Iron loss analysis of interior permanent-magnet synchronous motors-variation of main loss factors due to driving condition
TL;DR: In this article, the authors investigated the iron loss of interior permanent magnet motors driven by PWM inverters from both results of the experiments and the finite-element analysis, and clarified that the largest component at low speed condition under maximum torque control, whereas the loss caused by the harmonic magnetomotive forces of the permanent magnet remarkably increase at high-speed condition under flux-weakening control.
Abstract: In this paper, the authors investigate the iron loss of interior permanent magnet motors driven by pulsewidth modulation (PWM) inverters from both results of the experiments and the finite-element analysis. In the analysis, the iron loss of the motor is decomposed into several components due to their origins, for instance, the fundamental field, carrier of the PWM inverter, slot ripples, and harmonic magnetomotive forces of the permanent magnet in order to clarify the main loss factors. The Fourier transformation and the finite-element method considering the carrier harmonics are applied to this calculation. The calculated iron loss is compared with the measurement at each driving condition. The measured and the calculated results agree well. It is clarified that the iron loss caused by the carrier of the PWM inverter is the largest component at low-speed condition under the maximum torque control, whereas the loss caused by the harmonic magnetomotive forces of the permanent magnet remarkably increase at high-speed condition under the flux-weakening control
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TL;DR: The research results indicate that the IPMSM with V-shape PMs is more satisfying with comprehensive consideration, and the back-electromotive force (EMF), flux leakage coefficient, average torque, torque ripple, cogging torque, power per unit volume, power factor, and flux-weakening ability are investigated.
Abstract: As a kind of traction device, interior permanent-magnet synchronous machines (IPMSMs) are widely used in modern electric vehicles. This paper performs a design and comparative study of IPMSMs with different rotor topologies (spoke-type PMs, tangential-type PMs, U-shape PMs, and V-shape PMs). The research results indicate that the IPMSM with V-shape PMs is more satisfying with comprehensive consideration. Furthermore, the IPMSM with V-shape PMs is investigated in detail. The influences of geometrical parameters (magnetic bridge and angle between the two V-shape PMs under each pole, etc.) on the performances of V-shape motor are evaluated based on finite-element method (FEM). For accurate research, the effects of saturation, cross-magnetization, and the change in PM flux linkage on d - and q -axis inductances are considered. The back-electromotive force (EMF), flux leakage coefficient, average torque, torque ripple, cogging torque, power per unit volume, power factor, and flux-weakening ability are investigated, respectively. The experimental results verify the validity and accuracy of the process presented in this paper.
373 citations
Additional excerpts
...The efficiency is calculated by [36], [37]...
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TL;DR: In this article, the authors investigated losses of interior permanent magnet motors driven by pulsewidth-modulated inverters using 3D finite element analysis, which can estimate the Eddy-current loss in the permanent magnet accurately.
Abstract: In this paper, we investigate losses of interior permanent-magnet motors driven by pulsewidth-modulated inverters using 3D finite-element analysis, which can estimate the Eddy-current loss in the permanent magnet accurately. The calculated losses are compared with the measured results and the theoretical solution to verify the validity of the analysis. The variation of the magnet Eddy-current loss due to the division of the magnet is also investigated. It is clarified that the Eddy-current loss in the permanent magnet is mainly produced by the carrier harmonics of the inverter and that the axial length of the divided magnet should be smaller than the skin depth of the eddy currents produced by the major harmonics for the loss reduction.
204 citations
Cites background or methods from "Iron loss analysis of interior perm..."
...The conductivity is only considered in the permanent-magnet region and neglected in the laminated-core region....
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...On the other hand, in the main calculation considering the carrier, the following armature-voltage equation is coupled with (1) and (2): va = voa + Raia = dΦa dt + Raia (3) where va and ia are the armature voltage and current, respectively, Ra is the armature coil resistance, and Φa is the flux…...
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TL;DR: In this article, a flux-intensifying permanent magnet type with low-coercive-force magnets is used in the design due to positive Id operation and reduced loaded Iq effects.
Abstract: This paper presents a design approach for interior permanent-magnet (IPM) machines with variable-flux characteristics using low-coercive-force magnets for improved efficiency and extended operating speed range. A flux-intensifying IPM type with is used in the design due to positive Id operation and reduced loaded Iq effects. Design considerations of machine structures and variable-flux machine attributes are discussed. In addition, leakage flux in a rotor is particularly designed to also obtain another flux-varying capability. Evaluation of the designed machine is provided by finite-element analysis simulations and experiments on a proof-of-principle machine. The designed machine shows benefits in increasing efficiency and speed range in a low-torque region when variable magnetization control of the low-coercive-force magnets or the design of the leakage flux proposed in this paper is implemented.
163 citations
Cites background from "Iron loss analysis of interior perm..."
...In addition, rotor design for variable leakage flux characteristics is also investigated to increase variable-flux controllability....
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TL;DR: Novel rotor designs of interior-permanent-magnet motors are developed in order to reduce harmonic iron losses at high rotational speeds under field-weakening control using an optimization method combined with an adaptive finite-element method.
Abstract: In this paper, we develop novel rotor designs of interior-permanent-magnet motors in order to reduce harmonic iron losses at high rotational speeds under field-weakening control. First, an optimization method, combined with an adaptive finite-element method, is applied to automatically determine the shapes of the magnets and rotor core. The optimized motor is manufactured to confirm the validity of the calculation. It is clarified that the iron loss of the optimized motor is reduced to nearly half of that of the conventional motor, without a significant decrease in maximum torque. Next, the contribution of each part of the rotor to the iron-loss reduction is analyzed by the experimental design method. Finally, several designs of the rotors are proposed from the viewpoints of manufacturing cost and performance.
147 citations
Cites background or methods from "Iron loss analysis of interior perm..."
...where ke and kh are obtained by the Epstein frame test of the core material [4]....
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...In addition, both the experimental and calculated results indicated that the difference in harmonics included in the armature current [4] of the conventional and optimized motors is small....
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...In particular, at high rotational speeds under field-weakening control, the harmonic magnetomotive forces of the permanent magnet often cause large harmonic iron losses at the stator [3], [4]....
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...The armature current is set as 200 A, and the rotational speed is maintained as 8000 min−1 to avoid the effect of heat and to measure the iron loss correctly [4]....
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...It is determined by the ratio of carrier frequency (10 kHz) to fundamental frequency (533 Hz at 8000 min−1) [4]....
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TL;DR: In this article, the effect of eddy-current loss reduction by the magnet segmentation in synchronous motors with concentrated windings is investigated, and the effect depends on the types of the rotors, for instance, interior and surface permanent magnet rotors.
Abstract: In this paper, we investigate the effect of eddy-current loss reduction by the magnet segmentation in synchronous motors with concentrated windings in order to understand appropriate segmentation methods. The loss-reduction effects in each harmonic eddy current in the magnets are analyzed by both the theoretical solution and the three-dimensional finite-element analysis with Fourier transformation. The basic experiments using magnet specimens are carried out in order to support the calculated results. It is clarified that the loss-reduction effect varies with the harmonic orders and that the effect depends on the types of the rotors, for instance, interior and surface permanent-magnet rotors.
132 citations
References
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TL;DR: In this article, the authors present a flux-weakening control algorithm for the interior permanent magnet (IPM) synchronous motor, which is compatible with extended-speed-range constant power operation by means of flux weakening control.
Abstract: The interior permanent magnet (IPM) synchronous motor is compatible with extended-speed-range constant-power operation by means of flux-weakening control. Flux weakening uses stator current components to counter the fixed-amplitude magnetic airgap flux generated by the rotor magnets, performing a role similar to field weakening in a separately excited dc motor. The nature of current regulator saturation caused by the finite inverter dc source voltage is described, marked by premature torque and power degradation at high speeds in the absence of flux-weakening control. This is followed by presentation of a new flux-weakening control algorithm developed as a modification of an established feedforward IPM torque control algorithm described previously in the literature. Attractive features of this new algorithm include smooth drive transitions into and out of the flux-weakening mode, fast response, as well as automatic adjustment to changes in the dc source voltage. Simulation and empirical test results from a 3-hp laboratory IPM motor drive are used to confirm the constant-power operating envelope achieved using the new flux-weakening control algorithm.
750 citations
"Iron loss analysis of interior perm..." refers background in this paper
...I. INTRODUCTION INTERIOR permanent-magnet motors driven by pulsewidth-modulation (PWM) inverters are widely applied to the industry....
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TL;DR: In this article, Park's model of salient pole synchronous machines was improved by adding a nonbilateral coupling between the direct and quadrature axis equivalent circuits, which is shown to improve the steady state model greatly.
Abstract: The usual uncoupled d - q model of salient pole synchronous machines (Park's model) may be insufficient for accurate modeling of buried magnet permanent magnet machines. The addition of a nonbilateral coupling between the direct and quadrature axis equivalent circuits is shown to improve the steady-state model greatly. The cross coupling reactance has important implications in improving operation in the constant horsepower mode. In particular, it is demonstrated that the cross coupling term acts to reduce the effective internal voltage so that some field weakening can be achieved. The results should be useful in permanent magnet machine design for variable speed drive applications.
231 citations
"Iron loss analysis of interior perm..." refers background in this paper
...I. INTRODUCTION INTERIOR permanent-magnet motors driven by pulsewidth-modulation (PWM) inverters are widely applied to the industry....
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TL;DR: In this paper, the stator iron loss of a brushless DC motor with due account of the operating condition of the drive system is predicted using finite element analysis, for which the instantaneous currents are derived from a dynamic simulation of a drive system.
Abstract: A procedure has been developed to predict the stator iron loss of a brushless DC motor with due account of the operating condition of the drive system. Finite-element analysis is used to obtain a series of instantaneous magnetostatic field distributions within a motor, for which the instantaneous currents are derived from a dynamic simulation of the drive system. Analysis of the temporal and spatial variation of the flux density distribution then enables localized iron loss densities to be determined. It is shown that the iron loss changes markedly with the operating condition. >
128 citations
TL;DR: A verification model of the surface permanent magnet (SPM) motor is manufactured and measured by the investigation committee of the IEE of Japan as discussed by the authors, and the effect of stress due to the insertion to aluminum case on magnetic characteristics can also be investigated by using the model.
Abstract: In order to examine estimation methods of iron losses of rotating machines, a verification model of the surface permanent magnet (SPM) motor is manufactured and measured by the investigation committee of the IEE of Japan. The effect of stress due to the insertion to aluminum case on magnetic characteristics can also be investigated by using the model. In this paper, features of the benchmark model are discussed, and some results of calculation and measurement are shown. Various kinds of methods for estimating iron losses due to distorted elliptical rotating flux are discussed. It is illustrated that the difference between results estimated using those methods and measured iron loss is within 10%.
128 citations
"Iron loss analysis of interior perm..." refers background in this paper
...Note that the reaction field caused by the eddy currents in the stator and the rotor is neglected in the calculation because it can be regarded as small compared with the main field produced by the armature current and magnet....
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...D) nonlinear time-stepping analysis is −∇ · ( 1 µ ∇Az ) = Ja + 1 µ0 ( ∂My ∂x − ∂Mx ∂y ) (1) where Az is the magnetic vector potential, µ is the permeability, Ja is the armature current density, and M is the magnetization of the permanent magnet....
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TL;DR: In this article, a method to estimate characteristics of interior permanent magnet motors considering effects of iron loss is introduced, where the equivalent circuit parameters including the iron loss resistance are calculated as functions of d-q axis currents by the finite-element method with the consideration of movement of the rotor.
Abstract: A method to estimate characteristics of interior permanent magnet motors considering effects of iron loss is introduced. The equivalent circuit parameters including the iron loss resistance are calculated as functions of d-q axis currents by the finite-element method with the consideration of movement of the rotor. The characteristics of the motor are calculated from the equivalent circuit. By using this procedure, we can calculate the torque and the efficiency of the motor considering the harmonic iron losses of both the stator and rotor at any operating conditions instantaneously after parameter calculation. The results of the calculated characteristics are compared with the experimental results to examine the validity.
111 citations
"Iron loss analysis of interior perm..." refers background in this paper
...Note that the reaction field caused by the eddy currents in the stator and the rotor is neglected in the calculation because it can be regarded as small compared with the main field produced by the armature current and magnet....
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...On the other hand, the iron loss of the motors, which is the sum of the eddy current and hysteresis losses of the stator and rotor core, often increase due the harmonic magnetic field in the motor....
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...D) nonlinear time-stepping analysis is −∇ · ( 1 µ ∇Az ) = Ja + 1 µ0 ( ∂My ∂x − ∂Mx ∂y ) (1) where Az is the magnetic vector potential, µ is the permeability, Ja is the armature current density, and M is the magnetization of the permanent magnet....
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