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This paper presents the design, construction, and testing of a double-sided, dual airgap linear Vernier generator for wave energy conversion. Both the electromagnetic as well as mechanical design concepts are explored with a particular emphasis on the mechanical aspect given the fact that maintaining a dual airgap for this topology is challenging and has not been previously implemented.
This paper presents analysis of cogging torque and torque ripple according to unevenly magnetized magnet patterns in permanent magnet synchronous motor. In previous studies it has confirmed that non-uniformly magnetized permanent magnet causes unexpected increase of cogging torque and torque ripple because of slot harmonic components. However, these studies investigated insufficient number of irregular...
In order to reduce the permanent magnet (PM) volume and combine the advantages of in-wheel motor, a novel modular-stator outer-rotor flux-switching permanent-magnet motor (MSOR-FSPM) whose PM volume is half of that in conventional outer-rotor flux-switching permanent-magnet (COR-FSPM) motor is proposed. However, cogging torque and torque ripple of MSOR-FSPM motor are especially worse due to the inherent...
Permanent magnet track linear motor drives offer a cost-effective motion control solution in numerous industrial manufacturing processes, covering a wide range of material handling and conveyor applications. To further reduce the initial costs of a permanent magnet track linear motor drive system, discontinuous magnet tracks can be considered. However, in a discontinuous magnet track, the armature...
High torque density at low speed is one of the main characteristics of applications such as wind turbines and traction systems. Permanent magnet transverse flux machines exhibit this features owing to their high-energy magnetic flux, which is normal to current and motion vector. The machine's specific geometry magnifies cogging torque that further increases torque ripple, noise, and mechanical vibrations...
This paper presents the analysis of using segmented permanent magnet instead of single pole units on a synchronous generator. The main reason of using such solutions is the fact that smaller, simple shapes permanent magnets with standardized dimensions can easily be found on the market at low costs.
Periodic speed errors can occur in permanent magnet linear synchronous machines for two reasons: 1) a periodic reference signal; 2) cogging force and friction. For reducing such periodic errors, iterative learning control or repetitive control approaches, used in conjunction with more common control actions, can be strongly effective. However, the design of the stability filter, robustness filter...
The paper presents the results of field calculations of cogging torque of a 12-pole torque motor with an 18-slot stator. A constant angular velocity of the magnet and the same size gap between n-1 magnets were assumed. In these conditions, the effect of change of the nth gap between magnets on the cogging torque was tested. Due to considerable length of the machine the calculations were performed...
Two permanent magnet linear machines, i.e. partitioned stator flux reversal permanent magnet (PS-FRPM) and conventional switched flux permanent magnet (SFPM) linear machines, are compared, in terms of electromagnetic performance and demagnetization withstand capability. It is found that compared to the conventional SFPM linear machine, the PS-FRPM linear machine shows lower cogging force, higher thrust...
The paper includes simulation results of the Hybrid Excited Claw Pole Generator with skewed and non-skewed permanent magnets. The test machine has claw poles on two rotor sections, between which an excitation control coil is placed. The novelty of this machine is existence of non-skewed permanent magnets on claws of one part of the rotor and skewed permanent magnets on the second one. The paper presents...
Permanent magnet track linear motor drives are used in numerous industrial manufacturing processes covering a wide range of material handling and conveyor applications. A traditional solution is a permanent magnet linear motor (PMLM) in which the stationary part consists of permanent magnets and the moving part of the armature. To further reduce the initial costs of such a permanent magnet track linear...
Torque pulsation in permanent magnet synchronous motor impairs their performance in critical applications, particularly for direct-drive. A practical approach to compensation of selected torque harmonics is presented. The approach consists of two steps: identification of dominant torque harmonics (the cogging harmonics and the flux linkage harmonics) and cuckoo search algorithm to tune the compensation...
The aim of this study is to explore the possibility of using flux switching linear tubular machines in a free piston energy conversion (FPEC) system. In FPEC systems, acceleration and therefore speed are often relatively high, which impose to have a reduced number of poles, meanwhile the cogging force will be relatively high. In order to reduce the cogging force two techniques are combined. The analysis...
Flux reversal permanent magnet (FRPM) machine, with magnets mounted on or inserted into the stator, is favorable for the direct drive applications. In this paper, a novel FRPM machine with Ralbach array magnets in stator slot opening is proposed. While the magnets are moved to the slot opening, effective airgap length is reduced and slot area is enlarged. The analysis results indicates that the torque...
This paper reviews recent trends in the application of flux switching machines (FSMs) in industry, the variation in FSM designs and control strategies to achieve enhanced performance. FSMs offer advantages such as high torque density, high speed capability, ease of control and low vibration and acoustic noise compared with competing technologies. These features enable FSMs to be applied in transportation,...
Linear permanent magnet (LPM) machines are used in various fields. In order to generate high thrust force, the size of LPM machine becomes large. Then, magnetic geared linear motor (MGLM) has been proposed. MGLM realizes a high thrust force and downsizing. This paper proposes a new design of MGLM. In addition, two designs of magnetization direction, axial direction and radial direction, are compared...
In this paper, a proposed analytical model is introduced for acceptable optimization of an axial flux permanent magnet (AFPM) machines. Nowadays the finite-element model is one of the most powerful tool to analysis the electrical machine. However, sometimes this method can be very time-consuming for further optimization. Therefore, in this paper, a hybrid analytical model based on sub-domain algorithm...
The cogging torque of variable flux reluctance machines (VFRMs) is usually large, which will result in undesired vibrations and acoustic noises. This paper introduces several methods to reduce the cogging torque of VFRMs including asymmetrical rotor teeth, circumferential rotor teeth pairing, rotor teeth shaping and rotor dummy slots. First, the cogging torque of VFRMs are analytically calculated,...
Interior permanent magnet synchronous motor (IPMSM) has stronger reluctance torque and mechanical strength and better dynamic performance, being highly suitable for high-speed operation. Practically, the performance of IPMSM is dramatically influenced by various rotor structures. This paper studies a fractional-slot IPMSM and it is analyzed that how those parameters, such as the number of permanent...
This paper investigates methods of magnet mass reduction in linear flux switching permanent magnet (LFSPM) machines by introducing tapered consequent poles. Based on the finite element analysis (FEA) three different models are designed, investigated and compared. The obtained results indicate that by adopting the proposed tapered ferromagnetic poles a considerable saving of material cost and weight...
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