| 1. |
- Amlinger, Hanna, et al.
(author)
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Impact of PWM switching frequency on the radiated acoustic noise from a traction motor
- 2017
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In: 2017 20th International Conference on Electrical Machines and Systems, ICEMS 2017. - : Institute of Electrical and Electronics Engineers Inc.. - 9781538632468
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Conference paper (peer-reviewed)abstract
- The radiated acoustic noise from a traction motor at low speeds is dominated by the noise of electromagnetic origin. For a motor operated from pulse width modulated (PWM) converters, the switching frequency of the converter will have a large impact on the noise. The total harmonic distortion of the motor phase currents and thus also the exciting forces, will decrease with increasing switching frequency. Furthermore, changing the switching frequency will shift the frequencies of the exciting forces, hence have an influence on the coincidence with structural resonances of the motor. Tests have been performed on a traction motor and a decrease in sound pressure level with increasing switching frequency has been quantified and analyzed.
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| 2. |
- Amlinger, Hanna, et al.
(author)
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Operational deflection shapes of a PWM-fed traction motor
- 2016
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In: Conference Proceedings of the Society for Experimental Mechanics Series. - Cham : Springer. - 9783319300832 ; , s. 209-217
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Conference paper (peer-reviewed)abstract
- Operational deflection shapes of an asynchronous traction motor for railway applications are investigated. The radiated noise from the tractionmotor on a train is, especially at low speeds, dominated by noise generated by electromagnetic forces. The tested motor is fed by a pulse-width-modulated (PWM) frequency converter for which the voltage is modulated as a series of pulses that are switched with a certain frequency. In this case, PWM force lines can be expected to influence the radiated noise. Therefore, detailed knowledge about the frequencies and deflection shapes of vibrations generated by PWM forces is of great importance for understanding and controlling the radiated noise and its spectral content. Vibration levels are measured on the stator shield and the operational deflection shapes are studied for several PWM switching frequencies and motor speeds. The deflection shapes with the largest vibration levels are determined. These are then compared to the expected excitation resulting from the pure PWM force lines. Changing the switching frequency, will shift the frequencies of the exciting forces. An appropriate selection of the PWM switching frequency is therefore important for the resulting acoustic radiation from the motor.
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| 3. |
- Amlinger, Hanna
(author)
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Reduction of Audible Noise of a Traction Motor at PWM Operation
- 2018
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Licentiate thesis (other academic/artistic)abstract
- A dominating source for the radiated acoustic noise from a train at low speeds is the traction motor. This noise originates from electromagnetic forces acting on the structure resulting in vibrations on the surface and thus radiated noise. It is often perceived as annoying due to its tonal nature. To achieve a desirable acoustic behavior, and also to meet legal requirements, it is of great importance to thoroughly understand the generation of noise of electromagnetic origin in the motor and also to be able to control it to a low level.In this work, experimental tests have been performed on a traction motor operated from pulse width modulated (PWM) converter. A PWM converter outputs a quasi-sinusoidal voltage created from switched voltage pulses of different widths. The resulting main vibrations at PWM operation and their causes have been analyzed. It is concluded that an appropriate selection of the PWM switching frequency, that is the rate at which the voltage is switched, is a powerful tool to influence the noise of electromagnetic origin. Changing the switching frequency shifts the frequencies of the exciting electromagnetic forces. Further experimental investigations show that the trend is that the resulting sound power level decreases with increasing switching frequency and eventually the sound power level reaches an almost constant level. The underlying physical phenomena for the reduced sound power level is different for different frequency ranges. It is proposed that the traction motor, similar to a thin walled cylindrical structure, shows a constant vibration over force response above a certain frequency. This is investigated using numerical simulations of simplified models. Above this certain frequency, where the area of high modal density is dominating, the noise reducing effect of further increasing the switching frequency is limited.
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| 4. |
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| 5. |
- Andersson, Evert, et al.
(author)
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On the environmental performance of a high-speed train
- 2014
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In: International Journal of Rail transportation. - : Taylor & Francis Group. - 2324-8378 .- 2324-8386. ; 2:1, s. 59-66
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Journal article (peer-reviewed)abstract
- Environmental performance is one of the major considerations of future high-speed trains. Two main issues have been closely investigated in the Green Train programme, namely (1) energy use and (2) external noise. Analysis, development and testing in the Green Train programme have focused primarily on speeds up to 250 km/h, although the energy issues have also been studied at top speeds up to 320 km/h. The energy use is estimated for both long-distance trains with few stops and for fast regional services with relatively tight underway stops. These estimations result in an energy use of 46–62 Wh per passenger-km – or 30–40 Wh per seat-km – accounted as electricity taken from the public electric power grid. Improved aerodynamic performance, efficient space utilization, electric regenerative brakes, eco-driving advice and improved energy efficiency in the propulsion system make this possible. Trackside noise has also been analysed and tested in the programme. In order to maintain the same or lower noise level at 250 km/h as at lower speeds with current trains, a number of measures are proposed. These include bogie skirts, wheel absorbers and careful aerodynamic design of the front area and of all protruding objects. In sensitive residential areas, further improvement may be achieved with rail absorbers or low trackside screens.
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| 6. |
- Botling, Fredrik, et al.
(author)
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Combined Experimental and Analytical Vibro-Acoustic Model of an Electrical Motor
- 2016
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Other publication (other academic/artistic)abstract
- A vibro-acoustic modal model of a traction motor forrailway applications is presented based on an experimentalmodal analysis of the system. Noise requirements forrailway traction motors are getting more and moredemanding as part of the overall levels of new rolling stock.It is therefore of great interest to understand and predict thevibro-acoustic behaviour of electromagnetic noisegenerated by traction motors. The modal parameters arederived from an experimental modal analysis. The primarysource for the radiated sound of the tested traction motor isthe radial deflections of the stator shield. The modalparameters for the radial deflections are implemented in areduced order modal model in a state space format usingMatlab/Simulink. Only the structural modes that have amatch in both the frequency and the spatial domain withthe electromagnetic excitation force will cause animportant vibro-acoustic response. This makes it possibleto create an accurate and efficient reduced order modalmodel with only a fraction of the total number of structuralmodes. The simulation results from the modal model arecompared to measured levels of vibration and acousticmeasurements of the motor.
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| 7. |
- Botling, Fredrik
(author)
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Modelling and simulation of electromagnetic audible noise generated by traction motors
- 2016
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Licentiate thesis (other academic/artistic)abstract
- An annoying tonal noise is produced by modern electrical trains duringacceleration and deceleration. This noise is caused by electromagneticforces generating structural vibrations, especially from the traction motors.The electromagnetic noise is dominant at low train speeds and affectsboth the passengers on the train and on platforms, as well as peopleliving near the track. The focus on this issue has increased the last years,both regarding legislation, contractual requirements and also because ofexpectations from citizens and travelers. To be able to design low noiseelectric drive systems, a thorough understanding of the cause and thepossibility to predict the electromagnetic noise is needed. This thesisdescribes the modelling and simulation of an complete multi-physicsreal-time environment for prediction and analysis of the electromagneticnoise. The simulation results are validated against measurements of thestructural vibration and acoustic response of a real traction motor fed bya power converter running in the entire operational range.
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| 8. |
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| 9. |
- Botling, Fredrik, et al.
(author)
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Modelling framework for electromagnetic noise generation from traction motors
- 2016
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In: Journal of Notes on Numerical Fluid Mechanics and Multidisciplinary Design. - Cham : Springer Nature. - 1612-2909.
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Journal article (other academic/artistic)abstract
- Electromagnetic noise from traction motors is often the single most dominating noise source from trains at low trainspeeds. This electromagnetic noise is tonal and annoying for both passengers on the train and people near the track andon the platform. A thorough understanding of the cause and the prediction of the electromagnetic noise is needed to beable to design low noise components. This paper describes a real time multi-physics modelling framework forprediction of the audible electromagnetic noise generated by traction motors fed by power converters. The cause of theelectromagnetic noise is influenced by several different domains. To be able to fully simulate the final acoustic sound,all these domains needs to be modelled and simulated together. Simulations of some relevant operational conditionsfor acoustic noise generation has been performed and discussed. Some of these results have been compared to realmeasurements from a converter fed traction motor.
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| 10. |
- Botling, Fredrik, et al.
(author)
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Vibro-acoustic modal model of a traction motor for railway applications
- 2016
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In: Conference Proceedings of the Society for Experimental Mechanics Series. - Cham : Springer. - 9783319300832 ; , s. 197-208
-
Conference paper (peer-reviewed)abstract
- A vibro-acoustic modal model of a traction motor for railway applications is presented based on an experimental modal analysis of the system. Noise requirements for railway traction motors are getting more and more demanding as part of the overall levels of new rolling stock. It is therefore of great interest to understand and predict the vibro-acoustic behaviour of electromagnetic noise generated by traction motors. The modal parameters are derived from an experimental modal analysis. The primary source for the radiated sound of the tested traction motor is the radial deflections of the stator shield. The modal parameters for the radial deflections are implemented in a reduced order modal model in a state space format using Matlab/Simulink. Only the structural modes that have a match in both the frequency and the spatial domain with the excited electromagnetic force will cause important vibro-acoustic response. This makes it possible to create an accurate and efficient reduced order modal model with only a fraction of the total number of structural modes. The simulation results from the modal model are compared to measurements of operational deflection shapes and acoustic measurements of the motor.
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| 11. |
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| 12. |
- Leth, Siv, et al.
(author)
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A primary noise source in oxygen cutting
- 1988
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In: Inter-noise 88. - Poughkeepsie, N.Y. : SFA. ; , s. 715-718
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Conference paper (peer-reviewed)abstract
- Oxygen cutting of steel is a process of oxidation at raised temperatures. A very high massrate of oxygen is needed. The exit velocity of the oxygen is often supersonic. Convergent-divergent nozzles of Laval type are used. The cutting gives rise to very high noise levels. Levels of up to 110 dB(A) at 1 meter distance from two burners have been measured at a steel plant. The central supersonic oxygen jet is surrounded by a burning coaxial jet. The noise source is a combination of the jet and the combustion. A reduction of the noise at the source is attempted by redesigning the nozzles used. This paper discusses the theoretical background and the experimental results relating to the redesigned nozzle.
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| 13. |
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| 14. |
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| 15. |
- Venkataraman, Siddharth, et al.
(author)
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An approach to improve railway rolling noise calculations in CNOSSOS-EU: Refinement and validation using TWINS calculations
- 2021
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Conference paper (other academic/artistic)abstract
- The reliability of CNOSSOS-EU methodology for evaluation of railway noise is dependent on the quality ofinput values that define the system’s excitation and transfer functions. Currently available input values are limited and of insufficient quality, resulting in large errors in noise level calculations. A case study wherein railway rolling noise mitigation measures are evaluated with both CNOSSOS-EU and TWINS show deviations in resulting sound power levels of up to 8 dB(A) and 4 dB(A) for absolute and relative measures respectively. An approach to process TWINS output to extract transfer functions as input values for CNOSSOS-EU is described in this paper. The updated CNOSSOS-EU calculations correspond well with those of TWINS, with the maximum deviation limited to 1.5 dB(A) and 1 dB(A), respectively, for the same absolute and relative measures.
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| 16. |
- Venkataraman, Siddharth, et al.
(author)
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Improving strategic noise mapping of railway noise in Europe : Refining CNOSSOS-EU calculations using TWINS
- 2022
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 839, s. 156216-
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Journal article (peer-reviewed)abstract
- The Environmental Noise Directive (2002/49/EC) requires all European Union Member States to produce strategic noise maps using a common assessment methodology: CNOSSOS-EU. The reliability of CNOSSOS-EU railway noise evaluation is dependent on the input vehicle and track transfer functions. The CNOSSOS-EU default database contains the currently available choices for these transfer functions. However, these available transfer functions are limited and of insufficient quality, resulting in large errors in noise level calculations. An approach is presented, introducing an established analytical railway rolling noise calculation technique (TWINS), to extract more reliable and specific transfer functions. A case study consisting of railway rolling noise mitigation measures is defined and used as the basis for extracting and testing these transfer functions. The extracted transfer functions reduce the average deviation between CNOSSOS-EU and reference calculations using TWINS from6.1 dB(A) to 0.8 dB(A) in absolute sound power levels, and from 1.2 db(A) to 0.3 dB(A) in estimates of noise reduction potential for the defined mitigation measures. Application of this approach shows potential to improve the quality and depth of the existing CNOSSOS-EU default database. This may lead to more reliable estimations of railway noise in the strategic noise maps and the subsequent assessment of its harmful effects.
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