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Permanent magnet synchronous motors (PMSMs) with nonconcentric magnetic poles (NCMP) structure are widely used as high-precision servo motors. The current subdomain method mainly equates the NCMP to a rectangular magnet to make each subdomain boundaries of magnet parallel when calculating the magnet eddy current loss (ECL), which results in a lower accuracy of the calculation. This article divides the NCMP into nonconcentric region and concentric region along the radial direction. The nonconcentric region is further divided along the circumferential direction, and each divided region has a single thickness. Based on the subdomain method, a novel analytical method of magnet ECL in PMSMs with NCMPs is proposed. Moreover, the three-dimensional distribution coefficient of ECL in the NCMP is derived by the equivalent impedance method. The effects of eddy current reaction and stator slotting are taken into account to improve the calculation accuracy. Then, through theoretical derivation, the relationship between the minimum magnet loss and the pole parameters is obtained, which provides a reference for the design of NCMPs. Finally, the loss separation experiment is performed on four prototypes with NCMPs. The experimental results, finite element method results and analytical results are compared to verify the correctness of the model. [ABSTRACT FROM AUTHOR]

This paper proposes a novel analytical model which combines subdomain method and magnetic equivalent circuit (MEC) method to predict the no-load performance of V-shape interior permanent magnet (IPM) motors with any slot-pole combination considering the nonlinearity of magnetic bridges (MBs). The V-shape magnets are equivalent to the form of distribution along radial and tangential directions, and the motor is divided into two corresponding structures to facilitate the establishment of subdomains. To consider the saturation of MBs, the MEC method are employed to obtain the permeability of MBs to establish the boundary conditions. The no-load magnetic field of slotless motor can be obtained by solving the equations established by boundary conditions, and the conformal mapping is used to consider the effect of slotting. The proposed model can be used to calculate the no-load magnetic field, back electromotive force, and cogging torque of IPM motor. The results are verified by finite element analysis (FEA) and experiments, which confirms the validity of the model for facilitating the motor design and optimization. Compared with FEA, the proposed method has the advantages of faster modeling, shorter time consuming and meanwhile achieves the approximate accuracy. In addition, U-shape motors with MBs can also be analyzed by this model. [ABSTRACT FROM AUTHOR]

This paper presents the modified core loss calculation of the high-speed (HS) permanent magnet synchronous machines (PMSMs) with amorphous metal (AM) stator cores. In the initial stage of the HS PMSM design, the calculation of stator core loss is obtained according to the data of AM ribbon provided by the manufacturer, which causes a large error of AM core loss. So how to make the accurate calculation of the AM core loss with only the AM ribbon data from the manufacturer is impending in the initial and advanced design stages of HS PMSM development. In this paper, the characteristics of AM ribbon and AM stator core is measured and compared. According to the experimental results, the modification factor for the accurate calculation of AM core loss is obtained based on the loss characteristics of AM ribbon. Then, the no-load loss of a HS PMSM prototype with an AM stator core is analyzed by numerical methods and verified by experiments. The proposed modification factor of the AM core loss calculation can provide a reference for the design and analysis of HS AM PMSMs in the industry. [ABSTRACT FROM AUTHOR]

This article investigates the electromagnetic vibration characteristics of high-speed (HS) permanent magnet synchronous machines (PMSMs) with amorphous metal stator cores (AMSCs) considering current harmonics. First, an analytical model of radial forces in PMSMs considering current harmonics due to both nonsinusoidal back electromotive force and pulsewidth modulation effects is developed. The cross influences of the two types of current harmonics on vibrations of HS PMSMs in different frequency bands are discussed. Second, the equivalent elasticity modulus parameters of laminated AMSCs are identified by utilizing modal experiment. Third, the influences of slot and pole number combinations on magnetic field harmonic contents and radial force orders for HS PMSMs are investigated by the analytical model. Then, the radial forces of a 15-kW HS PMSM fed by ideal sinusoidal current and experimental current are calculated under different rotational speeds by finite-element method. Finally, the vibrations of the prototype under rated torque and different rotational speeds are tested to verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

This article proposes a novel analytical model which combines subdomain method and magnet equivalent circuit (MEC) method to predict the cogging torque of surface-mounted permanent magnet (SPM) motors with rotor eccentricity and magnet defects in any slot-pole combination cases. Firstly, the general solution of open-circuit magnetic field distribution in a slotless SPM motor with magnet defects is derived. Then, the motor is divided into several subdomains along the air-gap circumferential direction to consider the non-uniform air-gap caused by rotor eccentricity, where the air-gap lengths of each subdomain are considered to be uniform. Finally, the methods of conformal mapping and MEC combined with equivalent current is used to consider the effect of slotting and saturation, which is beneficial to improve the calculation precision. The magnetic field distributions and cogging torque calculated by the proposed model are consistent with the results of finite element analysis (FEA). Compared with the FEA, the proposed model can perform fast calculations of air-gap flux density and cogging torque under rotor eccentricity and magnet defects for SPM motors, which can be utilized for optimizing the motor towards fault tolerance. [ABSTRACT FROM AUTHOR]

This paper proposes an analytical model for analyzing the electromagnetic performance of axial flux permanent magnet machines (AFPMMs) with the coexistence of static rotor radial deviation and angular eccentricity. Firstly, a quasi-3-D analytical model for the healthy AFPMMs is established using the scalar potential. Then, the analytical model of AFPMMs with the mixed eccentricity is derived by the coordinate transformation and air gap length function. The end effect under the mixed eccentricity is considered by an end coefficient, which improves the accuracy of back EMF by 1.3%. Based on the analytical model, the air gap flux density distribution, back EMF and cogging torque of AFPMMs with different rotor radial distances and angular eccentricities are calculated and compared with the corresponding results obtained by finite element analysis (FEA). The proposed model has higher analysis speed and less computer performance requirement than FEA with the similar accuracy. According to the results, the back EMF reduces obviously as the rotor radial deviation distance increases, and the back EMF almost unchanged as the angular eccentricity becomes serious. [ABSTRACT FROM AUTHOR]

Two types of surface-mounted permanent magnet synchronous machines (PMSMs) with the same physical dimensions but different stator core materials are comparatively analyzed, prototyped, and tested in this paper. In order to quantify the magnetization and loss characteristics of the stacked amorphous metal (AM) stator core, an experiment is conducted under different supply frequencies. Based on the data, the no-load iron losses, harmonic losses generated by the inverter-induced non-sinusoidal current harmonics, and the $d$ -axis and $q$ -axis inductances of two types of motors are comparatively analyzed by the finite-element method under different conditions and verified by experiments carried out on the two types of PMSM prototypes. The results illustrate that the AM PMSM has a characteristic of extremely low no-load iron losses, relative to the conventional silicon steel PMSM. [ABSTRACT FROM AUTHOR]

This paper investigates the no-load iron loss, on-load loss, and thermal performance of a high-speed surface-mounted permanent-magnet synchronous machine with an amorphous metal stator core (AMSC) and a titanium alloy retaining sleeve by numerical methods. The electromagnetic properties of the AMSC are tested by an experimental platform. The distributions of no-load iron loss, rated-load loss, and the thermal behavior of the motor are investigated under converter supply conditions. Finally, the loss and thermal performances of the prototype are tested and compared with the corresponding simulation results to verify the accuracy of the calculation results and the superiority of the prototype. [ABSTRACT FROM AUTHOR]

This paper presents a new numerical and experimental method of the electromagnetic vibration analysis of amorphous alloy (AA) permanent magnet synchronous machines (PMSMs) whose stator cores are made from AA materials. A numerical model which is used to calculate the electromagnetic vibration of AA PMSMs is developed on an experimental basis. Concerning the magnetic performance of AA cores greatly affected by stresses and the elasticity modulus parameters affected by the loose structure of AA cores, data for magnetostriction (MS) curve of AA materials and magnetization curve of AA-stacked core are obtained experimentally, and the elasticity modulus parameters are updated based on the modal testing of the AA-stacked core. The electromagnetic vibration of a 2.1 kW radial flux AA PMSM is analyzed using the proposed calculation method. The electromagnetic vibration of the AAPMSM under two different conditions, which are 1) only radial forces (RFs) and 2) both RFs and MS, is calculated, respectively; then, the effect of MS on the electromagnetic vibration of the AA PMSM is obtained. The accuracy of the calculation method is verified by comparing the calculated results with the experimental results. [ABSTRACT FROM AUTHOR]