This paper proposes a split-spoke-type vernier PM in-wheel (SSVPM-IW) motor for potential direct-drive applications. The key of this study is to utilize a biased-magnet topology, aiming at achieving high torque density and low torque ripple. First, the harmonic distribution coefficient of the first frequency airgap harmonics is defined to achieve the purpose of synchronically designing the multiple harmonics related to the torque. In addition, the relationship between the coefficient and torque performance is derived. Then, the effects of the PM topology and modulator design of stator and rotor on the harmonic distribution coefficient are discussed in detail. At the same time, the corresponding torque performance are also analyzed. And, the performances of the SSVPM-IW motor are evaluated, including the back-EMF, airgap flux density, torque performances, and so on. Finally, the results verify the validation of design and analysis of the proposed SSVPM-IW motor.

Pole-changing (PC) is an effective method to extend the speed range of electrical machines. However, when PC is applied to permanent magnet (PM) synchronous motors (PMSM), severe harmonic coupling exists between the two operation modes before and after PC, which distorts back-EMF, increases torque ripple and generates harmonic circulation. To solve this problem, this paper proposes a pole-changing permanent magnet synchronous motor (PC-PMSM), in which hybrid 60°/120° phase-belt windings are used before and after PC to realize harmonic decoupling between the two operation modes. More importantly, the low winding factor using the 120° phase-belt winding is converted into an advantage in reducing PM flux linkage and changing the characteristic current after PC operation, thus further improving the overall speed regulation capability. The effectiveness of the harmonic decoupling method and speed regulation capability of the proposed PC-PMSM are verified by finite element analysis and prototype experiments.

This paper proposes a collaborative design method for enhancing the power factor and torque of electric motors. First, the intrinsic relationship between flux linkage analysis of the permanent magnet (PM) and armature field and the power factor is explored. Then, the connection between flux linkage and harmonics is established, clarifying the mechanism for improving power factor and torque. Improvements are focused on the PM and permeance. Regarding the PM structure, employing a Y-shaped PM structure effectively increases PM utilization, reduces leakage flux at the outer ends, and enhances the PM flux linkage. Concerning permeance, stator tooth design is optimized to cooperatively improve permeance harmonics, reduce the non-working flux linkage of the armature field, and enhance the fundamental modulation wave of the armature field responsible for torque generation. This improves the power factor while maintaining motor torque. Finally, through PM structural design, the motor torque performance is optimized. Furthermore, the performance of the Y-shaped PM motor is evaluated. A prototype was manufactured and tested. Theoretical analysis and experimental results demonstrate the effectiveness of the proposed method to a significant extent.

An improved active disturbance rejection control (ADRC) strategy based on a differential compensation extended state observer (DC-ESO) is proposed to suppress speed ripple of permanent magnet hub motor (PMHM) under complex operating conditions. Based on the traditional extended state observer (ESO), the improved method differentiates the proportional correction term of the estimated speed and then compensates it into the correction term of the total estimated speed disturbance. The differential term can quickly adjust the estimated total perturbation at the initial stage of the perturbation change by feeding back the rate of change of the velocity error, realizing the composite correction of the estimated total perturbation by the proportional term and the differential term. Meanwhile, the corrected estimated total perturbation is fed forward to the control law, which realizes the decoupling of the system speed tracking performance and the anti-disturbance performance, and thus reduces the difficulty of parameter tuning. The method can realize accurate disturbance estimation and compensation without modifying the observer bandwidth, thus improving the speed stability of PMHM drive system. The theoretical analysis and experimental results verify the effectiveness of DC-ESO in terms of disturbance estimation accuracy and anti-disturbance performance.

This paper proposes a novel flux-controllable permanent magnet (FC-PM) motor design methodology. The core design is to achieve vibration and noise reduction through rotor magnetic source redistribution design while considering motor torque and magnetic regulation ability. An analytical magnetomotive force (MMF)-reluctance-circuit model is first established to reveal the vibration and noise mechanisms of the FC-PM motor under different leakage flux states. The harmonic evaluation factor is then defined to systematically identify the critical air-gap flux density components responsible for dominant radial forces via spatial-frequency analysis. These components are set as the design targets. By introducing the concept of magnetomotive force (MMF) superposition to investigate each PM contribution pattern, an improved rotor topology is developed to reshape the MMF waveform for targeted radial force suppression. Two prototype motors of the original and improved designs are manufactured and tested. Finite element analysis and experimental results collectively validate the proposed design method, demonstrating significant reductions in vibration and noise.

The sliding-mode observer (SMO) has been widely adopted in sensorless control systems of the five-phase permanent magnet synchronous motor (FP-PMSM) due to its simple structure and strong robustness. However, the internal and external uncertainties of SMO-based sensorless control strategies degrade the sensorless control accuracy of FP-PMSM under varying operation conditions. Currently, most studies fail to simultaneously account for both internal and external uncertainties, which limits the improvement in the estimation accuracy under multiple operation conditions. In this study, an autonomous sensorless control strategy of FP-PMSM considering operation uncertainties with dual control for exploration and exploitation (DCEE) is innovatively developed. First, an N -dimensional q -axis inductance estimator is designed to quantify and mitigate the external uncertainty from varying operation conditions, which can overcome limitations of traditional parameter identification. In addition, a new objective function is established to generate optimal sliding-mode gains under varying operation conditions, which can reduce the internal uncertainty of the sensorless control system. Therefore, by selecting sliding-mode gain autonomously according to varying operation conditions, internal and external uncertainties can be effectively decreased, which can improve sensorless control accuracy. Finally, effective improvement in sensorless control accuracy of FP-PMSM under varying operation conditions is verified through experiments.

Dual-active-bridge (DAB) converters have been widely adopted in DC microgrids due to their bidirectional power transfer capability and high power density. Under microgrid disturbances, DAB converters with conventional control exhibit poor dynamic performance and disturbance rejection capability. To alleviate this problem, a bandwidth-adaptive linear active disturbance rejection control (BA-LADRC) strategy is proposed in this paper. This strategy takes the converter output voltage error as the reference for bandwidth modulation, and introduces a sigmoid function into the linear active disturbance rejection controller (LADRC) to achieve smooth adjustment of the adaptive bandwidth parameters. A second-order low-pass filter is also incorporated into this strategy to suppress high-frequency error disturbances, improving the dynamic performance and disturbance rejection capability of the DAB converter. Furthermore, the Hurwitz stability criterion is employed to conduct a systematic stability analysis of the system. Finally, an experimental prototype is established. Comparisons among three different control strategies demonstrate that the voltage overshoot is reduced by approximately 56.25

Due to the strict synchronization performance requirements of the dual in-wheel motors distributed sensorless coordination control system, higher requirements for rotor position estimation and tracking accuracy of the corresponding in-wheel motor sensorless control are put forward. Yet, the estimation accuracy of the in-wheel motor sensorless control will be reduced by the uncertain interference under complex operating conditions, which will seriously affect synchronization performance. Most previous studies regarding coordination control may neglect the inherent limitations of sensorless systems, leading to the instability of system. In this article, a nonsmooth sensorless control strategy for the distributed dual in-wheel motors coordination drive system at zero/low speed is innovatively proposed, which is based on high-frequency voltage injection. First, a nonsmooth extended state observer is designed to improve the estimation accuracy and anti-interference performance of the sensorless control system. Additionally, a nonsmooth speed controller with disturbance observer feedback compensation is designed to improve the convergence performance of the sensorless coordination control. Therefore, the proposed algorithms for the dual in-wheel motor drive system have good estimation performance of the sensorless control, strong anti-disturbance capability, rapid transient response, as well as good synchronization performance under different operating conditions. The experimental results verify the feasibility and effectiveness of the proposed dual in-wheel motors sensorless coordination drive control strategy.

In order to further improve motor output torque, a harmonic-oriented design and analysis method is proposed for a dual-airgap flux modulated permanent magnet (FMPM) motor. In this paper, based on flux modulation theory, airgap flux harmonics are investigated, and the torque generation mechanism under different operation modes is analyzed in detail. Also, the leading airgap flux harmonics have a significant influence on the motor output torque. Then, numerical optimization methods are employed to specifically optimize key design parameters such as the tooth widths of inner and outer rotors, aiming to increase leading airgap flux harmonics under different operation modes. The results indicate that the motor performance following optimization demonstrates a significant enhancement in the effect of specific working harmonics, thereby improving the torque characteristics of the motor. The prototype was fabricated and tested, verifying the feasibility of the proposed DSFMPM motor and the effectiveness of the harmonic-oriented optimization design. This research not only elucidates the relationship between the mechanism of torque generation, airgap harmonics, and motor design parameters but also provides a new perspective and methodology for the design of efficient and high-performance dual-stator motors.

This article proposes a novel 2-D local hybrid computational method for permanent magnet (PM) machines, in which the airgap is divided into three distinct layers. The middle-layer is analytically modeled using a Fourier model as a connection domain, while the adjacent stator and rotor layers remain governed by the finite element method (FEM). By constraining the analytical boundaries entirely within the airgap region, severe permeability variations at the interface are avoided. Furthermore, a rigorous boundary coupling matrix is formulated to seamlessly connect the stationary and rotating domains. This cohesive formulation integrates the discrete Fourier transform (DFT) for Dirichlet condition extraction, analytical gradient edge integrals for Neumann condition enforcement, and FEM static condensation. Consequently, the boundary coupling problem of conventional hybrid methods is solved for PM motors, the multi-order harmonics is handled naturally by Fourier model, and the global matrix dimension is reduced compared with the conventional analytical-FEM hybrid method. Finally, the accuracy and efficiency of the proposed method are comprehensively verified by FEM and experimental measurements of a PM vernier machine (PMVM), demonstrating its superiority.

Abstract As the core power component in electric vehicle (EV) drive systems, motors directly determine dynamic performance and efficiency. Among various candidates, Interior Permanent Magnet Synchronous Motors (IPMSMs) have become the mainstream choice owing to their high power density and efficiency. Existing optimization approaches mainly focus on geometric parameters of stators, rotors, and permanent magnets. However, these methods often face high computational costs, dependence on initial designs, and limited generalization, thereby restricting efficiency and hindering the exploration of global optima. To address these limitations, this paper proposes an intelligent generative optimization framework for motor topology design by integrating machine learning and deep learning. First, latent variables are employed to uniformly encode topology features, and a Generative Adversarial Network (GAN) is trained to generate diverse topology images. Second, a Vision Transformer (ViT)-based regression model is constructed to predict key performance indicators of the generated topologies. Finally, the Non-dominated Sorting Genetic Algorithm II (NSGA-II) is applied to iteratively optimize latent variables, outputting Pareto-optimal solution sets. The proposed framework enables repeated invocation of trained models for topology generation, evaluation, and optimization. It efficiently produces both optimal designs and diverse candidate schemes tailored to user requirements. By unifying topology representation and integrating generative design, predictive modeling, and multi-objective optimization, this work establishes a novel paradigm for intelligent and efficient motor design in EV applications.

Owing to its high fault tolerance, stable low-speed high-torque output, and excellent sensorless operation capability, a fault-tolerant in-wheel motor with an obvious flux-intensifying effect is highly beneficial for distributed drive (DD) systems in new energy vehicles. However, the requirements for motor parameters imposed by good fault-tolerant performance and the motor's inherent characteristics differ from those for achieving obvious inverse salient characteristics. Consequently, there exist constraints and promotions among low-speed high-torque, fault tolerance, and sensorless operation, posing significant challenges to the design of such motors. Furthermore, existing research still lacks comprehensive flux-intensifying design criteria and guidance that systematically address these interrelated performance relationships. Hence, this article first establishes design criteria for such motors by clarifying the constraints and promotions among low-speed high-torque output, fault tolerance, and sensorless operation. On this basis, an innovative “Magnetic-Tolerance (MT) Cooperation” design concept is proposed. Through systematic optimization of the slot-pole combination, winding structure, and q-axis flux barriers, the sensorless performance is enhanced without compromising fault tolerance. Subsequently, a multi-objective optimization approach is applied to achieve an effective compromise among the inverse saliency ratio, torque performance, and comprehensive fault tolerance. As a result, the conflicts among these performances are significantly mitigated, enabling the motor to meet all design targets simultaneously. Finally, the simulation analysis and experimental tests verify the validity of the proposed method.

The linear active disturbance rejection control (LADRC) strategy, with its strong disturbance rejection and low reliance on an accurate system model, has been widely adopted in DC-DC converters. However, the control bandwidth parameter in the traditional LADRC is fixed, resulting in limited disturbance rejection capability of the converter under dynamic operating conditions. This paper proposes an adaptive linear active disturbance rejection control (A-LADRC) strategy for the asymmetric half-bridge (AHB) flyback converter. This strategy takes the output voltage error information of the converter as the basis of the control, establishes four distinct tracking phases in accordance with adaptive rules. Thus, it realizes the dynamic adjustment of the bandwidth parameters of both the observer and the controller. Meanwhile, it significantly improves the disturbance estimation capability of the observer, and effectively enhances the dynamic response and disturbance rejection performance of the output voltage of the converter. Theoretically, the stability and robustness of the closed-loop system are verified using the Routh-Hurwitz criterion and pole-zero map. Finally, experimental validation demonstrates that, under sudden load changes, the proposed strategy achieves an 84.3

In this article, the magnetic field modulation motors with V-shaped and I-shaped permanent magnet (PM) rotors are comparatively analyzed in terms of performance to provide the orientation for motor application, in which the key is to study and investigate the magnetomotive force (MMF) based on three key elements. First, to clarify the influence of MMF on motor performances, the modulation processes of the PM and armature MMFs are investigated and summarized. On this basis, three study and comparative cases considering different PM and armature fundamental MMFs are artfully proposed and conducted. Then, by means of finite element analysis (FEAs), the influences of magnetic fields on the motor performances, such as torque performance, overload capacity, back EMF, loss, and power factor, are comprehensively evaluated. In addition, some recommendations are provided for various motor applications according to specific requirements. Finally, a prototype motor with the V-shaped PM rotor is built and tested to verify the finite element predicted result.

Tractors have been one of the core pieces of equipment in the rapid transition towards electrification and intelligence in modern agriculture.Electric tractors can be the major direction in recent years,due to their zero emissions,high energy efficiency,and high precision.The distributed drive system with wheel-side motors can be used to further enhance the adaptability of electric tractors in complex terrain,such as high efficiency and precise control.Permanent magnet synchronous motors(known for their high-power density and reliability)can serve as the drive system.However,the cooperative control of dual wheel-side motors cannot fully meet the various agronomic requirements under complex terrain.Existing disturbances(like sudden soil variations and uneven loads)can easily lead to uneven ploughing depth and trajectory deviation,which seriously constrain the operational quality and efficiency.In this study,a coordinated drive control was proposed for the dual wheel-side motors of electric tractors using the load feedforward torque difference compensation with nonlinear predictive cooperative control(FTC-NPCC).Response speed and anti-interference were improved under variable working conditions.Current control was used as the motor torque equation.The intermediate conversion of voltage commands was eliminated to directly generate q axis current reference values,which were closely related to torque requirements.Thereby,the torque pulsations were effectively suppressed from the voltage error accumulation in the conventional system.The disturbance resistance was enhanced in the sliding mode load torque observer,where the feedforward compensation of disturbances was embedded in the obtained load torque into the control system.A feedforward compensation term was used to offset the load disturbances.The amplitude of the discontinuous terms was significantly reduced in the sliding mode control,thereby effectively suppressing chattering for the system's robustness.The control input was optimized in real time to adjust the q axis current reference value for the response speed.A nonlinear prediction cooperative control architecture was designed using torque difference compensation.Optimal torque difference commands were directly generated to effectively enhance the synchronization accuracy and disturbance rejection.An experimental platform was constructed to validate the effectiveness of the control strategy under multiple operations.Three control strategies were evaluated during the straight-line and curve driving tests:Strategy 1 was the PI-based cross-coupling control(PI-CCC),Strategy 2 was the load feedforward nonlinear predictive current-based cross-coupling control(FNPC-CCC),and Strategy 3 was the FTC-NPCC.The experimental results indicate that the FNPC-CCC reduced the synchronization error fluctuation from 3.47 to 2.37 r/min under straight-line driving with variable load conditions,which was reduced by 31.7％,compared with the PI-CCC.The synchronization error settling time was shortened from 4.3 to 3.1 s,which was reduced by 27.9％.Compared with the PI-CCC,the FTC-NPCC reduced the synchronization error fluctuation from 3.47 to 1.11 r/min,with a reduction of 68％;The synchronization error settling time was shortened from 4.3 s to 2.0 s,with a reduction of 53.4％.Under curve driving with variable load conditions,the FNPC-CCC reduced the synchronization error fluctuation from 6.11 to 2.61 r/min,with a reduction of 57.2％;The synchronization error settling time was shortened from 3.8 s to 3.2 s,with a reduction of 15.8％.The FTC-NPCC reduced the synchronization error fluctuation from 6.11 to 2.18 r/min,with the reduction of 64.3％;The synchronization error settling time was shortened from 3.8 s to 2.2 s,with the reduction of 42.1％.In conclusion,the FTC-NPCC significantly enhanced the cooperative control precision and disturbance resistance of the dual wheel-side motor system.The finding can provide an effective control approach for the high-precision and high-stability operation of electric tractors in complex field environments.

Existing model predictive speed control (MPSC) relies on the accuracy of the motor model and weight coefficients, making it difficult to meet the requirements of electric tractors under complex operating conditions. To address this issue, an ultra-local weightless model predictive speed control (ULW-MPSC) method is proposed in this paper. In the speed loop, this method adopts an ultra-local incremental prediction model to directly obtain the q-axis reference current. This eliminates the need for a load observer and ensures a fast motor response. Meanwhile, the proposed control strategy converts the speed tracking error into an improved speed term error in the cost function, unifying its time scale with that of the current. This resolves problems such as the degraded dynamic performance and robustness in traditional cost functions caused by inconsistent time scales of the constraint terms. Additionally, this feature removes the weight coefficients from the cost function, further enhancing the fast response capability of the motor under complex operating conditions. An experimental platform is established to achieve practical experimental verification of the proposed control strategy. The results indicate that, compared with field oriented control (FOC), the proposed strategy achieves superior performance. Under variable speed and load conditions, the steady-state ripple is reduced by up to 40

This paper investigates an aggregated design and optimization method for permanent magnet hub (PMH) motors, guided by permeance harmonics, to meet low-speed, high-torque requirements. The key lies in establishing the correlation between stator and rotor permeance harmonics and torque. Firstly, contribution equations describing the influence of stator and rotor permeance harmonics on torque are derived. It reveals that the contribution degree is affected by harmonic amplitude and phase. Then, the selection criteria for stator and rotor topology are formulated. The amplitude and phase characteristics of the permeance harmonic group are considered in criteria, which aim to achieve the aggregated design from a permeance harmonic perspective. Furthermore, based on the identified aggregated permeance harmonics, the airgap flux density harmonics directly linked to permeance harmonics are determined. Taking these harmonics as the goal, they are involved in the optimization process for high torque density. Sensitivity analysis and response surface analysis are adopted, respectively, to lock the design variables and their parameter ranges. Then, the motor topology with characteristics of high torque density is obtained through multi-objective optimization. Finally, a prototype experiment is conducted on the optimized PMH motor.

Conventional design of permanent magnet motor rotors follows a topology-first paradigm that requires repeated finite-element analysis (FEA) iterations separately for each candidate topology, resulting in low efficiency and strong topology dependence. To address these limitations, this paper proposes a requirement-driven motor topology generation (RMTG) framework that directly generates rotor topology designs under user-specified performance targets. The framework integrates a conditional generative adversarial network with a pre-trained, frozen parameter predictor to enforce consistency between the generated topology and the desired electromagnetic characteristics, and a coordinated stabilization strategy resolves the training instability introduced by performance conditioning. Trained on 40,000 rotor topology images across four IPMSM families, RMTG achieves R2 > 0.97 for all three performance parameters (average torque, torque ripple, and core loss) and 100% topology-type classification accuracy. Two fabricated prototypes further confirm close agreement (within 2% discrepancy) among generated designs, FEA, and experimental measurements, demonstrating that RMTG provides an efficient end-to-end path for requirement-driven cross-topology design of permanent magnet motors.

Five-phase flux-intensifying interior permanent magnet (FI-IPM) motors have the advantage of wide-speed regulation. To fully achieve the wide-speed regulation performance of five-phase FI-IPM motors, effective control strategies such as maximum torque per ampere (MTPA) and flux weakening (FW) need to be adopted. However, limitations of conventional MTPA and FW strategies, such as suboptimal reluctance torque utilization under extended speed ranges, can degrade the motor’s load capacity at medium and high speeds. Moreover, existing methods rely on an oversimplified constraint model, which leads to coarsely designed control commands. This undermines overall motor performance and restricts its operational range. To address these limitations, a novel dual-space control strategy is developed in this article. First, a dual-space maximum torque per peak ampere (DS-MTPPA) for optimized torque generation using third-harmonic currents in low-speed regions is proposed. In addition, a dual-space decoupling flux-weakening (DS-DFW) is promoted for speed extension at high speed. Thus, the load capacity and speed range are improved. The experimental validation confirms significant improvements in load capacity across constant-torque and constant-power regions by 7.5% and 6.7%, demonstrating effective wide-speed operation requirements.

In this article, an operating-mode-oriented collaborative vibration suppression methodology is proposed to suppress the vibration of permanent magnet brushless (PMBL) motors under wide open throttle (WOT) conditions. The WOT is naturally divided into two operating modes: maximum torque per ampere (MTPA) at low speed and flux weakening at high speed. Then, by constructing the correlation between the key radial electromagnetic force harmonics and the d -axis demagnetization current, it was clarified that the dominant vibration sources of the two operating modes are the electromagnetic force carrier harmonics force and (0, 6f(e)), (0, 12f(e)) electromagnetic force harmonics, respectively. For an extensive investigation, a 48-slot, 8-pole PMBL motor is chosen as a research example. Then, the vibration suppression methods of key harmonics reduction and carrier harmonics energy shifting are proposed. Next, the performances of the optimal PMBL motors are simulated to validate the proposed methodology. Finally, a prototype is fabricated and experimented. Both simulated and test results are presented to verify the validity of the theoretical analysis and design methodology.