Strength Of Rotor Research Articles

Electromagnetic-thermal-mechanical performance of novel interior permanent magnet motor

To mitigate the challenges of magnetic leakage and iron loss in the rotor of interior permanent magnet (IPM) motors, this article proposes a novel rotor structure that eliminates the bilateral bridge, relying solely on a central bridge to maintain rotor strength. This design reduces the overall bridge width of the rotor, thereby decreasing magnetic leakage and improving torque. The novel rotor features a distinctive design that combines high silicon steel sheets and low silicon steel sheets. High silicon steel sheets are used on the rotor's surface to minimize iron loss, while low silicon steel sheets are used internally to ensure rotor strength. This design takes advantage of the high silicon steel's low iron loss while mitigating its brittleness and saturation issues. The article describes the method for producing this combined rotor. Mechanical and electromagnetic property tests are conducted on both high and low silicon steel sheets, resulting in stress-strain curves, B-H curves, and iron loss characteristics. Finally, the rotor stress is calculated. The analysis indicates that this novel motor can reduce magnetic leakage, increase torque by 7.5 %, improve efficiency by 0.18 %, decrease rotor iron loss by 36.2 %, and lower rotor temperature by 3.9 % compared to the original motor.

Effects of rotor–rotor interaction for a small tandem rotor operating in a crosswind

This study investigates the effects of rotor–rotor interaction on the wake and thrust characteristics of a small tandem rotor operating in a crosswind. Flow velocity and force measurements were conducted in a wind tunnel with two rotors arranged parallel to a crosswind. The results show that the rotor–rotor interaction significantly influences the wake characteristics and thrust generations of the tandem rotor and its effects vary depending on the crosswind speed and distance between rotor tips. In the tandem rotor configuration, the front rotor wake prevents the crosswind flow from reaching the rear rotor wake, thereby reducing the crosswind influence on it. However, under the strong rotor–rotor interaction, such as that caused by high crosswind speeds and short distances between rotor tips, the wakes of both rotors collide with each other and rapidly break down as they proceed downward. Tip-vortex characteristics are also affected by rotor–rotor interaction, which is investigated in terms of variations in the time-averaged tip-vortex trajectory and dissipation ratio with the strength of rotor–rotor interaction. These wake variations by rotor–rotor interaction lead to a decrease in thrust coefficients of the front and rear rotors, with a more significant reduction observed for the rear rotor. The thrust of the rear rotor is more significantly reduced as the crosswind speed increases and the distance between rotor tips narrows. This is mainly attributed to the increased axially induced velocity near the leading tips on the advancing side, retreating side, and centerline.

Study on the Performance of a High-Speed Motor, Considering the Effect of Temperature on the Properties of High-Strength Non-Oriented Silicon Steel.

Considering the high-speed and high power density technical specifications of new energy vehicle motors, there is a growing demand for rotor strength as motor peak speeds reach 20,000 r/min and beyond. The utilization of non-oriented silicon steel with a high yield strength in rotors has emerged as a promising approach to increase motor speed. However, the magnetic and mechanical properties of high-strength silicon steel under variable temperature conditions have not been fully explored, particularly in regards to their impact on motor torque, efficiency, and speed. This manuscript investigates the behavior of high-strength silicon steel before and after annealing and at different temperatures, analyzing its influence on high-speed motor performance. The validity and feasibility of this study are confirmed through prototype testing, providing a comprehensive reference for engineering design.

On the Mechanical Strength of Rotors with a Dual-Phase Magnetic Material

On the Mechanical Strength of Rotors with a Dual-Phase Magnetic Material

Research Status of High-speed Permanent Magnet Motor Control System

In this paper, for the topology optimization design problem of low rotating iron consumption and high rotor strength high-speed permanent magnet motor and the high dynamic, high force-to-energy ratio and strong robust control problem of high-speed permanent magnet motor, we briefly introduce the research status of scholars at home and abroad on the two problems in order to realize the high-speed permanent magnet motor with low rotating iron consumption, high rotor strength, and fast dynamic response and to provide the basic conditions for further research.

Analysis of the Magneto-Thermal Bidirectional Coupling Strength of Macro and Micro Integration for Self-Starting Permanent Magnet Hysteresis Synchronous Motors

High-speed permanent magnet synchronous motors (PMSMs) are usually started with the hybrid low-speed open-loop and high-speed closed-loop control mode. However, low-speed open-loop control produces large starting current, or even current overload, resulting in demagnetization and motor damage. Therefore, there is an urgent need to develop a high-speed permanent magnet synchronous motor with self-starting ability at low speed, that is, a permanent magnet hysteresis motor (PMHM). This paper takes the permanent magnet ring hysteresis column rotor structure as the research object. Firstly, the performance of this type of rotor is improved using the micro level of effective layer material AlNiCo, and the mechanical properties of AlNiCo are calculated. Secondly, based on the thick-walled cylinder theory, the analytical model for calculating the strength of the composite rotor considering the temperature effect is deduced, and the tangential and radial stress distribution for each part of the rotor under no-load and load conditions are obtained. Then, the electromagnetic losses and temperature field distribution of the rotor are obtained using the magneto-thermal bidirectional coupling finite element method. Finally, strength of the thermal rotor is analyzed by substituting the temperature rise curve function and AlNiCo parameters at the operating temperature. The comparison of the stress calculation results of the semi-analytical solution and the finite element method showed that the error between both of them is less than 5%, which verified that the semi-analytical solution can accurately analyze the thermal stress distribution of the rotor during high-speed rotation.

Optimal design of rotor structure for vibration and noise reduction in electric vehicle generator

In order to reduce the vibration noise of an extended-range electric vehicle (EREV) generator, an optimization method based on changing the rotor structure is proposed in this paper. Firstly, the specific optimization scheme is determined by theoretical and simulation analysis to perform skew pole segmentation of the rotor, while using an eccentric pole arc design to determine the optimal parameters with the target of cogging torque. Then, in order to verify the feasibility of the scheme, the main performance of the generator before and after the optimization is analyzed, including radial electromagnetic force wave, counter-electromotive force (counter EMF), electromagnetic torque, and rotor strength. Finally, a high-precision finite element model of the generator was established, the vibration acceleration, as well as the sound pressure level before and after optimization, were calculated, and a noise test was completed. The results show that the optimized scheme significantly weakened the cogging torque of the generator, while reducing the radial electromagnetic force wave and counter EMF distortion rate to a certain extent, and finally significantly improved the vibration and noise performance of the generator.

Diamond rotors

The resolution of magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra remains bounded by the spinning frequency, which is limited by the material strength of MAS rotors. Since diamond is capable of withstanding 1.5–2.5x greater MAS frequencies, compared to state-of-the art zirconia, we fabricated rotors from single crystal diamond. When combined with bearings optimized for spinning with helium gas, diamond rotors could achieve the highest MAS frequencies to date. Furthermore, the excellent microwave transmission properties and thermal conductivity of diamond could improve sensitivity enhancements in dynamic nuclear polarization (DNP) experiments. The fabrication protocol we report involves novel laser micromachining and produced rotors that presently spin at ωr/2π = 111.000 ± 0.004 kHz, with stable spinning up to 124 kHz, using N2 gas as the driving fluid. We present the first proton-detected 13C/15N MAS spectra recorded using diamond rotors, a critical step towards studying currently inaccessible ex-vivo protein samples with MAS NMR. Previously, the high aspect ratio of MAS rotors (∼10:1) precluded fabrication of MAS rotors from diamond.

Design and Analysis of a Novel High-Speed Permanent Magnet Machine With Dual Semi-Cage Winding

This article proposes a novel high-speed permanent magnet synchronous machine (HSPMSM) topology. The characteristics of the proposed machine are: 1) The stator winding is divided into two parts and each part is connected by the end ring at one end, which is helpful to solve the existing shortage of overlong end length in traditional HSPMSM. 2) The stator of the machine is designed with closed slot, which can greatly weaken the eddy current loss and the cogging torque of the machine. 3) The machine is driven by two separate three phase converter, which can improve the fault tolerance. In this article, the topology, and the corresponding control system is analyzed firstly. After that the electromagnetic performance, including back electromotive force, cogging torque, torque, etc. are analyzed with finite element analysis (FEA). In addition, the losses, including the stator copper loss, the stator iron loss and the eddy current loss of the permanent magnet and sleeve of the rotor, are calculated by FEA. The mechanical strength and dynamic performance of rotor is also checked. Finally, a prototype was designed and manufactured. The experimental results the validity of the topology.

A comprehensive approach to the analysis of the static and dynamic strength of the rotor of the smoke cleaner

The work describes the process of assessing the static and dynamic strength of the rotor of an axial smoke exhauster with twin blades which allow significantly increasing its efficiency. To build a calculation model for the strength analysis, the geometric model was simplified by removing bolted connections, slicing small surfaces, as well as modeling welds in the form of roundings and chamfers. Such simplifications made it possible to build a high-quality finite-element mesh with the sufficient accuracy for performing engineering calculations. Calculation models include a finite-element model of one sector of cyclic symmetry of the impeller of the smoke exhauster, which is used to more accurately determine its stress-strain state and local maximum stresses in the places of their concentration in the root sections of the blades and in the places where they are connected by jumpers due to the action of centrifugal forces, aerodynamic loads on the blade and thermal loads due to wheel heating, as well as a finite-element model of the entire rotor with a less detailed meshing of the impeller, which in this case plays the role of a mass-inertia element, and a more detailed meshing of the shaft to analyze its static strength and reactions in bearing assemblies from the action of gravity and determine natural frequencies and mode shapes of rotor vibrations and the possibility of resonances with multiples of the frequency of excitating loads. The analysis of the static strength of the impeller and the rotor shaft of the smoke exhauster was performed by comparing the von Mises equivalent stresses with the allowable stresses, and the analysis of the dynamic strength of the smoke exhauster rotor was performed by determining the level of detuning of the natural frequencies of vibrations from multiples of the frequency of the excitating load, which in this case was assumed to be the centrifugal forces acting on the unbalance of the rotating rotor. A detailed analysis of the results of calculations made it possible to establish that the elements of the smoke exhauster rotor meet the requirements of static strength under the action of all possible types of loads, and the natural frequencies of the rotor oscillations have a sufficient level of detuning from multiples of the frequency of the excitating load. In this way, a conclusion was made about the static and dynamic strength of the rotor of the smoke exhauster, which affect its resource and durability of operation in the nominal mode.

A Novel High-Speed Permanent Magnet Synchronous Motor for Hydrogen Recirculation Side Channel Pumps in Fuel Cell Systems

In hydrogen recirculation side channel pumps, the motor rotor is exposed to a high-pressure mixture of steam and hydrogen, which makes hydrogen embrittlement occur in permanent magnets (PMs). A protective coating is necessary for the PMs in high-pressure hydrogen. However, in the process of sleeve interference installation, the protective coating of the PMs is easily damaged. This paper proposes two surface-mounted insert permanent magnet (SIPM) synchronous motor topologies, SIPM1 and SIPM2, in which the retaining sleeves can be eliminated and the PM protective coating is safe in the assembling process. A dovetail PM and rotor core structure is used to protect the PM with higher rotor strength without retaining the sleeve. The electromagnetic performance of the motors with different rotors, including airgap flux density, output torque, torque ripple, and energy efficiency is compared and optimized. It is concluded that the output torque of the SIPM motor can be promoted by 22.4% and torque ripple can be reduced by 2.9%, while the PM volume remains the same as that of the conventional SPM motor. At the same time, the SIPM motor can have lower harmonic contents of back electromotive force (EMF) and rotor loss compared to the SPM motor with a retaining sleeve. Furthermore, the stress of the PM is analyzed under conditions of PM glue action and failure. The proposed SIPM2 has the ability to operate safely at high-speed and high-temperature operating conditions when the PM glue fails.

Manufacture and Testing of a Magnetically Suspended 0.5-kWh Flywheel Energy Storage System

This article presents crucial issues regarding the design, manufacture, and testing of a steel rotor for a 0.5-kWh flywheel energy storage system. A prototype was built using standard industrial components. The rotor has a maximum operating speed of 24 000 min <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> and is magnetically suspended. The introduced critical issues regarding the manufacture include the thermal stress during the rotor hardening process, the fixation for the rotor components of the drive machine and the magnetic bearings, etc. The rotor strength was validated by the overspeed testing according to the standard <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IEC 60034-1</i> . A rotation of up to 28 800 min <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> (120% of the maximum speed) was realized and maintained for 2 min. The proved rotor was suspended by commercial magnetic bearings in the flywheel system. Despite simple decentralized control, the rotor was successfully driven up to the designed maximum speed. The rotor dynamic behavior is analyzed by analytical calculation, simulation, and measurements. Different eigenmodes are identified. The results prove the possibilities to build and operate a flywheel system using standard industrial components, showing potential for cost-effective designs.

Design and Analysis of the High-Speed Permanent Magnet Motors: A Review on the State of the Art

This paper provides an overview of the design and analysis of high-speed PM motors by focusing on prominent issues such as motor losses, temperature rise, rotor strength and vibration. The design challenges of high-speed PM motors are briefly described, and the application of various stator and rotor structures and materials is presented in electromagnetic design. Combined with the temperature distribution of the motor, various heat dissipation measures to suppress the temperature rise are summarized. Strength and dynamics analysis of the rotor are outlined with respect to the safety of rotor operation. The current status of coupled multi-physics domain design used to improve the comprehensive design capability of high-speed PM motors is reviewed. Future directions of technologies related to the design of high-speed PM motors are pointed out.

Rotor Strength Analysis of FeCo-Based Permanent Magnet High Speed Motor

To solve the problem of tension stress caused by centrifugal force and caused by high-speed operation of permanent magnet (PM) rotor, a FeCo-based PM rotor structure model is proposed. Based on the thick-walled cylinder theory, the uniform analytical calculation formulas of strain field, displacement field, and stress field of high-speed permanent magnet rotor are derived, and the stresses of FeCo-based PM and sleeve are obtained. The correctness of analytical calculation method (ACM) is verified by finite element method (FEM). Based on the derived analytical formula, the influence of static interference, sleeve thickness, rotating shaft, and PM thermal expansion coefficient on the strength of high-speed permanent magnet rotor is analyzed, and the mechanical design law of high-speed permanent magnet rotor is summarized. Alloy sleeves are usually fitted outside the high-speed permanent magnet rotor to protect the PM from damage. In order to ensure safe operation of PM rotor under hot rotating conditions, strength calculation and check of sleeve and PM must be carried out. Based on the characteristics of slender structure of high-speed rotor, a high-speed permanent magnet motor (HSPMM) with a rated power of 100 kW and a rated speed of 18,000 r/min was produced, and a continuous operation test was carried out to verify the validity of the above theoretical analysis.

Design and Analysis of a 30 kW, 30,000 r/min High-Speed Permanent Magnet Motor for Compressor Application

In this paper, the design and analysis of a 30 kW, 30,000 r/min high-speed permanent magnet motor (HSPMM) for compressor application are provided. In order to provide a reasonable electromagnetic design scheme, the electromagnetic performances of the HSPMM under different structures are analyzed and compared by the finite element method (FEM). The thermal performances and cooling system of the HSPMM are, respectively, analyzed and designed by computational fluid dynamics (CFD). Finally, the HSPMM’s rotor strength is studied by both FEM and analytical methods, and the influencing factors of which are also researched in this paper.

High-speed permanent magnet machine multi-physics fields design for turbine application

This paper presents the multi-physics fields research of a high-speed permanent magnet machine (HSPMM) for turbine application. At first, the design considerations for the HSPMM are introduced and presented. Then, the machine electromagnetic performances are comprehensively studied with machine stator slot numbers. Moreover, the influences from the PM magnetization methods and segmentation number on PM eddy current loss reduction are further investigated. Thermal analysis is also performed for the HSPMM with the cooling water fluid volume flow rate considered. In addition, rotor strength is studied for the HSPMM with several design factors on machine rotor strength performances further studied and researched.

Fast Reconstruction Method of the Stress Field for the Steam Turbine Rotor Based on Deep Fully Convolutional Network

Abstract Since it is difficult to directly measure the transient stress of a steam turbine rotor in operation, a rotor stress field reconstruction model based on the deep fully convolutional network for the startup process is proposed. The stress distribution in the rotor can be directly predicted based on the temperature of a few measurement points. First, the finite element model is used to accurately simulate the temperature and stress field of the rotor startup process, generating training data for the deep learning method. Next, data of only 15 temperature measurement points are arranged to predict the stress distribution in the critical area of the rotor surface, with the accuracy (R2-score) reaching 0.997. The time cost of the trained neural network model at a single case is 1.42 s in CPUs and 0.11 s in GPUs, shortened by 97.3% and 99.8% with comparison to finite element analysis, respectively. In addition, the influence of the number of temperature measurement points and the training size is discussed, verifying the stability of the model. With the advantages of fast calculation, high accuracy, and strong stability, the fast reconstruction model can effectively realize the stress prediction during startup processes, resulting in the possibility of a real-time diagnosis of rotor strength in operation.

Study on the Rotor Strength of High-Speed Permanent Magnet Motor Considering the Influence of Assembly Pressing Force

In engineering application, the hot press assembly technology is often used to improve the stability of the rotor structure, but the conventional design methods cannot effectively evaluate the influence of this process on the rotor strength, which easily causes the rotor strength to exceed its safety margin range, and seriously it will lead to the failure of the rotor structure. This paper takes the cylindrical magnet surface-mounted high-speed permanent magnet synchronous motor rotor as the research object. Firstly, the influence of the assembly pressing force on the rotor stresses and interference is analyzed; then, comprehensively considering the assembly pressing force, speed and temperature, the rotor strength’s design method with high structural stability is proposed. Finally, based on the proposed method, the rotor strength of a 100 kW/30,000 rpm high-speed motor is designed, and the feasibility of the design is verified by over-speed experiment.

Optimal design of magnetically suspended high-speed rotor in turbo-molecular pump

A large scale magnetically suspended turbo-molecular pump is optimized and designed in this paper. A multi-objective integral optimal design method is proposed to design the rotor applied in a magnetically suspended turbo-molecular pump with high pumping speed, considering the interactive influence on electromagnetic and mechanical performances. The analytical models of the rotor strength, the rotor modal and the electromagnetic field of the magnetic bearing and the permanent magnet motor are established. A multi-objective optimization is conducted and the optimized parameters include dimensions of magnetic bearing and motor. The optimal objectives include electromagnetic, dynamic and static performances. A series of optimal Pareto results is obtained and the correlations between input and output variables are analyzed. The analytical results are compared with the results using finite element method and show good agreement. A prototype is fabricated and the optimal results are validated.

A Dovetail Joint for a Segment Permanent Magnet on a Rotor

Specific weight-power parameters (kW/kg, (kW/dm3)) of rotary electric machines depend on the rotational speed of the rotor. Bandage in high-endurance titanium [1] or carbon fiber-based nonmagnetic materials is used conventionally to enhance the rotor strength of magnetoelectric excitation high-speed electric machines. Eddy currents induced by tooth harmonics are seen as a major flaw in weighty titanium bandage, while a widened mechanical gap between the rotor and the stator is the principal shortcoming of nonmagnetic bandage, as it reduces magnetic induction values within the gaps. This article discusses a way to increase the rotor top rotational speed (the radial speed) through a dovetail permanent magnet joint solution without using additional titanium or carbon fiber bandage.