Braking Regime Research Articles

Effective ways to compare two families of freight trains

The paper shows several use cases of the “relative approach” method, envisaged by international recommendations, for evaluating the safety of two families of freight trains. This is relevant when a decision is needed about a new technology or a new operating mode of freight trains to keep the same safety as existing trains. The paper discusses the heterogeneity of the database of trains and provides examples of the classic application of the “relative approach”, highlighting the effect of train operation. Furthermore, it shows the application to DAC and radio-controlled Traction Units. Finally, it introduces the “Iterative Proportional” algorithm to generate a freight train from an existing one just by changing the hauled mass of each wagon. This algorithm is helpful when the “relative approach” is applied to trainsets having articulated wagons and running with a similar braking regime.

Variable-speed drive with series-excited motors in dynamic braking mode

Variable-speed DC drives with series-excited motors are widely used in the mining industry, transport and lifting equipment. The purpose of the study is to determine the dynamic characteristics of a variable direct current (DC) drive with a series-excited motor in the dynamic braking mode. In the article, there have been developed schematic diagrams of the power section that ensure stable braking of a variable-speed electric drive with a series-excited motor. The requirements for the braking mode have been developed. The studies have been carried out for a saturated and unsaturated magnetic circuit of an electric motor. The scientific novelty of the work consists in determining the zone of stable operation of the dynamic braking mode. As a result, there has been proposed technical implementation of the power section of a variable-speed electric drive with a series-excited motor that ensures stable braking. A special place in the study is the development of two models of an electric motor with subsequent excitation taking into account the saturation of the magnetic circuit - mathematical and simulation. Thus, the article has not only theoretical but also visual and practical significance in the context of already conducted studies on the subject. Options for the technical implementation of the braking regime were also considered in the course of the sequential implementation of the planned stages of the study.

MINIMIZATION OF ELECTRICAL CONSUMPTION OF A FREQUENCY-REGULATION INDUCTION MOTOR WITH A FAN LOAD IN START-BRAKING REGIMES

Purpuse. To minimize the total power consumption in start-braking regimes by a three-phase squirrel-cage frequency-regulated induction motor, loaded a centrifugal fan (or smoke exhauster), and also to obtain analytical dependencies for calculating the optimal durations of acceleration and deceleration times, corresponding to minimizing the total energy consumption of this motor in start-braking regimes with the indicated type of load. Metodology. Based on the methods of calculus of variations and numerical solution of non-linear differential equations, the quasi-optimal type of trajectories of speed change (tachograms) of the motor with the considered load in start-braking regimes is determined. Using the methods of mathematical analysis and similarity, the acceleration and deceleration times of an induction motor with a fan load were optimized for different (linear, parabolic and quasi-optimal) types of tachograms. Using the method of computer simulation, the energy consumption in the start-braking regimes of an induction motor with the indicated load for these types of tachograms was quantified. Results. Refined analytical dependencies are obtained for calculating the consumed active power and energy in start-braking regimes by a frequency-regulated induction motor with a fan load for the mentioned various types of tachograms. Analytical optimization of the consumption of active energy of this motor in start-braking regimes has been carried out. The change at the optimal durations for the starting-braking regimes and the corresponding it’s total energy consumption of the motor with varying the maximum value of the motor speed in these regimes has been researched. A quantitative assessment of transient electromechanical and energy processes in the considered motor with a fan load has been carried out. For this motor, as applied to the non-regenerative version of the static frequency converter, a scalar automatic control system is proposed, by means of which the motor accelerates with a constant rotor flux linkage with a given (linear, parabolic or quasi-optimal) speed trajectory and brakes on freewheel. The expected annual saving of active energy by an induction motor, loaded with a smoke exhauster, in starting and braking regimes, achieved by optimizing the form of the tachograms and the duration of the acceleration and deceleration times, is determined. Originality. Analytical dependencies are obtained for calculating the optimal durations of the acceleration and deceleration times of an induction motor with a fan load, corresponding to minimizing the energy consumption of this motor in start-braking regimes. The "U"-shaped form of dependences of the total energy, consumed during acceleration (or the total generated energy during braking) of the induction motor in function the duration of the deceleration (or braking) times is established. An analytical dependence is obtained for changing the speed of a motor loaded by a fan or a smoke exhauster during the freewheel braking regime, and an analytical expression is proposed for determining the duration of the indicated braking time. Practical value. On the example of an induction motor loaded by a smoke exhauster, the possibility of saving the total energy consumption in start-braking regimes was identified: from 77 to 90 % – due to the use of the proposed quasi-optimal tachogram and the use of practically realizable optimal acceleration and deceleration times, and also in the amount of 10 % – through the transition from freewheel braking to regenerative braking. Figures 6, tables 6, references 22.

Voltage Unbalance, Power Factor and Losses Optimization in Electrified Railways Using an Electronic Balancer

Unbalanced currents, low power factor and high losses contribute to increasing the bill infrastructure managers must pay to the TSO/DSO operator that supplies electric energy to the railway system. Additionally, if regenerative energy coming from braking regimes is not allowed to be injected into the grid or even is penalized when it occurs, then the optimization of those parameters must be pursued. One of the possible measures that can be taken to counteract those phenomena is the installation of electronic balancers in heavy loaded substations in order to optimize the interface to the three-phase electric grid. This paper shows the benefit of such use taking examples from real conditions and realistic simulations assumed equivalent to field measurements.

MINIMIZATION OF ELECTRIC CONSUMPTION BY A FREQUENCY-REGULATED INDUCTION MOTOR IN START-BRAKING REGIMES

Purpuse. To minimize the total energy consumption in start-braking regimes of a three-phase frequency-regulated induction motor loaded with a constant static moment, as well as to take into account the effect of iron power losses of this motor on electrical losses of power and energy in its stator winding. Metodology. Based on the established similarity of mathematical dependences for calculating the electrical component of power losses in the stator winding of this motor, caused by the influence of iron power losses of the motor or the application of an additional fictitious static moment to it, the analytical dependences were refined to determine the total power and energy consumed by the motor in steady-state and start-braking regimes. Using the methods of calculus of variations and simulation, the form of energy-saving tachograms was determined, which ensure, in start-braking regimes, the minimization of the total power consumption of this motor, loaded with a constant static torque. Results. Analytical calculated dependencies are proposed for determining the energy consumption in the start-braking regimes of a frequency-regulated squirrel-cage induction motor loaded with a constant static moment, for various types of trajectories of speed change. Analytical dependencies are obtained, by means of which a quantitative assessment of the influence of iron power losses of the investigated motor on the values of the stator current modulus and electrical power and energy losses in its stator winding is carried out under steady-state and start-braking regimes. With regard to the constant load of this motor, the minimization of the active energy consumed by it in the start and braking regimes has been performed. For start-braking regimes with the proposed quasi-optimal and known types of tachograms, the optimal durations of acceleration and deceleration times, at which the consumption of active energy by the induction motor is minimal. Originality. The "U"-shaped form of dependences of the total consumed energy by the frequency-regulated induction motor on the durations of the acceleration and deceleration times has been established. For start-braking regimes, the minimization of the total energy consumed by this motor was carried out and quantified, achieved through the use of energy-saving tachograms and optimal durations of acceleration and deceleration times. Practical value. For start and braking regimes, a quantitative assessment of transient electromechanical and energy processes in a frequency-regulated short-circuited induction motor for driving vertical slab rolls was carried out and the expected annual saving of energy consumed by this motor in these regimes, achieved from the use of the proposed energy-saving tachograms, was determined. Figures 4, tables 5, references 19.

Self-Regeneration Effect of Three-Way Catalysts during Thermal Aging Procedure

One of the most important features of the three-way catalysts is their long-term stability. However, quite often, promising catalytic compositions with excellent activity become deactivated after a relatively short period of exploitation due to various reasons. Therefore, a study on the onboard regeneration of the deactivated three-way catalysts remains its actuality. The present work is mainly focused on the self-regeneration effect of the rhodium-containing component. Aging of the catalysts in the standard and model engine braking regimes revealed the difference in the catalytic performance. Deactivated rhodium species turned to the active state as a result of rapid cooling in air flow from 1200 to 600 °C. The regenerated catalyst shows improved activity towards NOx reduction and, therefore, widened operation window, which indicates higher accessibility of the rhodium species. X-ray diffraction analysis of the aged catalysts does not reveal any noticeable phase changes. Contrary, significant changes in the Rh oxidation state were registered by X-ray photoelectron spectroscopy. The observed effect opens new horizons for the development of the onboard purification systems with prolonged exploitation lifetime.

Study of the braking regime of rolling stock mining suspended monorail taking into account clearances in the coupling

Introduction. Currently, mine suspended monorails are becoming more common in coal mines for auxiliary cargo and people transportation. Compared to ground transport, monorail has significant differences, which does not allow to fully use the previously obtained results of braking modes studies. Research aims to establish regularities in the processes that occur during the mine suspended monorail road rolling stock braking mode, taking into account clearances in the couplings. Methodology. To substantiate the parameters and designs of brake and coupling devices of a mine suspended monorail, a mathematical model of rolling stock movement along the monorail has been developed. Results. Dependencies are established that describe the process of rolling stock braking on a monorail. Motion parameters for different values of stiffness, damping and clearances in the couplers are analyzed. It is established that the gaps in rolling stock coupling influence the value of undercarriage and suspension units longitudinal vibrations amplitudes. Conclusions. A mathematical model of rolling stock movement is developed with allowance for clearances in the coupling making it possible to simulate mine suspended monorail braking mode.

Increase of energy efficiency of electrically driven drilling installations by valorising the braking regime of the draw works upon descending the pipe line

The paper provides a method and, at the same time, a solution to increase the yield of electrically driven drilling machines by efficiently implementing the technological processes specific to hydrocarbon exploratory drill. It is known that one of these technological processes refers to the execution of deep drill wells (2000-10000 m) by using diamond system drilling installed on the top of a drill pipes driven by a draw works in repeated ascending – descending marches. If, upon ascending such columns, the primary energy is consumed, upon descending in the drilling process, a large amount of potential energy of the soil is lost for many of the drilling machines. This paper presents a method and a solution to use such potential energy in the braking process irrespective of the type of electrical drilling machines.

Tolerable longitudinal forces for freight trains in tight S-curves using three-dimensional multi-body simulations

With the need for increasing length of freight trains, the longitudinal train dynamics and its influence on the running safety become a key issue. Longitudinal train dynamics is a complex issue with contributions from both the vehicle and the operating conditions such as infrastructure design, braking regimes, etc. Standards such as the UIC Code 530-2 and EN-15839 detail the procedure for on-track propelling tests that should be conducted to determine the running safety of a single wagon. Also, it only considers a single S-curve and specifies neighbouring wagons and buffers. Hence, the resulting longitudinal train dynamics would not be able to judge the effects of various heterogeneities in the train formation such as the adjacent wagons, buffer types, carbody torsional stiffnesses, curvatures, etc. Here, there is a potential of using three-dimensional multi-body simulations to develop a methodology to judge the running safety of a train with regard to its longitudinal dynamic behaviour, subjected to various heterogeneities. In this study, a tool based on three-dimensional multi-body simulations has been developed to provide longitudinal compressive force limits and tolerable longitudinal compressive force for wagon combinations passing through S-curves of varying curvatures, and the sensitivities of the various heterogeneities present in the train are assessed. The methodology is applied to open wagons of the ‘Falns’ type on tight S-curves by calculating the corresponding tolerable longitudinal compressive force, and the effect of various parameters on the same is discussed.

Numerical model for distributors of railway vehicles equipped with composite blocks

The paper describes the main features of a new numerical model of distributor for railway vehicles equipped with type K composite blocks, available in the TrainDy software. The composite brake blocks (CBB) type K guarantee better braking performance and quieter operation than traditional cast iron blocks (P10). Railway wagons with this type of shoes have different braking systems compared to wagons with traditional shoes, since their performance changes, for example, depending on the load carried by the wagon and the type of braking regime. The paper shows a series of tests comparing the numerical results provided by the new module with the experimental data. In this work, the parameters of the numerical model of the distributor are automatically calculated, by using the Mathworks "Global Optimization toolbox" for comparison between numerical and experimental data, provided by Faiveley Transport (Wabtec group) during the revision process of Leaflet UIC 421. The Frechet distance, which allows evaluating the degree of similarity of two curves, is the basis for the comparison. This approach allows identifying, on a rational and numerical basis, the parameters of the distributor, without having to use the support of an expert user.

Modeling and simulation of charging and braking regimes of AC/AC powertrain of HEV vehicle

The paper deals with modeling and simulation of chosen operational modes of HEV vehicle with direct AC/AC transfer and five-phase IM traction motors. Such configuration yields smaller voltage drops com-pared with the serial AC/DC/AC converter and five-phase machines offer some inherent advantages over their three-phase counterparts. The advantages include reduced electromagnetic torque pulsation and also noise characteristics of the five-phase drives are better when compared with the three-phase ones. Charging and braking regimes were chosen as possible operational modes for modeling and analyses. The result of the simulation. carried out with using of Matlab/Simulink are given in the paper.

Mathematical Modeling of a Linear-Induction Motor Based on Detailed Equivalent Circuits

Electric drives based on traction linear-induction motors are used in industry and city transport. The main advantages of this electric drive are unrestricted acceleration and vehicle climbing angles, as well as ecological cleanliness. The development of high-speed design and analysis software tools for linear electric motors is thus becoming quite timely. The use of the finite-element method for solving field problems in a three-dimensional setting and dynamic vehicle-operation regimes is time-consuming. It is proposed to use a detailed magnetic equivalent circuit of a linear-induction-motor longitudinal section with the introduction of the Bolton coefficient to correct for the transverse-edge effect in a solid secondary element. Model features based on multilayer magnetic equivalent circuits are shown, and the effect of the number of layers on the designed motor-traction force is evaluated. When selecting an appropriate pole pitch-to motor gap ratio, a two-level equivalent circuit turns out to be suitable. The secondary element is represented in the model as a set of rectangular rods connected in parallel. The influence of the calculation method of the secondary rods’ motional EMF on the motor-traction-force accuracy is shown. The greatest error is observed in a low-slip region (when the motor passes into a generative braking regime) and the simplest spatial derivative of the magnetic flux. When the derivative calculation formula becomes more complicated, the indicated error sharply decreases. Another way to reduce the calculation error of the motional EMF in the secondary element circuit is to increase the number of these circuits by decreasing the width of the elementary rod. The prominence of the detailed magnetic equivalent-circuit method and convenience of online viewing should be noted.

STUDY OF ALLOWED BRAKING MODE WHEN CHANGING THE SPEED OF DISSOLUTION OF THE COMPOSITIONS

Purpose. The aim of the work is to study the configuration of the region of permissible braking regimes for сuts when the dissolution rate of the compositions changes and its effect on the separation conditions. Methodology. The research was carried out using the methods of mathematical modeling of dairy processes. Results. The article investigates the effect of composition dissolution rates on the configuration and the area of the regions of permissible exit сuts from the braking positions. To assess the quality of the sorting process, the risk of non-separating the сuts on the dividing arrows is used. With the increase in the dissolution rate, the risk of non-separating the hooks increases, and the area of the permissible withdrawal rates of the trailing brakes decreases. The initial rate of dissolution affects mainly only the value of the interval between the сuts at the top of the hump, its influence on the conditions of the aim control of the speed of rolling off the trains is insignificant. To increase the area of the permissible speed range it is possible to change the limitations and conditions of rolling – to shorten the range of rolling off the traps – to limit it by docking the father for the last column of the last switch. To increase the area of the area and to help reduce the risks of non-separation, it is advisable to install retarders at the second braking position, which have a high permissible entry speed on them. Scientific novelty. As a result of the performed studies, the dependence of the change in the permissible inhibition regimes of the detachment on its speed at the top of the slide is obtained, which makes it possible to simplify the evaluation of the effect of the dissolution rate on the value of the intervals on the separation elements. Practical significance. The results of the research can be used to develop recommendations to the mountain operators, duty on the sorting hump coaster and shunting dispatchers.

RESEARCH REGARDING THE DYNAMIC BEHAVIOUR OF AUTOMATIC TOOL FEEDING SYSTEMS FOR DIFFERENT TRANSITORY REGIMES

The total machining time for a part produced on machining centers is influenced, besides the actual machining time, by the auxiliary times which include the automatic changing of the tools. In order to increase the productivity of machining centers, the research presented in this paper has focused on enhancing the movement speed of an automatic tool feeding system. Increasing the movement speed of the mechanism`s components has led to the appearance of unwanted side effects, such as shocks and vibrations. In order to minimize these effects, we have proposed and tested a new solution to adjust the braking regime.

A Study of a Modernized Controlled Electrical Complex for the Production of Bulk Nonwoven Fabric

A compound electromechanical system for control of the self-weight of a carding machine is investigated. A functional diagram of the modernized system for control of the self-weight of a carding apparatus that assures a continuous regime of forming a blanket is developed. Requirements imposed on the electrical drives that assure a given intensity of the start-up and braking regimes as well as correction and matching of the linear velocities of fibrous product are formulated.

Discovery and modelling of a flattening of the positive cyclotron line/luminosity relation in GX 304−1 with RXTE

The Rossi X-ray Timing Explorer (RXTE) observed four outbursts of the accreting X-ray binary transient source, GX 304−1 in 2010 and 2011. We present results of detailed 3–100 keV spectral analysis of 69 separate observations, and report a positive correlation between cyclotron line parameters, as well as other spectral parameters, with power-law flux. The cyclotron line energy, width and depth versus flux, and thus luminosity, correlations show a flattening of the relationships with increasing luminosity, which are well described by quasi-spherical or disc accretion that yield the surface magnetic field to be ∼5 × 10^(12) Gauss. Since HEXTE (High Energy X-ray Timing Experiment) cluster A was fixed aligned with the Proportional Counter Array field of view and cluster B was fixed viewing a background region 1°.5 off of the source direction during these observations near the end of the RXTE mission, the cluster A background was estimated from cluster B events using HEXTEBACKEST. This made possible the detection of the ∼55 keV cyclotron line and an accurate measurement of the continuum. Correlations of all spectral parameters with the primary 2–10 keV power-law flux reveal it to be the primary driver of the spectral shape. The accretion is found to be in the collisionless shock braking regime.

Discovery and modelling of a flattening of the positive cyclotron line/luminosity relation in GX 304−1 withRXTE

The RXTE observed four outbursts of the accreting X-ray binary transient source, GX 304-1 in 2010 and 2011. We present results of detailed 3-100 keV spectral analysis of 69 separate observations, and report a positive correlation between cyclotron line parameters, as well as other spectral parameters, with power law flux. The cyclotron line energy, width and depth versus flux, and thus luminosity, correlations show a flattening of the relationships with increasing luminosity, which are well described by quasi-spherical or disk accretion that yield the surface magnetic field to be ~60 keV. Since HEXTE cluster A was fixed aligned with the PCA field of view and cluster B was fixed viewing a background region 1.5 degrees off of the source direction during these observations near the end of the RXTE mission, the cluster A background was estimated from cluster B events using HEXTEBACKEST. This made possible the detection of the ~55 keV cyclotron line and an accurate measurement of the continuum. Correlations of all spectral parameters with the primary 2-10 keV power law flux reveal it to be the primary driver of the spectral shape. The accretion is found to be in the collisionless shock braking regime.

Modelling and simulation of regeneration in AC traction propulsion system of electrified railway

This paper presents a robust model and its simulation to investigate the performance of an AC propulsion system in a rail vehicle for directly returning the regenerative braking power to the feeder substation of an AC traction network. This direct returning method can be an efficient approach for energy recovery if the regenerative braking is reliably applied. However, it is shown that this method can cause undesired voltage fluctuations if the regenerative braking regime or braking location of the rail vehicle change. The load torque on the traction motor (TM) is precisely modelled when pure electrical braking is applied. Different states of the direct torque controlled inverter are modelled when the TM regenerates. A circuit model for the utility grid, load impedances and the traction network is developed to evaluate the network receptivity against the regenerated power. The dynamics of the electromagnetic torque and the fluctuations of the DC-link voltage are investigated for two operational conditions: changes on the regenerative braking regime and changes on the rail vehicle braking location. The results justify how the DC-link voltage dramatically fluctuates with variations of the rail vehicle's operation conditions, whereas the electromagnetic torque is maintained on optimum rates.

Parameter estimation of squirrel‐cage motors with parasitic torques in the torque–slip curve

This paper studies parasitic torques in steady-state torque–slip curves of squirrel-cage induction motors. The curves of nine motors (small, medium and large size units), three of which were measured in the range s = 2 to 0, are analysed. The torque–slip curves of eight of these nine motors differ significantly from the smooth curves predicted by the classical single- and double-cage models: a torque dip at large slips in the motoring regime and a notable torque increase in the braking regime occur. As parasitic torques have been traditionally associated with space harmonics, two single-cage chain models (which consider the space harmonics) are tested to fit the measured torque and current of the three measured motors: one neglects the skin effect, leading to the wrong torque prediction, whereas the other (the chain model proposed in the early 60s in the literature) considers the skin effect, leading to an accurate torque prediction.

Sustainability Aspects of Energy Conversion in Modern High-Speed Trains with Traction Induction Motors

Some aspects are illustrated of energy conversion processes during the operation of electric railway vehicles with traction induction motors, in order to support transport systems’ sustainability. Increasing efforts are being expended to enhance the sustainability of transportation technologies and systems. Since electric drive systems are used with variable voltage variable frequency (VVVF) inverters and traction induction motors, these machines with appropriate controls can realize both traction and electric braking regimes for electric traction vehicles. In line with this idea, this paper addresses the operation sustainability of electric railway vehicles highlighting the chain of interactions among the main electric equipment on an electrically driven railway system supplied from an a.c. contact line: The contact line-side converter, the machine-side converter and the traction induction motor. The paper supports the findings that electric traction drive systems using induction motors fed by network-side converters and VVVF inverters enhance the sustainable operation of railway trains.