PM Rotor Research Articles

Multiobjective Optimization of High Power Density Outer Rotor PM Starter Generator Considering Electromagnetic and Temperature Characteristics

Multiobjective Optimization of High Power Density Outer Rotor PM Starter Generator Considering Electromagnetic and Temperature Characteristics

Vibration Performance Analysis of a Yokeless Stator Axial Flux PM Motor with Distributed Winding for Electric Vehicle Application

This article presents a detailed analysis of the electromagnetic force and vibration behavior of a new axial flux permanent magnet (AFPM) machine with a yokeless stator and interior PM rotor. Firstly, the configuration of an AFPM machine with a dual rotor and a sandwiched stator is introduced, including the structural design, fixation of the yokeless stator and segmented skew rotor structure. Then, the influence of anisotropic material and a fixed structure on stator modes is analyzed, including elastic modulus, shear model, the skew angle of slot and the thickness of stator yoke. Furthermore, a new non-equally segmented skew rotor structure is proposed and calculated for the reduction in vibration based on the multiphysics model. Three different segmented skew rotor schemes are compared to illustrate the influence of reducing vibration and noise. The predicted results show that the effect of the non-equally segmented skew rotor on reducing vibration is better than the other two schemes. Finally, a 120 kW AFPM motor is experimented with and the result matches well with the predicted data. The vibration performance of the AFPM motor with a dual rotor and sandwiched yokeless stator is revealed comprehensively.

Design and Analysis of a Novel Hybrid Rotor PM Machine Considering Negative Torque Ripple Contribution

Design and Analysis of a Novel Hybrid Rotor PM Machine Considering Negative Torque Ripple Contribution

Diagnostics of Interior PM Machine Rotor Faults Based on EMF Harmonics

This article presents a detailed study on the diagnosis of rotor faults in an Interior Permanent Magnet Machine based on a mathematical model. The authors provided a wide literature review, mentioning the fault diagnosis methods used for Permanent Magnet Machines. The research emphasizes the necessity of precise assumptions regarding winding construction to accurately analyze the additional harmonics appearing in rotor faults caused by electromotive force (EMF), i.e., rotor eccentricity and magnet damage. The article also discusses specific features appearing in the spectrum of air gap permeance functions and the impact of rotor eccentricity and magnet damage on PM flux density distribution and as a consequence on EMF stator windings. The novelty of the presented content is the analysis of induced EMFs for cases of the simultaneous occurrence of rotor eccentricity and PM damage. The findings of this study provide valuable insights for the diagnosis and understanding of internal asymmetries in Interior PM Machines.

Contributions of Stator and Rotor PMs in Dual-PM Machines With Different Stator and Rotor Pole Number Combinations

Contributions of Stator and Rotor PMs in Dual-PM Machines With Different Stator and Rotor Pole Number Combinations

Large-scale Design Optimization of an Axial-flux Vernier Machine with Dual Stator and Spoke PM Rotor for EV In-wheel Traction

Large-scale Design Optimization of an Axial-flux Vernier Machine with Dual Stator and Spoke PM Rotor for EV In-wheel Traction

Analysis of Hybrid Rotor PM Motor Caused by Atypical Vibration Sources

Analysis of Hybrid Rotor PM Motor Caused by Atypical Vibration Sources

Complementary Series Magnetic Circuit Based Stator-Yokeless Dual Rotor PM Vernier Reluctance Machine for In-wheel Propulsion

Complementary Series Magnetic Circuit Based Stator-Yokeless Dual Rotor PM Vernier Reluctance Machine for In-wheel Propulsion

Thermal Modeling of an Outer Rotor PM Assisted SynRM for the Electric Bike Applications Using a New 3-D LPTN

Thermal Modeling of an Outer Rotor PM Assisted SynRM for the Electric Bike Applications Using a New 3-D LPTN

Interaction Effects of PM Tolerances and Rotor Eccentricities on Cogging Torque of 12-slot/10-pole PM Machines

Interaction Effects of PM Tolerances and Rotor Eccentricities on Cogging Torque of 12-slot/10-pole PM Machines

Permanent Magnet with Direct Drive Synchronous Wind Turbine Generator System

This postulation illustrated a control framework for an immediate drive permanent magnet coordinated generator wind turbine system, with the goal of maximising the efficiency of this framework and capturing the maximum amount of wind energy. Additionally, in order to decrease the electric speed sensor installed on the rotor shaft of the PMSG (Permanent Magnet), as well as to reduce the complexity of the framework equipment and increase the stability of the framework, a sliding mode eyewitness-based PM rotor position and speed sensor less control calculation is shown here.The wind turbine and the permanent magnet combination machine with PMSG simulation models are first built in this proposal, and then largest force control calculations for this framework are presented. The best tip speed percentage based on the highest force point after control is used to achieve the strongest catch for the framework.

Deadbeat-Direct Torque and Flux Control of a Brushless Axial-Flux Magnetic-Geared Double-Rotor Machine for Power-Splitting HEVs

A deadbeat-direct torque and flux control (DB-DTFC) for brushless axial-flux magnetic-geared double-rotor machines (AMGDRMs) is presented in this paper. The AMGDRM is employed as a power-splitting component in hybrid electric vehicles (HEVs) to enable speed decoupling between the internal combustion engine (ICE) and load. Since the rigid connection between the ICE and the drive train is replaced by the AMGDRM, fast torque control of the AMGDRM is required for the ICE speed regulation. Furthermore, the ICE torque contains abundant harmonics, inevitable sinusoidal components are introduced to the modulating rotor torque for torque balance, and further to the PM rotor torque owing to the magnetic-gear effect. Since both the PM rotor of the AMGDRM and the traction motor contribute to the hybrid electric system total torque output (i.e., torque coupling), the cascaded traction motor should compensate the PM rotor torque ripple actively to guarantee smooth total output torque. However, proportional-integral (PI) regulator suffers from limited bandwidth and thus could not realize accurate torque decoupling. Therefore, DB-DTFC, where torque and flux linkage are decoupled and respectively achieve their reference commands within two sampling periods, i.e., deadbeat responses, is proposed to enable a faster and more robust ICE speed control and accurate torque decoupling. The DB-DTFC law is derived and discrete-time close-loop current and flux linkage observers of the AMGDRM are developed. The proposed scheme and its superiorities are experimentally validated on an AMGDRM prototype test bench.

Improving Torque Analysis and Design Using the Air-Gap Field Modulation Principle for Permanent-Magnet Hub Machines

The Double Permanent Magnet Vernier (DPMV) machine is well known for its high torque density and magnet utilization ratio. This paper aims to investigate the torque generation mechanism and its improved design in DPMV machines for hub propulsion based on the field modulation principle. Firstly, the topology of the proposed DPMV machine is introduced, and a commercial PM machine is used as a benchmark. Secondly, the rotor PM, stator PM, and armature magnetic fields are derived and analyzed considering the modulation effect, respectively. Meanwhile, the contribution of each harmonic to average torque is pointed out. It can be concluded that the 7th-, 12th-, 19th- and 24th-order flux density harmonics are the main source of average torque. Thanks to the multi-working harmonic characteristics, the average torque of DPMV machines has significantly increased by 31.8% compared to the counterpart commercial PM machine, while also reducing the PM weight by 75%. Thirdly, the auxiliary barrier structure and dual three-phase winding configuration are proposed from the perspective of optimizing the phase and amplitude of working harmonics, respectively. The improvements in average torque are 9.9% and 5.4%, correspondingly.

Demagnetization Modeling and Analysis for a Six-Phase Surface-Mounted Field-Modulated Permanent-Magnet Machine Based on Equivalent Magnetic Network

Demagnetization Modeling and Analysis for a Six-Phase Surface-Mounted Field-Modulated Permanent-Magnet Machine Based on Equivalent Magnetic Network

A High Power Factor Permanent Magnet Vernier Machine With Modular Stator and Yokeless Rotor

Permanent magnet vernier machines (PMVMs) have drawn increasingly more attention due to their high torque density. However, they suffer from low power factor due to the large harmonic inductance caused by abundant no-working harmonics. This paper proposes a high power factor PMVM endowed with modular stator and yokeless halbach-PM-array rotor. Benefited from the unique structure, the magnetic circuits of low order no-working harmonics are interrupted and their amplitudes can be effectively decreased. Meanwhile, multiple working harmonics are produced by the modulation effects of un-evenly distributed stator permeance. Thus, both the high power factor and average torque can be achieved. Moreover, the influence of critical dimension parameters, including slot bottom width, flux barrier width and PM thickness on average torque and power factor are comprehensively analyzed. Finite element analysis (FEA) and experimental results verify that at current density 10 A/mm2, the power factor and active volume torque density of proposed PMVM with 9-slot-stator 14-pole-pair PM rotor can be improved to 0.9 and 26 Nm/L, while regular PMVM counterpart is corresponding to 0.84 and 22 Nm/L, respectively.

Multiphysics Comparative Study of High Speed PM Machines for Ring PM Rotor and Solid PM Rotor

This paper presents a comprehensive comparison of ring PM rotor and solid PM rotor for high speed permanent magnet machines (HSPMMs) by considering the multiphysics performance, including the rotor stress, electromagnetic characteristics, loss characteristics, thermal characteristics, and rotor dynamics. Firstly, six rotor schemes with different rotor structures and different sleeve materials are designed for a 10 kW, 100 000 rpm ultra HSPMM. Secondly, the multiphysics characteristics of six rotor solutions are compared one by one through the corresponding finite element model, including the rotor stress, electromagnetic and loss characteristics, temperature distribution and rotor dynamic. Finally, based on the above analysis, the final rotor design parameters are determined. A prototype is manufactured and tested to verify the theoretical analysis.

A Less-Invasive Method for Accurately Diagnosing Demagnetization Fault in PMSM Using Rotor Partition

This paper presents a less-invasive method for accurately diagnosing of demagnetization fault in permanent magnet synchronous motors (PMSM) using rotor partition. The rotor PMs are partitioned according to certain rules. The PMs condition of each partition is sequentially diagnosed through the signals measured by two additional toroidal yoke coils, thus the conditions of all rotor PMs are diagnosed. Firstly, the working mechanism of the search coil is analyzed, and the partitioned model of SC residual voltage is also presented. Secondly, the relationship between residual voltage signatures of SC and different demagnetization fault modes is studied by the established model. From the analysis, a demagnetization fault location method is proposed. The simulation and experiment results validate the correctness of the proposed method and indicate the proposed fault location method applies to the online diagnosis of both local and uniform demagnetization faults. In addition, the location of demagnetized PMs can be detected under any demagnetization fault condition and is not affected by other fault signals. Lastly, a comparison with existing methods based on search coil is performed and indicates the proposed method can locate faults more quickly and accurately than that of existing methods when the PM is demagnetized by 10%, and it is less invasive, especially has advantages in locating demagnetization PMs in PMSM with numerous pole-pairs. This article provides a new idea for demagnetization fault location of PMSM, as well as provides a significant reference for a motor maintenance schedule and fault-tolerant control of PMSM.

Calculation of no‐load induced electromotive force of pole changing line‐start permanent magnet synchronous motor

AbstractPole changing line‐start permanent magnet synchronous motor (LSPMSM) can significantly improve the starting capability of LSPMSM by decreasing the braking torque and pulsating torque during starting process. The fundamental reason for the elimination of braking torque is that there is no generating effect during minor‐pole starting process. That is to say, induced electromotive force (EMF) does not exist when the magnetic field generated by multi‐pole rotor PMs cut the minor‐pole stator winding. Therefore, the induced EMF of pole changing LSPMSM is analysed theoretically and calculated analytically. Considering that the magnetic flux per pole of the coils under the adjacent pole are different, the induced EMFs of a conductor, a full‐pitch coil, a coil group in minor‐pole stator winding are, respectively, calculated, and then the general analytical expression of the induced EMF of a phase winding with different rotor/stator pole ratio is derived. Then, the motors with different rotor/stator pole ratios are simulated based on finite element method to obtain the corresponding EMFs. Meanwhile, a 6/8 pole changing LSPMSM is taken as prototype. The consistency of the simulation, experiment, and the analytical calculation results effectively verify the validity of the derived general analytical expression and theoretical analysis.

Composite PM Rotor Design and Alternating Flux Density Harmonic Component Analysis of a 200 kW High-Speed PMSM Used in FESS

The flywheel energy storage system (FESS) is a short-time high-power energy storage technology widely used in various fields. To improve speed and reduce air friction loss, the rotor of the high-speed permanent magnet synchronous machine (HSPMSM) used in FESS operates at a magnetic suspension state in vacuum. It is very difficult for the rotor to dissipate heat, which may even lead to PM demagnetization. In this paper, a 200 kW 20000 r/min HSPMSM is designed for FESS of an uninterruptible power supply (UPS), and a composite PM rotor with multilayer sleeves is proposed. Distinct from the previously proposed retaining sleeve design of the HSPMSM rotor, a silicon steel sleeve is added in the composite PM rotor, which can provide a bypass for alternating flux density harmonic components in the rotor and prevent them from entering the alloy sleeve and PM. Moreover, a post-processing method of finite-element analysis (FEA) results is proposed to obtain the alternating harmonic components in the rotor and further analyze the suppression effect of the silicon steel sleeve on them. As the silicon steel sleeve is introduced, the amplitudes of alternating harmonic components are effectively suppressed, which can mitigate the eddy current loss and heat generation of the HSPMSM rotor from the source.

Investigation of Air-Gap Field Modulation Effect in Spoke-Type PM Machines

In this article, the air-gap field modulation effects (AFMEs) in spoke-type permanent magnet (STPM) machines with concentrated winding are investigated and revealed by quantifying the torque contributions of the various air-gap flux density harmonics. Due to the relatively stronger flux concentrated effect, the STPM structure exhibits greater resulting air-gap field harmonics for torque generation. In order to provide an in-depth understanding of their torque generation mechanism, the contributed torque components of the various air-gap field working harmonics are quantified by employing the Maxwell stress tensor (MST) approach. It identifies a fact that the abundant air-gap flux density harmonics have participated in torque production in the STPM machine. As a consequence, the field-modulated harmonics contributed a nonnegligible torque component, and hence, a pronounced AFME can be obtained in the STPM machine. Besides, the influences of the key dimension parameters, including split ratio, stator slot opening ratio, rotor PM thickness, and length, on AFEM for torque performance of the STPM machines are evaluated by the finite-element (FE) method. Finally, the reliability and effectiveness of theoretical analysis and FE simulation are verified by experiments on an STPM machine prototype.