Search Results (132)

The lower-limb assistance exoskeleton is increasingly being utilized in various fields due to its excellent performance in human body assistance. As a crucial component of robots, the joint is expected to be designed with a high-output torque to support hip and knee movement, and lightweight to enhance user experience. Contrasted with the elastic actuation with harmonic drive and other flexible transmission, the non-elastic quasi-direct actuation is more promising to be applied in exoskeleton due to its advanced dynamic performance and lightweight feature. Moreover, robot joints are commonly driven electrically, especially by a permanent magnet synchronous motor which is rapidly developed because of its compact structure and powerful output. Based on different topological structures, numerous research focus on torque density, ripple torque suppression, efficiency improvement, and thermal management to improve motor performance. Furthermore, the elaborated joint with powerful motors should be controlled compliantly to improve flexibility and interaction, and therefore, popular complaint control algorithms like impedance and admittance controls are discussed in this paper. Through the review and analysis of the integrated design from mechanism structure to control algorithm, it is expected to indicate developmental prospects of lower-limb assistance exoskeleton joints with optimized performance. Full article

Rapid progress in lithium-ion batteries and AI-powered autonomous driving is poised to propel electric vehicles to a 50% share of the global automotive market by the year 2035. Today, there is a major focus on recycling electric vehicle motors, particularly on extracting rare earth elements (REEs) from NdFeB permanent magnets (PMs). This research is based on a single-furnace process concept designed to separate metal components within PM motors by exploiting the varying melting points of the constituent materials, simultaneously extracting REEs present within the PMs and transferring them into the slag phase. Thermodynamic modeling, via Factsage Equilib stream calculations, optimized the experimental process. Simulated materials substituted the PM motor, which optimized modeling-directed melting within an induction furnace. The 2FeO·SiO₂ fayalite flux can oxidize rare earth elements, resulting in slag. The neodymium oxidation reaction by fayalite exhibits a ΔG° of −427 kJ when subjected to an oxygen partial pressure ($P_{O_2}$) of 1.8 × 10⁻⁹, which is lower than that required for FeO decomposition. Concerning the FeO–SiO₂ system, neodymium, in Nd³⁺, exhibits a strong bonding with the ${\mathrm{S}\mathrm{i}\mathrm{O}}_4^{4^{-}}$ matrix, leading to its incorporation within the slag as the silicate compound, Nd₂Si₂O₇. When 30 wt.% fayalite flux was added, the resulting experiment yielded a neodymium extraction degree of 91%, showcasing the effectiveness of this fluxing agent in the extraction process. Full article

The proliferation of electric vehicle (EV) racing competitions, such as Formula electric vehicle (FEV) competitions, has intensified the quest for high-performance electric propulsion systems. High-speed permanent magnet synchronous motors (PMSMs) for FEVs necessitate an optimized control strategy that adeptly manages the complex interplay between electromagnetic torque production and minimal power loss, ensuring peak operational efficiency and performance stability across the full speed range. This paper delves into the optimization of high-speed PMSM, pivotal for its application in FEVs. It begins with a thorough overview of the FEV motor’s basic principles, followed by the derivation of a detailed mathematical model that lays the groundwork for subsequent analyses. Utilizing MATLAB/Simulink, a simulation model of the motor drive system was constructed. The proposed strategy synergizes the principles of maximum torque per ampere (MTPA) with the flux weakening control technique instead of conventional zero direct axis current (ZDAC), aiming to push the boundaries of motor performance while navigating the inherent limitations of high-speed operation. Covariance matrix adaptation evolution strategy (CMA-ES) was deployed to determine the optimal d-q axis current ratio achieving maximum operating torque without overdesign problems. The implementation of the optimized control strategy was rigorously tested on the simulation model, with subsequent validation conducted on a real test bench setup. The outcomes of the proposed technique reveal that the tailored control strategy significantly elevates motor torque performance by almost 22%, marking a pivotal advancement in the domain of high-speed PMSM. Full article

Thanks to the magnetic field modulation effect, the magnetic field modulation motor (MFMM) significantly improves torque density and magnetic field harmonic utilization by breaking the constraints of traditional motor excitation and armature pole number matching. This advantage enhances its development potential in fields such as new energy vehicles, aerospace, power generation, and the military. This article first starts with the basic principle of magnetic field modulation, and adopts the excitation unit position classification method to systematically summarize the evolution laws of major MFMM topology structures such as the permanent magnet synchronous motor, switch magnetic flux motor, and flux reversal motor in recent years. It also analyzes the research progress of key performance such as the torque characteristics and power factor of these motors. Research has pointed out that the MFMM still faces core challenges such as high torque ripple, complex structure, low power factor, and multiple losses. Based on a review of the main achievements in the field, the future development direction of MFMMs is proposed to promote its development in the fields of precision drive and efficient energy conversion. Full article

This article analyses the potential use of a Line-Start Permanent-Magnet Synchronous Motor (LSPMSM) in a drive system with a frequency converter that enables stable operation without internal feedback from the rotor position. In Fault-Tolerant Control (FTC) drives, resistant to measuring sensor faults, classical PMSM machines lose the possibility of stable operation in the event of damage to the position/speed sensor. LSPMSMs can operate without the presence of measuring sensors. However, most existing studies focus on the application of LSPMSMs powered directly from the grid, which is a suitable approach for large machines such as pumps and fans. Given the ongoing efforts to improve the efficiency of electric drives, it is reasonable to explore the application of LSPMSMs in drives controlled by frequency converters. The key advantage of this approach is that the motor, which typically operates in a vector control structure, can maintain stable operation even in the event of a speed sensor failure. This article presents a comprehensive research approach. Calculations of a new type of induced-pole LSPMSM were carried out, and simulation tests using Ansys software were performed. Next, a prototype of the machine was made. The induced-pole PMSM contains a two-times-lower number of permanent magnets but their volume in the motor rotor is the same due to demagnetization robustness. The motor has enclosure-less construction. The startup and running characteristics of the motor were investigated under direct-on-line supply. The article presents calculations, simulation analyses, and experimental validation under scalar control, confirming the feasibility of using this type of machine in Fault-Tolerant Control drives. Full article

The different pole–slot combinations of outer rotor surface-mounted permanent magnet (ORSPM) motors are designed and analyzed to satisfy EV driving requirements. Firstly, the analytical model for various slot–pole combinations of ORSPM motors is proposed based on the air-gap field modulation effect. Then, some of the in-wheel motor parameters and requirements are obtained for the vehicle system. In addition, some special pole–slot combination ORSPM motors are built to achieve higher flux density, and the electromagnetic performance is compared based on the finite element (FE) model, revealing that the 56-slot/48-pole (54s48p) in-wheel motor has a higher torque density and superior flux weakening capability than other cases. Finally, a 13 kW prototype with 54s48p is manufactured and tested to confirm the effectiveness of the FE analysis. Full article

In hub-motor electric vehicles (HMEVs), performance is adversely affected by the mechanical-electromagnetic coupling effect arising from deformations of the air gap in the Permanent Magnet Brushless Direct Current Motor (PM BLDC), which are exacerbated by varying road conditions. In this paper, a Model Predictive Control (MPC) strategy for HMEVs equipped with air suspension (AS) is introduced to enhance ride comfort. Firstly, an 18-degree of freedom (DOF) full-vehicle model incorporating unbalanced electromagnetic forces (UEMFs) induced by motor eccentricities is developed and experimentally validated. Additionally, a Minimum Model Error Extended Kalman Filter (MME-EKF) observer is designed to estimate unmeasurable state variables and account for errors resulting from sprung mass variations. To further improve vehicle performance, the MPC optimization objective is formulated by considering the suspension damping force and dynamic displacement constraints, solving for the optimal suspension force within a rolling time domain. Simulation results demonstrate that the proposed MPC approach significantly improves ride comfort, effectively mitigates coupling effects in hub driving motors, and ensures that suspension dynamic stroke adheres to safety criteria. Comparative analyses indicate that the MPC controller outperforms conventional PID control, achieving substantial reductions of approximately 41.59% in sprung mass vertical acceleration, 14.29% in motor eccentricity, 1.78% in tire dynamic load, 17.65% in roll angular acceleration, and 16.67% in pitch angular acceleration. Full article

This publication investigates the control of output voltage-boosting in a Quasi-Z-Source direct matrix converter operating as part of a PMSM drive system with an RLC grid filter. The structure and control algorithms enabling regulation of the converter’s output voltage in both step-down and step-up modes are presented. These methods are based on the $dq$ transformation, which provides a measurement signal for a linear PI-type controller. The article includes simulation results obtained using Matlab Simulink 2019a, which facilitated the preliminary verification of the applied structures and methods. The obtained model revealed the presence of nonlinearities in the Quasi-Z-Source voltage control system, which were subsequently confirmed through experimental verification. The system is stable but exhibits oscillatory behavior, with its parameters dependent on the amplitude of the step of the voltage gain coefficient. The voltage control system regulates the output voltage at least 10 times faster than a single period of the grid voltage sine wave. To enhance voltage control, a tunable controller with optimized parameters was proposed. The conducted studies demonstrated a 16.5% improvement in the IAE index and faster settling time for Quasi-Z-Source voltage control using the proposed controller compared to the reference controller. Full article

Traction motors in electric transport are most often synchronous permanent magnet motors (PMSMs). Induction motors (IMs) have large dimensions and stator current amplitudes under comparable loads. Traditional IM control methods do not solve these problems. Recent studies have shown that by changing the main magnetic flux in the IM in accordance with the load, these characteristics of the asynchronous electric drive can be significantly improved. Standard frequency converters do not allow for the implementation of these algorithms. But it makes sense to conduct a potential assessment of the capabilities of this algorithm to reduce the total stator currents of traction IMs. This article analyzes the results of real tests of a special vehicle for transporting rock inside mines, conducted several years ago at a mining equipment plant and in several mines in Russia. The prototype of the special transport vehicle has a load capacity of 15 tons, and its traction electric drive is based on four motor wheels with a total power of 100 kW and a frequency converter from the company “Vacon” (Vaasa, Finland). The tests were conducted at the plant’s testing ground and in real mine conditions. These tests allowed us to obtain information about the operation of the asynchronous electric drive under dynamically changing loads in a wide range, which is very difficult to obtain on laboratory benches or in industrial enterprise conditions. The experiments confirmed the efficiency of the optimization algorithm for asynchronous electric drives with frequency control. At the same time, the weight, size, and electrical parameters of the drive are as close as possible to those of direct current drives. Full article

This paper focuses on the latest advancements in diagnosing faults in Permanent Magnet Synchronous Machines (PMSMs), with particular attention paid to demagnetization, inter-turn short circuits (ITSCs), and eccentricity faults. As PMSMs play an important role in electric vehicles, renewable energy systems and aerospace applications, ensuring their reliability is more important than ever. This work examines widely applied methods like Motor Current Signature Analysis (MCSA) and flux monitoring, alongside more recent approaches such as time-frequency analysis, observer-based techniques and machine learning strategies. These methods are discussed in terms of strengths/weaknesses, challenges and suitability for different operating conditions. The review also highlights the importance of experimental validations to connect theoretical research with real-world applications. By exploring potential synergies between these diagnostic methods, the paper outlines ways to improve fault detection accuracy and machine reliability. It concludes by identifying future research directions, such as developing real-time diagnostics, enhancing predictive maintenance and refining sensor and computational technologies, aiming to make PMSMs more robust and fault-tolerant in demanding environments. In addition, the discussion highlights how partial demagnetization or ITSC faults may propagate if not diagnosed promptly, necessitating scalable and efficient multi-physics approaches. Finally, emphasis is placed on bridging theoretical advancements with industrial-scale implementations to ensure seamless integration into existing machine drive systems. Full article

This paper explores the potential of Digital Twin (DT) technology for Permanent Magnet Synchronous Motors (PMSMs) and establishes a foundation for its modeling and applications. While DTs have been widely applied in complex systems and simulation software, their use in electric motors, especially PMSMs, remains limited. This study examines physics-based, data-driven, and hybrid modeling approaches and evaluates their feasibility for real-time simulation, fault detection, and predictive maintenance. It also identifies key challenges such as computational demands, data integration, and the lack of standardized frameworks. By assessing current developments and outlining future directions, this work provides insights into how DTs can be implemented for PMSMs and drive advancements in industrial applications. Full article

Nowadays, Permanent Magnet Synchronous Linear Motors (PMLSMs) are widely applied as direct drive mechanisms in the industrial manufacturing sector, which can fulfill the requirements for high precision and high production rates. However, PMLSMs are characterized by significant thrust ripple issues, including cogging force, ripple force, and end force, which severely deteriorate the operational accuracy. This paper provides a review of analysis and suppression of the thrust ripple characteristics in PMLSM, aiming to offer guidance on how to mitigate the thrust ripples, and hence, enhancing the operational accuracy of PMLSM system. Firstly, the structural features and operating principles of PMLSMs are analyzed to understand the causes of thrust ripples. Then, strategies for mitigating the PMLSM thrust ripples are elaborated upon, respectively, from two main perspectives: structural optimization and control strategies. Finally, a summary and outlook are presented. Full article

Recently, the rapid proliferation of eco-friendly mobility solutions has driven an increasing demand for high-efficiency, high-power, compact, and reliable traction motors. In the eco-friendly mobility sector, electric mobility commonly employs Interior Permanent Magnet Synchronous Motors (IPMSMs) due to their high efficiency, high power, and compact size. However, ensuring reliability requires effective fault diagnosis. Among various faults, eccentricity in traction motors can degrade performance characteristics, including vibration, noise, and torque precision, thereby impairing driving performance. This paper proposes a novel winding method for Variable Reluctance (VR) resolvers and introduces a fault diagnosis approach for eccentricity using Finite Element Method (FEM) analysis. By employing this novel winding method, the direction of eccentricity occurrence can be effectively identified. Additionally, this method demonstrates robustness against defects, such as open-circuit faults, compared to a conventional winding method. Therefore, the proposed winding method contributes to improving the reliability and stability of IPMSMs through fault diagnosis and ensures robustness against open-circuit faults in the VR resolver. Full article

With the recent proliferation of electric vehicles, there is increasing attention on drive motors that are powerful and efficient, with a higher power density. To meet such high power density requirements, the cooling technology used for drive motors is particularly important. To further optimize the cooling effects, the use of direct oil-cooling technology for drive motors is gaining more attention, especially regarding the requirements for electric vehicle electric oil pumps (EOPs) in motor cooling. In such high-temperature environments, it is also necessary for the EOP to maintain its performance under high temperatures. This research explores the feasibility of using high-temperature-resistant ferrite magnets in the rotors of EOPs. For a 150 W EOP motor with the same stator size, three different rotor configurations are proposed: a surface permanent magnet (SPM) rotor, an interior permanent magnet (IPM) rotor, and a spoke-type IPM rotor. While the rotor sizes are the same, to maximize the power density while meeting the rotor’s mechanical strength requirements, the different rotor configurations make the most use of ferrite magnets (weighing 58 g, 51.8 g, and 46.3 g, respectively). Finite element analysis (FEA) was used to compare the performance of these models with that of the basic rotor design, considering factors such as the no-load back electromotive force, no-load voltage harmonics (<10%), cogging torque (<0.1 Nm), load torque, motor loss, and efficiency (>80%). Additionally, a comprehensive analysis of the system efficiency and energy loss was conducted based on hypothetical electric vehicle traction motor parameters. Finally, by manufacturing a prototype motor and conducting experiments, the effectiveness and superiority of the finite element method (FEM) design results were confirmed. Full article

To overcome the drawbacks of large torque ripples and high harmonic contents in a dual three-phase permanent magnet synchronous motor (PMSM) used in electric vehicle drive systems, a double-virtual-vector-based model predictive torque control (DVV-MPTC) strategy was proposed in this paper. Firstly, 12 virtual voltage vectors were constructed to minimize harmonic interference as much as possible. Then, the DVV-MPTC strategy is proposed to solve the problem of large torque ripples caused by single-virtual-vector-based MPTC (SVV-MPTC) method. On the other hand, an enhancement to the cost function was also introduced to resolve the challenges of tuning weight coefficients. Experimental comparisons between traditional direct torque control (DTC), SVV-MPTC method, and the proposed DVV-MPTC strategy were carried out, which show that the latter achieves significant improvements. In particular, it can reduce both harmonic components and torque ripple compared to traditional control strategies, resulting in a more efficient and stable performance for the electric drive system. Full article