Damijan Miljavec - Academia.edu (original) (raw)
Papers by Damijan Miljavec
2012 15th International Power Electronics and Motion Control Conference (EPE/PEMC), 2012
ABSTRACT The paper deals with some mitigation techniques of parasitic phenomenon in modern electr... more ABSTRACT The paper deals with some mitigation techniques of parasitic phenomenon in modern electric motors supplied by inverters. These techniques are commonly divided into two groups, namely modifications of inverter and modification of motor. The shaft voltage was found as a source of electromagnetic interference. Investigated mitigation techniques applied on outer rotor permanent magnet motors were: increased distance between stator end-windings and disc, faraday shield between stator end-windings and the housing, grounded shaft and electrical insulation between the rotor and the shaft. Effectiveness of analyzed techniques was tested on 6.5kW and 10kW brushless direct current motor.
... Duan Maga1, Mykhaylo Zagirnyak2, Damijan Miljavec3 ... These losses manifest themselves in f... more ... Duan Maga1, Mykhaylo Zagirnyak2, Damijan Miljavec3 ... These losses manifest themselves in further heating of PM thus moving the temperature-dependant working characteristic of PM (second quadrant of the BH curve) towards the co-ordinate origin point. ...
COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, 2013
ABSTRACT Purpose ‐ The purpose of this paper is the investigation of eddy currents induced in the... more ABSTRACT Purpose ‐ The purpose of this paper is the investigation of eddy currents induced in the axial-flux permanent-magnet machine housing by the leakage flux and the introduction of permanent magnets in the steady-state AC finite-element analysis and coupling their effects with the transient thermal analysis. Design/methodology/approach ‐ The proposed approach is based on the finite-element method as well as on using the basic analytical equations. The approach was first applied in the magneto transient analyses. Because of the different physical transient-time constants, the steady-state AC analysis coupled with transient thermal should be used. Findings ‐ The permanent magnets in the steady-state AC analysis coupled with the transient thermal analysis can be simulated by coils with an imposed current of a frequency depending on the number of pole pairs and rotation speed. Using any of the electrically conductive materials for the axial-flux inner slotless stator permanent-magnet machine housing should be avoided. Originality/value ‐ The leakage flux induced by permanent magnets and spreading into the axial-flux permanent-machine housing is first defined by using the magneto-transient finite-element analysis and further used in the steady-state AC analysis coupled with the transient thermal analyses, all in 3D. Based on the results of these analyses, the temperature distribution in entire machine is calculated and compared with the measurement results.
Problems of application of instantaneous power theory theses to the analysis of electromagnetic a... more Problems of application of instantaneous power theory theses to the analysis of electromagnetic and energy processes in nonlinear ferromagnetic circuits at different degrees of its saturation have been considered. Results confirm the necessity to revise the conventional methods and approaches to analyze the nonlinear circuits in saturation conditions. Streszczenie. Rozważono problemy związane z teorią mocy chwilowej zastosowaną do analizy elektromagnetycznych i energetycznych procesów w nieliniowych obwodach ferromagnetycznych w różnym stopniu nasyconych. Wyniki analiz potwierdzają konieczność rewizji metod konwencjonalnych i podejść do analizy obwodów nieliniowych w stanie nasycenia. (Badania procesów energetycznych w obwodach zawierających żelazo w warunkach nasycenia) Keywords: magnetic saturation, magnetic material, energy processes, iron losses. Słowa kluczowe: nasycenie magnetyczne, materiał magnetyczny, process energetyczny, straty w żelazie Introduction Changes of the state ...
14th International Conference Mechatronika, 2011
ABSTRACT The work handles with dependency of variations in the rotor design on the performance of... more ABSTRACT The work handles with dependency of variations in the rotor design on the performance of a three phase synchronous-reluctance motor (SRM). Analytical geometry-dependant equations for the d- and q-axis SRM magnetizing inductances are derived. The finite element analyze was used to include the magnetic nonlinearities and saturation effects on SRM performance calculation. The use of genetic algorithms (GA) as global optimization procedure in generating and optimization of un-predetermined rotor shape is shown. Rotor materials used in this analyze have two characteristics: non-ferromagnetic and nonlinear ferromagnetic. Goal of un-predetermined rotor design optimization is to achieve maximum torque for a given rotor volume.
The aim of proposed paper is to present the magnetic field calculation in aerial toroidal and pol... more The aim of proposed paper is to present the magnetic field calculation in aerial toroidal and poloidal coil systems arrangement. The magnetic system is in principal very similar to the Tokamak configuration. The coil models have been done in 2-D axisymmetry and/or in 3-D, depending on geometric arrangement and excitation of coils. The finite element method (FEM) was used in all analyses. The calculation of 2-D and 3-D electromagnetic quantities were performed in magneto-static mode and also in magneto-transient mode coupled with external circuit. Poloidal coil arrangement and magnetic field calculation were performed in 2-D axisymmetry in magneto-static mode. Meanwhile, the toroidal coil system requires a 3-D geometric model description.
The aim of this paper is to present the optimization of outer rotor permanent magnet transverse f... more The aim of this paper is to present the optimization of outer rotor permanent magnet transverse flux motor (TFM) using design of experiments. The 3-D time-stepping finite-element analysis (FEA) is used to calculate electromagnetic torque regarding variation of TFM geometric parameters. Further, in 3-D time-stepping finite-element analysis the TFM model is coupled with an external three phase current source which was used as to present the switched-mode power converter with pulse width modulated voltage. The main objectives of TFM geometry optimization are maximization of nominal electromagnetic torque and minimization of torque pulsations. All two optimization targets should be realized in one TFM design.
Powder Metallurgy and Metal Ceramics, 2011
The powder sintering process is modeled. A mathematical model and a system to control the tempera... more The powder sintering process is modeled. A mathematical model and a system to control the temperature field in the sintering process are proposed. Soft-magnetic iron-based samples produced using the proposed control system are tested. The mechanical properties and structure of the material are analyzed to show that the plasticizer is uniformly distributed over the grain surface.
2016 10th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG), 2016
IET Electric Power Applications, 2016
2016 10th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG), 2016
Advances in Electrical and Electronic Engineering, Jun 28, 2011
Journal of Magnetism and Magnetic Materials, Mar 1, 2008
The Jiles-Atherton hysteresis model (J-A model) exhibits a certain unphysical behavior when magne... more The Jiles-Atherton hysteresis model (J-A model) exhibits a certain unphysical behavior when magnetic excitation reaches or reverses from the extremity of the hysteresis loop. Introducing a domain flexing function, coherent with the magnetic excitation level, improves accuracy of the J-A hysteresis model and at the same time prevents its unphysical behavior. Moreover, applying this function also improves representation of inner (lower excitation level) hysteresis loops. Implementation of magnetic excitation dependence in the domain flexing function adds a valuable parameter to the J-A original model on the way towards its further optimization. In the proposed hysteresis model, genetic algorithms are used in parameters optimization.
Journal of Technical Physics, 2002
Proceedings of the 16th International Conference on Mechatronics - Mechatronika 2014, 2014
The XIX International Conference on Electrical Machines - ICEM 2010, 2010
The article discusses the eddy current losses generated in a transformer tank walls and other ele... more The article discusses the eddy current losses generated in a transformer tank walls and other electrically conductive construction parts. The losses are related to the magnetic leakage fields. A time harmonic 3D finite element method is used to compute the magnetic leakage field in the case of nominal load condition of the power transformer. The indirect measuring procedure based on the short circuit method was carried out on many different power transformer designs to validate the simulation results.
Journal of Magnetism and Magnetic Materials, 2008
... ashape parameter,. αmain-field parameter,. kdomain wall moving constant and. cdomai... more ... ashape parameter,. αmain-field parameter,. kdomain wall moving constant and. cdomain flexing constant. The parameter δ has no physical meaning and equals +1 for dH/dt>0 and −1 otherwise. 2.1. Parameter optimization of the original JA hysteresis model. ...
Journal of Magnetism and Magnetic Materials, 2011
A new ferromagnetic hysteresis model for soft magnetic composite materials based on their specifi... more A new ferromagnetic hysteresis model for soft magnetic composite materials based on their specific properties is presented. The model relies on definition of new anhysteretic magnetization based on the Cauchy-Lorentz distribution describing the maximum energy state of magnetic moments in material. Specific properties of soft magnetic composite materials (SMC) such as the presence of the bonding material, different sizes and shapes of the Fe particles, level of homogeneity of the Fe particles at the end of the SMC product treatment, and achieved overall material density during compression, are incorporated in both the anhysteretic differential magnetization susceptibility and the irreversible differential magnetization susceptibility. Together they form the total differential magnetization susceptibility that defines the new ferromagnetic hysteresis model. Genetic algorithms are used to determine the optimal values of the proposed model parameters. The simulated results show good agreement with the measured results.
IEEE Transactions on Magnetics, 2000
ABSTRACT Permeance variation in the air gap of the permanent-magnet synchronous machine induces e... more ABSTRACT Permeance variation in the air gap of the permanent-magnet synchronous machine induces eddy-current losses in its permanent magnets even in the absence of stator currents. This paper proposes a new analytical approach to analyze these losses using the permeance-variation vector function introduced for the air-gap magnetic-flux density distribution to take into account the stator teeth. The Laplace equation is employed to derive the radial dependency of the stator slotting effect on the magnetic-flux density distribution. The induced eddy currents are further calculated by using Faraday's law. The analytical results are compared with the numerical ones based on the finite-element analysis. The paper offers a faster alternative to the numerically intensive calculations of eddy-current losses, and the method is especially useful in initial design optimization of the electric machine.
2012 15th International Power Electronics and Motion Control Conference (EPE/PEMC), 2012
ABSTRACT The paper deals with some mitigation techniques of parasitic phenomenon in modern electr... more ABSTRACT The paper deals with some mitigation techniques of parasitic phenomenon in modern electric motors supplied by inverters. These techniques are commonly divided into two groups, namely modifications of inverter and modification of motor. The shaft voltage was found as a source of electromagnetic interference. Investigated mitigation techniques applied on outer rotor permanent magnet motors were: increased distance between stator end-windings and disc, faraday shield between stator end-windings and the housing, grounded shaft and electrical insulation between the rotor and the shaft. Effectiveness of analyzed techniques was tested on 6.5kW and 10kW brushless direct current motor.
... Duan Maga1, Mykhaylo Zagirnyak2, Damijan Miljavec3 ... These losses manifest themselves in f... more ... Duan Maga1, Mykhaylo Zagirnyak2, Damijan Miljavec3 ... These losses manifest themselves in further heating of PM thus moving the temperature-dependant working characteristic of PM (second quadrant of the BH curve) towards the co-ordinate origin point. ...
COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, 2013
ABSTRACT Purpose ‐ The purpose of this paper is the investigation of eddy currents induced in the... more ABSTRACT Purpose ‐ The purpose of this paper is the investigation of eddy currents induced in the axial-flux permanent-magnet machine housing by the leakage flux and the introduction of permanent magnets in the steady-state AC finite-element analysis and coupling their effects with the transient thermal analysis. Design/methodology/approach ‐ The proposed approach is based on the finite-element method as well as on using the basic analytical equations. The approach was first applied in the magneto transient analyses. Because of the different physical transient-time constants, the steady-state AC analysis coupled with transient thermal should be used. Findings ‐ The permanent magnets in the steady-state AC analysis coupled with the transient thermal analysis can be simulated by coils with an imposed current of a frequency depending on the number of pole pairs and rotation speed. Using any of the electrically conductive materials for the axial-flux inner slotless stator permanent-magnet machine housing should be avoided. Originality/value ‐ The leakage flux induced by permanent magnets and spreading into the axial-flux permanent-machine housing is first defined by using the magneto-transient finite-element analysis and further used in the steady-state AC analysis coupled with the transient thermal analyses, all in 3D. Based on the results of these analyses, the temperature distribution in entire machine is calculated and compared with the measurement results.
Problems of application of instantaneous power theory theses to the analysis of electromagnetic a... more Problems of application of instantaneous power theory theses to the analysis of electromagnetic and energy processes in nonlinear ferromagnetic circuits at different degrees of its saturation have been considered. Results confirm the necessity to revise the conventional methods and approaches to analyze the nonlinear circuits in saturation conditions. Streszczenie. Rozważono problemy związane z teorią mocy chwilowej zastosowaną do analizy elektromagnetycznych i energetycznych procesów w nieliniowych obwodach ferromagnetycznych w różnym stopniu nasyconych. Wyniki analiz potwierdzają konieczność rewizji metod konwencjonalnych i podejść do analizy obwodów nieliniowych w stanie nasycenia. (Badania procesów energetycznych w obwodach zawierających żelazo w warunkach nasycenia) Keywords: magnetic saturation, magnetic material, energy processes, iron losses. Słowa kluczowe: nasycenie magnetyczne, materiał magnetyczny, process energetyczny, straty w żelazie Introduction Changes of the state ...
14th International Conference Mechatronika, 2011
ABSTRACT The work handles with dependency of variations in the rotor design on the performance of... more ABSTRACT The work handles with dependency of variations in the rotor design on the performance of a three phase synchronous-reluctance motor (SRM). Analytical geometry-dependant equations for the d- and q-axis SRM magnetizing inductances are derived. The finite element analyze was used to include the magnetic nonlinearities and saturation effects on SRM performance calculation. The use of genetic algorithms (GA) as global optimization procedure in generating and optimization of un-predetermined rotor shape is shown. Rotor materials used in this analyze have two characteristics: non-ferromagnetic and nonlinear ferromagnetic. Goal of un-predetermined rotor design optimization is to achieve maximum torque for a given rotor volume.
The aim of proposed paper is to present the magnetic field calculation in aerial toroidal and pol... more The aim of proposed paper is to present the magnetic field calculation in aerial toroidal and poloidal coil systems arrangement. The magnetic system is in principal very similar to the Tokamak configuration. The coil models have been done in 2-D axisymmetry and/or in 3-D, depending on geometric arrangement and excitation of coils. The finite element method (FEM) was used in all analyses. The calculation of 2-D and 3-D electromagnetic quantities were performed in magneto-static mode and also in magneto-transient mode coupled with external circuit. Poloidal coil arrangement and magnetic field calculation were performed in 2-D axisymmetry in magneto-static mode. Meanwhile, the toroidal coil system requires a 3-D geometric model description.
The aim of this paper is to present the optimization of outer rotor permanent magnet transverse f... more The aim of this paper is to present the optimization of outer rotor permanent magnet transverse flux motor (TFM) using design of experiments. The 3-D time-stepping finite-element analysis (FEA) is used to calculate electromagnetic torque regarding variation of TFM geometric parameters. Further, in 3-D time-stepping finite-element analysis the TFM model is coupled with an external three phase current source which was used as to present the switched-mode power converter with pulse width modulated voltage. The main objectives of TFM geometry optimization are maximization of nominal electromagnetic torque and minimization of torque pulsations. All two optimization targets should be realized in one TFM design.
Powder Metallurgy and Metal Ceramics, 2011
The powder sintering process is modeled. A mathematical model and a system to control the tempera... more The powder sintering process is modeled. A mathematical model and a system to control the temperature field in the sintering process are proposed. Soft-magnetic iron-based samples produced using the proposed control system are tested. The mechanical properties and structure of the material are analyzed to show that the plasticizer is uniformly distributed over the grain surface.
2016 10th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG), 2016
IET Electric Power Applications, 2016
2016 10th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG), 2016
Advances in Electrical and Electronic Engineering, Jun 28, 2011
Journal of Magnetism and Magnetic Materials, Mar 1, 2008
The Jiles-Atherton hysteresis model (J-A model) exhibits a certain unphysical behavior when magne... more The Jiles-Atherton hysteresis model (J-A model) exhibits a certain unphysical behavior when magnetic excitation reaches or reverses from the extremity of the hysteresis loop. Introducing a domain flexing function, coherent with the magnetic excitation level, improves accuracy of the J-A hysteresis model and at the same time prevents its unphysical behavior. Moreover, applying this function also improves representation of inner (lower excitation level) hysteresis loops. Implementation of magnetic excitation dependence in the domain flexing function adds a valuable parameter to the J-A original model on the way towards its further optimization. In the proposed hysteresis model, genetic algorithms are used in parameters optimization.
Journal of Technical Physics, 2002
Proceedings of the 16th International Conference on Mechatronics - Mechatronika 2014, 2014
The XIX International Conference on Electrical Machines - ICEM 2010, 2010
The article discusses the eddy current losses generated in a transformer tank walls and other ele... more The article discusses the eddy current losses generated in a transformer tank walls and other electrically conductive construction parts. The losses are related to the magnetic leakage fields. A time harmonic 3D finite element method is used to compute the magnetic leakage field in the case of nominal load condition of the power transformer. The indirect measuring procedure based on the short circuit method was carried out on many different power transformer designs to validate the simulation results.
Journal of Magnetism and Magnetic Materials, 2008
... ashape parameter,. αmain-field parameter,. kdomain wall moving constant and. cdomai... more ... ashape parameter,. αmain-field parameter,. kdomain wall moving constant and. cdomain flexing constant. The parameter δ has no physical meaning and equals +1 for dH/dt>0 and −1 otherwise. 2.1. Parameter optimization of the original JA hysteresis model. ...
Journal of Magnetism and Magnetic Materials, 2011
A new ferromagnetic hysteresis model for soft magnetic composite materials based on their specifi... more A new ferromagnetic hysteresis model for soft magnetic composite materials based on their specific properties is presented. The model relies on definition of new anhysteretic magnetization based on the Cauchy-Lorentz distribution describing the maximum energy state of magnetic moments in material. Specific properties of soft magnetic composite materials (SMC) such as the presence of the bonding material, different sizes and shapes of the Fe particles, level of homogeneity of the Fe particles at the end of the SMC product treatment, and achieved overall material density during compression, are incorporated in both the anhysteretic differential magnetization susceptibility and the irreversible differential magnetization susceptibility. Together they form the total differential magnetization susceptibility that defines the new ferromagnetic hysteresis model. Genetic algorithms are used to determine the optimal values of the proposed model parameters. The simulated results show good agreement with the measured results.
IEEE Transactions on Magnetics, 2000
ABSTRACT Permeance variation in the air gap of the permanent-magnet synchronous machine induces e... more ABSTRACT Permeance variation in the air gap of the permanent-magnet synchronous machine induces eddy-current losses in its permanent magnets even in the absence of stator currents. This paper proposes a new analytical approach to analyze these losses using the permeance-variation vector function introduced for the air-gap magnetic-flux density distribution to take into account the stator teeth. The Laplace equation is employed to derive the radial dependency of the stator slotting effect on the magnetic-flux density distribution. The induced eddy currents are further calculated by using Faraday's law. The analytical results are compared with the numerical ones based on the finite-element analysis. The paper offers a faster alternative to the numerically intensive calculations of eddy-current losses, and the method is especially useful in initial design optimization of the electric machine.