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This article proposes a hybrid evaluation method of electromagnetic force and vibration for electrical machines considering high-frequency current harmonics caused by the inverter. First, the permeance and armature magnetomotive force (MMF) is calculated based on the virtual MMF and the slot matrix. Then, the air-gap flux density and electromagnetic force construction process under arbitrary current is thoroughly studied. The vibration transfer function is obtained by utilizing the modal analysis and the modal test. Finally, the vibration can be calculated according to the modal superposition method. By applying this method to an interior permanent magnet machine, it can significantly reduce the computation efforts compared with the multiphysics procedure due to the extensive use of the finite-element method. In addition, the accuracy of this method is validated by conducting an experimental study. [ABSTRACT FROM AUTHOR]

In this article, the influence of the rotor position error generated by the resolver on the electromagnetic noise of permanent magnet synchronous motors (PMSMs) is analyzed. The motor noise is mainly caused by the electromagnetic force acting on the surface of the stator teeth or permanent magnets. First, the influence of the rotor position error on current harmonics is deduced theoretically. The spatial and temporal characteristics of the electromagnetic force are then analyzed. The results show that the rotor position error will introduce extra sideband frequency harmonics to the current and electromagnetic force. This will lead to more abundant noise harmonics. The field-oriented control model and the electromagnetic finite-element model are then established to simulate the influence of the rotor position error on current harmonics and electromagnetic force. Finally, a test is carried out to capture the phase current and noise spectrum. Both the simulation and test results are consistent with the theoretical analysis results. This study can give a reference to the source identification and optimization of acoustic performance for PMSMs in electric vehicles. [ABSTRACT FROM AUTHOR]

This article focuses on the electromagnetic vibration source and its reduction design in fractional-slot concentrated-windings (FSCWs) permanent magnet (PM) machines. First, the electromagnetic force and vibration characteristics of a 12-slot/10-pole FSCW PM machine are investigated. Then, four electromagnetic vibration sources are investigated and compared, in which the machine operating state is considered. The result shows that the electromagnetic force modulation and stator magnetomotive force (MMF) harmonics are the two sources that contribute most to the vibration underrated and heavy load condition, respectively. Afterward, two new designs to reduce the vibration caused by the electromagnetic force modulation and stator MMF harmonics are proposed, and the reduction principles are described in detail. Finally, the prototypes of the existing and proposed 12-slot/10-pole FSCW PM machines are manufactured. The tests are conducted to validate the theoretical analysis and proposed vibration reduction design. [ABSTRACT FROM AUTHOR]

In this article, we have presented a three-dimensional transient electromagnetic (EM) force calculation model of the electromagnetic rail launcher (EMRL), which could quickly calculate the transient EM force of the armature and the rail through combining the finite-element method with experiment and proposed the model of structural stiffness nonlinearity of EMRL. To study the interior ballistic characteristics of the EMRL, through the self-programming and the development of commercial finite-element software for the second time, the article presents the first time that an interior ballistic simulation model (IBSM) of the EMRL with EM and structural coupling considering the structural stiffness nonlinearity of EMRL. The correction function is proposed to improve the prediction accuracy of armature dynamic parameters by IBSM and the calculation errors of displacement of IBSM can be guaranteed not to exceed 1% compared with the test results of magnetic probes array. A strain test platform with a demodulation frequency of 8000 Hz was established to verify the IBSM's ability to calculate dynamic characteristics of the armature and the rail. After considering the structural stiffness nonlinearity of EMRL, the simulation accuracy of IBSM has been greatly improved compared with that of linearity. The experimental test results show that the IBSM is ease of application and, meanwhile, performs satisfactorily in terms of high accuracy and low computation. [ABSTRACT FROM AUTHOR]

This paper presents a detailed analysis of the electromagnetic force and vibration behavior of an axial flux permanent magnet synchronous machine (AFPMSM). First, the AFPMSM configuration and two types of dual three-phase winding are introduced. Subsequently, the electromagnetic force of the double-stator inner-rotor AFPMSM is investigated. Its spatial and temporal characteristics are derived analytically and validated through two-dimensional Fourier decomposition. A multiphysics model is established to calculate the vibration of the AFPMSM, which includes control, electromagnetic, structural, and vibration model. The accuracy of this multiphysics model is verified by the modal and vibration test. Furthermore, the vibration of the AFPMSM with three winding types considering current harmonics are calculated based on the multiphysics model. The vibration performance of the AFPMSM with three different winding types are compared and the mechanism of vibration is discussed. It was concluded that the novel detached winding could mitigate the vibration of dual three-phase AFPMSMs. Finally, the vibration test is carried out to validate the theoretical analysis and the experimental results agree well-with the simulation results. This paper provides an effective method for double-stator permanent magnet synchronous machine (PMSMs) to reduce vibration. [ABSTRACT FROM AUTHOR]

The permanent magnet synchronous motors (PMSMs) with space vector pulsewidth modulation (SVPWM) technique will inevitably introduce sideband current harmonic components around the carrier frequency. The armature reaction field caused by the sideband current interacts with the permanent magnet field, generating sideband electromagnetic force and resulting in high-frequency noise. This paper provides a comparative study of the sideband electromagnetic force in internal and external rotor PMSMs with SVPWM technique. First, the analytical model of the electromagnetic force in internal and external rotor PMSMs is established based on the Maxwell tensor method. The source, spatial order, and frequency of the electromagnetic force is obtained. Then, the spatial and temporal characteristics of the sideband force in internal and external rotor PMSMs with different pole and slot combinations are derived and investigated. The results show that the frequency characteristics of the zeroth order sideband force in internal and external rotor PMSMs introduced by SVPWM are identical. However, the frequency characteristics demonstrate significant differences for the nonzeroth order sideband force. Finally, the theoretical analysis is validated through the finite element and experimental results, respectively. This study is benefit for the source identification and reduction of high-frequency acoustic noise for PMSMs. [ABSTRACT FROM AUTHOR]

This paper focuses on the design and analysis of a novel material-efficient permanent-magnet (PM) shape for surface-mounted PM (SPM) motors used in automotive actuators. Most of such applications require smooth torque with minimum pulsation for an accurate position control. The proposed PM shape is designed to be sinusoidal and symmetrical in the axial direction for minimizing the amount of rare earth magnets as well as for providing balanced axial electromagnetic force, which turns out to obtain better sinusoidal electromotive force, less cogging torque, and, consequently, smooth electromagnetic torque. The contribution of the novel PM shape to motor characteristics is first estimated by 3-D finite-element method, and all of the simulation results are compared with those of SPM motors with two conventional arched PM shapes: one previously reported sinusoidal PM shape and one step skewed PM shape. Finally, some finite-element analysis results are confirmed by experimental results. [ABSTRACT FROM PUBLISHER]

In miniature magnetically levitated rotating machines, permanent magnet bearings are generally used for rotor levitation in the radial directions, while electromagnetic actuators are used for stabilization in the axial direction. Rotor radial oscillations are inevitable in this configuration because no controllable force is applicable in these directions. The oscillations become excessively large as the rotor is running at speeds near the rotor's resonant frequency. This paper presents an implementation and control scheme for an electromagnetic actuator for these machines. The proposed actuator can produce axial as well as radial forces on the rotor. The axial force is used for rotor axial direction control, while the radial force is used to assist in rotor resonance-related oscillation suppression. Theoretical analysis and experimental investigations of the proposed actuator control are performed. [ABSTRACT FROM AUTHOR]