FE-Aided Synchronization Analysis of Line-Start Synchronous Reluctance Motors

Since line-start synchronous permanent magnet motors (LSPMs) entered the market, they have attracted research interest toward counterpart induction motors of low power-ratings. This paper reports an investigation of line-start synchronous reluctance motors (LS-SynRMs). LS-SynRMs has not been investigated as much as LSPMs have. A motor needs to maximize rotor saliency to achieve high efficiency and a high power-factor. This results in complicated rotor geometry because the rotor cage and multiple flux barriers share the same rotor space. This paper provides an approximate method based on steady state torque analysis by which to estimate the critical inertia of a LS-SynRM. A finite element analysis (FEA)-aided analytical approach to the approximation of steady state torque is proposed to replace the more typical approach based on equivalent circuit parameters. The critical inertia resulting from the proposed method is compared to the results obtained using the FEA.

A new robust control strategy for axial flux permanent magnet motor applied on legged lunar robots

Legged robots have the advantage of strong terrain adaptability in lunar exploration. A new robust controller is designed for axial flux permanent magnet motors applied on the legged lunar robots to diminish the disturbance from uncertainty and external circumstance. The theoretical verification is carried out through Lyapunov stability theory. The numerical simulation and real-time experiment are carried out to access the stability and dynamic property of the systems adopting the proposed controller. The results are compared with the traditional control strategies to demonstrate the advantages of the proposed controller. The new robust controller contributes to the dynamic stability of legged lunar robots and is also appropriate for the similar mechanical systems.

Direct Drive Applications: Possible Replacement of Rare-Earth Permanent Magnet Motors

This paper deals with the possibility to replace rare-earth permanent magnet (PM) motors in direct drive applications. According to previous researches, there are alternatives such as surface-mounted PM motors and spoke-type motors adopting Ferrite PMs, synchronous reluctance motors, with or without the assistance of low-energy PMs. Few studies have been carried out to compare all models at once, thus it is hard to choose which type motor is to be preferred as a valid alternative of rare-earth PM motors in direct drive applications. In this paper, the representative candidates listed above are analyzed and the results are compared with that of a rare-earth PM motor, which is considered as a reference motor. Additionally, the demagnetization phenomenon of the motors with Ferrite PMs is deeply analyzed because this kind of PM may be easily demagnetized by the stator flux. Finally, both strengths and weaknesses of each alternative motors are highlighted.

Performances analysis of interior permanent magnet motors having different rotor iron pole shapes

<p><span lang="EN-US">Interior permanent magnet motors (IPMMs) have been increasing in popularity, since the emergence of permanent magnet material with high energy products, i.e. rare earth permanent magnet material. This paper analyses the performances of IPMMs having different rotor iron pole shapes including eccentric, sinusoidal and sinusoidal with 3th order harmonic injected rotor pole arc shapes IPMMs. Cogging torque, static torque, torque ripple, torque-speed and power-speed curves of the mentioned motors have been compared. It must be noted that the mentioned motors have been designed with the same stator, PM shape and the same dimensions, in order to highlight the effect of the rotor pole arc shape on the performance of the such motors. Two-dimensional (2D) finite element analysis (FEA) has been utilized to design and analyze the mentioned machines. It has been found that rotor iron pole shape of the IPM has notably influence on the machine performance, practically on output electromagnetic torque and its ripple. The highest value of average electromagnetic torque as well as torque capability in the constant torque reign is delivered by 3th order harmonic injected rotor pole arc shapes machine, while the lowest torque ripple is obtained by the sinusoidal rotor pole arc machine.</span></p>

Analysis of Magnetic Forces in Axial-Flux Permanent-Magnet Motors with Rotor Eccentricity

In this study, an analytical model is established to efficiently compute the magnetic field and unbalanced magnetic pull (UMP) in axial-flux permanent-magnet motors (AFPMMs). The effects of stator slotting, end effect, and rotor eccentricity on the magnetic field and forces were investigated. Static and dynamic eccentricities are analyzed and considered in the model. An effective function of the air gap permeance was introduced for effect of the stator slots to compute the flux density. A specific coefficient function is defined to calculate the end effect. A Fourier transform is used to compute the variations of the permanent-magnet remanence and the air gap permeance due to the slotted stator opposite to a slotless stator. The unbalanced magnetic forces were evaluated as a function of the air gap magnetic field using analytical equations. The proposed analytical method dramatically reduces the model size and computational time. It can be applied to the analysis of AFPMMs and is much faster than the three-dimensional finite element method (FEM). By comparing with the obtained using the FEM, the model results are validated.

Brushless DC Permanent Magnet Motors State of the Art

The paper presents a study of the permanent magnet brushless DC machine, from two perspectives - from authors’ own experience in designing and manufacturing such motors, as well as from actual published research. Various constructive topologies and how they influence BLDC operation, windings used with emphasis on slot, concentrated windings, are also presented. The following part describes current techniques used for enhancing BLDC limited maximum speed, such as phase advance and dwell control, somewhat similar to flux weakening in AC permanent magnet brushless motors. The paper concludes with presentation of several methods used for sensing BLDC rotor position. Overall, the authors’ intention publishing this paper was to provide an insight regarding current BLDC development, as well as to assist in making documented choices when using BLDC in specific applications.

Optimization of Power Density of Axial Flux Permanent Magnet Brushless DC Motor for Electric Two-Wheeler

The main objective of this work is to optimize the power density of axial flux permanent magnet brushless dc (PMBLDC) motor based on genetic algorithm (GA) technique for performance improvement of electric 2-wheeler. Power density is one of the important performance parameter of motor as it significantly influences overall performance of electric 2-wheeler. Firstly, the rating of electric motor is determined according to the application requirements and vehicular dynamics. Axial flux PMBLDC motor of 250 W, 150 rpm is designed to fit in to the rim of electric 2-wheeler based on assumption of various design variables. The salient contribution of this work is to suggest the best combination of design variables with the application of GA optimization technique for power density optimization. Comparative performance analysis is carried out between initially designed motor and optimized motor. Finally, 3 dimensional (3-D) finite element analysis (FEA) is performed to verify the results obtained from design optimization. Results obtained from FEA fairly validates the initial design and optimized design. It is analyzed that the power density of motor is enhanced by 42.85 % with the proposed optimization technique. The proposed technique is implementable and complexity free. It may further be applied to the performance improvement of a non-linear design comprising different design variables. HIGHLIGHTS Axial flux permanent magnet motors are the most compatible in electric vehicle applications Power density is one of the important performance parameters of axial flux permanent magnet motors Optimization of power density improves drive range and overall performance of electric vehicle Influential design variables are identified based on parametric analysis and its optimization is carried out with an GA based optimization technique with an objective of power density optimization Proposed optimization technique is validated with finite element analysis GRAPHICAL ABSTRACT