E-core Stator Research Articles

Design and comparative analysis of three-phase conventional and E-core stator hybrid reluctance motor for electric three-wheeler

Design and comparative analysis of three-phase conventional and E-core stator hybrid reluctance motor for electric three-wheeler

Performance Investigation of Consequent-Pole PM Machines With E-core and C-core Modular Stators

This article investigates some novel modular consequent pole PM machines (CPMs) with E-core and C-core stators. Different slot-pole number combinations including 12-slot/10-pole ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ns&gt;2p</i> ) and 12-slot/14-pole ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ns&lt;2p</i> ) have been investigated. Their static and dynamic electromagnetic performances have been investigated, e.g. the phase back-EMF, on-load torque, torque-speed curves, power factor-speed curves and also efficiency maps are compared. It is found that the existence of flux gaps (FGs) can improve the average torque of the 12-slot/14-pole E-core modular CPMs while the C-core structure can be a better candidate where relatively low torque ripple is desirable. Moreover, by selecting proper FG width, the 12-slot/14-pole E-core modular CPMs can achieve better flux-weakening capability and higher efficiency while the 12-slot/10-pole C-core modular CPMs can have higher power factors over the whole speed range. The finite element simulation results have been validated by a series of experiments using 12-slot/14-pole modular CPMs with both C-core and E-core stators.

Analytical validation of novel consequent pole E‐core stator permanent magnet flux switching machine

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.

Investigation of E-Core Modular Permanent Magnet Wind Turbine

Under the adverse trend of fossil energy attenuation and air pollution, wind power effectively alleviates the global energy crisis and environmental pollution. For wind turbines, especially large offshore wind turbines, their transportation, installation, and maintenance are very inconvenient. In order to solve this problem, this paper presents an E-core stator modular machine which inserts stator gap into the unwounded teeth of the fractional-slot concentrated winding (FSCW) permanent magnet (PM) machine. The winding factor of the new stator structure machine was derived. The electromagnetic models of 12-slot/10-pole and 12-slot/14-pole modular FSCW PM machines and traditional FSCW PM machines were established using the finite element analysis (FEA) software, and the open-circuit flux density, cogging torque, load torque, loss, and efficiency were simulated and analyzed. The results showed that the modular structure of E-core stator not only simplified the transportation, installation, and maintenance of wind turbines, but also optimized the electromagnetic performance of the 12-slot/14-pole machine, i.e., improved the output torque and operation efficiency.

A novel doubly salient electro-magnetic generator with symmetrical phase magnetic circuits: Basic topology, analysis, and experimental verification

The field winding of conventional multiphase doubly salient electro-magnetic generator is wound across multiple stator poles. There is a problem that the flux paths of the respective phases are not completely symmetrical. A novel E-core stator was proposed, the basic topology of the multi-phase E-core doubly salient electro-magnetic generator (E-core DSEG) with symmetrical phase magnetic circuits is derived by using the electrical formulas. This establishes a theoretical basis for the design of multiphase E-core DSEG. Based on the finite element simulation software, the static characteristics of multi-phase E-core DSEG were analyzed, including magnetic field distribution no-load electromotive force, flux linkage, self-inductance of field winding, cogging torque and so on. Finally, a prototype of three phases 18/20-pole generator was made and tested. The rationality of theoretical analysis and generator topology was verified by simulation and experiment.

Linear consequent pole Halbach array flux reversal machine

This paper presents a linear variable reluctance permanent magnet (LVRPM) machine where the armature winding and inset Halbach array permanent magnets (PMs) are mounted on E-core stators. The Halbach array consists of a vertically magnetised PM pole and a salient ferromagnetic iron pole (split tooth) sandwiched between two horizontal PMs. The translator consists solely of laminations with salient iron poles. As a variable reluctance machine, it exhibits inherent magnetic gearing and a higher force and power density than the conventional synchronous PM machines. Finite element analysis (FEA) has been used to investigate the effect of machine parameters. The logical development of the LVRPM from the more conventional Vernier Hybrid machine is presented, including a near 50% reduction in magnetic flux leakage and a higher flux per unit magnet mass.

Performance Improvement of Torque and Suspension Force for a Novel Five-Phase BFSPM Machine for Flywheel Energy Storage Systems

To improve the electromagnetic performance of the machine for a flywheel energy storage system, in this paper, a five-phase bearingless flux-switching permanent magnet machine with an E-core stator is presented. The topology and structure are introduced and the operation principle of the generation of torque and suspension force is also explained. Based on the simple variable method and overall trial and error method, the influence of the machine parameters on machine performance is investigated by using a finite element analysis. Then, the parameters are optimized. The results show the improvement of the torque and suspension force with increased amplitude and smaller fluctuation.

Design and Optimization of a Homopolar Permanent-Magnet Linear Tubular Motor Equipped With the E-Core Stator

In this study, a new homopolar permanent-magnet (PM) linear tubular motor is designed, analyzed and optimized. Firstly, a mechanical structure of the linear oscillating motor (LOM) is proposed and the main working principles are introduced. A basic dynamic mathematic model of the motor is given. Secondly, the magnetic circuit of the motor is analyzed and equivalent magnetic modes are obtained to estimate the magnetic characteristic and force outputs. Thirdly, optimizations including the tooth stricter of the E-core stator, the size of the PM and the air gap length are carried out to improve the force output performance of the motor, increasing force outputs and reducing force ripples during the stroke. Finally, the motor prototype is manufactured according to the design and experimental tests involving force outputs and working efficiency are measured. The average force output and efficiency of the motor can achieve 60 N and 67 %, respectively. Results obtained by finite element method (FEM) and experiments prove the correctness of the design and the effectiveness of the LOM.

Cogging Torque Minimization in Transverse Flux Machines

This paper presents the design considerations in cogging torque minimization in two types of transverse flux machines. The machines have a double stator-single rotor configuration with flux concentrating ferrite magnets. One of the machines has pole windings across each leg of an E-Core stator. Another machine has quasi-U-shaped stator cores and a ring winding. The flux in the stator back iron is transverse in both machines. Different methods of cogging torque minimization are investigated. Key methods of cogging torque minimization are identified and used as design variables for optimization using a design of experiments (DOEs) based on the Taguchi method. A multilevel DOE is proposed as an optimization method to reach an optimum solution with minimum simulations. The case study is analyzed in a two-level DOE optimization. Finite element analysis (FEA) is used to study the different effects. Two prototypes are fabricated for validating the FEA results.

Design of a Modular E-Core Flux Concentrating Transverse Flux Machine

In this paper, a novel E-Core transverse flux machine (TFM) is proposed. The machine has a double stator-single rotor configuration with flux concentrating ferrite magnets and pole windings across each leg of an E-Core stator. E-Core stators with the proposed flux-concentrating rotor arrangement result in better magnet utilization and higher torque density. The machine also has a modular structure facilitating simpler construction. This paper presents a single phase and a two-phase version of the E-Core machine. Case study for a 1 kW, 400 r/min machine for both the single phase and two-phase TFM is presented.

Comprehensive Research of Modular E-Core Stator Hybrid-Flux Switched Reluctance Motors With Segmented and Nonsegmented Rotors

Modular switched reluctance motors (MSRMs) normally have better characteristics than conventional SRMs (CSRMs) such as lower cost, higher torque production, stronger fault-tolerance, less loss, etc. This paper comprehensively investigates two hybrid-flux MSRMs with the same E-core stator, but different rotor configurations, termed as segmented-rotor MSRM (SR-MSRM) and nonsegmented rotor MSRM (NSR-MSRM), as well as compares with a CSRM. To evaluate the effects of different rotor topologies, the electromagnetic performances of two MSRMs and a CSRM with the same basic dimensions, including machine cost, flux distribution, static flux linkage, and torque, dynamic and transient operation performances are comprehensively analyzed and compared. The results based on finite-element analysis and Simulink indicate that the SR-MSRM has lowest steel consumption, highest torque production, highest power and torque densities, and strongest starting capability. Finally, three motor prototypes, including one SR-MSRM, one NSR-MSRM, and one CSRM are manufactured. The experimental results of static magnetic characteristics, dynamic and transient performances of three SRM drives confirm the predictions.

Magnetic circuit model and finite‐element analysis of a modular switched reluctance machine with E‐core stators and multi‐layer common rotors

This study presents a novel switched reluctance machine (SRM) with modular E-core stators and multi-layer common rotors for high reliability applications. The stator is composed of six independent modular E-cores with the windings wound around the yoke of the E-cores. The rotor consists of three magnetically independent common rotors which are place in the same shaft without any angular shift. The equivalent magnetic circuit (EMC) models of this new SRM at the aligned and unaligned positions are described. To evaluate the motor performance, two types of analysis, namely, approximate simplified two-dimensional (2D) model and 3D model finite-element analysis (FEA) have been utilised. The 2D FEA static and dynamic results are compared with 3D FEA results. Furthermore, comparisons between the novel modular SRM and a conventional 6/4 SRM are made. Finally, a prototype of this modular SRM has been fabricated and tested in the laboratory. Comparison between FEA and EMC analysis for flux linkage are made and compared with measured characteristics. The simulated and measured phase currents and average torque are also presented and compared to verify the analytical and simulation results.

Modular switched reluctance machine with E-core stators and segmental rotors for high reliability applications

In this paper a novel modular switched reluctance machine (SRM) with E-core stators and segmental rotors is presented. Unlike the conventional SRMs, there are hybrid radial and axial magnetic paths in the E-core stators due to the particular construction. An approximate and simplified 2D finite-element analysis (FEA) model is proposed to calculate its magnetic characteristics and compared with 3D FEA model results. A comparison of the static magnetic characteristic and dynamic performance between the modular SRM and a conventional SRM is made to emphasize the superiority of this novel SRM. Furthermore, the fault tolerant performance of this modular SRM under open-circuit faults is also presented. Finally, a prototype machine is built and tested in the laboratory. The flux linkage characteristics are experimentally obtained by indirect method and are compared with FEA results. Other experimental results such as single-pulse operation, closed-loop control operation, fault-tolerant operation at open-circuits and sudden change in load torque operation are also presented to validate the analytical and simulation results of the modular SRM and its performance.

Analysis of Two-phase E-core Switched Reluctance Machines Using Magnetic Equivalent Circuit Technique

The modification of magnetic structures for an E-core switched reluctance machine (SRM) comprising two segmented stator cores or a monolithic stator core is presented for ease of assembly, good manufacturability, mechanical robustness, and electromagnetic performance improvement. The E-core stator has four small poles with phase windings and two or four large poles (hereafter referred to as common poles), in between. The common poles are shared by both phases for positive torque generation during the entire operation. The E-core SRMs are compared to a conventional two-phase SRM. The comparison includes cost savings, torque, copper and core losses, and efficiency in order to validate the distinct features of the E-core SRMs. Magnetic equivalent circuit (MEC) technique is employed for proving the benefits of the E-core common-pole structure.

Novel Two-Phase Switched Reluctance Machine Using Common-Pole E-Core Structure: Concept, Analysis, and Experimental Verification

A novel two-phase switched reluctance machine (SRM) with a stator comprised of E-core structure having minimum stator core iron is proposed. The E-core stator has three poles with two poles at the ends having windings and with the center pole containing no copper windings. The center stator pole in the E-core is shared by both phases during operation. The air gap around the common pole has constant and minimum reluctance irrespective of rotor position by its unique design and the two remaining stator poles at the ends experience variable reluctance with respect to rotor position. The stator is constructed with two independent and physically separate E- cores and the rotor is comprised of ten poles. Other pole combinations are possible. Phase excitation in the novel SRM gives short flux paths, hence reducing the magnetomotive force (MMF) required to drive the machine resulting in significant reduction of copper wire and core-losses compared to existing two-phase SRMs with flux-paths that traverse the entire stator back iron. The concept and principle of operation of this novel SRM and its comparison and contrast to existing two-phase SRMs are detailed in this paper. Comparison between finite element simulations and magnetic equivalent circuit analysis for inductance are made and compared to experimentally measured characteristics. Furthermore, a comparison between a conventional two-phase SRM and the novel SRM is be made in terms of its weight and output torque. Manufacturability and cost savings of the unique SRM structure are presented. It is shown that E-core SRM using common-pole SRM has 50% less iron in the magnetic path compared to the conventional two- phase SRM.

New Designs of a Two-Phase E-Core Switched Reluctance Machine by Optimizing the Magnetic Structure for a Specific Application: Concept, Design, and Analysis

Three new magnetic structures for an E-core switched reluctance machine (SRM) comprising two segmented stator cores or a monolithic stator core are proposed for good manufacturability, mechanically robustness, ease of assembly, and electromagnetic-performance improvement. The E-core stator has four small poles with phase windings and two or four large poles (hereinafter referred to as common poles) in between. The common poles do not have copper windings or permanent magnets. The common poles are shared by both phases for positive-torque generation during the entire operation. The air gap around the common pole has constant and minimum reluctance, irrespective of rotor position, by its unique design, and the two small stator poles experience variable reluctance with respect to rotor position. The segmented stator can be constructed with two independent and physically separate E-shaped cores with L- or I-shaped yokes so that the straight back iron in the stator rather than the curved back iron is suitable for assembly with other parts like end bells or brackets. The monolithic stator also has an L-shaped yoke for the same reason, and the new E-core SRMs are designed by means of pole-arc optimization. The novel E-core SRMs are compared to a conventional two-phase SRM. The comparison includes cost savings, torque, copper and core losses, efficiency, and radial force in order to validate the distinct features of the E-core SRMs. For experimental verification, laboratory testing of a segmented E-core SRM is conducted, and the simulated and measured phase currents and voltages correlate well.