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This work examines minimization of cogging torque in surface mounted permanent magnet synchronous machines (SPMSM). Cogging torque arises due to magnetic interaction between slotted stator and permanent magnets at no load. Fractional slot winding machines have low value of cogging torque as dissimilar positions of the magnets increase the frequency of tooth harmonics. This work verifies two methods—...
In this paper, the design and analysis of a modified outer rotor PMA has been presented, which increases the efficiency and machine capacity by minimizing the cogging torque. The modified outer rotor type PMA will be suitable for extremely low-speed wind turbine based power generation system. The performances of the machine are analyzed by simulation using ANSOFT MAXWEL software, and the results are...
In this paper, the cogging torque in coaxial planetary magnetic gear (CPMG) is investigated. The known method for estimation the cogging torque fundamental frequency in permanent magnet synchronous machines is adapted to the double-rotor structure of the CPMG. The work shows how various design parameters affects the fundamental frequency of cogging torque. Particular attention is given to the relation...
This paper aims to design a Double Rotor Multi-Tooth Flux-Switching Generator (DR-FSG) with DC excitation suitable for wind power generation. The proposed design has one stator, two mechanically coupled rotors, and two armature winding groups. Each armature winding group is connected with a bridge rectifier. The outputs from the rectifier circuits are connected in series. The performance of the machine...
This paper presents the analysis and compensation of cogging torque in the permanent magnet synchronous motor (PMSM). A magnetic circuit is used to derive the mathematical model of the system. This paper considers the following compensation methods: (i) feedforward controller, (ii) disturbance observer-based controller, and (iii) doubly coprime factorization controller, to attenuate the disturbance...
This paper presents the performance analysis and improvement of electric power generation for Oscillating Water Colum (OWC) wave energy converter using Finite Element Analysis (FEA). The existing power take-off system in OWC is based on induction machines which not only suffer from poor efficiency but require significant maintenance also. Conversely, synchronous permanent magnet (PM) generators offer...
This paper presents a double-stator permanent magnet brushless DC machine (DS-PMBLDC) which is proposed to be used in light electric vehicles and to replace a typical motor for electric vehicles in future. However, to fulfill the limitation of motor performance at different conditions, electric vehicles require their own specific motor design. Thus, a modular type of motor which can easily replace...
Cogging torque is a common design issue in Permanent Magnet Synchronous Machines (PMSMs). Altering the magnet shape is one of the solutions in reducing the cogging torque. This paper addresses the variation in the rotor magnet pole arc which would affect the cogging torque of the external rotor permanent magnet synchronous motor (ERPMSM). Analytical calculations to design a three-phase, 12slot/8pole...
This paper proposes a new modular arc-linear flux-switching permanent magnet motor (MAL-FSPM) used for directly driving objects rotate back and force within a limited angle. Due to double salient effect and end effect, cogging torque of MAL-FSPM is very high, especially for rotor end meeting stator end. A novel cogging torque reduction method is proposed. New structure of MAL-FSPM is established based...
A novel E-core transverse-flux permanent magnet linear motor (TFPMLM) is proposed in this paper. Firstly, the operational principle and structural advantages of the TFPMLM are presented. Then it is simplified equivalently to one that can be resolved by Schwarz-Christoffel (SC) transformation to obtain its no-load characteristics such as flux density, PM flux linkage and cogging force instead of time-consuming...
A 3D analytical model is developed for the computation of the no-load magnetic field distribution in flux reversal linear-rotary permanent magnet actuator (FR-LRPMA) with two PM poles (PM_pole) and two ferromagnetic poles (Fe_pole) on each stator tooth. Then a 3D model for calculating the air-gap permeance is presented considering the effect of stator slot and the permeance difference of Fe_pole and...
An improved configuration of flux-reversal permanent magnet (FRPM) machines is proposed by introducing a small air-gap between two adjacent magnets belonging to the same stator tooth to reduce cogging torque. A magneto-motive-force (MMF)-permeance model is employed to derive the analytical expression of cogging torque for FRPM machines, which takes the small air-gap into consideration. According to...
This paper proposes flux switching permanent magnet machines (FSPMMs) with improved performance for robot applications. The phase-group concentrated-coil (PGCC) windings are adopted for high torque density. The influence of the combinations of stator-rotor poles on machine performance are studied, and the model with 12 slots and 13 poles (12S13P) is chosen for the highest torque. Then, to reduce cogging...
This paper focuses on design analysis issues of direct driven permanent magnet synchronous generator (DDPMSG) which are widely used in large scale wind turbines. The permanent magnet synchronous generator (PMSG) of 1.5 MW output power which is driven directly without gear system is analyzed by Maxwell 2D RMxprt. The characteristics of generator include the cogging torque, induced coil voltages at...
This paper proposes methods of parameters calculation of single-phase flux-switching permanent-magnet (S_FSPM) machine, in terms of copper loss property. The purpose of the study is to improve efficiency of S_FSPM through loss minimization by a mathematical design optimization approach. Furthermore, Influence of the asymmetry of airgap of a S_FSPM is investigated by finite-element analysis with particular...
An Outer-PM tubular linear generator has been designed to increase the power density and distance of relative movement. The design of the two buoys has been completed. Detailed design process of the proposed generator is described. Considering the cogging force and voltage, the linear generator has been optimized and final parameters have been determined. The integrated wave converter system has been...
The paper presents the optimization and comparison of different rotor design concepts of an Electrically Controlled Permanent Magnet Excited Synchronous Machine (ECPMSM) possessing a field control capability. The experimental results of a no-load back electromotive force (back-EMF) waveforms, cogging torque and electromagnetic torque values are presented in detail. Moreover, in order to compare the...
This paper proposes a multi-step design and optimization strategy to minimize torque pulsations in a spoke-type PM motor with phase-group concentrated-coil windings. Different from the conventional techniques that work on the motor itself, in the first step (interim model I), an auxiliary inner stator is adopted to suppress the torque pulsations. In the second step (interim model II), the optimization...
Linear vernier permanent magnet machines (LVPMMs) for direct-drive servo applications are attracting more and more attentions due to its high force density, easy maintenance, rapid dynamic response, etc. This paper proposes a new LVPMM structure which has a similar secondary as that of a regular linear PM machine, while its primary mover is composed of three modules, which are separated by flux barriers...
This paper presents a performance comparison of dual airgap and single airgap spoke-type Vernier permanent magnet machines (VPMMs). The dual airgap VPMM adopts the topologies with dual stator windings (DSW) and single stator windings (SSW). The key point is to demonstrate that the dual airgap VPMM with SSW could maintain better torque performance as compared to the VPMM with DSW, but greatly release...
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