and were instead covered by the processes of Schwann cells with cell bodies located on the preterminal axons. NMJs in P30 slow soleus muscles were also fully innervated by single motor axons and only 5% of NMJs lacked a TSC cell body. At P60, about 25% of MG NMJs were denervated and lacked labeling for TSCs while about 60% of innervated NMJs lacked TSC cell bodies. In contrast, 96% of P60 soleus NMJs were innervated while 9% of innervated NMJs lacked TSC cell bodies. The pattern of TSC abnormalities found at P30 thus correlates with the pattern of denervation found at P60. Evidence from mice that express the G85R SOD1 mutation indicate that TSC abnormalities are not unique for mice that express G93A SOD1 mutations. These results add to an emerging understanding that TSCs may play a role in motor terminal degeneration and denervation in animal models of motor neuron disease.

P07.29 Point of care testing (poct) for hiv; can venipuncture be avoided for syphilis?

<h3>Abstract</h3> GCaMP is an optogenetic Ca²⁺ sensor widely used for monitoring neuronal activities but the precise physiological implications of GCaMP signals remain to be further delineated among functionally distinct synapses. The <i>Drosophila</i> neuromuscular junction (NMJ), a powerful genetic system for studying synaptic function and plasticity, consists of tonic and phasic glutamatergic and modulatory aminergic motor terminals of distinct properties. We report a first simultaneous imaging and electric recording study to directly contrast the frequency characteristics of GCaMP signals of the three synapses for physiological implications. Different GCaMP variants were applied in genetic and pharmacological perturbation experiments to examine the Ca²⁺ influx and clearance processes underlying the GCaMP signal. Distinct mutational and drug effects on GCaMP signals indicate differential roles of Na⁺ and K⁺ channels, encoded by genes including <i>paralytic</i> (<i>para</i>), <i>Shaker</i> (<i>Sh</i>), <i>Shab</i>, and <i>ether-a-go-go</i> (<i>eag</i>), in excitability control of different motor terminals. Moreover, the Ca²⁺ handling properties reflected by the characteristic frequency dependence of the synaptic GCaMP signals were determined to a large extent by differential capacity of mitochondria-powered Ca²⁺ clearance mechanisms. Simultaneous focal recordings of synaptic activities further revealed that GCaMPs were ineffective in tracking the rapid dynamics of Ca²⁺ influx that triggers transmitter release, especially during low-frequency activities, but more adequately reflected cytosolic residual Ca²⁺ accumulation, a major factor governing activity-dependent synaptic plasticity. These results highlight the vast range of GCaMP response patterns in functionally distinct synaptic types and provide relevant information for establishing basic guidelines for the physiological interpretations of presynaptic GCaMP signals from in situ imaging studies.

Overvoltage Minimization in Induction Motors employing Long Cable PWM Drives

The employment of PWM drives in induction motors control has been widely used in industry. However, in some applications in hazardous areas, such as drilling, the PWM drive cannot be physically close to the motor, being necessary the use of long cable drives. This fact leads to the generation of overvoltage peaks on the induction motor terminals, which can cause interference in the speed control, reduction of equipment lifetime, or even, permanent damages. In this context, this work presents alternatives to minimize the overvoltage effect based on the use of transformers and analyzes the performance of the speed control of each proposed technique.

Torque Ripple-Free Operation of PM BLDC Drives With Petal-Wave Current Supply

Further to the vector analysis in the stationary plane of the behavior of a permanent-magnet brushless dc (PM BLDC) drive, this paper proposes a method of synthesizing the current supply of the motor that ensures torque ripple-free operation of the drive. The synthesis is carried out analytically by the vector approach, and the resulting current vector is then expressed in motor phase coordinates. It comes out that the current vector has a petal-shape trajectory in the stationary plane. The operation of the drive with such a current supply is extensively examined; in particular, the torque capability for an rms value of the phase currents equal to the rated one, the requirements for the voltages to be applied across the motor terminals, and the base speed in correspondence to the supply voltage saturation are determined. At last, experimental traces obtained from an in-wheel PM BLDC drive used for the traction of light electric vehicles are included to corroborate the theoretical findings.

Contractile tone and contraction as important physiological properties of terminals on the processes of living neurons

An attempt to summarize some static morphological renderings of reversible structural alterations of nervous processes, as well as receptor and synaptic terminals, to compare them with the mechanisms of actual transformation of living neurons and to find a common kinetic characteristic for these phenomena has been made. The contractile tone and contraction of processes of living isolated neurons are reported. The dependence of the direction of retraction on the localization of the adhesion site of the isolated cell has been detected. The retraction bulb has been identified as an indicator of all contractions of motor and sensory terminals, both alive and fixed. The process of transformation of growth cones into retraction bulbs has been investigated. The presence of mechanical tension in preterminals and interneuronal contacts has been demonstrated in vitro. Similarity of the kinetics of tissue receptor sensory terminals and growth cones has been detected during in vivo experiments. The kinetics of asynaptic dendrite contraction has been compared to the well-characterized structural variability of dendritic spines. The hypothesis of a common origin of the contractile tone of all nervous elements as one of the principal nonelectrophysiological properties of a neuron has been put forward.

Adenosine receptors and muscarinic receptors cooperate in acetylcholine release modulation in the neuromuscular synapse.

Adenosine receptors (ARs) are present in the motor terminals at the mouse neuromuscular junction. ARs and the presynaptic muscarinic acetylcholine receptors (mAChRs) share the functional control of the neuromuscular junction. We analysed their mutual interaction in transmitter release modulation. In electrophysiological experiments with unaltered synaptic transmission (muscles paralysed by blocking the voltage-dependent sodium channel of the muscle cells with μ-conotoxin GIIIB), we found that: (i) a collaborative action between different AR subtypes reduced synaptic depression at a moderate activity level (40Hz); (ii) at high activity levels (100Hz), endogenous adenosine production in the synaptic cleft was sufficient to reduce depression through A1 -type receptors (A1 Rs) and A2 A-type receptors (A2 A Rs); (iii) when the non-metabolizable 2-chloroadenosine (CADO) agonist was used, both the quantal content and depression were reduced; (iv) the protective effect of CADO on depression was mediated by A1 Rs, whereas A2 A Rs seemed to modulate A1 Rs; (v) ARs and mAChRs absolutely depended upon each other for the modulation of evoked and spontaneous acetylcholine release in basal conditions and in experimental conditions with CADO stimulation; (vi) the purinergic and muscarinic mechanisms cooperated in the control of depression by sharing a common pathway although the purinergic control was more powerful than the muscarinic control; and (vii) the imbalance of the ARs created by using subtype-selective and non-selective inhibitory and stimulatory agents uncoupled protein kinase C from evoked transmitter release. In summary, ARs (A1 Rs, A2 A Rs) and mAChRs (M1 , M2 ) cooperated in the control of activity-dependent synaptic depression and may share a common protein kinase C pathway.

A Fault-Tolerant Three-Phase Adjustable Speed Drive Topology With Active Common-Mode Voltage Suppression

A fault-tolerant adjustable speed drive (ASD) topology is introduced in this paper. A conventional ASD topology is modified to address: 1) drive vulnerability to semiconductor device faults; 2) input voltage sags; 3) motor vulnerability to effects of long leads; and 4) minimization of common-mode (CM) voltage applied to the motor terminals. These objectives are attained by inclusion of an auxiliary IGBT inverter leg, three auxiliary diodes, and isolation-reconfiguration circuit. The design and operation of the proposed topology modifications are described for different modes: 1) fault mode, 2) active CM suppression mode, and 3) auxiliary sag compensation (ASC) mode. In case of fault and sag, the isolation and hardware reconfiguration are performed in a controlled manner using triacs/antiparallel thyristors. In normal operation, the auxiliary leg is controlled to actively suppress CM voltage. For inverter IGBT failures (short circuit and open circuit), the auxiliary leg is used as a redundant leg. During voltage sags, the auxiliary leg, along with auxiliary diodes, is operated as a boost converter. A current-shaping control strategy is proposed for the ASC mode. A detailed analysis of CM performance of the proposed topology is provided, and a new figure of merit, CM distortion ratio (CMDR), is introduced to compare the attenuation of CM voltage with that of a conventional ASD topology. The output filter design procedure is outlined. A design example is presented for an 80 kW ASD system, and simulation results validate the proposed auxiliary leg based fault-tolerant scheme. Experimental results from a scaled prototype rated at 1 hp are discussed in this paper.

Part II: Application Guidelines for High-Resistance Grounding of Low-Voltage Common AC-Bus and Common DC-Bus PWM Drive Systems

High-resistance ground (HRG) systems have gained popularity in process applications due to their ability to continue operation after a single line-to-ground fault and to limit the escalation of a single line-to-ground fault to a multiphase event. Part I of the companion paper has set the guidelines for designing safe and reliable HRG systems on industrial power systems used with linear loads and the effect of increased line-ground voltage stress on motor loads during fault conditions. However, literature on characteristics and pitfalls of HRG systems when used with nonlinear power converter systems is limited. Part II investigates anomalies of HRG systems used with nonlinear power converters such as neutral voltage shifting, increased line-ground transient fault voltages for both motor and ac source terminals and their voltage compatibility issues, increased neutral grounding resistor power dissipation, susceptibility of ground fault sensing equipment to nuisance tripping, and dc-bus voltage resonance on faults. Part II also investigates HRG zero-sequence fault current characteristics and paths observed under various fault locations in a common ac or a common dc-bus pulsewidth-modulated adjustable speed drive (ASD) system. Part II concludes with a summary of application guidelines when using ASD HRG systems.

Efficient braking energy recovery using bidirectional step-up converter in fuel cell and battery electric vehicles

The topology of the power conditioning unit (PCU) that is used with energy storage system (ESS), has a vital role especially in braking energy recovery. In recent studies, conventional bidirectional half-bridge topology is widely used as a PCU for ESSs. Due to its structure, it does not have the capability of capturing braking energy when the voltage across the motor terminals is lower than ESS voltage. This study investigates the feasibility of utilising a PCU with stepping up capability in regenerative braking operation mode, focusing on the additional braking energy that can be captured in comparison with that of the conventional half-bridge buck/boost converter. In order to verify the advantageous of the proposed approach in braking energy recovery, two 1 kW prototypes, a conventional half-bridge buck-boost and cascaded buck-boost converters are designed and tested for three different drive cycles including normalised version of ECE-15.

A Novel Filter Topology With Active Motor CM Impedance Regulator in PWM ASD System

This paper presents a novel hybrid output filter topology for the inverter-motor system. It is shown that the proposed filter drastically reduces the common mode (CM) voltage at the motor terminals. The proposed filter is composed of a conventional LC filter cascaded with an active motor CM impedance regulator. The active circuit, utilizing an integrated high-voltage op-amp, is very efficient in decreasing the motor CM equivalent capacitance, as well as damping the high common voltage on the motor terminal. Therefore, the motor impedance is also used as part of the filter, and the common voltage can be eliminated dynamically in the active impedance regulator by feedback control. Furthermore, the size of the passive filter can be reduced to a large extent. Experimental verification of the filter topology is provided with a laboratory system consisting of a 380-V inverter and a 0.37-kW induction motor.

Performance evaluation of a transformerless multiphase electric submersible pump system

Using of low-voltage variable-frequency drive followed by a step-up transformer is the most preferable way to feed an electrical submersible pump motor. The existence of long feeder between the motor and drive systems usually causes over-voltage problems because of the travelling wave phenomenon, which makes the employment of filter networks on the motor or inverter terminals mandatory. The so-called boost-inverter inherently can solve this problem with filter-less operation as it offers a direct sinusoidal output voltage. As boost inverters have voltage boosting capability, it can provide a transformer-less operation as well. This study investigates the performance of a five-phase modular winding induction machine fed from a boost-inverter through a long feeder. A simulation study using a 1000 Hp system and experimental investigation on a 1 Hp prototype machine are used to support the presented approach.

Dysfunctional mitochondrial Ca(2+) handling in mutant SOD1 mouse models of fALS: integration of findings from motor neuron somata and motor terminals.

Abundant evidence indicates that mitochondrial dysfunction and Ca2+ dysregulation contribute to the muscle denervation and motor neuron death that occur in mouse models of familial amyotrophic lateral sclerosis (fALS). This perspective considers measurements of mitochondrial function and Ca2+ handling made in both motor neuron somata and motor nerve terminals of SOD1-G93A mice at different disease stages. These complementary studies are integrated into a model of how mitochondrial dysfunction disrupts handling of stimulation-induced Ca2+ loads in presymptomatic and end-stages of this disease. Also considered are possible mechanisms underlying the findings that some treatments that preserve motor neuron somata fail to postpone degeneration of motor axons and terminals.

Chronic proximal axonopathy in rats is associated with long-standing neurofilament depletion in neuromuscular junctions and behavioral deficits.

In rodents exposed to 3,3'-iminodipropionitrile (IDPN), neurofilaments (NFs) accumulate in swollen proximal axon segments; this also occurs in motor neurons of patients with amyotrophic lateral sclerosis. We hypothesized that early loss of NFs in neuromuscular junctions (NMJs) in IDPN proximal neuropathy would result in neuromuscular dysfunction and lead to neuromuscular detachment. Adult male rats were given 0 or 15 mmol/L IDPN in drinking water for up to 1 year. The IDPN-exposed rats dragged their tails and had impaired endurance in a grip test. Neuromuscular junctions and distal axons were examined in the levator auris longus muscle after 3, 6, 9, and 12 months. Neuromuscular junctions showed a progressive reduction in NF immunolabeling, which became undetectable in up to 70% of the NMJs after 12 months. Neurofilament labeling was also reduced in preterminal axons and in a more proximal axon level within the muscle. Triple-label analysis with antisyntaxin demonstrated that the terminals remained in place and usually contained a few minute NF bundles. Electron microscopy revealed the disappearance of terminal NFs, reduced content in synaptic vesicles, and accumulation of multilamellar bodies, but scant degeneration. Thus, IDPN proximal neurofilamentous axonopathy is associated with NF depletion in motor terminals; motor weakness and structural changes in the NMJs suggest impaired synaptic function despite long-term preservation of the NMJs.

The Effects of Cable Parameters on Over-Voltage at Motor Terminals in the PWM System

In PWM system, the reflected voltage in the cable transmission process generates overvoltage and damps high-frequency ringing at motor terminals and further stresses the motor insulation, even leads to insulation breakdown in premature period. Firstly, in this paper, the cable equivalent mathematical model was established based on three-phase cable. Then the propagation velocity, the oscillation frequency and the oscillation duration of the pulse in the cable was described by mathematical method, and the effects of cable parameters on over-voltage at motor terminals was analyzed under the conditions of high-frequency. Secondly depending on the simulation by PSpice software, we tested and verified the conclusion by building simulation models.

Use of Synchronous Modulation to Recover Energy Gained From Matching Long Cable in Inverter-Fed Motor Drives

As inverter-fed motor drives generate fast-switching voltage pulses, the transmission-line effects on long motor cable and motor stator windings lead to overvoltage on the cable and motor terminals, as well as inside motor stator windings, and also an increase in the common-mode current. Such phenomenon would cause premature failure of motor and cable insulation. A general protective measure is the use of a passive filter, such as RC and RLC filter, to reduce the voltage surges by matching the cable impedance and/or altering the rise time of the voltage pulses. However, passive filters are bulky and lossy. This paper presents an active motor terminal filter with energy recovery function that can achieve the same functions as the passive filters, but consumes much less power. The proposed filter recovers energy gained from suppressing motor terminal voltage surges and regenerating the recovered energy back to the whole system. An experimental filter has been built and evaluated on a 1-hp three-phase motor drive system. A comparative study into the performance among commonly used RC filter and RLC filter and the proposed filter will be given.

A modeling method and EMTP simulations of an inverter surge

AbstractA numerical simulation of the inverter surge is carried out using a frequency‐dependent model of a cabtyre cable. The frequency‐dependent model is based on the Semlyen line model in the EMTP, for which the required parameters are determined from the measured results of the wave propagation characteristic in the cable. A simple model of an induction motor is proposed considering resonances in the motor. The simulated result by the EMTP agrees reasonably well with the measured result. The proposed model can be useful for predicting the peak voltages observed at the motor terminal of inverter‐operated motors. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley &amp; Sons, Inc.

Abnormal mitochondrial transport and morphology are common pathological denominators in SOD1 and TDP43 ALS mouse models

Neuronal mitochondrial morphology abnormalities occur in models of familial amyotrophic lateral sclerosis (ALS) associated with SOD1 and TDP43 mutations. These abnormalities have been linked to mitochondrial axonal transport defects, but the temporal and spatial relationship between mitochondrial morphology and transport alterations in these two distinct genetic forms of ALS has not been investigated in vivo. To address this question, we crossed SOD1 (wild-type SOD1(WT) and mutant SOD1(G93A)) or TDP43 (mutant TDP43(A315T)) transgenic mice with mice expressing the fluorescent protein Dendra targeted to mitochondria in neurons (mitoDendra). At different time points during the disease course, we studied mitochondrial transport in the intact sciatic nerve of living mice and analyzed axonal mitochondrial morphology at multiple sites, spanning from the spinal cord to the motor terminals. Defects of retrograde mitochondrial transport were detected at 45 days of age, before the onset of symptoms, in SOD1(G93A) and TDP43(A315T) mice, but not in SOD1(WT). At later disease stages, also anterograde mitochondrial transport was affected in both mutant mouse lines. In SOD1(G93A) mice, mitochondrial morphological abnormalities were apparent at 15 days of age, thus preceding transport abnormalities. Conversely, in TDP43(A315T) mice, morphological abnormalities appeared after the onset of transport defects. Taken together, these findings demonstrate that neuronal mitochondrial transport and morphology abnormalities occur in vivo and that they are common denominators of different genetic forms of the ALS. At the same time, differences in the temporal and spatial manifestation of mitochondrial abnormalities between the two mouse models of familial ALS imply that different molecular mechanisms may be involved.

α-Synuclein A30P decreases neurodegeneration and increases synaptic vesicle release probability in CSPα-null mice

α-Synuclein and Cysteine-string protein-α (CSPα) are presynaptic proteins that participate in the maintenance of synaptic function. Mutations or overexpression of the wild type form of α-synuclein have been related to Parkinson's disease, and CSPα mutations cause one type of neuronal ceroid lipofuscinosis. Both are adult-onset neurodegenerative diseases characterized by neuronal protein aggregations. Strikingly, while in mouse the lack of CSPα produces defective neurotransmission and neurodegeneration of motor terminals, blindness and early lethality, the moderate overexpression of wild-type α-synuclein fully rescues the CSPα-null phenotype. Contrarily, the overexpression of the mutated human α-synuclein A30P (α-synucleinhA30P) has much less effect in CSPα KO mice. To explore how the A30P mutation affects the neuroprotective function of α-synuclein we investigated synaptic structure and neurotransmission in motor nerve terminals of wild-type and CSPα-null mice transgenic for α-synucleinhA30P. We found that although α-synucleinhA30P did not fully prevent neurodegeneration, it significantly improved synaptic organization and function in CSPα-null mice by enhancing quantal content, release probability, synaptic vesicle content, active zone number, postsynaptic area, and microtubule appearance. These results demonstrate that α-synucleinhA30P is able to ameliorate synapse degeneration, despite its apparent lack of functionality and its long-term pathogenic effects in neurons. These findings may help to understand better the dual function of α-synuclein regarding neurodegeneration.This article is part of the Special Issue entitled ‘The Synaptic Basis of Neurodegenerative Disorders’.

Development of Two Novel Power Electronic Circuits for Dynamic Braking of Motors

The goal of this study was to develop two dynamic braking schemes for a triac voltage-controlled variable-speed motor. In the beginning, it is proposed to operate the AC voltage controller as a half-wave-controlled AC-to-DC converter by inhibiting firing pulses to the triac in one half-cycle of supply voltage so that dynamic braking can be affected. It is found that such an attempt has failed, and during half-wave-controlled converter operation, the motor runs at very low speed. The causes of the failure are investigated, and then two power electronic circuits capable of affecting dynamic braking of motors with a half-wave-controller-fed operation are proposed. The first circuit employs controlled free-wheeling across the motor terminals, and the second method uses disconnection of auxiliary winding. Both methods are shown to achieve dynamic braking of the motor. Simulated and measured results are presented to show the effectiveness of the two circuits.