Impact of supply voltage variations on external magnetic field emitted by induction machines

2017 ◽  
Vol 36 (3) ◽  
pp. 692-701
Author(s):  
Mohamed Omar Younsi ◽  
Olivier Ninet ◽  
Fabrice Morganti ◽  
Jean-Philippe Lecointe ◽  
Farid Zidat ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Circuit ◽  
Supply Voltage ◽  
Induction Machines ◽  
Tangential Component ◽  
Content Type ◽  
Internal Fault ◽  
Torque Estimation ◽  
Numerical Finite Element

Purpose This paper aims to study the influence of supply voltage variations on the external magnetic field emitted by grid-powered induction machines (IMs). Design/methodology/approach Two models are developed in the paper to analyse, for different supply voltage values, the influence of the variations of the magnetizing voltage for which there is a link with the tangential component of the external flux. The first is an analytical model based on the IM single-phase-equivalent circuit with variable magnetizing reactance to take into account the saturation of the magnetic circuit. The second is a numerical finite element simulation to model the same phenomenon. Results of both models are analysed with experimental measures of the external flux. Findings The study shows that the amplitude of the external field strongly depends on supply voltage values. Research limitations/implications The investigation is mainly focused on the tangential component of the external magnetic field which is of high importance concerning the applicability of non-invasive methods of diagnosis, as electromagnetic torque estimation developed by the authors or internal fault determination. Originality/value The originality of the paper concerns the characterization of the external flux with the supply voltage for IMs. It is shown that the magnetic circuit radiates external flux differently with the load and with the supply voltage.

Effect of temperature on the MHD stagnation-point flow past an isothermal plate for a Boussinesquian Newtonian and micropolar fluid

2018 ◽  
Vol 28 (6) ◽  
pp. 1315-1334 ◽  
Author(s):  
Alessandra Borrelli ◽  
Giulia Giantesio ◽  
Maria Cristina Patria
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Stagnation Point ◽  
Micropolar Fluid ◽  
Stagnation Point Flow ◽  
Content Type ◽  
Environment Temperature ◽  
Uniform External Magnetic Field

Purpose This paper aims to analyze the steady two-dimensional stagnation-point flow of an electrically conducting Newtonian or micropolar fluid when the obstacle is uniformly heated. Design/methodology/approach The governing boundary layer equations are transformed into a system of ordinary differential equations using appropriate similarity transformations. Some analytical considerations about existence and uniqueness of the solution are obtained. The system is then solved numerically using the bvp4c function in MATLAB. Findings If the temperature of the obstacle Tw coincides with the environment temperature T0, then the motion reduces to the usual orthogonal stagnation-point flow; if Tw = T0, then it is necessary to include in the similarity function describing the velocity an oblique part due to the temperature. Also, the presence of a uniform external magnetic field orthogonal to the obstacle is examined. In all cases, the motion is reduced to a system of nonlinear ordinary differential equations with boundary conditions, whose solution is discussed numerically when the Prandtl and the Hartmann number varies. Originality/value The present results are original and new for the problem of magnetohydrodynamic mixed convection in the plane stagnation-point flow of a Newtonian or a micropolar fluid over a vertical flat plate. At infinity, the motion approaches the orthogonal stagnation-point flow of an inviscid fluid; the effect of an uniform external magnetic field is considered, and the obstacle has a uniform temperature.

Hybrid simulation approaches for induction machine calculation

2018 ◽  
Vol 37 (5) ◽  
pp. 1744-1754 ◽  
Author(s):  
Georg von Pfingsten ◽  
Martin Marco Nell ◽  
Kay Hameyer
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Hybrid Simulation ◽  
Induction Machines ◽  
Maximum Error ◽  
Magnetic Flux Density ◽  
Content Type ◽  
Loss Analysis ◽  
Rotor Flux ◽  
Simulation Time

Purpose Induction machines for traction applications are operated at working points of high ferromagnetic saturation. Depending on the working point, a broad spectrum of harmonic frequencies appears in the magnetic flux density of induction machines. Detailed loss analysis therefore requires local and temporal highly resolved nonlinear field computation. This loss analysis can be performed in the post processing of nonlinear transient finite element simulations of the magnetic circuit. However, it takes a large number of transient simulation time steps to build up the rotor flux of the machine. Design/methodology/approach In this paper, hybrid simulation approaches that couple static FEA, transient FEA and analytic formulations to significantly decrease the number of simulation time steps to calculate the magnetic field in steady state are discussed, analyzed and compared. Findings The proposed hybrid simulation approaches drastically decrease the simulation time by shortening the transient build-up of the rotor flux. Depending on the maximum error of the rotor flux linkage amplitude compared to the steady state value, a reduction of simulation time steps in the range of 55.5 to 98 per cent is found. Originality/value The presented hybrid simulation approaches allow efficient performing of the transient FE magnetic field simulations of induction machines operated as traction drives.

Effect of high frequency harmonic voltage on the performance of line start permanent magnet synchronous motor

2019 ◽  
Vol 38 (2) ◽  
pp. 777-792
Author(s):  
Hongbo Qiu ◽  
Kaiqiang Hu ◽  
Ran Yi ◽  
Wei Yanqi
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Supply Voltage ◽  
Permanent Magnet Synchronous Motor ◽  
Low Frequency ◽  
Space Harmonic ◽  
Content Type ◽  
Harmonic Voltage ◽  
High Frequency Harmonic ◽  
Frequency Harmonic

Purpose A large number of high-frequency harmonic voltages exist in the output voltage of the inverter, which will affect the performance of the motor. The purpose of this paper is to obtain the influence of high frequency harmonic voltage on the performance of the line start permanent magnet synchronous motor (LSPMSM) and reveal the mechanism of influence. The research results can provide help for the design of LSPMSM driven by inverter drives. Design/methodology/approach First, the actual output voltage data of the inverter is collected, and then the fundamental voltage and high frequency harmonic voltage data can be obtained by performing the fast Fourier transformation method on the voltage data. Second, the finite element model is established. During the finite element calculation, the obtained fundamental voltage and the main harmonic voltage components are used as the voltage source. To research the effect of high frequency harmonic voltage on the performance of motor, a reference group without high frequency harmonic voltage is set up, which is used to compare and analyze the effect of high-frequency harmonics on the performance of the motor. To verify the correctness of the model, a prototype based on the model parameters is manufactured, and then the back EMF experiment and load experiment are performed. The test data and calculation results are compared and analyzed. Findings The coupling relationship between high frequency time harmonic magnetic field and low frequency space harmonic magnetic field is obtained. The stator copper loss and rotor eddy-current loss are calculated and analyzed under normal supply voltage and abnormal supply voltage, and the influence mechanism is revealed Originality/value The coupling relationship between high frequency time harmonic magnetic field and low frequency space harmonic magnetic field is obtained. The sensitivity of the high frequency harmonic voltage to the stator copper loss and rotor eddy-current loss is obtained, and the mechanism of losses change is revealed.

Ferrofluid lubrication for ball bearings to avoid starvation

2020 ◽  
Vol 72 (10) ◽  
pp. 1227-1231
Author(s):  
Mancheng Xu ◽  
Guanghu Jin ◽  
Qingwen Dai ◽  
Wei Huang ◽  
Xiaolei Wang
Keyword(s):  
Magnetic Field ◽  
Service Life ◽  
Peer Review ◽  
Design Methodology ◽  
Ball Bearing ◽  
Magnetic Circuit ◽  
Ball Bearings ◽  
Rolling Bearings ◽  
Content Type ◽  
Circuit Structure

Purpose This paper aims to prevent oil starvation and improve the service life of the rolling bearings. Design/methodology/approach A thrust ball bearing with magnetic circuit structure is proposed for ferrofluid lubrication. With the aid of magnetic field, ferrofluid can be maintained in the contact area of rolling bodies to delay lubricant loss. Experiments are performed to ensure the validity of the designed bearing. Findings Compared with conventional lubricant, service life of the ferrofluid lubricated bearing can be prolonged under magnetic field. In addition, with a proper magnetic field distribution, lubricant starvation may be limited under the conditions of present experiments. Originality/value This work provides a method to control the starved lubrication of rolling bearings with restricted lubricant supply. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0132/

Two-fluid flow under the constraint of external magnetic field

2017 ◽  
Vol 27 (11) ◽  
pp. 2565-2581 ◽  
Author(s):  
Luca Marioni ◽  
Mehdi Khalloufi ◽  
Francois Bay ◽  
Elie Hachem
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Level Set ◽  
Degrees Of Freedom ◽  
Stokes Equations ◽  
Small Scale ◽  
Variational Multiscale Method ◽  
Time Step ◽  
Content Type ◽  
Induction Equation

Purpose This paper aims to develop a robust set of advanced numerical tools to simulate multiphase flows under the superimposition of external uniform magnetic fields. Design/methodology/approach The flow has been simulated in a fully Eulerian framework by a {\it variational multi-scale} method, which allows to take into account the small-scale turbulence without explicitly model it. The multi-fluid problem has been solved through the convectively re-initialized level-set method to robustly deal with high density and viscosity ratio between the phases and the surface tension has been modelled implicitly in the level-set framework. The interaction with the magnetic field has been modelled through the classic induction equation for 2D problems and the time step computation is based on the electromagnetic interaction to guarantee convergence of the method. Anisotropic mesh adaptation is then used to adapt the mesh to the main problem’s variables and to reach good accuracy with a small number of degrees of freedom. Finally, the variational multiscale method leads to a natural stabilization of the finite elements algorithm, preventing numerical spurious oscillations in the solution of Navier–Stokes equations (fluid mechanics) and the transport equation (level-set convection). Findings The methodology has been validated, and it is shown to produce accurate results also with a low number of degrees of freedom. The physical effect of the external magnetic field on the multiphase flow has been analysed. Originality/value The dam-break benchmark case has been extended to include magnetically constrained flows.

Influence of temperature and magnetic field on the oblique stagnation-point flow for a nanofluid past a vertical stretching/shrinking sheet

2018 ◽  
Vol 28 (12) ◽  
pp. 2874-2894 ◽  
Author(s):  
Alessandra Borrelli ◽  
Giulia Giantesio ◽  
Maria Cristina Patria ◽  
Natalia C. Roşca ◽  
Alin V. Roşca ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Stagnation Point ◽  
Design Methodology ◽  
Dual Solutions ◽  
Stagnation Point Flow ◽  
Shrinking Sheet ◽  
Content Type ◽  
Similarity Transformations ◽  
Stretching Or Shrinking Sheet

Purpose This paper aims to consider the influence of the temperature and of an external magnetic field on the steady oblique stagnation-point flow for a Boussinesquian nanofluid past a stretching or shrinking sheet. Design/methodology/approach The flow is reduced through similarity transformations to an ordinary boundary value problem, which is solved numerically in MATLAB using the bvp4c function. The behavior of the solution is discussed physically, and some analytical considerations concerning existence of the solution and the occurrence of dual solutions are drawn. Findings The study of the influence of an external magnetic field on the oblique stagnation-point flow of a Buongiorno's Boussinesquian nanofluid is carried out. The fluid clashes on a vertical stretching or shrinking sheet. Dual solutions appear for suitable values of the parameters. Originality/value The present results are new and original.

Calculation approach of reluctance in the magnetic circuit of transformer employed to convert into equivalent electric circuit

2018 ◽  
Vol 37 (5) ◽  
pp. 1668-1677 ◽  
Author(s):  
Yingying Wang ◽  
Jiansheng Yuan
Keyword(s):  
Magnetic Field ◽  
Single Phase ◽  
Magnetic Circuit ◽  
Electric Circuit ◽  
Inrush Current ◽  
Equivalent Electric Circuit ◽  
Content Type ◽  
Three Phase ◽  
Simulation Results ◽  
Peak Value

Purpose The theoretical method of converting the magnetic circuit into an electric circuit is mature, but the way to determine the inductances in the electric circuit is not reliable, especially for the core working in saturation status, and it is impossible to determine the inductances by the transformer terminal measurements, as the measurement information is not enough to determine a number of inductances. This paper aims to propose an approach of calculating the reluctances. Design/methodology/approach In this paper, an approach of calculating the reluctances is proposed based on the numerical simulation of magnetic field in transformer with different values of current excitation. The reluctance of a core segment or air region as a branch of magnetic circuit is obtained by the magnetic energy and magnetic flux. By this way, all the reluctances as function of flux can be determined, and then the inductances can be determined. The reluctances and equivalent electric circuit of three-phase integrative transformer is determined, and its validation is proved in the paper. Findings The single phase example shows that the proposed method has a good performances on analysis of the inrush current in deep saturation. The peak value of the inrush current derived from the proposed approach matches well with the results obtained by coupled circuit-FEM analysis, and the difference is about 4.8 per cent. For studies on dual models of single phase transformers, the leakage inductances have important effects on the peak value of the inrush current. The reluctances of three-phase transformer are calculated, and the equivalent circuit simulation results are slightly smaller than the coupled circuit-FEM simulation results. Originality/value Approach of calculating the reluctances based on the numerical simulation of magnetic field in transformer is proposed. The magnetic core and air space are divided into several segments, and the reluctance for each segment is calculated based on the energy in the region and the flux of the cross-sectional area. By applying various excitation currents, all the reluctances as function of flux can be determined, and then all the non-linear inductances including the non-linear leakage inductances are obtained. The proposed approach is reliable to determine a number of inductances in the dual electric circuit, especially for deep saturation status.

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