IEEE International Electric Machines and Drives Conference, 2003. IEMDC'03., 2003
1 -The paper deals with the electromagnetic forces in induction machines when the rotor is perfor... more 1 -The paper deals with the electromagnetic forces in induction machines when the rotor is performing eccentric motion with respect to the stator. The studied eccentric motions of the rigid cage rotor are cylindrical circular whirling motion, symmetric conical whirling motion and the combination of these two basic modes of eccentric motions.
Page 1. Abstract Deformations in a cage-induction machine are investigated with simulations. Th... more Page 1. Abstract Deformations in a cage-induction machine are investigated with simulations. The contribution of the Maxwell stress in the air gap and coil regions of the machine on the deformation is studied by comparing ...
COMPEL International Journal of Computations and Mathematics in Electrical
Recent investigations on magnetic properties of Non-Oriented steel sheets enhance the comprehensi... more Recent investigations on magnetic properties of Non-Oriented steel sheets enhance the comprehension of the magnetic anisotropy behaviour of widely employed electrical sheets. Our investigation consists of developing an analytical model to consider these magnetic properties while modelling electromagnetic systems. From rotational measurements, the anhysteretic curves are interpolated in order to extract the magnetic energy density for different directions and amplitudes of the magnetic flux density. Furthermore, the analytical representation of this energy is suggested based on statistical distribution which aims to minimize the intrinsic energy of the material. Our model is validated by comparing measured and computed values of the magnetic field strength. Finally, it is implemented into a finite element method.
A method for determining the signatures of dynamic eccentricity in the airgap force distribution ... more A method for determining the signatures of dynamic eccentricity in the airgap force distribution and vibration pattern of induction machine is presented. The radial electromagnetic force distribution along the airgap, which is the main source of vibration, is calculated and developed into a double Fourier series in space and time. Finite element simulations of faulty and healthy machines are performed. They show that the electromagnetic force distribution is a sensible parameter to the changes in the machine condition. The computations show the existence of low frequency and low order force distributions, which can be used as identifiable signatures of the motor condition by measuring the corresponding low order vibration components. These findings are supported by vibration measurements and modal testing. The low frequency components offer an alternative way to the monitoring of slot passing frequencies, bringing new components that allow to discriminate between dynamic eccentricity and rotor mechanical unbalance. The method also revealed a non linear relationship between loading, stress waves and vibration during dynamic eccentricity.
... Figure 10 Difference in the electromagnetic torque between the cases of non-eccentric rotor a... more ... Figure 10 Difference in the electromagnetic torque between the cases of non-eccentric rotor and ... [10] DEBORTOLI MJ, SALON SJ, BUROW DW, SLAVIK CJ: 'Effects of rotor ... and parallel windings on induction machine behaviour: a study using finite element analysis', IEEE Trans. ...
This paper aims to investigate core losses in induction motors running under different loading co... more This paper aims to investigate core losses in induction motors running under different loading conditions. The investigation is conducted using 2-D finite-element methods incorporating two different core-loss models. The simplified model disregards the minor loops and skin effect in the lamination. The second approach solves the magneto-dynamic problem in the lamination taking hysteresis and viscosity effects into account. The simulation results show that the core losses increase significantly with loading and the effect of slot harmonics on the eddy-current loss and minor loops can be remarkable. The distribution of the fluxes change dramatically with loading, leading to an overall increase in the harmonic content and a general decrease in the amplitude of the fundamental flux components. Therefore, even though the fundamental flux components decrease by increasing the load, the core losses rise as a result of the increase in the flux distortions and higher harmonics.
This article introduces a magnetodynamic vector hysteresis model for predicting alternating and r... more This article introduces a magnetodynamic vector hysteresis model for predicting alternating and rotational iron losses. The model is based on the well-known Mayergoyz model, whereas the identification of the proposed model requires no further modification of the measured scalar data. The model can be used for a wide variety of frequencies, enhancing its generality and use. A 1D finite-element formulation
ABSTRACT The effect of rotor pole-shoe construction on the electromagnetic losses of a 12.5-MW fr... more ABSTRACT The effect of rotor pole-shoe construction on the electromagnetic losses of a 12.5-MW frequency-converter-fed wound-field synchronous motor is studied by numerical simulations. The simulations are done with the finite-element method including a dynamic model for the eddy-current, hysteresis, and excess losses in the core laminations. In the machine under examination, a reduction of 6.8% in the rated-load total electromagnetic losses was achieved merely by modifying the rotor pole-shoe shape and the damper-winding slots. Furthermore, a 15.4% reduction was achieved by removing the damper winding and changing the rotor lamination material to a 0.5-mm Fe–Si sheet instead of the original 2-mm steel sheet. Calorimetric measurements with a 150-kVA generator confirm the significant effect of the rotor lamination material under frequency-converter supply.
2013 International Conference on Electrical Machines and Systems (ICEMS), 2013
ABSTRACT In the numerical analysis of electrical machines, there exist various methods for the co... more ABSTRACT In the numerical analysis of electrical machines, there exist various methods for the computation of electromagnetic torque. Maxwell stress tensor method is the most commonly used for computing torque numerically. However, several other methods have been developed and are being used. In this paper, different numerical methods for torque computation in an electrical machine are reviewed and compared. A complementary method of torque computation, based on the power balance of the electrical machine is studied and used as a reference to assess the accuracy of other torque computation methods.
Temperature rise of the form-wound multi-conductor stator winding of a 1250-kW cage induction mot... more Temperature rise of the form-wound multi-conductor stator winding of a 1250-kW cage induction motor was analyzed. Eddy currents in the winding significantly affect the temperature rise. The eddy current was modeled using time-discretized finite-element analysis (FEA). The resistive losses in each of the bars obtained from the FEA are used as input for thermal modeling. The distance from the air gap to the topmost bar in the stator has a significant effect on the eddy-current loss as well as temperature rise in the winding. An acceptable distance for winding design was recommended. By using magnetic slot wedges the eddy-current losses can be reduced.
A directly coupled magneto-mechanical model is proposed for simulating the effect of the magnetos... more A directly coupled magneto-mechanical model is proposed for simulating the effect of the magnetostriction and electromagnetic stress in iron. The model is based on the general balance laws of electromagnetism, mechanics, and continuum thermodynamics. It is implemented in 2-D by using a conforming finite element method for the magnetic vector potential and the displacement field. The method is applied to two different types of induction machines.
This paper describes a rare-earth-transition metal alloy permanent-magnet (Nd 2 Fe 14 B) hysteret... more This paper describes a rare-earth-transition metal alloy permanent-magnet (Nd 2 Fe 14 B) hysteretic behavior model within finite-element analysis. The present work analyzes the demagnetization states of permanent magnets during fault conditions in a permanentmagnet synchronous motor and characterizes the ability of the motor to sustain the designed rated outputs after the fault conditions occur.
The effects of magnetic saturation on the radial magnetic force in induction machines when the ro... more The effects of magnetic saturation on the radial magnetic force in induction machines when the rotor is performing cylindrical circular whirling motion are studied in this paper. Impulse method in the finite element analysis is used to calculate the forces and the eccentricity harmonics from both, the air gap flux density and rotor currents. The forces are studied as a function of supply voltage in order to find out the effects of the saturation on them. The maximum radial force is found to be limited by saturation and saturation also couples the eccentricity harmonics together.
COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, 2003
There is an unbalanced magnetic pull between the rotor and stator of the cage induction motor whe... more There is an unbalanced magnetic pull between the rotor and stator of the cage induction motor when the rotor is not concentric with the stator. These forces depend on the position and motion of the centre point of the rotor. In this paper, the linearity of the forces in proportion to the rotor eccentricity is studied numerically using time-stepping finite
Interdependence of demagnetization, loading, and temperature rise in a permanent-magnet synchrono... more Interdependence of demagnetization, loading, and temperature rise in a permanent-magnet synchronous motor. IEEE Transactions on Magnetics, volume 46, number 3, pages 949-953.
IEEE International Electric Machines and Drives Conference, 2003. IEMDC'03., 2003
1 -The paper deals with the electromagnetic forces in induction machines when the rotor is perfor... more 1 -The paper deals with the electromagnetic forces in induction machines when the rotor is performing eccentric motion with respect to the stator. The studied eccentric motions of the rigid cage rotor are cylindrical circular whirling motion, symmetric conical whirling motion and the combination of these two basic modes of eccentric motions.
Page 1. Abstract Deformations in a cage-induction machine are investigated with simulations. Th... more Page 1. Abstract Deformations in a cage-induction machine are investigated with simulations. The contribution of the Maxwell stress in the air gap and coil regions of the machine on the deformation is studied by comparing ...
COMPEL International Journal of Computations and Mathematics in Electrical
Recent investigations on magnetic properties of Non-Oriented steel sheets enhance the comprehensi... more Recent investigations on magnetic properties of Non-Oriented steel sheets enhance the comprehension of the magnetic anisotropy behaviour of widely employed electrical sheets. Our investigation consists of developing an analytical model to consider these magnetic properties while modelling electromagnetic systems. From rotational measurements, the anhysteretic curves are interpolated in order to extract the magnetic energy density for different directions and amplitudes of the magnetic flux density. Furthermore, the analytical representation of this energy is suggested based on statistical distribution which aims to minimize the intrinsic energy of the material. Our model is validated by comparing measured and computed values of the magnetic field strength. Finally, it is implemented into a finite element method.
A method for determining the signatures of dynamic eccentricity in the airgap force distribution ... more A method for determining the signatures of dynamic eccentricity in the airgap force distribution and vibration pattern of induction machine is presented. The radial electromagnetic force distribution along the airgap, which is the main source of vibration, is calculated and developed into a double Fourier series in space and time. Finite element simulations of faulty and healthy machines are performed. They show that the electromagnetic force distribution is a sensible parameter to the changes in the machine condition. The computations show the existence of low frequency and low order force distributions, which can be used as identifiable signatures of the motor condition by measuring the corresponding low order vibration components. These findings are supported by vibration measurements and modal testing. The low frequency components offer an alternative way to the monitoring of slot passing frequencies, bringing new components that allow to discriminate between dynamic eccentricity and rotor mechanical unbalance. The method also revealed a non linear relationship between loading, stress waves and vibration during dynamic eccentricity.
... Figure 10 Difference in the electromagnetic torque between the cases of non-eccentric rotor a... more ... Figure 10 Difference in the electromagnetic torque between the cases of non-eccentric rotor and ... [10] DEBORTOLI MJ, SALON SJ, BUROW DW, SLAVIK CJ: 'Effects of rotor ... and parallel windings on induction machine behaviour: a study using finite element analysis', IEEE Trans. ...
This paper aims to investigate core losses in induction motors running under different loading co... more This paper aims to investigate core losses in induction motors running under different loading conditions. The investigation is conducted using 2-D finite-element methods incorporating two different core-loss models. The simplified model disregards the minor loops and skin effect in the lamination. The second approach solves the magneto-dynamic problem in the lamination taking hysteresis and viscosity effects into account. The simulation results show that the core losses increase significantly with loading and the effect of slot harmonics on the eddy-current loss and minor loops can be remarkable. The distribution of the fluxes change dramatically with loading, leading to an overall increase in the harmonic content and a general decrease in the amplitude of the fundamental flux components. Therefore, even though the fundamental flux components decrease by increasing the load, the core losses rise as a result of the increase in the flux distortions and higher harmonics.
This article introduces a magnetodynamic vector hysteresis model for predicting alternating and r... more This article introduces a magnetodynamic vector hysteresis model for predicting alternating and rotational iron losses. The model is based on the well-known Mayergoyz model, whereas the identification of the proposed model requires no further modification of the measured scalar data. The model can be used for a wide variety of frequencies, enhancing its generality and use. A 1D finite-element formulation
ABSTRACT The effect of rotor pole-shoe construction on the electromagnetic losses of a 12.5-MW fr... more ABSTRACT The effect of rotor pole-shoe construction on the electromagnetic losses of a 12.5-MW frequency-converter-fed wound-field synchronous motor is studied by numerical simulations. The simulations are done with the finite-element method including a dynamic model for the eddy-current, hysteresis, and excess losses in the core laminations. In the machine under examination, a reduction of 6.8% in the rated-load total electromagnetic losses was achieved merely by modifying the rotor pole-shoe shape and the damper-winding slots. Furthermore, a 15.4% reduction was achieved by removing the damper winding and changing the rotor lamination material to a 0.5-mm Fe–Si sheet instead of the original 2-mm steel sheet. Calorimetric measurements with a 150-kVA generator confirm the significant effect of the rotor lamination material under frequency-converter supply.
2013 International Conference on Electrical Machines and Systems (ICEMS), 2013
ABSTRACT In the numerical analysis of electrical machines, there exist various methods for the co... more ABSTRACT In the numerical analysis of electrical machines, there exist various methods for the computation of electromagnetic torque. Maxwell stress tensor method is the most commonly used for computing torque numerically. However, several other methods have been developed and are being used. In this paper, different numerical methods for torque computation in an electrical machine are reviewed and compared. A complementary method of torque computation, based on the power balance of the electrical machine is studied and used as a reference to assess the accuracy of other torque computation methods.
Temperature rise of the form-wound multi-conductor stator winding of a 1250-kW cage induction mot... more Temperature rise of the form-wound multi-conductor stator winding of a 1250-kW cage induction motor was analyzed. Eddy currents in the winding significantly affect the temperature rise. The eddy current was modeled using time-discretized finite-element analysis (FEA). The resistive losses in each of the bars obtained from the FEA are used as input for thermal modeling. The distance from the air gap to the topmost bar in the stator has a significant effect on the eddy-current loss as well as temperature rise in the winding. An acceptable distance for winding design was recommended. By using magnetic slot wedges the eddy-current losses can be reduced.
A directly coupled magneto-mechanical model is proposed for simulating the effect of the magnetos... more A directly coupled magneto-mechanical model is proposed for simulating the effect of the magnetostriction and electromagnetic stress in iron. The model is based on the general balance laws of electromagnetism, mechanics, and continuum thermodynamics. It is implemented in 2-D by using a conforming finite element method for the magnetic vector potential and the displacement field. The method is applied to two different types of induction machines.
This paper describes a rare-earth-transition metal alloy permanent-magnet (Nd 2 Fe 14 B) hysteret... more This paper describes a rare-earth-transition metal alloy permanent-magnet (Nd 2 Fe 14 B) hysteretic behavior model within finite-element analysis. The present work analyzes the demagnetization states of permanent magnets during fault conditions in a permanentmagnet synchronous motor and characterizes the ability of the motor to sustain the designed rated outputs after the fault conditions occur.
The effects of magnetic saturation on the radial magnetic force in induction machines when the ro... more The effects of magnetic saturation on the radial magnetic force in induction machines when the rotor is performing cylindrical circular whirling motion are studied in this paper. Impulse method in the finite element analysis is used to calculate the forces and the eccentricity harmonics from both, the air gap flux density and rotor currents. The forces are studied as a function of supply voltage in order to find out the effects of the saturation on them. The maximum radial force is found to be limited by saturation and saturation also couples the eccentricity harmonics together.
COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, 2003
There is an unbalanced magnetic pull between the rotor and stator of the cage induction motor whe... more There is an unbalanced magnetic pull between the rotor and stator of the cage induction motor when the rotor is not concentric with the stator. These forces depend on the position and motion of the centre point of the rotor. In this paper, the linearity of the forces in proportion to the rotor eccentricity is studied numerically using time-stepping finite
Interdependence of demagnetization, loading, and temperature rise in a permanent-magnet synchrono... more Interdependence of demagnetization, loading, and temperature rise in a permanent-magnet synchronous motor. IEEE Transactions on Magnetics, volume 46, number 3, pages 949-953.
Uploads
Papers by A. Arkkio