Stator Teeth Research Articles

Trade-off between torque ripple and vibration in an IPMSM by examining the temporal and spatial harmonics of flux density

Despite continuous effort to minimize torque ripple, the reduction of vibration has not been yet achieved due to the lack of link between these two performances. The difficulty of investigating the relationship stems from the fact that torque is solely influenced by tangential force whereas vibration is directly tied to radial force. In this paper, the correlation between torque ripple and vibration in an IPMSM (Interior Permanent Magnet Synchronous Motor) is established by examining the air-gap flux density in both radial and tangential directions. Its temporal and spatial harmonics are analyzed. A six-pole nine-slot IPMSM is used as a base configuration, and the air-gap flux density is varied by changing the height of a stator tooth tip. In the previous study, the same approach has been done to observe how to reduce torque ripple effectively. In this study, however, it is found that the trend of torque ripple is not the same as that of vibration with respect to the height of a pole tip, and the relation between the two is thoroughly observed and explained.

Research on Fault Indicator for Integrated Fault Diagnosis System of PMSM Based on Stator Tooth Flux

Research on Fault Indicator for Integrated Fault Diagnosis System of PMSM Based on Stator Tooth Flux

Analysis of magnetostriction of oriented silicon steel under motor magnetic field

The performance requirements of motors are gradually increasing, and anisotropic soft magnetic materials have been applied in motors to improve performance, The magnetostriction of anisotropic soft magnetic materials is one of the main contributors in extensive research on anisotropic soft magnetic material transformers. Compared to transformers, the magnetic field in motors has more complex harmonic and multi-directional characteristics. In this paper, the magnetic field of motors stator teeth under both no-load and load conditions is calculated and analyzed to research magnetostriction of anisotropic soft magnetic materials in motor magnetic field and predict the NVH performance of anisotropic soft magnetic material motors accurately. Furthermore, the magnetostriction in different magnetization angles is investigated for the multi-directional characteristics, and the result is explained from microscopic principles. This paper focuses on a splicing oriented silicon steel (OSS) motor, the magnetization angle of OSS in motor varying from 0° to 90°. Firstly, the equivalent formulas of magnetic field are obtained under the analytical and finite element calculations. After that, the frequency and direction of experiment magnetic field are confirmed and the magnetostriction of OSS in different magnetization angle and frequency is measured. In the end, the variation character of magnetostriction of OSS is summarized.

Performance Enhancement of Flux Switching Motor for Electric Vehicle Applications: An Overview

As the reduction of greenhouse gas emissions becomes crucial, electric vehicles (EVs) are expected to enter the market extensively in the coming years. The efficiency of the electrical motor used in EVs plays a significant role in their overall performance. This paper explores the flux switching motor (FSM) and its applications in EVs. The FSM is compared to other electrical motors, highlighting its potential as a suitable choice for EV traction. Various configurations and techniques are reviewed to enhance the performance of FSMs, including magnetic materials, torque ripple alleviation, and magnetic flux weakening. The advantages and disadvantages of these methods are discussed, providing valuable insights for designing FSMs for EVs. Generally, EV traction requires high torque density and high power density electrical motor. To achieve these goals, high electric and magnetic loading must be considered in design stage of the motor. Application of the FSM may be one of the appropriate option. For many reasons, three-phase FSM is preferred. Considering the base speed of machine in the EV and high electric loading, the FSM with 12 stator teeth and 10 rotor teeth may be the most appropriate choice in which the stator core is oriented and rotor core is nonoriented iron. To enhance the torque density and applied flux weakening method, combination of Nd and Al–Ni–Co magnets is preferred.

Comparative Study of Cogging Torque, Torque Ripple and Vibration on Stator Tooth Chamfer Types in Permanent Magnet Synchronous Motors

Comparative Study of Cogging Torque, Torque Ripple and Vibration on Stator Tooth Chamfer Types in Permanent Magnet Synchronous Motors

Design and Analysis of Permanent Magnet Synchronous Machine with Stator Tooth Splicing Structure Using Grain Oriented Electrical Steel

Design and Analysis of Permanent Magnet Synchronous Machine with Stator Tooth Splicing Structure Using Grain Oriented Electrical Steel

Fast Calculation of Electromagnetic Vibration of Surface-Mounted PMSM Considering Teeth Saturation and Tangential Electromagnetic Force

In view of the shortcomings of the existing calculation methods of electromagnetic forces, this paper proposes an analytical method (AM) combining the magnetomotive force (MMF)-permeance method and the improved subdomain method. The amplitude of each force density component considering stator teeth saturation and current harmonics is calculated, and the specific order and frequency components in the radial and tangential electromagnetic force densities are analyzed and sorted out. In modal analysis, the stator core and the casing are regarded as cylindrical shells with axial ribs, the natural frequencies of the stator are obtained based on the energy method, and the accuracy is well verified by the modal test. Finally, the frequency response functions of low-order modes of the stator only related to the stator structure parameters are determined, and the vibration accelerations under different working conditions are obtained based on the linear superposition principle by only updating the electromagnetic forces. Compared with the multi-physical coupling finite element analysis, the total calculation time of the proposed AM is reduced by more than 92%, which facilitates the fast prediction and effective reduction of electromagnetic vibrations in the motor design stage.

Multiple Fault Diagnosis of PMSM Based on Stator Tooth Flux and Parallel Residual Convolutional Neural Network

Multiple Fault Diagnosis of PMSM Based on Stator Tooth Flux and Parallel Residual Convolutional Neural Network

TRACTION ALTERNATOR FOR ELECTRIC DRIVE OF FRONT LOADER CHASSIS

For heavy construction equipment with a hybrid electric transmission, the power center of a group of traction electric drives can be formed by an electric generator and a renewable energy storage device (battery array) with the possibility of their joint operation to provide a surge of current in a group of traction electric drives. The battery array can be used to power a generator in a starter mode when starting a diesel internal combustion engine.
 
 The purpose of the study is to substantiate the choice of the magnetic system of the power generator for the electric transmission and the possibility of a starter mode for an internal combustion engine drive. The study was carried out within the framework of a subsidized project to create mass production of a family of front loaders with a hybrid electric drive in Chuvashia.
 
 Materials and research methods. The studies were carried out by the method of finite element analysis using the Russian software ELCUT (professional version and a set of reference books for domestic electrical and magnetic materials).
 
 Results. The stage of analytical calculation of the active parts of a transmission electric generator for the preliminary design stage is presented. It was carried out for the following conditions: the use of Russian electrical and magnetic materials, the use of common industrial bearings and antifreeze, compatibility with existing technological equipment in the production of traction electric motors, engine mode for performing the starter function. The substantiation of the choice of the magnetic system based on the ratios of magnetic fluxes of different sizes of stator teeth is given. The article is illustrated with diagrams of magnetic and thermal fields for given operational characteristics and properties of a transmission electric generator.
 
 Conclusions. For a given type of drive diesel engines installed on the front loaders, the highest efficiency indicators of the proposed generator magnetic system occur when using a multiplier. The power supply of the generator in the starter mode is provided by the installed array of traction batteries of the front loader without additional step-up converters.

Numerical-field analysis of the magnetic conductivity of the slot dispersion of the stator winding of induction motors

Introduction. The magnetic fields and the corresponding magnetic conductivities of the slot dispersion of the stator winding of three-phase induction motors (IM) are studied. Such studies are relevant in their design and are one of the bases for calculating a number of energy parameters and characteristics of motors. In the classical design of an IM, which is still valid, the specified magnetic conductivities are determined analytically according to the simplified slot dispersion model, therefore they may not always provide sufficient accuracy due to a number of assumptions and conventions. Goal. Further development of the IM design system by means of a numerical-field calculation analysis of the magnetic conductivity of the slot dispersion of their stator winding, as well as a comparative check of the relevant analytical formulas from various methods of classical design. Results. The slot dispersion of IM is determined by numerical calculations using the FEMM program within the stator tooth steps. For the research, four variants of the shapes of the stator slots, which are common in modern IMs of small and medium power, are accepted. In the calculations, calculation models with strongly saturated and unsaturated in the magnetic relation with the stator core teeth are considered. The numerical-field method shows that the classical design method can give both sufficiently accurate results and unacceptable errors in determining the magnetic conductivities of slot dispersion of IM. Discussion and prospects for further development. The provided numerical-field analysis method and the obtained results of the calculation of slot dispersion of IM windings are recommended as a basis for improving the system of their design.

Structure and characteristic analysis of a novel magnetic bearing without thrust disk

Conventional thrust magnetic bearing (TMB) uses large thrust disk to generate axial levitation force. However, due to the existence of thrust disk, it will lead to many problems in assembling and dynamic balance. Moreover, it will even limit rotational speed. In order to solve these shortcomings, a novel TMB with uniform teeth on the stator and rotor is proposed. It replaces the conventional thrust disk with staggered teeth structure between the stator and rotor. This paper obtains analytical expressions of levitation force, current stiffness and displacement stiffness of the novel TMB by equivalent magnetic circuit method and method of air–gap ratio permeance. Considering slot effect between the teeth of stator and rotor, its influence is analyzed by finite-element analysis (FEA) and the expression of displacement stiffness has been modified. The simulation and experiment results show that the proposed TMB can ensure enough bearing capacity by reasonably designing the staggered distance between the teeth of stator and rotor. In addition, under the reasonable tooth structure, TMB can achieve self-recovery ability by utilizing the influence of slot effect on levitation force. Compared with conventional TMB, the proposed TMB has greater advantages in assembly, dynamic balance and high speed. It will be conducive to its application in medical, aerospace and other fields.

СВЯЗЬ ПАРАМЕТРОВ СТАТОРА И РОТОРА В ЭЛЕКТРИЧЕСКИХ МАШИНАХ МЕХАТРОННЫХ СИСТЕМ С СОСРЕДОТОЧЕННЫМИ ОБМОТКАМИ СТАТОРА И ВОЗБУЖДЕНИЕМ НА РОТОРЕ

The issues of choosing design relationships when designing electrical machines with single-tooth windings are considered.
 Based on the property of symmetry of the m-phase system of an electric machine, relationships are derived that connect the number of pairs of rotor poles and stator teeth in single-tooth machines, taking into account the number of phases and the number of teeth in a phase group.
 The relations derived in the work, in comparison with the previously known ones, allow us to consider a larger number of working options, among which there may be more rational ones, in addition, the proposed relations are easier to use for the developer, since they determine the nomenclature of phases and the direction of winding in both the case of even and and an odd number of phases.
 Structural dependencies allow the developer to design a wide range of devices, such as engines, generators and synchronous tachometers with excitation from the rotor side, including from permanent magnets, which can be used in the development of electric machines built into the design of mechatronic modules. In this way, a base of options is created for further in-depth design using finite element modeling and other design tools.
 The proposed approach is compared with known and previously used relationships. Using the example of an electric machine with one pair of poles, it is shown that by expanding the options under consideration, more rational implementation options can be obtained.

Magnetic Coupling Effect and Performance Analysis of Dual Rotor Permanent Magnet Flux Switching Generator for Counter Rotating Wind Power Generation

To eliminate slip rings, brushes, and terminate gear-box mechanism, ferrite permanent magnet (PM) based counter rotating dual rotor PM flux switching generator (CRDRPMFSG) for direct drive counter rotating wind turbine (D <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> CRWT) application is proposed in this paper. Initially, the mechanism of gearless and brushless counter rotating wind power generation is discussed, and a simplified formulation opted for the slot/pole combinations. The proposed CRDRPMFSG encapsulate inner and outer machines with circumferentially magnetized PM enclosed by non-overlapped armature windings; thus, offering reduced overhang with compact design. However, co-axially linking the inner and outer machines through a shared stator yoke results in serious issues of magnetic coupling due to dual air-gap fields. To this end, eight topologies with various slot/pole combinations are comprehensively investigated using finite element analysis (FEA) for magnetic coupling effects and its influence on electromagnetic performance. From the analysis, it is shown that magnetic coupling level influence electromagnetic performance i.e., average torque, ripple rate, power factor, efficiency, losses, and output power. Moreover, it is noted that coupling level can be reduced by adopting same stator teeth in inner and outer machines or same stator teeth with different rotor poles. Finally, the predicted FEA calculations are verified experimentally with four benchmarked CRDRPMFSG prototypes.

Design and Optimization of a Pole Changing Flux Switching Permanent Magnet Motor

A flux switching permanent magnet (FSPM) motor is designed and optimized in this paper to achieve high torque density and expanded speed regulation range from a design viewpoint of pole-changing (PC). Based on the field modulation theory, the PM field in the FSPM motor is modulated by the stator and rotor teeth, generating rich harmonics with different pole-pair numbers in the air-gap flux density. By adopting an appropriate slot pole combination, working harmonics with different slot pitch angles are obtained to establish a basis of the PC-FSPM motor. Then, different working harmonics can be used to achieve different energy conversions with different winding configurations, so the PC operation can be performed to realize the high torque and wide speed regulation range by switching the working modes. Based on the field modulation theory, the operation principle of conventional and PC-FSPM motors are analyzed and compared. Then, according to the design principle of the PC-FSPM motor, a 24/22-pole PC-FSPM motor with the E-core is designed and optimized by a multi-level optimization method. Finally, the electromagnetic performances are analyzed by finite element analysis and the test results of the prototype have verified the feasibility of the motor.

Arranging coil winding circuits of synchronous permanent-magnet machines on rotor

&lt;span lang="EN-US"&gt;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.&lt;/span&gt;

Stator Core Loss Analysis and Suppression of Permanent Magnet Vernier Machines

Permanent magnet vernier machine is a new type of permanent magnet machine, which is operated based on flux modulation effect. In this paper, the stator core loss of the permanent magnet vernier machine is investigated based on the relationship of the stator core loss to harmonic components of the airgap magnetic flux density crossing airgap and leakage flux not crossing airgap. In this manner, the stator core loss can be analyzed with consideration of flux modulation effect and flux modulation pole structure. First, stator core losses generated by magnetic fields of permanent magnet and armature winding are analyzed. Then, stator tooth fluxes coming from airgap magnetic flux and leakage flux are derived. Also, non-working stator tooth flux contributing stator core loss but not contributing torque is identified. Based on this, two approaches to suppress the stator core loss of the permanent magnet vernier machine are proposed. Finally, the effectiveness of the stator core loss analysis and suppression is verified by finite element analysis and experiments.

Multi-material laser powder bed fusion additive manufacturing of concentrated wound stator teeth

Multi-material laser powder bed fusion additive manufacturing of concentrated wound stator teeth

Torque Improvement of Vernier Permanent Magnet Machine With Larger Rotor Pole Pairs Than Stator Teeth Number

Vernier permanent magnet machines (VPMM) have attracted extensive interest owing to high torque density. However, VPMM with larger rotor pole pair <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P_r</i> than stator teeth number <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Z_s</i> has weak torque capability due to the opposite phase of fundamental back EMF <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> induced by the fundamental and modulated flux density i.e. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_Pr</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_Pa</i> . Thus, the pole ratio (PR, defined as the ratio of rotor pole pair <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P_r</i> to winding pole pair <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P_a</i> ) of VPMM with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P_r</i> > <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Z_s</i> is labelled as “bad”, and has long been abandoned. This paper puts forward two novel design tools i.e. Unequal Element Coil (UEC) and Stator Teeth Unit (STU), via which the torque-improvement method of VPMM with “bad” PR is proposed. Firstly, constructing the winding via UEC, in which both <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_Pr</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_Pa</i> induce <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> of the same phase, meanwhile the total <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> is maximized. Secondly, designing the stator teeth structure via STU, so that multiple flux density harmonics are exploited and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> can be further enhanced. A VPMM with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P_r</i> = 10, PR = 10 is designed by the proposed method. The FEA and experimental results prove that at current density 7.5A/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , the torque density of the proposed VPMM is improved to 18.3Nm/L while the regular counterpart is only 13Nm/L.

Operating characteristics and design parameter optimization of permanent magnet linear generator applied to free-piston energy converter

A tubular permanent magnet linear generator (PMLG) with axial magnetized is proposed for the free-piston engine generator (FPEG). The structures and test rigs of the PMLG and FPEG prototypes are introduced. The working characteristics of the PMLG in FPEG system are analyzed under ignition conditions. A 2D finite element model of the PMLG is designed and verified based on initial design parameters and test results. The influences of key operating parameters on the output performance of PMLG are studied. On these basis, when considering the actual motion characteristics of the PMLG in FPEG system, the effects of different structural parameters on the power generation performance and efficiency (h) are investigated. Results show that when the working frequency of the FPEG is relatively small, the displacement profile resembles a sinusoidal curve. As the working frequency and stroke length increase, the power generation increases rapidly. As the air gap length and back iron shaft diameter decrease, and the stator slot number increases, the output voltage (U), current (I), power (Pout), and total loss power (Ploss) show an approximately linear increasing trend. As the pole arc coefficient and stator tooth width increase, the U, I, Pout, and Ploss first increase and then decrease. As the stator yoke thickness increases, the U, I, and Pout increase rapidly and then tend to stabilize. Besides, these structural parameters have little impact on power generation efficiency of this PMLG.

Asymmetric air gap fault detection in linear permanent magnet Vernier machines

PurposeThe aim of this paper is to introduce an accurate asymmetric fault index for the diagnosis of the faulty linear permanent magnet Vernier machine (LPMVM).Design/methodology/approachThree-dimensional finite element method is applied to model the LPMVM. The geometrical and physical properties of the machine, the effect of stator and translator teeth, magnetic saturation of core and nonuniform air gap due to asymmetric fault are taken into account in the simulation. The air gap asymmetric fault is proposed. This analytical method estimates the air gap flux density of an LPMVM.FindingsThis paper presents an analytical method to predict the performance of a healthy and faulty LPMVM. The introduced index is based on the frequency patterns of the stator current. Besides, the robustness of the index in different loads and fault severity is addressed.Originality/valueIntroducing index for air gap asymmetry fault diagnosis of LPMVM.