Showing papers on "Magnetic circuit published in 2021"
TL;DR: A particular parallel-magnetic-circuit hybrid-excitation pattern consisting of the axial and radial magnetic paths is innovatively developed in the HEFS machine, which is an effective solution for improving the flux-regulation ability.
Abstract: This article proposes a novel hybrid-excitation flux-switching (HEFS) machine with axial partitioned stator (APS) arrangement, which can achieve the independent accommodation of armature winding and field-excitation winding, thus enhancing the field-excitation capability and improving the winding heat dissipation More importantly, a particular parallel-magnetic-circuit hybrid-excitation pattern consisting of the axial and radial magnetic paths is innovatively developed in the HEFS machine, which is an effective solution for improving the flux-regulation ability Consequently, the PMC-based flux-regulation principle is comprehensively illustrated Moreover, by investigating the flux-regulation characteristics of three structural feasible APS-HEFS topologies, the bilateral complementary structure is finally determined as the preferred option By using the multiobjective optimization method and the three-dimensional finite-element analysis (FEA), the dimensional parameter optimization design of the proposed machine is conducted, and the performance comparison with conventional HEFS counterparts is also carried out to prove the flux-regulation superiority of the proposed design Finally, a prototype is fabricated for experimental testing, and the measured results are in good agreement with the FEA, which verifies the validity of the proposed APS-HEFS topology and its theoretical flux-regulation principle analysis
76 citations
TL;DR: A novel multi-tooth hybrid-excited switched reluctance motor (MT-HESRM) with PMs placed between the end teeth of the adjacent modules, which has unique features in terms of high output power and torque with a negligible cogging torque is introduced.
Abstract: Permanent magnets (PMs) have been widely used in different types of electrical machines to improve their performance. This article introduces a novel multi-tooth hybrid-excited switched reluctance motor (MT-HESRM) with PMs placed between the end teeth of the adjacent modules. Thanks to the innovative method of embedding PMs, a unique design is developed. First, the operating principle of the motor is explained, and the magnetic circuit model of the motor is analyzed. The magnetic characteristics in terms of flux density, flux linkage, inductance, and torque are obtained and compared with those of its PM-less counterpart. The mathematical model of the reluctance and PM torques is presented. The reluctance and PM torques are decoupled using the finite-element analysis, and the torque contribution of the PMs is discussed. The steady-state operations of both motors with both current chopping and single-pulse controls are analyzed and compared under different speeds. Finally, both motors are manufactured, the laboratory tests are done, and the experimental results are extracted. Both the simulation and test results elucidate that the MT-HESRM, which has only three small PMs as auxiliary flux sources, has unique features in terms of high output power and torque with a negligible cogging torque.
43 citations
TL;DR: This article reviews the domain of soft magnetic materials suitable for handling large electrical power from grid frequency to high-frequency applications and elaborates the role of a transformer for one specific application.
40 citations
TL;DR: In this paper, an optimized magnetic coupler featuring with an orthogonal magnetic structure with a flexible soft magnetic core in receiver is proposed to ensure high efficiency and low-leakage magnetic flux interference.
Abstract: Design and fabrication of a wireless charging system, which includes a wireless charging base station and an unmanned aerial vehicle (UAV) with wireless charging capability is proposed for enlarging the UAV's working range. First, an optimized magnetic coupler featuring with an orthogonal magnetic structure with a flexible soft magnetic core in receiver is proposed to ensure high efficiency and low-leakage magnetic flux interference. Second, a wireless charging circuit topology and a closed-loop power controller implemented on the primary side are designed and analyzed in detail to maintain constant current/constant voltage charging for the UAV. Then, a wireless charging station with position correction aid device is developed, which can achieve high-precision alignment. A prototype of the UAV wireless charging system with the proposed magnetic structure, primary-side control, and position correction are built and tested. Experimental results show that the fabricated wireless charging system can deliver 87.4 W at a dc-to-battery efficiency of 87.3%, and the system is adapted autonomous charging of UAV.
35 citations
01 Jun 2021
TL;DR: In this paper, the authors proposed a transverse-flux tubular linear switched reluctance (TF-TLSR) machine for long-stroke applications, in which the armature windings are placed on the short primary, while the long secondary is made of only low-cost iron ring.
Abstract: This article proposes a novel transverse-flux tubular linear switched reluctance (TF-TLSR) machine for long-stroke applications, in which the armature windings are placed on the short primary, while the long secondary is made of only low-cost iron ring. The key for the proposed machine is to innovatively introduce the complementary tooth structure into the primary salient-pole design and equip the complementary machine unit configuration in the primary construction for the purpose of minimizing the force ripple. The principle of force ripple reduction by using these complementary structure configurations is illustrated in depth. The analytical calculations of the winding inductance and thrust force of the proposed machine are developed with the air-gap magnetic path modeling. By using the 3-D finite element analysis (3-D-FEA), the sensitivity study of two key structural parameters on the force characteristics is also carried out, based on which a satisfactory TF-TLSR machine is finally determined. Consequently, a prototype is fabricated for experimentation testing, and the FEA and experimental results are comparatively demonstrated, which verifies the validity of the design ideas of using a complementary concept for minimizing force ripple in the proposed machine.
35 citations
TL;DR: In this paper, a double-layer delta-type permanent magnet (PM) was employed for variable flux memory motors (VFMMs) for traction applications, and a prototype of a compact size VFMM was fabricated, and experiments were also carried out to investigate accuracy of magnetization characteristic analysis.
Abstract: This article consists of two important topics regarding variable flux memory motors (VFMMs). The first topic is magnetization characteristic analysis of VFMMs having a double-layer permanent magnet (PM). Two-dimensional simulations are executed to clarify relationship between magnetization characteristic and ratio of the double-layer PM. In addition, a prototype of a compact size VFMM is fabricated, and experiments are also carried out to investigate accuracy of magnetization characteristic analysis. The second topic is the proposed VFMM employing double-layer delta-type PM arrangements and extended flux barriers for traction applications. Conventional VFMMs have three critical issues, which are as follows: asymmetric positive and negative magnetizing current pulses, increase in the iron loss due to harmonics caused by demagnetized variable flux PMs (VPMs), and unintentional demagnetization of VPMs under load condition. The proposed VFMM can overcome the abovementioned problems by employing double-layer delta-type PM arrangements and extended flux barriers. In addition, the proposed VFMM achieves much higher efficiency than that of the target motor mounted in TOYOTA Prius fourth-generation over a wide operating range.
34 citations
TL;DR: In this paper, a topological structure of coreless permanent magnet synchronous machine (AFPMSM) is proposed, the magnetic circuit and the air-gap flux intensity are discussed in detail to improve stable operation of machine.
Abstract: The multi-disc axial flux permanent magnet synchronous machine (AFPMSM) can provide high fault tolerance capability in applications requiring high reliability. Firstly, a topological structure of coreless AFPMSM is proposed, the magnetic circuit and the air-gap flux intensity are discussed in detail to improve stable operation of machine in this paper. The relationship between air-gap flux density and the parameters of rotor are clarified respectively based on finite element algorithm (FEA). Furthermore, the winding structure and power driver topology with fault tolerance are presented. And the 3D FEA analyzes the operation characteristics and stress of the machine. Finally, the prototype is manufactured. The results are demonstrated that the torque output and fault tolerance performance is better.
27 citations
TL;DR: A new controllable leakage flux multilayer barrier permanent magnet (PM) motor is proposed by adopting a new design concept of controllables leakage flux, where the PMs are uniquely placed in the d-axis magnetic circuit of the synchronous reluctance motor (SynRM).
Abstract: In this article, a new controllable leakage flux multilayer barrier permanent magnet (PM) motor is proposed by adopting a new design concept of controllable leakage flux, where the PMs are uniquely placed in the d -axis magnetic circuit of the synchronous reluctance motor (SynRM). Compared to the conventional q -axis PM placement SynRM, the higher PM utilization and better flux-weakening capability can be obtained. For further comparison and verification, both of the controllable leakage flux multilayer barrier PM motor and the motor with traditional q -axis PM setting are designed. In addition, a multiobjective optimization method based on the correlation analysis method is proposed to obtain the optimized output torque and flux-weakening performances. Then, the performances of the two optimal motors are analyzed and compared in detail. Finally, two prototype motors are manufactured and tested. Both the theoretical and experimental analyses verify the effectiveness of the flux-weakening enhancement design and the proposed motor.
24 citations
TL;DR: In this paper, an active magnetic regenerator composed of eight porous beds of Gd/Gd-Y spheres, a two-pole magnetic circuit responsible for the magnetic field changes, a set of solenoid valves for flow control, and fan-supplied finned tube heat exchangers on the cold and hot sides of the wine cooler apparatus.
Abstract: This work presents the design and performance evaluation of a novel magnetic refrigeration unit capable of controlling the temperature of a 31-bottle wine cooler cabinet. The main components of the system are: an active magnetic regenerator composed of eight porous beds of Gd/Gd-Y spheres, a two-pole magnetic circuit responsible for the magnetic field changes, a set of solenoid valves for flow control, and fan-supplied finned tube heat exchangers on the cold and hot sides of the wine cooler apparatus. Synchronization of the magnetic field variation and fluid flow processes was performed using real-time magnetic field measurements. The system was capable of reaching a mean temperature of 10.8 o C inside the retrofitted wine cooler cabinet by generating 27.9 W of cooling capacity for an ambient temperature of 25 o C. The coefficient of performance and second-law efficiency for this operating point were estimated as 0.21 and 1.0%, respectively. When operating at a cabinet temperature of 12.5 o C, the coefficient of performance and second-law efficiency achieved by the magnetic system were 0.38 and 1.6%.
22 citations
TL;DR: A new hybrid reluctance machine is proposed, in which an integrated dual-layer PM source is introduced into stator slots, aiming to relieve dc saturation and, meanwhile, evoke flux modulation effect, and the torque density is improved distinctly, especially under relatively high current density.
Abstract: The reluctance machine with dc field coils in stator is an emerging brushless candidate for the in-wheel direct drive for its wide speed range and robust mechanical structure, while it suffers from relatively low torque density and efficiency, due to the poor excitation ability of dc field coils and worse extra dc saturation effect in the stator core. To address this issue, a new hybrid reluctance machine is proposed in this article, in which an integrated dual-layer PM source is introduced into stator slots, aiming to relieve dc saturation and, meanwhile, evoke flux modulation effect. In this way, the stator core utilization factor can be boosted due to dc saturation elimination by inner-layer slot permanent magnets (PM). On the other side, extra PM torque is generated by the flux modulation effect of outer-layer slot PMs. Hence, with synthetic assistance from dual-layer slot PMs, the torque density is improved distinctly especially under relatively high current density. Besides, slot PMs share a parallel magnetic circuit with dc field coils, which enables a bidirectional dc magnetization control for speed range extension. In this article, the proposed new topology is fully evaluated by both finite element (FE) analysis and prototype experiments.
20 citations
TL;DR: In this paper, a simplified phase-controlled switching strategy is proposed for three-phase unloaded transformer with Y-connected windings in the primary side, which can limit the inrush current under 46.7% of the captured maximum inrush currents.
Abstract: High inrush current severely threats the safe operation of the power system and transformers, which may lead to mal-operation of overcurrent protection device, internal short-circuit fault in transformers. Phase-controlled switching technology is an alternative method to reduce inrush current effectively by controlling the front-mounted circuit breaker (CB) to break or make at the predetermined phase angles of current or voltage. In this paper, a new simplified phase-controlled switching strategy is proposed for three-phase unloaded transformer with Y-connected windings in the primary side, which can limit the inrush current under 46.7% of the captured maximum inrush current. Meanwhile, this strategy is independent on the residual fluxes in the iron cores. The optimal making angle is obtained by theoretical analysis based on an equivalent circuit model of unloaded transformer. The comparison of the proposed method and the random switching approach is also presented with considering residual flux. A simulation model is established to calculate the amplitudes of inrush currents against various residual fluxes when using the proposed phase-controlled switching strategy and random switching method. The simulation results show that the proposed strategy can limit the inrush current under a low value. A test platform with high and low voltage instruments is built and some measurements are carried out. The experimental results are in good agreement with the theoretical analysis and simulation results, which verifies the effectiveness and practicability of the proposed strategy.
TL;DR: In this paper, a hybrid-PM variable-flux PMSM with series-parallel magnetic circuits is proposed for electric vehicle propulsion, and the electromagnetic performances of the proposed machine are analyzed and compared with the series-connected and parallel-connected variable-fluctuated PMSMs.
Abstract: The development of traditional permanent magnet synchronous machines (PMSMs) in electric vehicle (EV) industry is limited by the unalterable permanent magnet (PM) excitation field. Variable-flux PMSMs are considered as a good candidate for EV propulsion for their ability to operate in a wide speed range with high efficiency by manipulating the magnetization state dynamically. A novel hybrid-PM variable-flux PMSM with series–parallel magnetic circuits is proposed in this article. The structure and operating principle of the proposed machine are introduced. The electromagnetic performances of the proposed machine are analyzed and compared with the series-connected and parallel-connected variable-flux machines, and the proposed machine combines the advantages of these two kinds of machines. The inductance characteristics of the proposed machine are analyzed by frozen permeability method (FPM), and the variation laws of inductance are quite different in different magnetization states and load conditions. The torque capacity of the proposed machine is analyzed. The torque ripple can be significantly reduced and the output torque can be improved by properly applying flux-weakening control.
TL;DR: A new approach for modeling the electromagnets of the magnetic levitation (Maglev) vehicle Transrapid intending to effectively and efficiently represent the statics and the dynamics in a frequency range relevant for Maglev control design and for the use in mechatronic simulation models.
Abstract: This work provides a new approach for modeling the electromagnets of the magnetic levitation (Maglev) vehicle Transrapid intending to effectively and efficiently represent the statics and the dynamics in a frequency range relevant for Maglev control design and for the use in mechatronic simulation models. It includes the effects of magnetic reluctances, fringing and leakage flux, magnetic saturation, and eddy currents. The modeling follows a systematic approach by setting up the equivalent magnetic and electric circuits, and coupling the equations using Ampere’s circuital law and Faraday’s law of induction resulting in a system of differential algebraic equations. It allows to study effects occurring in the magnet design process or different operating points, resulting, e.g., from aerodynamic uplift, for which an extended validity range is needed. Since the computational effort of such models is significant, additionally, a numerical procedure for model reduction is presented yielding a simplified version, which possesses a nearly identical input–output behavior and is usable for control design or in large vehicle models. The proposed approach can be applied to any levitation or guidance magnet of the vehicle and is shown exemplarily for a Transrapid’s levitation magnet. The model is validated for the parameters of the latest Transrapid vehicle, called TR09, showing good correspondence with the measured static force-current-gap characteristics and the inductance.
TL;DR: Amorphous FeSiB/Ni-Zn ferrite soft magnetic composites (SMCs) with significantly improved permeability and core loss were fabricated in an external magnetic field during the compression molding as discussed by the authors.
TL;DR: A multiobjective optimization method is newly proposed which not only focuses on the magnet characteristics variation effect but also considers output torque, torque ripple as well as antidemagnetization capability under three typical operation conditions.
Abstract: In this paper, a parallel-series magnetic circuit multi-permanent magnet motor is designed and optimized considering magnet characteristic variation effects, where two kinds of PMs are utilized as co-magnetic. Based on the equivalent magnetic circuit method, the detailed design method for the multi-permanent magnet motor is illustrated. And considering the various operation conditions in potential EV applications, the B-H curves of two PMs of different typical operation conditions are obtained. Then, a multi-objective optimization method is newly proposed which not only focuses on the magnet characteristics variation effect, but also considers output torque, toque ripple as well as anti-demagnetization capability under three typical operation conditions. And the performance of the initial motor and optimal motor are compared under typical operation conditions. Finally, a prototype machine is built and tested. Both theoretical analysis and experimental results verify the validity of the motor and the proposed design optimization method.
02 Jun 2021
TL;DR: In this paper, a hybrid field analytical method for a recently developed hybrid-magnetic-circuit VFMM (HMC-VFMM), which combines the magnetic equivalent circuit (MEC) solution, the Schwarz-Christoffel (SC) transformation, and the subdomain model, is proposed.
Abstract: Variable flux memory machine (VFMM) is considered a promising solution for traction drives due to their distinctive merits of globally high efficiency over an extended operating range. However, the variable flux property of the low-coercive-force (LCF) permanent magnet (PM) together with an interior hybrid magnet rotor structure brings great challenges for the magnetic field modeling of VFMM. To address the above issues, this article proposes a new hybrid field analytical method for a recently developed hybrid-magnetic-circuit VFMM (HMC-VFMM), which combines the magnetic equivalent circuit (MEC) solution, the Schwarz–Christoffel (SC) transformation, and the subdomain model. First, the remanences of LCF PMs subject to different $d$ -axis magnetizing currents are determined by the MEC model, in which the nonlinear magnetic reluctances are calculated by the finite element (FE) model. Subsequently, the air-gap flux density distributions of the slotless stator model under different magnetization states (MSs) are predicted by adopting the open-circuit MEC model. Afterward, the relative permeance function is obtained by using SC transformation considering the stator slotting effect. Then, the no-load flux density distributions of the machine under different MSs are predicted by the proposed method. Besides, a subdomain model taking into account the armature reaction is employed to further obtain the torque characteristic of the machine. Finally, the effectiveness of the proposed method is verified by both FE simulations and test results.
TL;DR: In this paper, a novel structure featuring enhanced harmonic elimination capability is proposed to address the asymmetrical issue in magnetic-geared machines (MGMs), which employs modular structure and axially embedded permanent magnets to achieve symmetrical back electromotive force (EMF) waveforms and improved torque capability, respectively.
Abstract: This paper reveals the fundamental reason for the asymmetrical issue in magnetic-geared machines (MGMs) based on flux modulation theory. The analysis indicates that the magnetic circuits of three-phase windings in MGMs are inherently asymmetrical. This asymmetrical issue is even more severe in conventional consequent-pole MGMs (CP-MGMs) because of the more distorted magnetic field. Hence, to address the asymmetrical issue, a novel structure featuring enhanced harmonic elimination capability is proposed in this paper. Consequently, torque density can also be improved. In particular, the proposed CP-MGM employs modular structure and axially embedded permanent magnets (PMs) to achieve symmetrical back electromotive force (EMF) waveforms and improved torque capability, respectively. To further improve the electromagnetic performance of the proposed CP-MGM, the PM arc ratio and flux modulator width ratio are analytically designed, which provides a general design guideline for CP-MGMs. To illustrate the merits of the proposed CP-MGM, a few other MGMs are included for a fair comparison based on finite element analysis (FEA). Results show the proposed CP-MGM can achieve more symmetrical back EMF waveforms and lower torque ripple, as well as lower PM consumption and higher torque density, as compared with its MGM counterparts.
TL;DR: A new partitioned stator (PS) hybrid excitation (HE) machine with slot Halbach permanent magnet (PM) arrays with key difference of proposed machine is that Halbach PM arrays are employed in the inner stator slot openings, so that the parallel magnetic circuit between PM field and wound field is performed and the ratio of PM field short-circuited in theinner stator is effectively reduced.
Abstract: A new partitioned stator (PS) hybrid excitation (HE) machine with slot Halbach permanent magnet (PM) arrays is proposed in this paper. Due to the adoption of PS structure, its armature winding (AW) is located in the outer stator, and the PMs and the field winding (FW) are housed in the inner stator, thus the space utilization is significantly enhanced. The key difference of proposed machine is that Halbach PM arrays are employed in the inner stator slot openings, so that the parallel magnetic circuit between PM field and wound field is performed and the ratio of PM field short-circuited in the inner stator is effectively reduced. Thus a wider speed regulation region and a higher torque/power density can be achieved. Firstly, the configuration of proposed machine is described, based on which its operating principle is discussed. Then the electromagnetic performances are calculated and compared based on 2-dimensional finite element analysis (FEA). The results show that the torque can be improved by 76% with a similar magnetic field regulation ratio compared with an existing PS-HE machine with slot PMs. Finally, a prototype machine is built and tested to verify the analysis and FEA results.
TL;DR: In this paper, a distributed magnetic circuit method (DMCM) was proposed to solve the problem that coupled magnetic flux and saturation of active magnetic bearing (AMB) cannot be taken into account in the traditional magnetic circuit calculation method together.
Abstract: To solve the problem that coupled magnetic flux and saturation of active magnetic bearing (AMB) cannot be taken into account in the traditional magnetic circuit calculation method together, this paper proposes a novel analytical calculation method based on distributed magnetic circuit method (DMCM). First, a magnetic circuit model with multiple magnetic circuits is built, we can obtain the initial flux density of each section by magnetic circuit calculation. Next, the magnetomotive force (MMF) of each magnetic circuit is calculated by the B-H curve of the ferromagnetic material. Then, the air-gap flux density under each magnetic pole center is obtained by further iterative calculations according to the magnetic potential error. On the basis, the flux density distribution along the air-gap circumference is obtained by one-dimensional (1D) relative permeance function, and thus the bearing capacity is derived and a loss calculation method is introduced. Finally, the finite element method (FEM) and experimental results show that the proposed method is feasible and effective.
TL;DR: In this paper, the authors proposed an inrush current reduction strategy that combines prefluxing and controlled switching technology, which can reduce the inrush currents to 0.5 times rated current below in any situation where the residual flux is unknown and the core flux equalization effect are not obvious.
Abstract: Inrush current with high amplitude is generated when the transformer is energized. On the one hand, it will have a negative impact on the safety of the transformer itself, and even cause the relay protection to malfunction. On the other hand, it may reduce operation speed of the protection when there is slight fault because of the protection restraint criteria. Both aspects will affect grid security. Based on the generation mechanism of inrush current, this paper proposes an inrush current reduction strategy that combines prefluxing and controlled switching technology. By constructing an equivalent magnetic circuit model of the large-capacity three-phase transformer with a universal core structure, the analytical formulas of the magnetic flux at each stage of implementing the strategy are obtained, and then the parameters design method of this strategy is proposed. The accuracy of the theoretical analysis of magnetic flux is verified through the accurate simulation. Compared with common inrush current reduction strategies, this strategy can reduce the inrush current to 0.5 times rated current below in any situation where the residual flux is unknown and the “core flux equalization” effect are not obvious, avoiding the problem of residual flux measurement. Finally, in the case of the transformer differential protection, the influence of this strategy on the protection is analyzed from the perspective of theory and simulation, and it shows that it can improve the performance of various protections effectively.
TL;DR: In this article, an active magnetic bearing (AMB) with power electronic control for high-speed machinery, which are termed active magnetic bearings (AMBs), is presented, which is a contactless-type bearing, which uses magnetic force to support the rotor.
Abstract: This article reviews electromagnetic bearings with power electronic control for high-speed machinery, which are termed active magnetic bearings (AMBs). AMB is a contactless-type bearing, which uses magnetic force to support the rotor. This is suitable for high-speed applications, harsh operating conditions, and also clean environments. However, the AMB has nonlinear characteristics and is inherently unstable. Due to recent advancements in fast-switching power devices, high-switching-frequency power converters, high-bandwidth current control, nonlinear control strategies, advanced digital controllers, and sensors, AMBs have become promising for high-speed aerospace, industrial, and energy applications. This article contains a brief tutorial on the AMB, covering its operating principle, system-level block diagram, magnetic-circuit-based analysis, dynamic load due to rotor mass unbalance, load capacity, force slew rate, and response to large force disturbance. Furthermore, a design example of an eight-pole AMB with four excitation coils is presented to achieve a load capacity of 180 N. A preliminary design, based on magnetic circuit analysis, is seen to fall short in terms of load capacity. Iterative changes to the AMB dimensions achieve the required load capacity, but the characteristics are still nonlinear. Finite-element analyses bring out the effects of magnetic saturation on load capacity, linearity between force and current, force slew rate, and relationships between maximum force generated and AMB dimensions. An improved design procedure is presented to achieve both desired load capacity and linear characteristics, while balancing the compactness requirement. The improved design also achieves the desired slew rate besides faster response and improved stability.
TL;DR: In this article, an analytical model based on magnetic equivalent circuit (MEC) method is proposed to provide radial and tangential components of open-circuit magnetic field in the slotless air gap.
Abstract: To accurately and quickly predict the open-circuit air-gap magnetic field in interior permanent magnet synchronous machines (IPMSMs), an analytical model based on magnetic equivalent circuit (MEC) method is proposed. The analytical model can provide radial and tangential components of open-circuit magnetic field in the slotless air gap. The radial component is obtained from the MEC model, and the tangential component is obtained from boundary conditions of macroscopic equations. Then, a complex relative air-gap permeance is applied to take the effect of slots into account. As a result, an accurate solution of both radial and tangential components of the flux density in the slotted air gap is obtained. Additionally, the no-load back electromotive force (EMF) and cogging torque are calculated based on the open-circuit air-gap magnetic field. All the analytical results are verified by the finite element (FE) analysis and they are well matched. In the end, a direct measurement experiment of open-circuit air-gap magnetic field is proposed to verify the validity of both radial and tangential open-circuit air-gap magnetic fields.
TL;DR: In this article, a new axial-flux hybrid-excitation machine (AFHEM) with double consequent-pole rotors is proposed, which combines the high torque density of the AFPM machine and the flexible flux regulation of the hybrid excitation machine.
Abstract: In order to solve the problems of poor capacity and unsatisfactory efficiency of flux-weakening control for the axial-flux permanent magnet (AFPM) machines with surface-mounted permanent magnet (PM) rotor structure, a new axial-flux hybrid-excitation machine (AFHEM) with double consequent-pole rotors is proposed, which combines the high torque density of the AFPM machine and the flexible flux regulation of the hybrid excitation machine. It meets the stringent requirements of the distributed in-wheel motor electric drive vehicle for high efficiency and high torque density. The topology, principle, and basic electromagnetic properties of the new axial-flux hybrid-excitation in-wheel motor are presented in this article. Based on the complex magnetic circuit of the AFHEM, a 3-D equivalent magnetic network (EMN) model is established. The air-gap flux density, flux linkage, back EMF, torque, and fault tolerance ability of the motor are solved through the EMN model and compared with the 3-D finite element analysis (FEA) to verify its validity and correctness. It is hoped to form a rapid design method for the new type of motor with the complex structure of 3-D magnetic flux path property. Finally, based on the EMN model, the influences of the magnetic saturation on the excitation regulation capability of the proposed AFHEM are analyzed, which provides a guideline for the optimization design of the new AFHE in-wheel motor.
TL;DR: In this paper, the electromagnetic performance of two hybrid-magnetic-circuit variable flux memory machines (HMC-VFMMs) with different hybrid permanent magnet (PM) configurations was investigated and compared.
Abstract: This article investigates and compares the electromagnetic performance of two novel hybrid-magnetic-circuit variable flux memory machines (HMC-VFMMs) with different hybrid permanent magnet (PM) configurations. The investigated HMC-VFMMs are both geometrically characterized by a combination of series and parallel magnetic circuit topologies, but with different positions of series and parallel PM branches. The developed HMC design can combine the merits of wide flux adjustment range in parallel structure and excellent unintentional demagnetization withstand capability in series structure. The topologies, features, and working principles of the studied HMC-VFMMs with different hybrid magnet configurations are described, respectively. The magnetic circuit model is utilized to analytically reveal the performance metrics of the two machines. The electromagnetic characteristics of the radially magnetized (RM) and circumferentially magnetized LCF types of HMC-VFMMs are evaluated and compared by the finite-element method. Furthermore, the performance comparison of the proposed RM-type HMC-VFMM with a benchmark interior PM machine is conducted. The experiments on RM-type HMC-VFMM prototype with RM-structure are carried out to validate the FE analyses.
TL;DR: In this article, the authors proposed a novel robust and energy-efficient rad-hard latch based on a new C-element-based keeper, which is employed to design a highly reliable non-volatile magnetic latch using MTJ.
Abstract: By scaling down the technology node to the deep nanoscale, the vulnerability of digital circuits to radiation and the intensive increase of leakage power have become of concern. Accordingly, designing radiation-hardened (rad-hard) memory elements based on non-volatile devices such as magnetic tunnel junction (MTJ) is a promising approach to address these issues. This study proposes a novel robust and energy-efficient rad-hard latch based on a new C-element-based keeper. Moreover, the proposed rad-hard latch is employed to design a highly reliable non-volatile magnetic latch using MTJs. The proposed latches can also be exploited to form a rad-hard magnetic master–slave flip-flop. Simulations based on the 14 nm FinFET and the spin Hall effect (SHE)-assisted perpendicular MTJ models suggest that the proposed designs offer advantageous figures of merit over the prior works. Specifically, the proposed circuits offer up to 52% and 82% improvements in power and delay, respectively, when compared to their state-of-the-art counterparts. Moreover, Monte Carlo simulations validate the robust operation of the proposed design in the presence of process variations.
13 Feb 2021
TL;DR: Magnetic current sensors are used in switched-mode power supplies and motor drivers, where both galvanic isolation and wide bandwidth are desired and Hall-effect sensors are widely used.
Abstract: Magnetic current sensors are used in switched-mode power supplies and motor drivers, where both galvanic isolation and wide bandwidth (BW) are desired. In CMOS, Hall-effect sensors are widely used, but their resistance results in a fundamental trade-off between BW and resolution. Coils have a differentiating characteristic and so can achieve much wider BW and resolution, but cannot sense DC.
TL;DR: In this article, a variable stiffness torsional vibration absorber with a magnetorheological elastomer (MRE) as an intelligent controlling element is designed, and the modal analysis, frequency tracking scheme, and damping effects have been studied.
Abstract: . The semi-active torsional vibration absorber can effectively reduce the torsional vibration of the power-train system. In this paper, a new type of variable stiffness torsional vibration absorber with a magnetorheological elastomer (MRE) as an intelligent controlling element is designed, and the modal analysis, frequency-tracking scheme, and damping effects have been studied. A transient dynamic simulation is utilized to validate the rationality of the mechanical structure, the magnetic field parameters of the absorber are matched, and the magnetic circuit simulation analysis and the magnetic field supply analysis are carried out to verify the closed magnetic circuit. The principle prototype of the innovative vibration absorber is manufactured, the magnetic field strength of the absorber is tested by a Gauss meter, and the results show the efficacy of magnetizing the vibration absorber with a conductive slip ring by solving the magnetizing problem of the rotating parts of the vibration absorber. A special-purpose test rig with a torsional vibration exciter as a power source has been implemented. A comparative experiment has been carried out to test the frequency shift characteristics and authenticate the vibration-reduction effect of the new MRE torsional vibration absorber.
TL;DR: This article proposes a practical design guide for a linear electromagnetic actuator based on the concept of magnetic screw transmission, in which manufacturing and assembly technologies are investigated and different topologies are developed using the 3-D finite-element analysis aided design.
Abstract: This article proposes a practical design guide for a linear electromagnetic actuator based on the concept of magnetic screw transmission, in which manufacturing and assembly technologies are investigated. The surface-inserted design is first used to form a required helical-shape magnetic pole, which exhibits simple processing, high precision, and robust structure. Moreover, different topologies are developed using the 3-D finite-element analysis aided design, with the goal of optimizing thrust force. In addition, different number of permanent-magnet (PM) segments are first proposed to reduce the cogging effect. Afterward, the linear actuator integrates the rotary machine and the magnetic screw together to construct a compact design and decouples the magnetic circuits. The decoupling design focuses on the self-shielding effect of the Halbach PM array, and the special bearing supports are selected to avoid the eccentricity. Finally, a prototype is built using the developed techniques. Experiments are carried out on a linear test bench, verifying the theoretical analysis.
TL;DR: A novel dual-consequent-pole transverse flux motor and its analytical model are proposed, which improves the no-load permanent magnet flux linkage interlinking with armature winding, thus leading to an enhanced torque density.
Abstract: In this article, a novel dual-consequent-pole transverse flux motor and its analytical model are proposed. Differ from existed transverse flux machines, the proposed motor owns core-tooth-to-magnet types of the consequent-pole configuration on both stator and rotor. This unique motor configuration improves the no-load permanent magnet flux linkage interlinking with armature winding, thus leading to an enhanced torque density. The structure and working principle of the proposed motor are introduced as the first half part. Then, based on the combination of equivalent magnetic circuit method and subdomain method, an analytical modeling method is proposed to estimate the electromagnetic performance of the proposed motor. The parameters of the equivalent magnetic circuit model, e.g., the magnetomotive force and reluctances are calculated based on the subdomain model technique, considering the influence of the cores’ saturation and the axial end effect during calculation. Based on the magnetic field distribution result, the electromagnetic performance is estimated. The analytical results are verified by both the finite-element method and the prototype experiment.
10 May 2021
TL;DR: In this paper, a hybrid analytical model combining the subdomain method and the lumped-parameter magnetic circuit method (LMCM) is presented for the analysis of a high-torque-density spoke-type permanent magnet in-wheel motor considering rotor slot and eccentric magnetic pole.
Abstract: In this article, a hybrid analytical model combining the subdomain method and the lumped-parameter magnetic circuit method (LMCM) is presented for the analysis of a high-torque-density spoke-type permanent magnet in-wheel motor considering rotor slot and eccentric magnetic pole. In the proposed model, the air-gap field distribution is derived using the subdomain method, while the saturation and the axial flux leakage of the iron core are considered by LMCM. The rectangular-shaped spoke magnets, eccentric magnetic poles, and rotor slots are approximated by multiple layers of arc-shaped subdomains. The magnetic equivalent circuit (MEC) of the stator and rotor is established, and the nonlinearity of the iron core is taken into account. Based on the developed hybrid analytical model, electromagnetic performance, such as cogging torque, electromagnetic torque, flux linkage, and back electromotive force, are obtained. The analytical results are verified by the finite-element method, and its application in the optimization process is investigated. Finally, a 1800-Nm high-torque prototype machine is manufactured and tested, and the results validate the accuracy and efficiency of the analytical method.