Stator Teeth Research Articles

Innovative Strategies for designing acoustic encapsulations for e-motors to tackle NVH performance challenges

The automotive industry's rapid transition towards E-mobility is presenting novel challenges for NVH engineers having broadband frequency composition and tonal characteristics. The purpose of the paper is to present innovative strategies for electric motor NVH development by directly applying acoustic encapsulation made of poro-elastic materials onto the casing of the electric motor. The first strategy is a pure simulation approach with combination of finite element analysis (FEA) and statistical energy analysis (SEA). Finite Element Analysis is used to calculate radiated power of electric motor casing for Maxwell electromagnetic excitations on stator teeth. This radiated power is then applied as excitation on the SEA model of the electric motor casing for prediction of exterior noise using Statistical Energy Analysis. The second strategy is a hybrid approach of simulations and experimental measurements. Electric motor is characterized as a source in terms sound power from experimental measurements of sound pressure as per ISO Standard: ISO 3745:2003. This power is applied as excitation in the interior of SEA model of the electric motor for prediction of exterior noise. Both the strategies allow design of optimized sound package on the SEA model of electric motor using statistical energy analysis to achieve the NVH performance.

Diversity of Stator Teeth Modulation Effect on Radial Pressure in PM Machines

Diversity of Stator Teeth Modulation Effect on Radial Pressure in PM Machines

Evaluation of magnetic orientation in dual-stator linear permanent magnet vernier machine for wave energy conversion

The Permanent Magnet Vernier Machine (PMVM) is favored for wave energy conversion due to its high torque production at low speeds and straightforward design. This study introduces the innovative Dual Stator Linear Permanent Magnet Vernier Machine (DSLPMVM) with concentrated winding. In this design, permanent magnets (PMs) are strategically placed on both the stator and a segmented translator, enhancing system reliability. The stator utilizes a simple PM layout, while the translator features a Halbach array. This research advances the DSLPMVM’s performance through the optimal placement and orientation of magnets, alongside a meticulous selection of tooth types. The paper rigorously evaluated all possible magnetic orientations and eight distinct stator tooth models. Detailed comparisons of flux linkage, back electromotive force (back-EMF), inductance, efficiency, power factor (PF), and force were conducted to identify the most effective designs.

Comparative analysis and optimization design of dual-side-permanent-magnet Halbach array vernier machine for high torque density

PurposeThe purpose of this paper is to introduce and analyze a dual-side-permanent-magnet Halbach array vernier (DSPMHV) machine and to propose methods for achieving high torque density.Design/methodology/approachFlux harmonics and torque characteristics are analyzed by using finite element analysis. First, a suitable pole-slot combination is selected by comparison. Second, field modulation processes of DSPMHV machine are analyzed to identify the reason for high torque density. And it is compared with dual-side-PM (DSPM) machine to analyze flux harmonic and verify the flux concentrating effect of the Halbach array.FindingsThe permanent magnet (PM) field of the DSPM machine is approximately equal to the superposition of stator-PM field and rotor-PM field, which is the reason for high torque density. And the Halbach array can reduce flux leakage and increase the amplitude of main flux harmonics, then further improves torque. Improvement of torque can be achieved by choosing right pole-slot combination, adopting DSPM machine structure, reducing flux leakage and adopting field modulation principle.Originality/valueThe DSPMHV machine with split-tooth is proposed in this paper by combining the Halbach array with DSPM structure. This paper analyzes the bidirectional field modulation process, the reason for high torque density of the DSPM machine is obtained. Comparison with the DSPM machine verifies the flux concentrating effect of Halbach array. To alleviate the magnetic saturation in part of stator teeth, this paper proposes an improved DSPMHV machine with shaped auxiliary magnet.

Heat dissipation design and performance optimization of high speed train PMSM based on coupled electromagnetic-thermal field

The permanent magnet synchronous motor (PMSM) has been widely recognized as the most promising driving system. This research presents a hybrid cooling system to improve the cooling effect of high speed train PMSM. At first, the cooling system includes the water jacket, heat pipes, Aluminum Nitride Ceramic sheets (AINC) inserted in the stator teeth, potting material at both ends of winding, and fins bonded to the evaporation section of heat pipes. In addition, the 3D model of PMSM is constructed with the error between experiment and simulation less than 5 %. Subsequently, using the Response surface method (RSM), this study investigates the sensitivity and the coefficient of correlation by varying AINC size on the electromagnetic properties. Finally, Particle Swarm Optimization (PSO) is employed to establish the mathematical optimization model of this cooling system. The results show that the optimized cooling system reduces the maximum temperature (Tmax) for each component of the PMSM while achieving a more uniform temperature field without compromising its electromagnetic properties. This significantly enhances the reliability and contributes to advancements in multi-physical field optimization for PMSM cooling.

A High Torque Density Dual-Stator Flux-Reversal-Machine with Multiple Poles Halbach Excitation on Outer Stator

This paper proposes a high torque density dual-stator flux-reversal-machine with multiple poles Halbach excitation (MPHE-DSFRM), which uses two pole pairs’ numbers (PPNs) of PM excitation on one outer stator tooth, and one PPN of PM excitation on one inner stator tooth. The introduction of different PPNs of PM excitation on the outer and the inner stators can optimize magnetic circuit and airgap flux density. A Halbach array is formed by inserting three pieces of circumferentially magnetized PMs into four pieces of radially magnetized permanent magnets (PMs) on the outer stator, which aims to further enhance torque density, and reduce torque ripple. Based on the flux modulation effect, the analytical modeling of the proposed MPHE-DSFRM is established, together with the evolution process, and the working principle is presented. Then, the key design parameters of MPHE-DSFRM are optimized to achieve high torque density and low torque ripple for high torque quality. Three representative DSFRMs and a conventional FRM are designed and analyzed, and they share the same design key parameters, including PM usage, outer radius of the outer stator, and active airgap length. The electromagnetic performances, including airgap flux density, back electromotive force (back-EMF), and torque characteristics, are analyzed and compared by finite element analysis (FEA). The calculated results show that the proposed MPHE-DSFRM can provide high torque density and high PM utilization.

Electromechanical Modeling and Analysis of Motor Whine in Electric Propulsion Systems

Electric motor whine is a major source of tonal noise and vibration for electric propulsion systems. The lack of engine masking noise in electric vehicles (EVs) further pronounces the pure tones, which are annoying to the occupants. The associated vibration can cause durability issues due to resonance and lead to failure of the sub-assembly or the supporting structure. A source-level NVH assessment of electric propulsion systems in modern EVs aims to achieve first-time quality designs at the advanced design stage. Accurate modeling of the motor stator and the electromagnetic (EM) forces at the air gap between the stator and rotor are critical to the NVH assessment. This work investigates the interaction between EM force application and the stator design in all four quadrants in which the electric motor operates, including both driving and regenerative braking in both clockwise and counterclockwise directions. A finite element (FE) model of the stator is developed, and the EM forces are mapped on the stator teeth, including different clocking and application directions. The stator model is integrated in the electric drive unit (DU) model, which enables the evaluation of the NVH performance of the propulsion system due to the reversal the EM force directions. The predicted analysis results are compared with the measured mount vibration

Rotor pole and stator tooth shaping in FSPM machines for torque performance optimization

Purpose This study aims to obtain the minimum torque ripple at the maximum average torque for Flux-switching permanent magnet (FSPM) machines. Design/methodology/approach This paper is about torque performance optimization of the FSPM machines. To achieve that, finite element analysis and genetic algorithm (GA) are used. Five different designs are simulated, optimized and compared on their air gap flux density, back electromotive force, cogging torque, average torque, torque density and torque ripple. Findings After the thousands of iterations, its proved that all proposed shaping techniques have potential for reducing torque ripple and cogging torque, with slightly reduced average torque. The best design is the joint stator and rotor shaping, Design V, which results in the lowest torque ripple and cogging torque. The techniques should be applicable to FSPMs with other stator slot/rotor pole number combinations. Originality/value In this paper, rotor pole shaping by notching, chamfering and generic shaping, stator tooth shaping and joint shaping techniques are investigated for 12 s/10p FSPM machines. Rotor and stator flanks are optimized separately and jointly, by using finite element analysis and GA for optimization to achieve maximum average torque and minimum torque ripple. Five different design is implemented and compared, respectively.

Improved air gap permeance modelling for single-slice magnetic equivalent circuits of skewed induction motors

PurposeWhen rotor and stator teeth are close, the connecting air gap flux tube's cross-sectional area exceeds the tooth overlap area. This flux fringing effect is disregarded in the air gap permeance calculation of single-slice magnetic equivalent circuits (MECs) of electric motors with skewed rotors. This paper aims to extend an air gap permeance calculation method incorporating flux fringing for unskewed rotors to skewed and radially eccentric rotors.Design/methodology/approachAssuming axial independence, the unskewed air gap permeance is rotated according to the skew and integrated along the axial dimension, resulting in a first method. The integral is approximated analytically, resulting in a second method. Results are compared to a commonly used reference method and validated using a non-linear finite element method (FEM) simulation.FindingsThe proposed methods provide better alignment with the FEM validation compared to the reference method for skewed rotors and common rotor eccentricity, i.e. below 50% of the air gap length. The analytical method is shown to be competitive with the reference method regarding computational time cost.Originality/valueTwo novel air gap permeance methods are proposed for single-slice MECs with skewed rotors. Their characteristics are discussed and validated.

Tracking of cogging stiffness using the multi-bin SDFT

Due to the high power density and wide speed range, a permanent magnet synchronous motor (PMSM) is commonly used in industry. Efficient production requires optimized motion control of the mechanism driven by the PMSM. Unfortunately, designing the controller is usually based on a model of the mechanism without including parameters originating from the motor. Cogging stiffness originates from the magnetic forces between rotor magnets and stator teeth and is one of these forgotten parameters. The performance is sub-optimal when this stiffness is not considered during control design. The stiffness also changes over time due to changing load conditions such as temperature. Aiming for optimized motion control of high-speed mechanisms, this article proposes to expand the classic motion controller with an on-line stiffness tracker. The tracker is based on the sliding discrete Fourier transform (SDFT). The tracking technique is conceptually analyzed and experimentally validated on a PMSM-driven rod. The classic Welch technique having an update time of at least 100 s is used as a benchmark. With similar accuracy and a much faster update time of 1.25 ms, the stiffness is tracked on-line using SDFT. The developed stiffness tracker is implemented on the provided commercial motion controller, proving its computational efficiency.

Design and experimental verification of hybrid excitation magnetic field modulation machine for electric vehicle propulsion

As one sort of flux modulation machine based on magnetic gear effect, field-modulated machine features with low speed large torque. A novel hybrid excitation field-modulated machine (HEFMM) is proposed by introducing the concept of hybrid excitation, the flux modulation poles (FMPs) and excitation winding of which are emplaced in stator teeth and the adjacent FMPs. It can be maintained wide speed range operation through the processes of flux-enhancing and flux-weakening with no increasing machine bulk, as well as the numbers of stator and rotor slot. The working principle of proposed machine is deeply studied, as well as basic electromagnetic characteristics are calculated by finite element method, including no-load magnetic flux linkage, no-load back electromotive force, cogging torque and output torque. In addition, the processes of flux-enhancing and flux-weakening are analyzed. Finally, one prototype with one kilowatt was built and its static characteristics were tested. The results show that the proposed HEFMM has the features of high torque density, small cogging torque and wide speed range, which is promising candidate for electric vehicle direct drive field.

Design and Analysis of Permanent Magnet Machines With Multiple Arc Pole Ratios in Stator Teeth

Design and Analysis of Permanent Magnet Machines With Multiple Arc Pole Ratios in Stator Teeth

Mitigation of Radial Force for Permanent Magnet Machines With Shifted Notch on Stator Teeth

Mitigation of Radial Force for Permanent Magnet Machines With Shifted Notch on Stator Teeth

Design and shape optimization of interior permanent magnet synchronous machine based on hybrid cores

By designing stator teeth using grain-oriented sheets (GO) and other parts still with non-grain-oriented sheets (NGO), the electromagnetic performance of the interior permanent magnet synchronous machine (GO-IPMSM) can be improved greatly. As the stator core of the designed GO-IPMSM is a hybrid core that is composed of two different silicon sheets, both the electromagnetic and mechanical performances are affected by the stator joint shape between GO and NGO sheets. Meanwhile, with the adoption of GO, the torque ripple of GO-IPMSM is increased though the average torque is increased as well. For reducing the torque ripple, optimizing the rotor barrier shape is an effective way. In this paper, the piecewise linear interpolation method is employed for establishing the stator joint shape between GO and NGO sheets, and the polynomial method is proposed to establish the rotor barrier shape. Through the analysis, it can be seen that the stator joint shape plays a strong role in affecting the mechanical performance of the GO-IPMSM, while the effect on the electromagnetic performance is weak. The genetic algorithm is used to optimize the rotor barrier shape for achieving high average torque and low torque ripple. Lastly, a quick and accurate efficiency map calculation method based on the Kriging model is proposed for GO-IPMSM with less finite element method (FEM) samples are required.

Optimal Rotor Design and Analysis of Energy-Efficient Brushless DC Motor-Driven Centrifugal Monoset Pump for Agriculture Applications

The agricultural sector emphasizes sustainable development and energy efficiency, particularly in optimizing water pumping systems for irrigation. Brushless DC (BLDC) motors are the preferred prime mover over induction motors due to their high efficiency in such applications. This article details the rotor design and analysis of an energy-efficient BLDC motor with specifications of 1 hp, 3000 rpm, and 48 V, specifically tailored for a centrifugal monoset pump for irrigation. The focus lies in achieving optimal energy efficiency through grey wolf optimization (GWO) algorithm in the rotor design to determine optimal dimensions of the Neodymium Iron Boron (NdFeB) magnet as well as its grade. The finite element method analysis software, MagNet, is used to model and analyze the BLDC motor. The motor parameters, such as speed, torque, flux functions, temperature, and efficiency, are analyzed. For performance comparison, the same model with different magnet models is also analyzed. Validation via 3D finite element analysis highlights improvements in magnet flux linkage, stator tooth flux density, and rotor inertia with increased magnet thickness. Simulation results affirm the consistent performance of the designed BLDC motor, preferably when efficiency is increased. This efficiency and the constant speed lead to an improvement in the overall conversion efficiency of 7% within its operating range, affirming that the motor pump system is energy-efficient.

Investigation of torque and sensitivity analysis of a two-phase hybrid stepper motor

Abstract Stepper motors are extensively used in various automated systems, notably hybrid stepper motors (HSMs), renowned for their high torque density. Optimizing and improving their performance and torque density is highly beneficial. The first step in motor optimization is to perform a sensitivity analysis to identify the parameters most significantly affecting motor performance and torque density. Using Ansys Maxwell, a finite element method (FEM) software, we modeled and analyzed a commercially available HSM. After validating the computer model’s accuracy, we investigated the motor’s sensitivity to various parameters and discussed their effects on performance. Our findings highlight the significance of parameters such as air gap, magnet diameter, wire-turn numbers in the coils, and the shapes of the rotor and stator teeth in influencing HSM sensitivity—conversely, factors like magnet height and stator pole thickness exhibit negligible impact on motor performance.

Semi‐flooded cooling for high torque density modular permanent magnet machines

AbstractThe authors investigate a semi‐flooded cooling technology for modular permanent magnet machines using flux gaps (FGs) in alternate stator teeth for extra cooling channels. The investigated machine is separated into stationary and rotational components by a polyether ether ketone sleeve. Liquid is directed into the stationary component to achieve a significant temperature reduction, at the same time, avoiding the liquid leakage into the rotating component that will cause an increase in friction losses. The FGs in the modular machine increase the contact area between coolant and machine components, resulting in better cooling efficiency. Furthermore, the FGs contribute to reduced pressure loss by minimising system flow resistance. The influence of the FG width on improving machine cooling efficiency, lowering machine temperature, and reducing pressure losses is delved. Additionally, the investigation considers the impact of inlet and outlet areas to reveal the influences stemming from fluid expansions and contractions in these regions. Computational fluid dynamics (CFD) modelling is employed to simulate the cooling performances of the investigated machines. In addition, the flow network analysis has also been employed to help understand the fluid behaviour within machines. A series of tests have been carried out to validate the CFD modelling.

Rotor design optimization of a 4000 rpm permanent magnet synchronous generator using moth flame optimization algorithm

The goal of this paper is to optimize the rotor design parameters of 4000 rpm permanent magnet synchronous generator. The factors namely embrace, offset, outer diameter, and magnet thickness are selected as the design parameters those will be optimized in order to hold the magnetic flux density (MFD) distribution and the flux density on stator teeth and stator yoke within a desirable range while maximizing efficiency. The numerical simulations are carried out in the Maxwell environment for this purpose. The mathematical relationships between the responses and the factors are then derived using regression modeling over the simulation data. Following the modeling phase, the moth flame optimization is applied to these regression models to optimize the rotor design parameters. The motivation is determining mathematical relation between the important design parameters of the high speed generator and the measured responses, when standard M530-50A lamination material is used and then to demonstrate the utility of MFO to the readers on this design problem. The optimum factor levels for embrace, offset, outer diameter, and magnet thickness are calculated as 0.68, 30, 161.56, and 8.92 respectively. Additionally, confirmations are done by using Maxwell and the efficiency is calculated as 94.85%, and magnetic distributions are calculated as 1.64, 0.26, and 0.93 Tesla for stator teeth flux density, stator yoke flux density, and MFD; respectively. The results show that the efficiency is maximized and the magnetic distributions are kept within an appropriate range.

Iron loss calculation model of high‐voltage multi‐pole asynchronous motors considering high harmonic flux density

AbstractA variable coefficient segmented iron loss calculation model is proposed for high‐voltage multi‐pole asynchronous motors, which fully considers the influence of high‐order harmonic magnetic density on such motors. This model introduces additional hysteresis loss, improved eddy current loss coefficients, and rotation magnetisation coefficients to account for changes in losses due to small hysteresis loops and skin effect, as well as rotation magnetisation losses. A 710 kW 10‐pole asynchronous motor is used as the research object. A full‐domain iron loss calculation model considering stator and rotor tooth top surface losses is developed. The model can be used to accurately calculate the overall and local harmonic iron losses in the stator and rotor cores of high‐voltage multi‐pole asynchronous motors. And quantitatively analyse the distribution pattern of any harmonic iron loss at any location in the motor core. It realises the refinement calculation and analysis of iron losses in the whole domain of high‐voltage multi‐pole asynchronous motor. Finally, no‐load and load tests were conducted on the 710 kW 10‐pole asynchronous motor. The iron losses of the 710 kW 10‐pole asynchronous motor at no load and load are calculated using the above mentioned model and the classical trinomial constant factor model. The results are compared with the measured iron loss values. It is proved that the iron loss model is more accurate in calculating the iron loss of high‐voltage multi‐pole asynchronous motor. The result helps researchers to calculate the iron loss distribution of high voltage motors more accurately. Thus, the design and operating parameters of the motor can be optimised to improve the efficiency and performance of the motor. It provides the necessary technical support and key basis for the reduction of loss and energy saving of high‐voltage motors and the optimisation of their core structure.

Calculation of Magnetic Losses with Non-Uniform Distribution of Magnetic Induction in the Stator Tooth of a Switched Reluctance Motor

The aim of this study is to investigate and determine the effect of accounting for the non-uniform distribution of magnetic induction (by detailing the stator tooth model) on the calculation results of magnetic losses in the stator teeth of a switched reluctance motor in quasi-steady-state modes. To achieve this goal, dependencies of phase flux linkage, electromagnetic torque of the motor, and additionally, dependencies of the root mean square values of magnetic inductions in stator tooth elements on the rotor angle and current have been determined using the finite element method. An investigation of dynamic modes of the switched reluctance motor based on an improved simulation model has been conducted at various values of constant load torque. Dependencies of magnetic inductions over time for each stator tooth element for the studied quasi-steady-state operating modes have been obtained. Magnetic losses have been calculated, taking into account the maxima of the temporal dependencies of root mean square values of magnetic induction in stator tooth elements. The most important outcome is a quantitative assessment of the influence of the non-uniform distribution of magnetic induction on the calculated value of magnetic losses based on the detailing of the stator tooth model in the operational modes of the switched reluctance motor compared to the traditional approach. The significance of the work lies in developing an approach to refining the calculation of magnetic losses by considering local saturation in the magnetic circuit during the operation of the switched reluctance motor.