Radial Electromagnetic Force Research Articles

Study on the Effect of Suspension Windings on the Electromagnetic Vibration and Noise of Ultra‐high‐Speed Bearingless Permanent Magnet Synchronous Motor for Air Compressor

The electromagnetic vibration and noise level of ultra‐high‐speed bearingless permanent magnet synchronous motor (UBPMSM) for air compressors used in the fuel‐cell vehicle (FCV) is an important evaluation. A 10 kW, 100 k r/min UBPMSM is adopted as the object of study in this research. The expression of radial electromagnetic force of UBPMSM is derived through theoretical analysis, and the order and frequency characteristics of radial electromagnetic force harmonics are summarized. Through the two‐dimensional (2D) Fourier decomposition of radial electromagnetic force by finite element analysis (FEA), the main sources of radial electromagnetic force causing the electromagnetic vibration and noise are studied. The correctness of the mathematical model is verified by FEA. In addition, the three‐dimensional (3D) finite element model of the motor is established to calculate the radial modal, natural frequency, and electromagnetic vibration and noise of UBPMSM. The research shows that the spatial order of radial electromagnetic force of UBPMSM is kN and kN ± 1 (N = GCD [2p, Z], k = 1, 2, 3, …), and the noise change of UBPMSM caused by the addition of suspension windings could be ignored compared with ordinary motor. It provides reference values for the design and optimization of UBPMSM. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Modeling and Analysis of Radial Electromagnetic Force and Vibration Characteristics Based on Deflection Dual-Stator Switched Reluctance Generator.

In this paper, a mechanical model of the deflection dual-stator switched reluctance generator (DDSRG) is developed, and the advantages of the dual-stator structure for the deflecting motion are analyzed. Secondly, the spatio-temporal and spatial distribution characteristics of the inhomogeneous electromagnetic force are derived analytically and further verified by fast Fourier transform (FFT).Thirdly, the spatial and temporal distributions of electromagnetic forces of DDSRG are calculated based on finite element software, and the distributions of electromagnetic forces under different motion states are analyzed. By combining the analysis of modal analysis and harmonic response analysis, the free mode and vibration response acceleration variation laws of the internal and external stator are determined. The results show that the order of electromagnetic forces on the stator at rated speed is mainly 8 times the fundamental frequency, and the modal vibration order is more violent in the order of 2–7. Finally, the experimental platform of DDSRG is built, and the vibration characteristics are tested to verify the validity and accuracy of the proposed simulation results.

Simulation Analysis on Electromagnetic Vibration and Noise of Novel Mechatronic-Electro-Hydraulic Coupler

The mechatronic-electro-hydraulic coupler (MEHC) is a novel type of multisource coupling power device which integrates a traditional permanent magnet synchronous motor with a swash plate axial piston pump/motor to realize the mutual conversion of electrical energy, mechanical energy, and hydraulic energy. In order to improve the MEHC’s noise, vibration, and harshness performance, an electromagnetic vibration and noise simulation analysis was performed with a six-pole 36-slot motor as the research object. Firstly, the spatial order and frequency of the radial electromagnetic force were deduced by an analytical method. Subsequently, the electromagnetic field was simulated, and the electromagnetic force was extracted via a fast Fourier transform using Ansys/Maxwell software for the numerical verification. Thereafter, the harmonic response module coupled the electromagnetic field with the structural field for the harmonic response analysis. Ultimately, the research results were imported into the harmonic acoustics module for a noise simulation analysis and two different-shape magnetic isolation bridges optimization schemes were proposed. The results suggested that both optimisation solutions could effectively reduce motor vibration and noise. Scheme one reduced the maximum noise by about 6.5% and scheme two by 10.4%. The analysis process and conclusion provide a theoretical basis for the vibration and noise analysis of permanent magnet synchronous motors with different integer slots.

Effect of unbalancing mass placement in hydropower generators with floating rotor rim

Dynamic models for hydropower generators treat the rotor part as a rigid body; however, many studies have shown the opposite. The electromagnetic force distribution of deformed rotors is uneven, creating Unbalance Magnetic Pull, causing high forces on generator components leading to a risk of fatigue, therefore shortening the life of machines. Unbalancing masses can worsen the asymmetries of the rotor, which would further increase the effect of the electromagnetic interactions. This paper evaluates the rotor response using different unbalancing masses at the rotor and at the poles to quantify their impact in displacements and exciting frequencies. The model employed in this paper is based on the equation of motion derived using Lagrange equations in both co-rotating and stationary frames of reference, considering the effects of Centrifugal loads, Coriolis, and magnetization of poles. Different unbalancing mass placements affect different variables; extra weights in the poles contribute predominantly to the deformation of the rim, while the unbalance in the shaft affects the position of the shaft; a combination of placements was also studied. The simulations were performed and compared with and without radial electromagnetic forces, showing how the presence of magnetized poles further deforms the shapes of the rotor.

Electromagnetic Characteristics Analysis of Quadrupole Compound Orbital Electromagnetic Launcher with Different Configurations

During the operation of the Quadrupole Compound Orbital electromagnetic launcher, the current is easy to gather in the armature and the rail contact surface. Serious turn and arc ablation can occur, causing damage to the rail and the armature and affecting the life of the launcher. To better solve the thermal ablation problem of the armature and the rail, three different configurations of the rail and the armature are established, and the current density, magnetic field distribution and electromagnetic force of the rail and the armature are compared and analyzed using the finite element method, and the effect of concave and convex values of the armature rail on current distribution and electromagnetic force is discussed. The results show that the planar armature can effectively reduce the maximum current density and mitigate thermal damage. The concave elliptical rail produces the largest electromagnetic thrust and the smallest radial electromagnetic force, and the armature is more stable during firing. The maximum current density and magnetic field strength are negatively correlated with the concave and convex values; the electromagnetic thrust applied to the concave elliptical armature is negatively correlated with the concave value, while the electromagnetic force applied to the convex elliptical armature is positively correlated with the convex value.

Research on vibration and noise of magnetic pole eccentricity tangential magnetizing parallel structure hybrid excitation synchronous motor

In order to research vibration and noise of TMPS-HESM. The Magnetic pole eccentricity TMPS-HESM is established. The order and frequency characteristics of radial electromagnetic force are discussed The vibration and noise coupling model is built by ANSYS Workbench simulation platform. The vibration response and noise variation are discussed. The results show that magnetic pole eccentricity can effectively reduce air gap flux density harmonic content, and third harmonic is significantly decreased. The excitation current will significantly affect the harmonic (8,2f1), (16,4f1), (0,12f1) components of radial electromagnetic force of magnetic pole eccentricity TMPS-HESM. Although the (0,12f1) component is not the same order of magnitude as other components, it will still worsen the vibration noise of the motor.

An Improved Model for Five-Phase Induction Motor Based on Magnetic Noise Reduction Part I: Slot Opening Width

Based on the winding function considering the slot width and the air-gap permeability considering the slot opening width, the main radial electromagnetic force wave expressions of the induction motor are determined. The electromagnetic force-vibration prediction model of the induction motor is established. The natural frequency and acoustic radiation model of a finite-length cylindrical shell with two ends clamped is deduced. On this basis, an improved magnetic noise prediction model of cage induction motor is improved, which can calculate the combined effects of electromagnetic force on the axis and circumferential modes of the stator system. Aiming at two different noise reduction targets, an optimization method is proposed to reduce the overall electromagnetic noise of the motor without sacrificing efficiency and output torque. The feasibility of the model for electromagnetic noise prediction is verified by finite element simulation and experiments. For a 30/26 slots five-phase induction motor, low-noise analysis and optimization schemes of the opening width for two different targets are given. The results show that the larger slot opening scheme can also result in less magnetic noise for the right selection, which is contrary to the common design rule that recommends minimizing slot opening to reduce magnetic noise.

Magnetic Field and Radial Force Analysis of Six-Phase Rotary Machine

Six-phase permanent magnet synchronous machine and the control system are also widely used in industry, precision instruments and aerospace. However, most PMSMs employ magnet patterns either in alternatively radial magnetization or Halbach array, which may constrain the performance improvement in a certain degree. Therefore, a novel six-phase trapezoidal Halbach magnet array (THMA) is proposed in this paper. Six-phase permanent magnet synchronous machines (PMSMs) can reduce the harmonic components of magnetic flux in air gap, and decrease the iron loss and electromagnetic vibration caused by harmonic torque. Thus, it helps to improve the working efficiency and depress the torque ripple of the electrical machine. Dual three-phase windings are employed for the stator design to further improve the power density and reliability of the machine. Six-phase vector model of the machine is built based on dual dq control. It can minimize the electric coupling, magnetic coupling and thermal coupling. The radial electromagnetic force of the machine under load or no load is extracted, then the harmonic decomposition of the radial electromagnetic force for the spatial with time Fourier decomposition is carried out to obtain the force amplitude of different orders which is conducive to analyze the vibration characteristics of the machine.

Influence of excitation current on electromagnetic vibration and noise of rotor magnetic shunt hybrid excitation synchronous motor

To explore the influence of the excitation current in the rotor magnetic shunt hybrid excitation synchronous motor (HESM) on the vibration and noise of the motor, the finite element analysis of the hybrid excitation motor was carried out by using ANSYS Workbench software and noise sources for analysis. Firstly, air-gap flux density at different excitation currents and density vector diagrams are studied. Secondly, radial electromagnetic force’s order and frequency characteristics under different excitation currents are discussed. Finally, the modal analysis of the stator of the motor is carried out. The motor’s vibration response and noise variation under different excitation current conditions are summarized. The simulation analysis and experimental verify that the motor’s vibration response and noise increase obviously when the excitation current is significant, and the vibration acceleration of different orders increases.

Coupling Analysis of Electromagnetic Vibration and Noise of FeCo-Based Permanent-Magnet Synchronous Motor

Addressing the problem of the vibration and noise of a permanent-magnet synchronous motor (PMSM), this paper optimizes the structure of a permanent-magnet motor rotator, introduces the electromagnetic-structure-acoustic coupling calculation model, and optimizes the motor rotator to reduce the vibration and noise of a permanent-magnet motor. Using the theory of Maxwell’s stress equation, the radial electromagnetic force on the stator teeth of the permanent-magnet motor is deduced and analyzed, and the correctness of the analysis calculation is verified by using the finite element multi-physical field coupling method. Based on the deduced analytical expression of the radial electromagnetic force, the sources of the radial electromagnetic force for each order and the frequency of the permanent-magnet motor are summarized. A 12-slot, 8-pole, permanent-magnet motor is taken as an example. A calculation model considering the spatial distribution of the radial electromagnetic force and the electromagnetic vibration of an iron-cobalt-based stator is established. The harmonic response of the electromagnetic vibration of the motor is analyzed, and a modal analysis is carried out. The optimized acceleration vibration noise cascade of the FeCo-based permanent-magnet drive motor under load is given. The correctness and validity of the theoretical derivation and simulation are verified by experiments.

Research on Electromagnetic and Structural Characteristics of Canned Electric‐Actuated Valve Permanent Magnet Synchronous Motor under Eccentricity

The high‐temperature canned electric‐actuated valve permanent magnet synchronous motor (CEAV‐PMSM) directly drives the valve load, which is prone to eccentricity operation, causing greater system vibration and shortening the valve operating life. In order to analyze the electromagnetic and structural characteristics of CEAV‐PMSM under different eccentricity faults, this paper uses analytical methods to derive the magnetic field distribution of the motor under normal and eccentricity conditions. Then, the Maxwell Stress Tensor method is used to derive the expression of the radial electromagnetic force under normal and eccentricity conditions, and the order of space–time harmonics that have a greater impact on CEAV‐PMSM are summarized. After that, the electromagnetic performance comparison of the three pole‐slot combinations under different eccentricity conditions, and the harmonic orders during eccentricity is analyzed by Fourier transform to obtain the optimal pole‐slot combination, which verified the correctness of the analytical calculations. In addition, the influence of different eccentricity conditions on the radial force density and unbalanced magnetic pull are studied. On this basis, the vibration response of the motor under eccentricity is analyzed, and the influence of the canned sleeve on the vibration performance of the motor is discussed. Finally, the modal analysis of CEAV‐PMSM is carried out to prevent the occurrence of resonance under eccentricity, which provides some references for reducing the vibration and noise of the canned electric‐actuated valve. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Analytical representation and characteristics optimization for radial electromagnetic force of the switched reluctance motor under airgap eccentricity

Aiming at the influence of radial electromagnetic force on vibration and noise of the switched reluctance motor (SRM), the radial electromagnetic force under airgap eccentricity is represented based on the virtual displacement principle and Maxwell stress tensor. Multi-objective optimization of motor electromagnetic characteristics including magnetostatic torque, radial electromagnetic force fluctuation, and unbalanced radial force amplitude is completed. First, the analytical representation for the radial electromagnetic force is obtained by the virtual displacement principle, and the expression of the unbalanced radial force caused by airgap eccentricity is deduced. Then, the spatial distribution of the radial electromagnetic force is modeled by the Maxwell stress tensor, which makes the radial electromagnetic force characterization more comprehensive. In order to improve the electromagnetic characteristics of the SRM under airgap eccentricity, sensitivity analysis and multi-objective optimization are carried out to obtain the optimal solution set of the motor structure parameters. The simulation results show that the radial electromagnetic force fluctuation and the unbalanced radial force amplitude decreases by 64.09% and 23.05%, respectively, when the magnetostatic torque is sacrificed by 6.36%, which provides a framework for multi-objective optimization of motor structure parameters.

Principle and Analysis of Radial-Force-Based Swirling Actuator for Low-Speed High-Torque Applications

This article proposes a swirling actuator that uses the electromagnetic radial force and mechanical gears to generate rotational torque. The proposed actuator generates a rotating radial force between an inner stator and a swirler. The gears on the swirler and outer rotor convert the circular motion of the swirler to low-speed rotor rotation. Thus, the proposed actuator is aimed at low-speed high-torque applications. In this study, the air-gap radial flux density and electromagnetic radial force are investigated analytically and verified through finite-element analysis. The static radial force and output torque are measured in a prototype of the actuator. The system efficiency and the gear efficiency are evaluated. A peak torque density of 27 Nm/L with a small volume of 0.16 L is realized in the prototype.

Identification of prominent noise components of an electric powertrain using a psychoacoustic model

Because of the electric power transmission system has no sound masking effect compared with the traditional internal combustion power transmission system, electric powertrain noise has become the prominent noise of electric vehicles, adversely affecting the sound quality of the vehicle interior. Because of the strong coupling of motor and transmission noise, it is difficult to separate and identify the compositions of the electric powertrain by experiments. A psychoacoustic model is used to separate and identify the noise sources of the electric powertrain of a vehicle, considering the masking effect of the human ear. The electric powertrain noise is tested in a semi-anechoic chamber and recorded by a high-precision noise sensor. The noise source compositions of the electric powertrain are analyzed by the computational auditory scene analysis and robust independent component analysis. Five independent noise sources are obtained, i.e., the fundamental frequency of the first gear mesh noise, fundamental frequency of the second gear mesh noise, double frequency of the second gear mesh noise, radial electromagnetic force noise and stator slot harmonic noise. The results provide a guide for the optimization of the sound quality of the electric powertrain and for the improvement of the sound quality of the vehicle interior.

A Design Method of the Rotor Auxiliary Slot for the Water-filled Submersible Induction Motors

Aiming at the problem of electromagnetic vibration of the water-filled submersible induction motor (WSIM), a method of opening auxiliary slots on the rotor side is proposed to weaken the air-gap field harmonics caused by the rotor slot permeance harmonics. By analyzing the research status of electromagnetic vibration of the WSIM and the composition of the air-gap magnetic field of the motor, the idea that the auxiliary slots mainly affect the air-gap field harmonics by changing the air-gap permeance of the motor is put forward. The mathematical model of air-gap permeance of WSIM is established to simulate the influence of auxiliary slots on the air-gap permeance. Through the parametric analysis of the mathematical model, the change of auxiliary slot size is simulated. The air-gap permeance waveform is decomposed by the two-dimensional Fourier transform, and then the variation of the air-gap permeance harmonics with the size of the auxiliary slot is analyzed. Finally, the finite element simulation model of the WSIM with the auxiliary slots is established, and the waveform of the air-gap flux density of the motor is analyzed to verify the effectiveness of the mathematical model. Meanwhile, the results show that after opening the auxiliary slot, the radial electromagnetic force of the motor was reduced by 28.4%.

Effects of Rotor Skewing on the Vibration of Permanent Magnet Synchronous Motors With Elastic-Plastic Stator

Rotor-step straight skewing is a common method to reduce electromagnetic vibration of permanent magnet synchronous motors (PMSMs). However, the difference of the radial electromagnetic forces received by different axial positions of the stator caused by the elastic-plastic material is generally ignored in the theoretical analysis to determine the skewing structure, which makes the vibration suppression effect of the structure far less than expected in practical applications. Take a 48-slot 8-pole interior PMSM as an example, this paper compares the suppression effects of rotor-step straight skewing and rotor-step zigzag skewing when the elastoplasticity of the stator material is considered. It is pointed out that the rotor-step zigzag skewing can overcome the limitation of the straight skewing in restraining electromagnetic vibration in practical application. Based on the theoretical formula and multi-physical field simulation, the selection rules of the rotor-step zigzag skewing angle and segment number are summarized. Finally, the rationality and effectiveness of the simulation method are verified by experiments on the prototype.

Research on Electromagnetic Force of Transformer in Different Short-circuit Modes

When a short-circuit fault occurs on a power transformer, the windings of the transformer under the combined action of the short-circuit current and the leakage magnetic field, which is easy to deform the winding or damage the insulation of the transformer. Therefore, it is necessary to research on the force of the transformer under short-circuit situation, analyze and calculate the size and distribution characteristics of the electromagnetic force in different short-circuit modes. Based on the structural parameters of a transformer with a rated capacity of 200kVA, a three-dimensional model of a three-phase transformer is established by finite element simulation software. The axial and radial electromagnetic forces of windings in different short-circuit modes are analyzed by this model, comparing and analyzing the experimental results. In the simulation model, It can be known that the electromagnetic force of voltage zero-crossing closing phase when three-phase short-circuit occurs on low-voltage winding is basically the same as that of short-circuit phase electromagnetic force when single-phase short-circuit occurs. The analysis results have a certain reference value for improving transformer short-circuit withstand ability.

Evaluation and comparison of sideband harmonics and acoustic responses with continuous and discontinuous PWM strategies in permanent magnet synchronous motor for electric vehicles

High-frequency vibro-acoustics, introduced by voltage source inverter (VSI) and control strategies, are the critical features affecting the noise, vibration and harshness (NVH) performances of electric vehicles (EVs). In this paper, a comprehensive evaluation and comparison into sideband current harmonics and high-frequency vibro-acoustic responses has been studied with different control strategies in the study case of permanent magnet synchronous motor (PMSM). At first, the principles and implementation of continuous and discontinuous pulse-width modulations (PWM) techniques are explored. Then, the features of the sideband current harmonic and radial electromagnetic forces are deduced with analytical derivations, in which the frequency characteristics are also presented. Furthermore, all PWM schemes have been improved by a standard periodic dithering modulation with square signal-based to reduce the sideband harmonics. The experimental results show that the sideband current harmonics and vibro-acoustics are generally clustered around the carrier frequency and have a particular orders and spectral distributions. The overall level of the obtained DPWM schemes present a slight deterioration compared to the SVPWM ones. With the periodisation of the carrier frequency, the sideband components show a significant suppression, which is above 15 dBA reduced in the acoustic noise responses.

Effect of Pole Number on Generator End Winding Electromagnetic Force and Mechanical Response before and after RISC

This paper comparatively studies on the end winding electromagnetic force and mechanical response for generators with different numbers of poles. The analytical expression of the end winding electromagnetic force is derived under the rotor winding interturn short circuit (RISC) considering the pole number. Meanwhile, the three-dimensional transient finite element simulation is carried on two generators with one-pair poles and three-pair poles. Then, the frequency composition and amplitude variation characteristics of the radial, axial, and tangential electromagnetic forces are analyzed. Further, the maximum stress and deformation on the end winding are calculated and the similarity and difference of the coil failure law are obtained for two kinds of generators. It is found that RISC will bring odd harmonics to electromagnetic force for one-pair pole generators but it will bring odd and fraction harmonics for multipair pole generators. Moreover, the max mechanical response under RISC will decrease for one-pair pole generators but it will increase for multipair pole generators.

Vibration and Noise Analysis of Flux-Modulation Double Stator Electrical-Excitation Synchronous Machine

This paper studies the vibration and noise analysis of flux-modulation double-stator electrical-excitation synchronous machine (FM-DSEESM) in both no-load mode and on-load mode by using the mode superposition method. First, the theoretical excitations of vibration and noise, namely the radial electromagnetic force harmonics, are deduced and classified by their sources. Second, the finite element analyses (FEA) of these radial electromagnetic force harmonics are analyzed via Fourier decomposition and compared to their theoretical results for validation. Third, to perform the vibration and noise analysis, the modal test is conducted, and the modal FEA model is established based on the tested modal results. Also, the radial electromagnetic forces are coupled with the modal FEA model to conduct the vibration and noise analysis, and the responses of sound power levels in A-weighting are calculated. By using the modal participating factors, the main contributing modes are determined in the vibration and noise responses.