Reduction of the High Harmonics at the Electromagnetic Force and the Electromagnetic Torque in Synchronous Machines with Permanent Magnet (original) (raw)
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Investigation of winding MMF harmonic reduction methods in IPM machines equipped with FSCWs
International Transactions on Electrical Energy Systems, 2018
In this paper, implementation of fractional-slot concentrated windings (FSCWs) into an interior permanent magnet (IPM) machine, designed by using the same geometrical and operational specifications as Toyota Prius 2010 IPM machine, has been presented. In detail, the Toyota Prius's IPM equipped with integer-slot distributed windings has been considered as a reference machine. Then the geometry of the stator has been adequately modified in other five models to equip FSCWs and adopt different magnetomotive force (MMF) reduction methods. It has been validated that the FSCW technique causes a significant increase in the rotor losses due to increase in the rate of the total harmonic distortion of the MMF harmonics. To reduce the effect of these harmonics, different MMF harmonic reduction methods including phase-winding coils with different number of turns, multilayer winding with phase shifting, and stator with flux barriers have been investigated. To reveal the effectiveness of the investigated MMF harmonic reduction methods, the key thermal and electromagnetic performance characteristics including torque, torque ripple, power losses, and efficiency have been numerically calculated by finite element method and have eventually been compared.
Arranging coil winding circuits of synchronous permanent-magnet machines on rotor
International Journal of Power Electronics and Drive Systems(IJPEDS), 2023
Methodology of constructing coil winding electrical circuits for salient-pole stator of electrical permanent-magnet machines on the rotor is proposed, which is based on the required number of pole pairs (synchronous speed) and the number of phases. The methodology algorithm is based on determining the value of the number of stator teeth as the closest to the number of rotor poles number value, multiple of phase number, which provides a sufficient level of pitch coefficient and winding coefficient. The algorithm was tested by several examples of constructing synchronous machines winding circuits, known from electrical engineering theory and practice, including mass-produced ones. In all the examples, if the proposed methodology guidelines were formally and strictly followed, the correct circuit designs came out as a result. For high power motor pilot design, one and the same machine design variants were compared, having thirty six slots on stator, three-phase and nine-phase windings, synthesized according to the proposed algorithm for thirty two-pole rotor. Engine torque calculation with both circuit options performed by finite elements method showed the nine-phase winding developed torque advantage by 20%, due to less discretion of MMF slot distribution.
Analysis of a Brushless Wound Rotor Synchronous Machine Employing a Stator Harmonic Winding
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This study proposes a new topology for brushless operation of a wound rotor synchronous machine (WRSM) employing a stator harmonic winding. It is based on generating an additional six-pole magneto-motive force component without the use of an inverter. In this topology, six thyristor switches are used to create harmonic currents for brushless operation of the machine. The usage of stator harmonic winding has the advantage of configuring the winding for six poles or any other combination based on the output requirement. In the proposed topology, a six-pole winding arrangement is used to generate a six-pole air-gap flux component aimed at rotor excitation for brushless operation. On the rotor side, two windings, namely rotor harmonic winding (to intercept the air-gap harmonic flux) and field winding, along with a diode rectifier are mounted. 2-D finite element analyses and experiments were carried out to analyze the brushless operation of the WRSM.
International Journal of Power Electronics and Drive System (IJPEDS) , 2019
Permanent magnet synchronous motor (PMSM) is the most reliable and efficient machine that widely used in robotics and automation, industrial applications, electric vehicles, home appliances, aircraft and aerospace technology due to its high efficiency, good dynamic performance and high torque density. In this paper, the influence of various types of winding configuration and different magnetization patterns in the performance of a five-phase PMSM is investigated. Three types of magnetization patterns such as radial magnetization (RM), parallel magnetization (PaM), and multisegmented Halbach magnetization (SH) are applied to the five-phase 10slot/4-pole PMSM during open-circuit and on-load conditions. A 2D finite element method (FEM) is intensively used in this investigation to model and predict the electromagnetic characteristics and performance of the PMSM. The detailed results from the finite-element analysis (FEA) on the cogging torque, induced back-emf, airgap flux density and electromagnetic torque are analysed. The induced back-emf of the machine is computed further into its harmonic distortions. Additionally, the skewing method for minimization of cogging torque of PMSM is proposed. From the results, it is observed that the five-phase, 10-slot/4-pole PMSM with double layer distributed winding and parallel magnetization gives the best machine performance.
Proceedings of the Institution of Electrical Engineers, 1967
Real electrical machines differ from the conventional models of generalised theory primarily in three ways: they are magnetically nonlinear, windings produce m.m.f. harmonics in addition to the fundamental, and air-gap permeance harmonics higher than the second are significant. The practical effects of the latter two complications on terminal characteristics are discussed with particular reference to waveforms in a small but otherwise conventional synchronous machine. Axis transform methods are of little or no value in such situations, and two numerical techniques for direct solution of the machine equations are discussed. A Runge-Kutta computation establishes that high accuracy is obtained by consideration of a modest number of harmonics, so that a highly efficient procedure based on Newton-Raphson reduction is possible. In the case of the popular 3-wire star connection, the equations reduce to essentially the conventional d, qaxis equations plus an additional one giving the neutral potential. On the other hand, the 4-wire star and the mesh connections yield equations not in accord with the d, q equations, and significant time harmonics can result.
Study of winding method to reduce stray loss and stator core vibration of synchronous machine
2013 International Conference on Electrical Machines and Systems (ICEMS), 2013
The fractional slot windings are widely used in rotating machine in order to increase the flexibility of design and improve the voltage waveform. However, the MMF wave of fractional-slot windings are found to contain unique harmonic component, which are designated as even order space flux harmonics, fractional number flux harmonics ,or both. They may cause stray loss and stator core vibration. This paper proposes new winding methods "novel interspersed windings" and "expanded group windings" to reduce these harmonics. The advantages of two proposed windings are verified by using numerical analysis and measurement test of winding model.
Electrical and Magnetic Model Coupling of Permanent Magnet Machines Based on the Harmonic Analysis
A widely used method for the magnetic field calculation in permanent magnet (PM) machines is the harmonic modeling (HM) method. Despite its many advantages, the application of this method is limited to machines in which armature currents, as a source of the magnetic field, are known. Since most of the PM machines are supplied with three-phase voltages, any variation of parameters in the armature electric circuit could lead to the uncertainty in knowing the armature currents, and therefore, limit use of the HM method. In this paper, an approach for overcoming this limitation is presented, which enables the calculation of the magnetic field in the PM machines without a priori knowledge of the armature currents. Index Terms— Harmonic modeling (HM), high-speed machines, permanent magnet (PM) machines, rotor eddy currents.
IEEE Transactions on Industrial Electronics, 2012
This paper investigates a material-efficient axial pole pairing method for torque ripple reduction in a direct-drive outer-rotor surface-mounted permanent-magnet synchronous machine. The effects of the magnet pole arc width on the torque ripple characteristics of the machine are first established by both analytical and two-dimensional finite element approaches. Furthermore the effectiveness of the axial pole pairing technique in mitigating the machine cogging torque, back electromotive force harmonics and overall torque quality is comprehensively examined. Finally three-dimensional finite element analysis and experiments are carried out to validate the proposed approach, and the results show that axial pole pairing can be cost-efficiently implemented in terms of magnet material usage and assembly. Index Terms-Axial pole pairing, back electromotive force, cogging torque, direct drive, finite element analysis, fractional slot, magnet pole arc width, permanent magnet synchronous machine, torque ripple reduction. NOMENCLATURE A 2 nN Phase angle of the nN th harmonic of B 2 mag. p Magnet pole arc width ratio. pj Magnet pole arc width ratio of the j th magnet set. B ag Open-circuit air gap radial magnetic flux density. B mag Open-circuit air gap radial magnetic flux density without slot effect consideration. B n Peak value of the n th harmonic of B mag. B 2 nN Peak value of the nN th harmonic of B 2 mag. e Phase back electromotive force (EMF). e a , e b , e c Back EMFs of phase a, b, c. E 1 Peak value of the fundamental component of phase back EMF. E 6n±1 Peak value of the (6n±1) th harmonic of phase back EMF. i Magnet set number. i a , i b , i c Currents of phase a, b, c. I 1 Peak value of the fundamental component of phase current. Electrical angle by which current leads the back EMF. k wn Winding factor of the n th harmonic. l e Active axial length of the machine. l ej Active axial length of the j th magnet set. ag Relative permeance function in air gap with slot effect consideration. m Peak value of the m th harmonic of ag. 2 nN Peak value of the nN th harmonic of 2 ag. 0 Air permeability. N Least common multiple of 2p and p s. N s Number of turns in series of each phase winding. p Magnet pole pair number. p s Stator slot number.
Analytical Method for Magnetic Field Calculation in a Low-Speed Permanent-Magnet Harmonic Machine
IEEE Transactions on Energy Conversion, 2000
Magnetic-gearing effect has become increasingly attractive when designing direct-drive low-speed permanent-magnet machines. The machines derived from the magnetic-gearing effect can be termed as harmonic machines. Unlike the conventional types, harmonic machines rely on the field harmonics to achieve energy conversion and transmission. The detailed knowledge of the field distributions in the air gap is vitally important for predicting and optimizing its performance. In this paper, we present an analytical approach to calculate the magnetic field distribution in a low-speed permanent-magnet harmonic machine. A series-slot model which is composed of a group of partial differential equations concerning the scalar magnetic potential is built up. Then, the field solutions are obtained by using the method of separating variables and analyzing the field boundary conditions. Finally, the flux densities are derived from the scalar magnetic potentials. All the results agree well with those obtained from the finite element method.