Stator Shape Research Articles

Prototype Verification of Flux Reversal Motor With Cross-Pole Shape Stator

Prototype Verification of Flux Reversal Motor With Cross-Pole Shape Stator

A Study on New Straight Shape Design to Reduce Cogging Torque of Small Wind Power Generator

In this paper, a 150 W small wind power generator which has a permanent magnet synchronous generator type is proposed with a new straight shape stator and rotor to reduce the cogging torque. The advantages of the proposed structure are introduced through a comparison between the basic and the proposed models. By comparing the pole slot combination of the proposed generator, the combination with optimal cogging torque characteristics was selected. The electromagnetic characteristics of the proposed shape are analyzed for design variables using a finite element analysis of ANSYS 2021 R1 Maxwell. The final model of the proposed structure is designed by considering the cogging torque and electromagnetic characteristics of the generator. The electromagnetic and structural simulations of the final model are performed to satisfy the required performance of the generator and mechanical safety. To verify the FEA results of the final model, a prototype is manufactured, experimented, and compared with the FEA results.

Theoretical, CFD modelling and experimental investigation of a four-intersecting-vane rotary expander

Expansion devices significantly impact the performance of the Vapor Compression Refrigeration system and Organic Rankine Cycles. Its improvement has been identified as one of the most crucial parts of future studies. The experiments were carried out using an improved experimental rig with direct coupling of the prototype and the dynamometer. This is done to correct any misalignments caused by external forces. The internal pressure in the working chambers was measured using six pressure transducers at various locations on the expander. A three-dimensional computational fluid dynamics and theoretical model was developed to investigate the effect of losses and inherent physical processes on the prototype. The actual geometry of the stator is taken in the computational fluid dynamics model. Conversely, employing the equation for an irregular stator shape in the theoretical model is difficult. Therefore, a circular stator is considered. The experimental results were used to validate the developed models. The prototype was tested up to 1550 rpm rotating speed, 5 bar (abs) suction pressure, and 1 bar discharge pressure (abs). The computational fluid dynamics and theoretical model results showed that though the volumetric and adiabatic efficiency was generally overpredicted, the trends were very closely predicted. The computational fluid dynamics and the theoretical model could predict the volumetric and adiabatic efficiency with a variance of <19.5% and 14.7%, respectively, for most of the experimental data points.

A hybrid approach based on Lagrangian particles and immersed-boundary method to characterize rotor–stator mixing systems for high viscous mixtures

In-line multi-stage rotor–stator mixing systems are the recent industrial solution for mixing highly viscous liquids in a short period of time while minimizing temperature increase throughout the mixing process. Unlike their predecessors, namely batch mixers, in-line rotor–stator mixers facilitate a continuous mode of operation. However, there is a lack of detailed insight into their flow patterns, power consumption, and mixing behavior, as these mixers, particularly the multi-stage variants, are rarely studied in the scientific community. In this work, we propose a computational framework for modeling rotor–stator mixers using Lagrangian particle tracking and the immersed-boundary method. The tracer particles present an alternative to the commonly used Eulerian approach, which is susceptible to numerical diffusion. The use of the immersed-boundary method for modeling the motion of the rotor not only significantly reduces pre-processing time but also facilitates the modeling of various rotor–stator shapes with different motion patterns, making it possible to complete the modeling in a short time. The proposed method is used to investigate an industrial in-line multi-stage rotor–stator mixer, and the accuracy of the numerical results is verified by comparing them with experimental data. The simulations unveiled that at a rotational Reynolds number of up to 4000, significant back-mixing occurs, whereas for lower Reynolds numbers, the flow maintains a smooth forward motion without any back-mixing. The study also examines the residence time of the additive in the mixer, revealing that, particularly when dealing with high-viscosity mixtures, the additive has the potential to persist in the mixer for up to 3.5 times the theoretical residence time. Additionally, the obtained results are utilized to derive empirical equations that enable predicting the mixer’s performance for different Reynolds numbers.

Analysis and Comparison of Permanent Magnet Synchronous Motors According to Rotor Type under the Same Design Specifications

A surface-mounted permanent magnet synchronous motor (SPMSM) is an electric motor with a simple magnetic circuit design, fast responsiveness, linear torque–current characteristics, speed–voltage characteristics, and constant operating speed. SPMSMs use only magnetic torque; however, interior PMSMs (IPMSMs) have high power densities because they can use reluctance torque. In addition, when flux-weakening control is used, the operating range is wide compared with the SPMSM. This study presents a comparative analysis of the characteristics of SPMSM and bar-type IPMSM. Characteristic analyses are performed by setting the same stator shape, rated speed, number of turns, winding specifications, voltage limit, and magnet usage in a pole/slot combination of six poles and 27 slots. Next, we compare the no-load back electromotive force, cogging torque, and loss characteristics, and perform a characteristic analysis of each model while satisfying the design specifications. No-load and load tests are performed using a back-to-back system. The results of the analysis and experimental results are in good agreement, and the reliability of the analysis results is guaranteed. The SPMSM is approximately 8.5% superior to the IPMSM in terms of core loss, and the eddy current loss is greater than that of the IPMSM.

헤어핀 권선이 적용된 IPMSM의 구동 속도별 고정자 슬롯 형상 파라미터 변화에 따른 AC동손 민감도 분석

High-output, high-efficiency, and light-weight technologies of electric motors are attracting attention. Among related technologies, the technology of improving SFF(Slot Fill Factor), which means the ratio of the coil area to the stator slot area, enables weight reduction through high power density. As a method of improving SFF, there is a hairpin winding method using a rectangular coil. This has the advantage of high output because it takes up more slot area than when using a general round coil. However, this winding method has limitations in achieving high efficiency with AC copper loss under specific operating conditions such as high frequency and high current. Therefore, the hairpin model considering the reduction of AC copper loss can maximize its advantages. In this paper, the cause of AC copper loss is analyzed to reduce AC copper loss, and the AC copper loss sensitivity to changes in stator shape parameters and driving speed is analyzed through simulation analysis.

Optimum design and performance analysis of permanent magnet synchronous motor for vehicle

As the core of electric vehicle, the driving motor should have the advantages of high-power density, wide speed range and small volume. Aiming at the demand of vehicle drive motor and the structural characteristics of permanent magnet synchronous motor, by using Motor Cad, a internal rotor permanent magnet synchronous motor (PMSM) was designed and analysed in detail in this paper. In order to improve the anti-demagnetization ability and power density of the motor, the rotor structure was designed as a built-in compound type. At the same time, 8 poles and pear shape stator slot were adopted to reduce the loss of the motor and improve the efficiency of the motor. The simulation model of the motor was established by the simulation software, and its various performances were analysed. The simulation results showed that the design parameters of the prototype fully meet the design requirements of vehicle motor.

COMPARATIVE ANALYSIS OF FLUID COOLING SYSTEMS IN MOTORIZED SPINDLES

This paper analyzes geometrical approaches to optimize the fluid cooling circulation of motorized spindles. The spindle fluid cooling’s effectiveness, efficiency and influence on the machine’s precision are analyzed through observations of the stator temperature, pressure drop and thermal asymmetry, respectively. The observation is based on a validated coupled thermal/fluid mechanical simulation model. The widely used helix and meander shape stator cooling sleeves are primarily investigated. Additionally, a so-called S-meander shape was developed, which combines the advantages of the formerly mentioned sleeves. In order to understand the nonlinear thermal interactions properly, width and height of the cooling channels were varied separately and simultaneously. While keeping the flow rate identical, the average stator temperature could be decreased by 2.3 K solely with geometrical optimizations. Interestingly, the motor temperature is not continuously decreased by raising the fluid velocity through a reduction of the cooling channels size. For the helix and the S-meander, the temperature actually increases after passing a certain geometrical sweet spot. Additionally, this optimum is different for the helix, meander and S-meander cooling sleeve. The results imply that the geometrical optimization of fluid cooling channels in motorized spindles has a significant potential. Furthermore, the developed cooling sleeves are trans-ferable to any electric motor with fluid cooling.

Proposal of a radially differential type magnetic-geared motor

PurposeThis paper aims to propose a new magnetic-geared motor (MGM) which can easily increase the gear ratio up to approximately several hundred. The operational principle is described, and the relationship between the maximum transmission torques of each layer of the differential harmonic magnetic gear is investigated using a mathematical model and finite element method (FEM).Design/methodology/approachThe operational principle and maximum transmission torque are described using a mathematical model. The FEM is used to investigate the operational principle and torque characteristics.FindingsAs the proposed model can realize a larger gear ratio than the conventional model, the torque constant can be approximately 100 times as large as that of the conventional model.Research limitations/implicationsThe proposed and conventional models have the same shape stator, and it is not optimized.Originality/valueThe relationship between the maximum transmission torques of each layer is described, and this helps the design of a differential type MGM.

Topology Optimization to Reduce Electromagnetic Force Induced Vibration for the Specific Frequency of PMSM Motor Using Electromagnetic-Structural Coupled Analysis

Vibration and noise reduction are very important in electric vehicle driving motors. In this study, topology optimization of housing was performed to reduce vibration in a specific frequency caused by electromagnetic force generated by a permanent magnet synchronous motor (PMSM). The vibration induced by the electromagnetic force of the motor was calculated using electromagnetic-structural coupled analysis. Then, the magnitude of the acceleration for a specific frequency at which peak occurs in the rectangular and circular shape housing concept design model was reduced by using the topology optimization method. As a result, the rectangular and circular shape housing design reduced 92.9% and 96.0%, respectively. Finally, the vibration was effectively reduced while maintaining the electromagnetic characteristics of the motor, for which topology optimization was conducted while not changing the rotor or stator shape design (electromagnetic design factor) but by changing the motor housing shape design (mechanical and structural design factor).

Study of the stator geometry for a Moineau pump

Moineau pumps are volumetric pumps with progressive cavities and have an eccentric rotor towards the rotation axis. The eccentric rotor performs a rotational movement towards a stator, usually made of an elastomer moulded in a cylindrical tube. Producing the pump involves knowing the cross-section of the helical rotor model, as well as knowledge of the stator shape as a complex surface, and of the enwrapping of the rotor lobes in their relative movement, in relation to the stator. An analysis for the trilobed helical pump case is proposed, in which, by defining the rotor shape, the stator model can be formed. The two objects, the rotor and the stator are in reciprocal enwrapping movement, as a result of the revolving without sliding movement (rolling) of two circular centrodes, defined in relation to their front sections. The helical surfaces of the rotor and stator are cylindrical helical surfaces.

A Sinusoidal Current Control Strategy Based on Harmonic Voltage Injection for Harmonic Loss Reduction of PMSMs With Non-Sinusoidal Back-EMF

In permanent magnet synchronous machine design, a limited number of stator and rotor slots distorts the air-gap flux distribution and its effective length. It causes machine parameters to vary with the rotor position. The rotor flux linkage harmonics introduce nonsinusoidal back-EMF, which causes current harmonics when conventional PI current controller is adopted. Those machines suffer from high-frequency torque ripple due to air-gap flux harmonics in low-speed region. However, in high-speed region, where the torque ripple is filtered out by the mechanical system, the torque ripple may be disregarded. In this case, torque-ripple suppression methods and the associated harmonic current components generate losses. Therefore, a sinusoidal current control is required to reduce the undesired harmonic losses. In this manner, this article focuses on the sinusoidal current control strategy based on harmonic voltage injection, which requires knowledge of rotor magnet flux linkage harmonics. This article also proposes both off- and on-line schemes for the identification of rotor magnet flux linkage harmonics. These methods do not require any proprietary machine design details such as the shape of stator or rotor for finite element analysis. Commonly used PI plus resonant controller is also designed and its disadvantages in terms of speed-dependent gain and stability, in comparison to the proposed scheme, are highlighted. Finally, experimental results are presented to compare the proposed scheme with the conventional method at different operating conditions.

Analysis of Torque disturbance in of BLDC motor using soft computing technology for various shape of Stator and rotor pole

Analysis of Torque disturbance in of BLDC motor using soft computing technology for various shape of Stator and rotor pole

Reducing Secondary Flow Losses in Low-Pressure Turbines: The “Snaked” Blade

This paper presents an innovative design for reducing the impact of secondary flows on the aerodynamics of low-pressure turbine (LPT) stages. Starting from a state-of-the-art LPT stage, a local reshaping of the stator blade was introduced in the end-wall region in order to oppose the flow turning deviation. This resulted in an optimal stator shape, able to provide a more uniform exit flow angle. The detailed comparison between the baseline stator and the redesigned one allowed for pointing out that the rotor row performance increased thanks to the more uniform inlet flow, while the stator losses were not significantly affected. Moreover, it was possible to derive some design rules and to devise a general blade shape, named ‘snaked’, able to ensure such results. This generalization translated in an effective parametric description of the ‘snaked’ shape, in which few parameters are sufficient to describe the optimal shape modification starting from a conventional design. The “snaked” blade concept and its design have been patented by Avio Aero. The stator redesign was then applied to a whole LPT module in order to evaluate the potential benefit of the ‘snaked’ design on the overall turbine performance. Finally, the design was validated by means of an experimental campaign concerning the stator blade. The spanwise distributions of the flow angle and pressure loss coefficient at the stator exit proved the effectiveness of the redesign in providing a more uniform flow to the successive row, while preserving the original stator losses.

Optimal design to reduce torque ripple of IPM motor with radial based function meta-model considering design sensitivity analysis

In this study, optimum design process to reduce a torque ripple was presented for an interior permanent magnet (IPM) type electric traction motor. Firstly, 2-D electromagnetic finite element analysis was conducted to analyze the characteristics of the torque ripple in a view of magnetic saturation as well as cogging torque. Then, design factors of stator shape and rotor shape affecting to the torque ripple was selected as design variables. Secondly, using selected design variables, sensitivity analysis was performed to select design variable more affecting to the torque ripple and output torque by using design of experiments method. Thirdly, radial based function meta-model was constructed based on the results of the design of experiments (DOE). Finally, the optimum design was performed by using the constructed meta-model and method of feasible direction. By using the presented optimum design process, it is confirmed that the torque ripple of the optimum design was reduced to compare with the initial design and that output torque performance of the optimum design was maintained.

Stator tooth shape optimization for double salient hybrid excitation generator based on asymmetric circuit analysis

PurposeThis paper aims to clarify the relationship between stator tooth shape and DC voltage fluctuation of a double salient hybrid excitation generator (DSHEG). It analyzes the asymmetrical characteristics of the magnetic circuit and inductance between each phase. The study aims to reduce voltage fluctuation by using a stator shape optimization scheme, which helps reducing inductance difference.Design/methodology/approachThis paper opted for a method combined with theoretical analysis, simulation and experimental verification. The stator tooth optimization scheme is given based on theoretical asymmetrical analysis and Taguchi method. A series of two-dimensional finite element analysis simulation of different conditions are conducted. Two prototypes with different stator tooth shape are made and experiments are carried out.FindingsThe paper provides empirical insights into how the stator tooth shape influences the asymmetry of inductance and DC voltage fluctuation. Compensation adjustments to the stator tooth shape can narrow the inductance differences of each phase. It suggests that “LTL” shaped DSHEG has lower voltage ripple than “III” shaped DSHEG without sacrificing output power.Research limitations/implicationsBecause of the chosen research approach, the gap between magnets and stator and end effect are not considered. Errors exist between simulation and experimental results.Practical implicationsThe paper includes implications for other “C” shaped tooth optimization. Study on phase asymmetry of the special machine can further improve quality testing and simplify control strategy.Originality/valueThis paper analyzes the asymmetry of DSHEG and proposes an optimized stator tooth shape to reduce DC voltage fluctuation.

Reduction of Inverter Carrier Harmonic Losses in Interior Permanent Magnet Synchronous Motors by Optimizing Rotor and Stator Shapes

In this paper, we investigate rotor and stator designs of interior permanent synchronous motors for variable speed/load applications to reduce the carrier harmonic losses caused by pulsewidth modulated inverters. The rotor core and magnet shapes are determined by automatic optimization methods with electromagnetic field analysis, which considers the inverter carrier. Appropriate stator-winding configurations are also investigated by this analysis. It is clarified that the total carrier harmonic loss can be reduced by more than 20% by optimizing both the stator and rotor shapes, whereas the other important characteristics are not deteriorated. The mechanism of carrier loss reduction is also clarified.

Prediction of hydrodynamic performance of pump propeller considering the effect of tip vortex

There is a strong gap flow in the pump jet propulsor, in order to predict the hydrodynamic performance of the pump jet propulsor, the steady-state hydrodynamic disturbance model was established by the panel method. The pump jet propulsor was divided into two systems, rotor-hub and stator-duct, and inter-system interference was considered by induced velocity. Aiming at the geometric shape of stator, a method of leaf meshes based on circular cone was proposed. Based on the actual situation of the internal flow of the pump, a tip leakage vortex model suitable for the flat-topped blade was proposed. Comparing the results of pressure, circulation, and propulsion performance, it was found that when the influence of tip vortex is considered, the overall annular distribution of rotor blade and tip load are closer to the actual situation, and the performance curve is in good agreement with the viscous flow, which shows that this method can effectively predict the steady hydrodynamic performance of the pump jet propulsor.

Optimal design of spoke type motor and magnetizer using FEM and RSM

PurposeThis study aims to propose criteria for both optimal-shape and magnetizer-system designs to be used for a high-output spoke-type motor. The study also examines methods of reducing high-cogging torque and torque ripple, to prevent noise and vibration.Design/methodology/approachThe optimal design of the stator and rotor can be enhanced using both a response surface method (RSM) and finite element method (FEM). In addition, a magnetizer system is optimally designed for the magnetization of permanent magnets for use in the motor.FindingsThe criteria not only improve performance but also reduce manufacturing costs. The criteria are verified FEM together with an RSM. These methods are used to optimize the stator and rotor shape and the magnetization system. These methods allow us to produce an efficient system for mass production of the motor.Originality/valueThis study proposed a design method that uses rare earth magnets in a system to replace the spoke-type IPM. To verify the optimal design, torque characteristics were analysed using FEM and RSM. Excellent results were achieved regarding the reduction of cogging torque and torque ripple. In addition, the design of the magnetizer enables a cost-effective mass production system for the motor.

A Novel Design Procedure for Designing Linear Generators

A number of research works have been carried out based on the optimization of linear generators for harvesting oceanic wave energy, but no significant method of shape optimization for determination of the optimal shape of linear generator has been found. Moreover, inclusion of some parameters, such as shape of linear generator's translator and stator, has been considered out of the scope of the conventional-, adaptive-, or knowledge-based genetic algorithms. This paper proposes a novel method through which any type of linear generator's shape can be optimized graphically. A mathematical model of the proposed method including human intervened genetic algorithm is presented. The proposed method has been applied to a direct-drive system-based linear generator where the maximization of electrical power output and minimization of steel core volume have been considered as the optimization objectives. The optimization parameters have been further optimized graphically within functional volumetric and electromagnetic constraints to achieve improved design solutions. The proposed method has included comprehensive geometric dimensions, magnetic, and electrical parameters. Finally, the shape of steel cores of the translator and special m-shaped stator of the linear generator is determined and simulated using the copper wire. This optimized shape of the linear generator is capable of satisfying the multiobjectives of maximal electrical power generation and reduction of its size. The ANSYS/Ansoft software has been used to create the platform for analyses of the whole system.