Flux switching machines (FSMs) encompass unique features of conventional direct current machine, permanent magnet (PM) synchronous machine and switch reluctance machine. Permanent magnet FSM (PMFSM) is capable of high torque density and applicable for high-speed application, however conventional PMFSM exhibits demerits of high PM volume, high torque ripples and significant stator flux leakage. In this paper, a novel consequent pole E-core stator PMFSM is proposed and compared with conventional topology utilising 2D finite-element analysis (2D-FEA). Finite-element analysis revealed that proposed design enhanced flux modulation effects by introducing flux bridges and flux barriers as a result reduced cogging torque by reducing 46.53% of the total PM volume, reduce torque ripples by reducing PM slot effects and reduce flux leakage utilising flux bridges in the stator. Furthermore, analytical model for flux linkages, cogging torque, mechanical torque, no load and on-load magnetic flux density (MFD) is developed for initial design of conventional and proposed model. 2D analytical methodologies resolve equivalent magnetic circuits for open-circuit flux linkages, Fourier analysis for cogging torque, Laplace equations for MFD and Maxwell stress tensor for mechanical torque. Finally, results obtained from 2D-FEA and analytical methodologies are validated and compared.
Permanent Magnet Flux Switching Machines (PMFSMs) enclose unique features of permanent magnet (PM) synchronous machine, direct current machine, and switch reluctance machine therefore, applicable for high speed brushless AC applications. However, conventional PMFSMs exhibits demerits of high PM volume )(VPM, high torque ripples )(Trip, low average torque )(Tavg, lower torque density )(Tden, power density )(Pden and leakage flux. In this paper, a new topology of 12S‐13P and 6S‐13P E‐Core PM Consequent Pole Flux Switching Machines (PMCPFSM) with flux barrier and partitioned PM is proposed that eliminate leakage flux, enhanced flux modulation effects through flux barriers and reduces the PM volume up to 46.53%. Moreover, due to non‐linear behaviour of PM and complex stator structure alternate analytical sub‐domain model is utilized for initial design and Multi‐Variable Geometric Optimization (MVGO) is opted to investigate influence of design parameters on electromagnetic performances such as Tavg, Trip, Tden and Pden. Analysis and comparison with the existing 12S‐10P E‐Core PMFSM, 6S‐10P E‐Core PMFSM, 6S‐10P C‐Core PMFSM and 12S‐14P C‐Core PMCPFSM reveals that proposed 6S‐13P PMCPFSM produced Tavg higher up to 88.8%, suppress Trip maximum up to 14.72% and offer 2.45 times Tden and Pden capabilities, when compared with the aforesaid state of the art.
Computational complexity, magnetic saturation, complex stator structure and time consumption due to repeated iteration compels researchers to adopt alternate analytical model for initial design of electric machines especially Switched Flux Machine (SFM). To overcomes the abovesaid demerits, In this paper alternate analytical sub-domain model (SDM) for magnetic field computation in Segmented PM switched flux consequent pole machine (SPMSFCPM) with flux bridge and flux barriers accounting boundary and interface conditions, radial magnetized PMs (RM-PMs) and circumferential magnetized PMs (CM-PMs), interaction between stator slots and inner/outer rotor topologies is proposed. Overall field domain is divided into air gap, stator slots and Permanent Magnet (PM) accounting influence of CM/RM-PMs under no-load and on-load conditions. Analytical expression of field domain is obtained by solving magnetic vector potential utilizing Maxwell's equations. Based on the magnetic field computation especially no-load and on-load condition, Magnetic Flux Density (MFD) components, open-circuit flux linkage, mechanical torque and cogging torque are computed utilizing Maxwell Stress Tensor (MST) method. Moreover, developed analytical SDM is validated with globally accepted Finite Element Analysis (FEA) utilizing JMAG Commercial FEA Package v. 18.1 which shows good agreement with accuracy of ~98%. Hence, authors are confident to propose analytical SDM for initial design of SPMSFCPM to suppress computation time and complexity and eliminate requirements of expensive hardware and software tools.
In this paper counter rotating (CR) dual rotor permanent magnet flux switching generator (CR-DRPMFSG) is designed and relatively studied with co-rotating DRPMFSG (CoR-DRPMFSG) for wind turbine applications. The developed CR-DRPMFSG and CoR-DRPMFSG share same stator linked with flux bridge which provide flux route. A comprehensive relative assessment of both CR-DRPMFSG and CoR-DRPMFSG are presented with static attributes, over-load, and over-speed capability for generating output voltage, output current, output power, power density, losses, and efficiency. Comparative study with static characteristics illustrates that developed CR-DRPMFSG shows 34.34% elevated phase flux which improve output power, cumulative output torque is improved by 23.86%, and suppressed cogging torque by 66.87% at CoR-DRPMFSG that results lower pulsation in instantaneous torque. Furthermore, a detailed performance analysis is investigated with different number of armature winding turns per phase and combined over-load and over-speed capability. Study discloses that in contrast with CoR-DRPMFSG counterpart CR-DRPMFSG offer 27.17% higher output power that results 1.25 times power density at a good voltage regulation factor of 18.67%. In additional, despite of 2.27% improvement of efficiency in case of turns analysis and 4.81% increase in overload and overspeed capability, contour efficiency map unveils that CR-DRPMFSG offer wide range of higher efficiency operating region during over-load and over-speed conditions accompany with stable voltage with the varying load profile.
INDEX TERMSFlux switching machines, Ferrite permanent magnet, counter rotation, wind turbines, Wind power generator, Wind power application I.
PurposeThe purpose of this paper is to investigate an alternative simplified analytical approach for the design of electric machines. Numerical-based finite element method (FEM) is a powerful tool for accurate modelling and electromagnetic performance analysis of electric machines. However, computational complexity, magnetic saturation, complex stator structure and time consumption compel researchers to adopt alternate analytical model for initial design of electric machine especially flux switching machines (FSMs).Design/methodology/approachIn this paper, simplified lumped parameter magnetic equivalent circuit (LPMEC) model is presented for newly developed segmented PM consequent pole flux switching machine (SPMCPFSM). LPMEC model accounts influence of all machine parts for quarter of machine which helps to reduce computational complexity, computational time and drive storage without affecting overall accuracy. Furthermore, inductance calculation is performed in the rotor and stator frame of reference for accurate estimation of the self-inductance, mutual inductance and dq-axis inductance profile using park transformation.FindingsThe developed LPMEC model is validated with corresponding FEA using JMAG Commercial FEA Package v. 18.1 which shows good agreement with accuracy of ∼98.23%, and park transformation precisely estimates the inductance profile in rotor and stator frame of reference.Practical implicationsThe model is developed for high-speed brushless AC applications.Originality/valueThe proposed SPMCPFSM enhance electromagnetic performance owing to partitioned PMs configuration which make it different than conventional designs. Moreover, the developed LPMEC model reduces computational time by solving quarter of machine.
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