With the trend toward electrification in the aerospace sector, oil-flooded high-speed permanent-magnet (PM) machines are gaining increasing attention for electric actuator applications due to their high power density and compactness. However, as operational speeds rise, viscous losses become dominant and critically affect machine performance and reliability, yet accurate prediction remains challenging due to complex flow regimes and limited high fidelity data. This paper presents a hybrid mode-data-driven approach for temperature-dependent viscous loss modeling of oil-flooded high-speed PM machines with coupled temperature-loss analysis. A transfer-learning-based neural network is developed to construct an accurate surrogate model by leveraging low-cost analytical data and limited high-fidelity computational fluid dynamics (CFD) samples. The proposed model captures the temperature-dependent viscous loss behavior and is further embedded into a temperature-aware performance evaluation framework in which oil temperature and viscous loss are updated iteratively. Finally, an oil-flooded high-speed PM machine is built to validate the proposed approach, and experimental results across a wide operating range confirm the accuracy and effectiveness of the proposed approach

Voltage-source-inverter (VSI) nonlinearity causes current distortion and degrades the accuracy of parameter identification and sensorless control in permanent magnet synchronous machine (PMSM) drives. This letter proposes a novel online estimation method for VSI nonlinearity voltage based on third-order generalized integrators (TOGIs). The impacts of limited current control bandwidth and phase misalignment on estimation accuracy are systematically investigated for the first time. To address these issues, the proposed method employs TOGIs to extract the sixth-order harmonic amplitudes from both the d-axis reference voltage ud,ref and the dead-time coefficient Dd, and easily estimates the nonlinearity voltage through their ratio, thereby enabling more accurate estimation by effectively eliminating errors induced by limited current control bandwidth and phase misalignment. Experimental results validate the effectiveness and superiority of the proposed method.

To improve optimization efficiency and torque performance of an asymmetric rotor hybrid interior permanent magnet synchronous machine (AR-HIPMSM), this paper proposes a novel surrogate model (SM)-based optimization method. First, an analytical model is established to determine the initial design and parameter ranges. The random forest algorithm identifies parameter importance from the finite element model (FEM) database based on Latin hypercube sampling. A fast computational SM is then created through a hybrid method that combines back propagation neural networks (BPNN) with particle swarm optimization (PSO), called PSO-BPNN. Subsequently, the genetic algorithm (GA) improved by sequential subspace optimization (SSO)—denoted as SSO-GA—is introduced to optimize torque performance based on PSO-BPNN model. Results indicate that the proposed PSO-BPNN and SSO-GA offer superior accuracy and optimization capability compared to mainstream methods. Compared to the direct optimization method based on FEM, the proposed method significantly improves optimization efficiency while increasing average torque and reducing torque ripple. Furthermore, the optimized AR-HIPMSM outperforms the conventional IPMSM in torque performance and PM cost. Finally, a prototype of the optimal AR-HIPMSM is manufactured and tested, validating the suitability of the proposed optimization method for PMSMs with complex rotor topologies.

This brief presents a new wireless mains-voltage-level DC motor fed by low-voltage DC source. At the secondary side, a control-free symmetrical voltage multiplier (SVM) is employed to provide high-gain and stable boosted voltage for the DC motor. A novel Hopf link structured coil system is specifically devised to achieve integrated and symmetrical single-input dual-output (SIDO) wireless power transfer (WPT). It serves to symmetrically energize SVM, thus providing a SVM output with low voltage ripple. Moreover, a new series/inductor-parallel-parallel (S/L-P-P) compensation is specially designed for the SIDO WPT system. The proposed wireless motor exhibits several merits, including full primary control, compact coil design, and steady, high output voltage with superior voltage gain. Compared to existing wireless motors, this work achieves notable motor terminal voltage and voltage gain—244.67 V and 10.2, respectively—with an efficiency of 88.55%.

Permanent magnet Vernier motors demonstrate high torque density characteristics, making them a promising candidate for low-speed direct drive applications. However, achieving high torque density and power factor requires excessive consumption of permanent magnets. This article investigates the topology of a Vernier motor with the combination of both rare earth and ferrite magnets, to achieve the goal of significantly reduced rare earth material. The working principle is modeled by using the combined subdomain and analytical method. Various slot/pole combinations are investigated and compared for optimal performance metrics. A comprehensive comparison is conducted between the proposed topology and conventional counterparts with rare-earth magnet. By using parallel magnetization for rare-earth and ferrite magnets, the proposed topology achieves high torque density of 32 N & centerdot;m/L, high power factor of 0.87 and high torque per unit of rare-earth magnet volume of 730 N & centerdot;m/L. A prototype is fabricated to verify the proposed assumption.

To effectively attenuate current ripple of the permanent magnet synchronous motor (PMSM), this paper proposes an enhanced active disturbance rejection control (EADRC) based on a dual error constraint observer with novel resonant controller (NRDEO). Within the proposed architecture, the dual error constraint observer (DEO) is designed to improve disturbance estimation performance by introducing an auxiliary error correction term on top of the conventional single error extended state observer. Meanwhile, a novel resonant controller (NRC), which is embedded in the disturbance estimation loop of the DEO, is developed to eliminate the resonant peak near the target frequency. With the direct current and alternating current disturbances accurately estimated, the feedback control law of EADRC is presented to effectively reject these disturbances. Furthermore, theoretical analysis comprehensively investigates the disturbance estimation and rejection capabilities, the convergence of the NRDEO, and the stability of the EADRC, which reveals that the proposed scheme can effectively enhance current dynamic performance and steady-state accuracy. Finally, the feasibility of the proposed scheme is evaluated on the PMSM experimental platform under various operational conditions.

Eddy current losses in motors and transformers are undesirable because they degrade energy efficiency. Several methods have been proposed to reduce it in additively manufactured (AM) soft magnetic materials but suffer from low design efficiency and reduced stacking factors. In this study, a novel laser-powder bed fusion (LPBF) method (i.e., Line-and-Space (L&S) structure) was proposed and demonstrated to enable the fabrication of ultra-thin laminated structures with high stacking factors and high design efficiency. Dimensional control of L&S structure was realized by only controlling LPBF scanning parameters of laser power, scanning speed, and hatching space, where a minimum “Line” thickness of ∼0.06 mm and stacking factors as high as ∼87% for ∼0.13 mm and ∼97% for ∼0.26 mm were achieved. Compared to bulk samples, L&S laminated structure revealed a substantial reduction in eddy current losses, where eddy current loss of the bulk sample was ∼46 times higher than that in L&S sample at an AC frequency of 1 kHz. Overall, the proposed L&S method represents a significant advancement in loss optimization of AM electrical steels by simultaneously achieving ultra-thin lamination, high stacking factor, and high design efficiency. This approach offers a practical and scalable solution for reducing eddy current losses in LPBF-fabricated motors and transformers.

In this paper, a nonlinear analytical model for no-load analysis of external-rotor permanent magnet machines is presented. In contrast to conventional subdomain analytical approaches, virtual equivalent current sheets are introduced to emulate the nonlinearity effects occurring at distinct stator regions, including the tooth tips, slot bottoms and slot openings, where the value of equivalent current sheets can be determined via magnetic circuit method. A comparative study against finite element analysis reveals that the nonlinear analytical model can rapidly and accurately calculate the key electromagnetic characteristics of the machine under no-load condition accounting for magnetic saturation. Furthermore, the reliability of this model is confirmed by experimental test obtained from a prototype, where the test results perfectly match the simulation results, validating the effectiveness of the method.

In conventional bearingless slice permanent magnet (PM) motors, the inherent DC-biased flux component often induces magnetic saturation, which detrimentally limits the suspension force density. To address this challenge, this paper proposes a novel stator-dual-PM (stator-DPM) bearingless slice motor that features saturation relieving capabilities, rotor angle decoupled suspension, and a disposable rotor structure. By incorporating PMs into the stator slots in addition to the yoke, the proposed topology effectively mitigates stator saturation and significantly enhances the suspension force density. First, the motor topology and operational principles are introduced. Subsequently, a magnetomotive force and permeance model is developed to analytically calculate the air-gap flux density, accounting for slotting effects. The electromagnetic performance is then evaluated and optimized through finite element analysis, demonstrating superior torque and suspension force characteristics compared to traditional stator-yoke-PM motors. Finally, a prototype is fabricated and tested to validate the feasibility of the proposed design and the accuracy of the theoretical models.

In wind power generation, stator modular technology for permanent magnet machines reduces manufacturing and transportation costs. Redundant teeth added at both ends of each module in the modular stator of the dual three-phase machine serve to reduce wear between the coils. However, current modular technologies do not fully decouple the two sets of windings, providing only physical isolation. This paper proposes a new stator structure where the effective teeth of each minimal unit are wound with only one phase winding. Electromagnetic performance under nor mal and open-circuit conditions, comparing 0° and 30° phase shifts, is analyzed. The 30° configuration performs better than 0° in both normal and open-circuit fault conditions, with a larger output torque. Finite element analysis results show minimal coupling between the two sets of windings, with mutual inductance nearly zero. Experimental verification on the prototype confirms the accuracy of the analysis.

Rotor topology optimization (TO) becomes a critical tool in interior permanent magnet (IPM) machine design for better performance and material utilization. Existing optimization methods mainly focus on electromagnetic performance, neglecting manufacturability during the optimization process. In this article, a novel derivative-free design method is proposed for rotor topology geometrical optimization of IPM machines, which can consider manufacturability robustness. Explicitly expressed elementary components (ECs) are developed for the representation of the material distribution. Projective transformation (PT) and Boolean operations are employed to improve the diversity of material distribution. Geometrical constraints are applied to guarantee the manufacturability without introducing additional computational burden. The comparisons between optimized results obtained from the proposed and conventional NGnet methods verify that the proposed method can effectively enhance the electromagnetic performance of IPM machines while securing manufacturability, using finite element analysis (FEA). A prototype has been manufactured and experimentally tested for validation.

Sensorless control of permanent magnet synchronous machine (PMSM) not only is susceptible to DC offset, high-order harmonics and inverter nonlinearity, etc., but also affected by the negative-sequence disturbance, which is rarely considered in conventional rotor flux observers. To deal with these issues, a reduced-order generalized integrator (ROGI) flux observer with positive and negative sequence separation (PNSS) is proposed to reduce the influences of those undesired disturbances and thereby improve the position estimation accuracy. First, the frequency response of ROGI-PNSS to different components is analyzed through bode diagrams. Then, the flux observer based on ROGI-PNSS is structured to eliminate the negative-sequence fundamental disturbances and achieve smooth estimation of rotor flux considering the speed reversal operation. In addition, an adaptive frequency-locked loop (FLL) with integrated speed estimation is introduced, which not only can work under both positive and negative speeds, but also exhibit better speed estimation accuracy. Finally, the feasibility and effectiveness of the proposed sensorless control method are verified through experiments on a PMSM prototype.

This paper proposes a low-voltage source powered wireless mains-voltage-level DC motor with bidirectional rotation capability. The mains-voltage-level DC motor under full load can be wirelessly driven by a low-voltage source, with fully primary-controlled speed and rotational direction. A novel secondary-side polarity-reversible voltage multiplier (PRVM) is proposed to simultaneously achieve voltage step-up and voltage polarity reversal for the mains-voltage-level DC motor, without requiring secondary-side signal coils, transformers, high-frequency isolated gate drivers, isolated auxiliary power supplies, or microcontroller units (MCUs). Furthermore, it is demonstrated that among all basic compensations, the series-parallel (SP) compensation is best suited for the wireless power transfer (WPT) module in this work considering PRVM characteristics. Among existing wireless DC motor examples, this system offers superior experimental records of 254.22-V motor terminal voltage and 10.6 voltage gain, with an efficiency of 84.43%. The efficiency of proposed PRVM reaches 95.80%, coupled with zero isolation complexity and a power density of 1.2112 W/cm3.

In the permanent magnet synchronous motor (PMSM) drive system, the electrolytic capacitorless (ECL) drive system uses small film capacitors instead of traditional electrolytic capacitors to improve the system’s lifetime, reduce system volume and cost. This paper first analyzes the angle estimation impact caused by the high power factor control and DC-link voltage fluctuation. Both DC offset and harmonics in estimated angle are apparent to IPMSM if still adopting traditional active flux observer. Secondly, to reduce DC offset and fluctuation in estimated angle, an extended state observer (ESO) with a double complex coefficient filter (DCCF) is proposed to compensate for active flux errors. Besides, its performance under parameter mismatches is investigated, which shows the control robustness can be effectively enhanced. Finally, the effectiveness of this proposed DCCF-ESO based active flux observer is verified by experiments.

This article proposes and implements a novel wireless Hall position signal detector with full primary control for wireless brushless direct current (BLDC) motors. The crucial aspect is to combine the standard Hall-effect position sensor with wireless sensor coils. The sensor coils possess functions of detector excitation and wireless information transfer (WIT) regulated by secondary-side bidirectional switches. A novel combination of unipolar, horizontal bipolar, vertical bipolar, and quadrupole coils is employed to achieve four-channel decoupling, thus realizing coil integration. A new snubber, consisting of two resistor-capacitor-diode (RCD) snubbers connected in antiparallel, is proposed to suppress the significant bidirectional voltage spikes across bidirectional switches. This detector possesses strong robustness against motor power and commutation as its excitation is independent from the wireless power transfer (WPT) channel of wireless BLDC. Besides, it enables extremely low delay since no complex commutation protocols like those in Bluetooth are involved. Moreover, its binary output signals can be directly recognized by the primary-side controller, not requiring additional algorithms or circuits for decoding or filtering. This detector holds the highest experimental speed record at 10 000 rpm among all existing wireless position sensors for wireless motors, with a delay of only 0.9% of the minimum Bluetooth communication latency.

This article proposes a stator-inset-permanent magnet (PM) bearingless slice motor, which is capable of producing a constant directional force with direct suspension current regardless of the rotor’s angular position. The motor allows for flexible combinations of stator tooth and PM/rotor pole pair combinations, providing enhanced torque/force capability. Initially, the motor topology and operational principle are introduced. The magnetomotive force and permeance model is developed to calculate the air-gap flux density analytically, taking into account both the PM and suspension excitation. Subsequently, the finite-element method is utilized to comparatively examine the torque capability and suspension force quality. Finally, a prototype is manufactured to validate the analysis.

Stator-permanent magnet (stator-PM) motor has garnered significant attention due to its high robustness, making it more suitable for operation in textile industry, small conveyor belt, tracked robot etc. However, the use of rare-Earth permanent magnets (PM) in such motors, while possessing desirable properties, comes with a high cost, limiting its widespread industrial application. In this article, a less rare-Earth flux reversal permanent magnet (FRPM) motor with integer slot distributed winding is proposed, which can significantly improve the utilization ratio of PM material. An orthogonal modulation analysis method is proposed to clarify the operation principle of the proposed FRPM motor. Utilizing this method, the harmonic distributions of radial and tangential magnetic fields generated by PM material and armature current can both be derived. Additionally, employing maxwell tensor method, the torque generated by each harmonic is calculated, which verifies that the static fundamental harmonic can also generate the main output torque. Furthermore, the multiobjective genetic algorithm method is applied to optimize the parameters. Three existing PM motors, namely one flux-switching PM motor and two conventional FRPM motors, are used to compare with the proposed motor. The results indicate that the proposed motor can reach higher torque with less PM consumption. Finally, a prototype is processed and tested to validate the correctness of the design and analysis.

Permanent magnet (PM) linear motor is widely used in the electromagnetic launch system due to the merits of high thrust and rapid response. Inheriting the advantages of linear motor, the PM arc-linear motor (PMAM) has been recognized as an eminent competitor for driving servo turntables and large telescope. This article designs a dual-PM excited PMAM (DPM-PMAM) having different PM arrangements and three-unit distributed complementary structure. Benefiting from the special stator-PM layouts, the DPM-PMAM exhibits the essential flux concentration effect, which contributes to enhance the torque capability. The motor topology and working principle of the studied DPM-PMAM are introduced. The feasible stator slot/rotor pole combinations and the major design parameters are optimized for improving electromagnetic performances. Then, the DPM-PMAM is quantitatively compared with the slot-PM excited PMAM (SPM-PMAM) and the yoke-PM excited PMAM (YPM-PMAM) based on the optimal designs. By comparison, it is found that the DPM-PMAM shows the improved average torque and good overload capability. Finally, the 2-D finite-element (FE) predicted results are validated by 3-D FE results.

In traditional electrical steel production oxide inclusions are conventionally perceived as deleterious elements for the functional and structural properties. The present work describes the fabrication of a high silicon content electrical steel alloy (Fe-6.5wt%Si) using directed energy deposition (DED), coupled with oxide inclusions to mitigate core energy losses. Abnormal Grain Growth (ABG) was observed after thermal post-processing at 1000 degrees C for 24 h (1000-24), together with the creation of oxide inclusions mainly around the grain boundaries. Magnetic properties were assessed through dynamic and quasi-static measurements for both as-printed (AP) and 1000-24 samples. The quasi-static analysis revealed hysteresis losses of 206.9 J/m3 for the AP and 19.02 J/m3 for the 1000-24, with maximum flux densities of 1.295 T and 1.031 T, at the magnetic field of 3000 A/m. Dynamic magnetic analysis demonstrated an improvement of 39.2% in the total core losses of the 1000-24 sample (2088.8 J/m3), compared to the AP sample (3436.9 J/m3). The microstructure of the 1000-24 sample revealed the formation of Goss texture via ABG, ultimately decreasing the static hysteresis loss. Furthermore, an improved electrical resistivity compare to conventional electrical steel alloys was demonstrated at 119 mu Scm for the 1000-24 sample, and 105 mu Scm for the AP sample. This work introduces a promising avenue to minimize core energy losses by incorporating oxide inclusions and ABG Goss texture in additively manufactured soft magneitc components after thermal post-processing.

In order to achieve fast convergence of the estimated state and improve the estimation accuracy, a fixed-time adaptive extended state observer (FAESO) is developed for electric motor drives within the active disturbance rejection control (ADRC) framework. First of all, an error adaptive arctangent function is introduced in the design of the FAESO to dynamically improve the lumped disturbance estimation performance of the motor mechanical dynamics. Then, the fixed-time convergence property of the studied FAESO is demonstrated based on the homogeneous theory and Lyapunov function. After the disturbance is estimated quickly and accurately, the error feedback control law is presented to achieve disturbance rejection of the speed loop. The proposed scheme improves the estimation accuracy and convergence rate and enhances the disturbance rejection performance. Finally, the validity and superiority of the proposed FAESO-based enhanced ADRC are verified through three sets of comparative simulation results.