With the rapid development of power electronic techniques and the increasing cost of permanent magnets (PMs) materials, switched reluctance motors (SRMs) have recently gained more attention. However, ...traditional SRMs have a relatively low torque density. For the sake of increasing the motor torque density, this paper proposes a novel segmental rotor type SRM. The proposed motor adopts hybrid stator poles and concentrated windings in the stator side and a segmental rotor structure in the rotor side, which is completely different from the structures of the traditional SRM. The special structure of the motor shortens the magnetic flux paths of the motor, separates the parts of the magnetic flux paths from one another, and eradicates the magnetic flux reversal in the motor stator in order to improve the electric utilization and output torque density of the motor. Meanwhile, the requirement of the magneto-motive force and the core loss of the motor is also decreased, thereby improving the efficiency of the motor. For the purpose of proving the proposed structure, the characteristics of the motor are analyzed using the finite element method and are compared to those of the traditional 12/8 SRM, which is designed for the same application. Moreover, the prototypes of the traditional 12/8 and proposed SRMs are manufactured, and experiments based on the prototypes are performed. Finally, the effectiveness of the structure of the proposed motor is further proven by the experimental results.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Switched reluctance machine (SRM) produces vibration and acoustic noise due to the significant torque ripple. The widespread use of SRM is thus limited. For the discussed axial-field dual-rotor ...segmented switched reluctance machine (ADS-SRM), this paper describes a proposal for a new rotor profile featured by the rotor segment splits. These splits minimize the undesired torque ripple. The effects of each geometric parameter, such as split width and split offset, are investigated using finite-element method (FEM). After optimizing the rotor-segment geometry, the approximately flat-top torque profile is achieved. The motion-coupled analysis further validates the effectiveness of this novel technique. It is found that, by incorporating the optimization of the turn-on and turn-off angles, the torque-ripple coefficient decreases by about 73%, from 0.995 to 0.27. However, the average torque decreases by only 4.2%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To deeply study the segmental rotor flux switching machine (SRFSM), an analytical subdomain model is first developed to achieve the magnetic field distribution and electromagnetic performance such as ...back-electromotive force (EMF), cogging torque, electromagnetic torque, unbalanced magnetic pull, and eddy current losses in the permanent magnet (PM) and rotor support. Then, the number of rotor segments is determined according to the magnetic field modulation theory, and the effect of rotor segment number on the amplitude and total harmonic distortion of speed-normalised back-EMF is investigated as well. Using the proposed analytical model, the magnetic field regulation capacity and PM demagnetisation withstand capacity of the series and parallel hybrid excited SRFSMs are investigated and compared. The PM and parallel hybrid excited SRFSM prototype machines with 12 stator slots and 7 rotor segments are manufactured and tested to validate the proposed analytical model.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
This study presents the design and analysis of the segmented rotor design for an electrical machine embedded onto the more electric aircraft gas turbine engine shaft. The high-speed operational ...environment imposes high stress levels due to centrifugal forces; thus, the feasibility of this segmented rotor topology for such application is explored and a suitable design is proposed to overcome mechanical stresses. Finite element structural analysis was performed to compare the mechanical behaviour of a different rotor segment fixing structure and the proposed design. Also, electromagnetic analysis is carried out on a high-speed switched reluctance machine to study the impact of a new design on machine electromagnetic performance.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
In this article, a targeted step skewing of rotor segments scheme is proposed to reveal the modulated vibration reduction mechanism in integral-slot interior permanent magnet synchronous machines ...(IPMSMs). First, the vibration characteristics of a 72-slot/12-pole integral-slot IPMSM are investigated. The dominant vibration at specific frequency band is introduced. Then, in order to analyze the main source of vibration, the magnetic field modulation effect and radial force modulation effect are investigated in detail. The results show that the high-order radial force can excite large vibration by radial force modulation effect. This kind of vibration is defined as modulated vibration. Afterwards, the optimal shift angle and number of rotor segments are determined by comparison. Finally, the conventional and proposed 72-slot/12-pole integral-slot IPMSMs are manufactured to validate the theoretical analysis. The experimental results verify that the proposed method can effectively reduce the modulated vibration of the 72-slot/12-pole integral-slot IPMSM.
Rotor excited flux-switching permanent magnet machines (REFSPMs) have been recently introduced exhibiting high power density and low permanent magnet consumption. Despite the advantages, 12/8 ...configuration of REFSPM has an intrinsic unbalanced voltage waveform due to the existence of even-order harmonics. Aiming to improve the machine voltage THD, using notches on the rotor segments is proposed. To study the effects of the rotor notch on machine performance with low computational time, the non-linear magnetic equivalent circuit is developed taking into account the effects of fringing fluxes, iron saturation, and rotor transition. An optimisation procedure based on Taguchi method is applied to minimise the voltage THD value taking the effects of uncontrollable factors into account. Finally, the REFSPM is prototyped and the measured results are compared with the analytical and numerical results.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Axial flux permanent magnet (AFPM) motors are widely applied in many applications due to their performance advantages. A novel AFPM which owns a special winding form (120-degree phase belt toroidal ...windings) and a distinct rotor structure (sinusoidal rotor segments) is proposed in this paper to further improve the torque density of this kind of machine. First, the structure and working principle of the 120-degree phase belt toroidal windings sinusoidal rotor segments AFPM interior synchronous motor (120D-TWSRSAFPMISM) are clarified. Then, the design formula and crucial parameters of the motor are presented. Subsequently, the cogging torque is optimized by dividing the magnet grouping. Finally, the characteristics of the 120D-TWSRSAFPMISM are analyzed and compared with those of the traditional toroidal windings sinusoidal rotor segments AFPMISM (T-TWSRSAFPMISM) and another T-TW motor without the sinusoidal rotor segments (T-TWAFPMISM) by finite element method (FEM). The results show that the 120D-TW can significantly increase the back electromotive force (EMF) compared with the T-TW, and the sinusoidal rotor segments can increase the air-gap flux density compared with the traditional interior rotor. Therefore, the 120D-TW and sinusoidal rotor segments are combined in the AFPM motor. This combination can further increase the torque density compared with the contrast motors.
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IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Dispersive mixing performance of special rotor segments, commercially named VCMT (various clearance mixing technology) in an intermeshing co-rotating twin-screw extruder has been studied using a ...numerical analysis method. Characteristics of residence time distribution of fluid have also been studied. In this study, the barrel was assumed to be fully filled with isothermal molten polymer and the properties of polypropylene were applied in the computation. Commercial computational software "POLYFLOW" was used and the particle tracking method was adopted for evaluation. As the evaluation index of dispersive mixing performance, maximum 1st principal stress was selected. The results were compared with those of two kinds of kneading disk (KD) segments. From the results, it is found that VCMT has better dispersive mixing and uniformity of residence time than KDs. Furthermore, for investigation of mixing mechanism, the observation of trajectories of characteristic particle groups in peak region of two dimensional probability distribution was proposed. One dimension was residence time and the other was the maximum 1st principal stress. We also suggested the relationships between mixing performance and the shape of mixing segments by focusing on maximum stress points of characteristic particle groups and flow fields around the point.
An intermeshing corotating twin-screw extruder is often used for producing polymer composites. In this study, we discussed mixing performance of special rotor segments in molten zone. These rotor ...segments have several tip clearances for achievement of self-cleaning and effective mixing, and these are named various clearance mixing technology. We studied about dispersive mixing performance of configuration, which consists of various clearance mixing technologys (various clearance mixing technology configuration) using numerical analyses and experiments. For the analytical evaluation of mixing performance, we have adopted a particle tracking method. As evaluation indices of dispersive mixing performance, we focused on following three values (1) maximum value in a history of first principal stress of each particle, (2) time-integrated shear rate of each particle, and (3) time-integrated first principal stress of each particle. And we made the probability distributions of the indices. We adopted weighted probability as approximation of volume probability in each region. The results were compared with those of kneading disk segments configuration (kneading disk configuration). Furthermore, we validated the accuracy of the analytical evaluation by performing experiments under same conditions as those of numerical analyses. For the experimental evaluation of mixing performance, we used twin-screw extruder. Polypropylene was selected as suspending media. And CaCO
3
was selected as filler. To compare just the mixing performance of various clearance mixing technology configuration with that of kneading disk configuration, side feeding and screw configuration which had third mixing segments zone were adopted. From the experimental result, it is found that various clearance mixing technology configuration dispersed better than kneading disk configuration. And from the comparison between the experimental evaluation and the analytical evaluation, it is found that the first principal stress is more appropriate for evaluation index of dispersive mixing. Finally, it can be mentioned that various clearance mixing technology configuration has better mixing performance than kneading disk configuration, and large stress is important for dispersive mixing.
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