The advantages and disadvantages of two permanent magnet motor designs – slotted and slotless – are analyzed. A commercially available micromotor was adopted as the slotted design. Their performance is compared in terms of torque production and permanent magnet heating under intensive operating conditions. The rotor geometry was as-sumed to be identical, the maximum flux density in the magnetic cores was set to 1,7 T, and the rotational speed was considered constant. Modeling was carried out using COMSOL Multiphysics, with the results for the slotted design validated using the Simcenter Motorsolve software package. The torque and the amplitude of torque pulsations for both designs were evaluated, and the differences between them were analyzed. The causes of magnetic flux density pulsa-tions in the magnets were studied, and their impact on eddy current losses was assessed. Numerical results for the out-put parameter ratios of the two designs were presented. The possibility of neglecting magnet heating in the slotless de-sign was emphasized. References 11, figures 8, table 1.

High Torque Density Design Investigations of High-speed Homopolar Type Permanent Magnet Motor

Design of an Equivalent 2-D Finite Element Analysis Model for Axial Flux Permanent Magnet Motors Considering Radial End Effects and Inductance Based Evaluation

High temperatures underground can cause demagnetization in the hollow permanent magnet motor of the intelligent well electric control sliding sleeve, affecting the motor's output performance. To address this issue, this paper establishes a finite element simulation model for the motor and, through comparative analysis, selects the outer rotor type hollow permanent magnet motor solution. Environmental temperature and motor structure are the main factors affecting the performance and demagnetization of the intelligent well electric control sliding sleeve permanent magnet motor. Using Taguchi methods and simulation experimental data, the motor structure is optimized. The optimized motor parameter combination is a slot opening width of 2mm, an air gap of 0.3mm, a pole arc coefficient of 0.76, and a permanent magnet thickness of 3.1mm. After optimization, the motor torque increased by 17.219%, the cogging torque decreased by 27.521%, the demagnetization rate decreased by 55.223%, and the efficiency decreased by only 0.149%. After optimization, the torque difference of the motor increased, the motor's working capacity improved, the torque ripple rate also increased, and its stability decreased slightly, but still within an acceptable range.

This study investigates a small-sized high-speed permanent magnet motor used in the drive of unmanned aerial vehicles. As part of this study, a numerical simulation field mathematical model of a high-speed permanent magnet motor has been built, implemented by the finite element method. That made it possible to obtain the distribution of the electromagnetic field and forces, to estimate the total losses in all conductive and magnetically conductive media in individual structural elements of the permanent magnet motor under study. Unlike existing ones, the model built enables deriving the total losses in the calculation area; in permanent magnets, structural conductive elements, the armature winding, and in the magnetic core with hysteresis losses, eddy currents and additional losses caused by higher harmonics. The task addressed is predetermined by the pressing scientific-practical issue related to increasing the energy efficiency of a high-speed permanent magnet motor used for electric transport systems and unmanned aerial vehicles. The use of a simplified, more technological rectangular shape of permanent magnets has been proposed. Applying permanent magnets of this configuration makes it possible to reduce the total losses in the motor by 23…41% depending on the type of power supply – sinusoidal or when powered by an inverter with PWM. The use of a more technological form of permanent magnets leads to a decrease in the electromagnetic torque of the motor by approximately 18…30%, which is attributed to a decrease in the volume of active materials and an increase in the value of the equivalent air gap. At the same time, applying a modified form of permanent magnets makes it possible to reduce pulsations of the electromagnetic torque by 12%

The aim of this research is to present both a sensorless control and a torque derating algorithm in the overload region of a permanent magnet motor for e-bikes. First, the theoretical backgrounds and the field-oriented control are presented. Then, a sensorless control is designed based on the back-emf estimation with a second-order generalized integral flux observer for the permanent magnet motor. The second-order generalized integral flux observer is an adaptive filter which can eliminate the DC offset and strongly attenuate the harmonics of the estimated rotor flux. The algorithms have been simulated and then validated by means of tests on a permanent magnet motor for e-bikes.

Inter-turn short-circuit (ITSC) faults in motor drives can induce substantial circulating currents and localized thermal stress, ultimately degrading winding insulation and compromising torque stability. To enhance the operational reliability of open-winding (OW) five-phase fault-tolerant fractional-slot concentrated-winding interior permanent-magnet (FTFSCW-IPM) motor drive systems, this paper proposes a real-time fault-tolerant control strategy that provides current suppression and torque stabilization under ITSC conditions. Upon fault detection, the affected phase is actively isolated and connected to an external dissipative resistor, thereby limiting the fault-phase current and inhibiting further propagation of insulation damage. This reconfiguration allows the drive system to uniformly accommodate both open-circuit (OC) and ITSC scenarios without modification of the underlying control architecture. For OC operation, an equal-amplitude modulation scheme based on carrier-based pulse-width modulation (CPWM) is formulated to preserve the required magnetomotive-force distribution. Under ITSC conditions, a feedforward compensation mechanism is introduced to counteract the disturbance generated by the short-circuit loop. A principal contribution of this work is the derivation of a compensation term that can be estimated online using zero-sequence voltage (ZSV) together with measured phase currents, enabling accurate adaptation across varying ITSC severities. Simulation and experimental results demonstrate that the proposed method effectively suppresses fault-phase current, maintains near-sinusoidal current waveforms in the remaining healthy phases, and stabilizes torque production over a wide range of fault and load conditions.

This paper presents a comprehensive sensorless control approach for interior permanent magnet (IPM) motors, integrating high-frequency injection (HFI) and model-based observer techniques to ensure accurate rotor position estimation across a wide speed range. Two HFI strategies—pulsating and rotating—are investigated experimentally and compared in combination with two observer structures: the conventional Sliding Mode Observer (SMO) and Adaptive-Gain SMO (AG-SMO). The AG-SMO dynamically adjusts its observer gain according to the estimated back-electromotive force (back-EMF) amplitude, significantly reducing chattering and improving estimation performance under varying load and noise conditions. A Frequency-Adaptive Complex Coefficient Filter (FACCF) and an Orthogonal Phase-Locked Loop (PLL) are incorporated to eliminate phase delay and enhance demodulation accuracy. Simulation and experimental results obtained using a 30 W, 20 V IPM motor demonstrate that the pulsating HFI + AG-SMO configuration achieves superior stability and noise immunity, while the rotating HFI + AG-SMO provides smoother and more accurate estimation. Overall, the proposed hybrid control framework achieves robust, high-precision, and sensorless operation for IPM motors over the wide speed range, offering a practical solution for applications such as inverter-driven compressor systems operating in noisy environments.

Interior Permanent Magnet (IPM) motors are widely used in electric vehicles (EVs) due to their high torque density and efficiency. However, at high speeds, the mechanical integrity of the rotor becomes a limiting factor in achieving optimal electromagnetic performance. This research presents a unified design optimisation strategy that simultaneously considers both electromagnetic performance and mechanical constraints for high-speed IPM rotors. A range of rotor diameters (110 mm to 180 mm) was analysed to determine the optimal trade-off between torque generation and structural stress limits, focusing on an 8-pole, 120 kW IPM motor operating primarily at 4500 rpm, with a maximum of 13,000 rpm. The proposed method utilises 2D and 3D finite element analysis (FEA), harmonic analysis, and mechanical stress simulations in ANSYS and MATLAB/Simulink to evaluate the impact of rotor geometry, material selection, and interference fitting. The optimal configuration, 130 mm rotor paired with a 48-slot stator, achieves a torque density of 2.8 kW/kg and ensures mechanical safety within the 230 MPa stress threshold. This paper contributes a comprehensive design framework that balances electromagnetic and mechanical factors, offering practical guidelines for developing reliable and high-performance IPM machines in electric vehicle applications.

Electric vehicles are gaining popularity due to their environmental friendliness and the need to conserve dwindling fossil fuel resources. In this field, interior permanent magnet (IPM) motors are considered the top choice for propulsion systems due to their high efficiency, high torque-to-current ratio, durability, and low noise. To optimize the speed control performance of IPM motors in the presence of disturbances, a nonlinear speed control algorithm for IPM systems using the backstepping method is developed in this paper. Additionally, a load torque observer using the extended state observer (ESO) method is implemented to enable the system to respond quickly and accurately to load changes while minimizing the effects of disturbances, thereby enhancing the operation and reliability of electric vehicles. The simulation results, conducted in MATLAB/Simulink, demonstrate that the combination of backstepping control and ESO offers good stability for the motor system, while mitigating the impact of disturbances and load variations. This is an important step in optimizing the control system of electric vehicles, contributing to the improvement of performance and reliability in electric vehicle applications.

<p>Permanent magnet brushless DC (PMBLDC) motors are widely used in a variety of industrial applications due to their high-power density and ease of regulation. The three-phase power semiconductors bridge is the standard way for controlling these motors. In order to initiate the inverter bridge and switch on the power devices, rotor position sensors must be provided with the correct commutation sequence. The power devices commutate progressively 60 degrees, depending on the location of the rotor. The right speed controllers are necessary for the motor to run as efficiently as possible. PI controllers are commonly employed with permanent magnet motors to achieve speed control in simple manner. Nevertheless, these controllers provide challenges in managing control complexity, including nonlinearity, parametric fluctuations, and load disturbances. PI controllers need accurate linear mathematical models. To overcome this, in this paper adaptive fuzzy logic controller (FLC) for controlling the speed of a BLDC motor is presented. When the motor drive system uses the adaptive FLC technology for speed control, it exhibits better dynamic behavior and is more resistant to changes in parameters and load disturbances. The main objectives of this work are to analyze and appraise the functioning of an electric tractor driven by a PMBLDC motor drive using adaptive FLC. The PMBLDC motor drive controllers are simulated using MATLAB/Simulink software.</p>

Cogging Torque Reduction in Axial Flux Permanent Magnet Motor Using Arc-Notched Rotor: Design and Experimental Validation

This study provides a comprehensive process of designing an electric motor that will be used for a small two-wheeled electric vehicle. Due to high performance capability in term of power and torque, brushless permanent magnet topology is chosen so that a compromise between size constraint and performance can be met. For an accurate motor design sizing, the design process is initially carried out by determination of power rating that derived from vehicle dynamic calculation. Based on winding factor calculation, fractional-slot 12-slot/10-pole and 9-slot/10-pole motors equipped with non-overlapping winding are chosen and analyzed using finite element analysis (FEA) software. For an optimum electromagnetic performance, parametric optimization is included, mainly on the stator dimension. Despite the performance of both designs improved, only 9-slot motor results a convincing performance as the rated torque is 18% higher than the 12-slot design. For verification purpose, 1-D analytical solution is also included and compared with results deduced by the FEA. According to the analysis, the proposed motor designs are adequately reliable for a light electrically powered electric vehicle application.

Surface-inserted high-speed permanent magnet motors (SHPMM) find extensive application in high-speed and ultra-high-speed motors as permanent magnets are fixed easily and have small assembling stress and high overload capability. However, because of the complex rotor structure, there is still a lack of analytical solutions for rotor strength. In this paper, the rotor of an SHPMM was divided into four parts: sleeve, permanent magnets, convex plates, and cylindrical core. According to the elasticity theory, an analytical solution of the rotor stress intensity of the SHPMM was derived by using the polar coordinates. Subsequently, the effective feasibility of the scheme designed proposed in the paper is verified by performing simulations in finite elements. On this basis, the four-dimensional visualization algorithm was employed to examine the influences of the parameters in the scheme design on the strength of the rotor, which incorporates the amount of interference, sleeve thickness, and rotational speed. It follows that the analytical method mentioned in this paper demonstrates precise calculations of stresses in the rotor of the SHPMM. The stresses in the permanent magnets exhibit a notable increase with the growth of interference and sleeve thickness whereas they gradually decrease with an increase of rotational speed.

This paper presents a multiphysics, Life Cycle Assessment (LCA)-based design optimization framework for an interior permanent-magnet traction motor tailored to electric-vehicle duty. The workflow couples driving cycle realism, electromagnetic–thermal analysis, and life cycle assessment within a unified, computationally efficient process. Representative operating points are extracted from WMTC and ECE cycles using clustering, after which a multi-level Taguchi refinement searches the design space from coarse to fine. A weighted composite objective balances machine cost and life cycle cumulative emissions under hard constraints on torque capability and hotspot temperature. The optimized design satisfies performance and thermal limits while simultaneously reducing both cost and life cycle burden, as confirmed through phase-wise assessment of raw material, use-phase, and end-of-life contributions. Iterative improvements are accompanied by rising signal-to-noise ratios and reduced parameter-level spread, indicating greater robustness to operating variability. Overall, the study demonstrates that an LCA-driven, multiphysics-constrained optimization can deliver sustainable, high-performance IPM designs that are aligned with realistic vehicle operating conditions and readily adaptable to alternative motor and drive architectures.

Today, in the face of the urgent need to decarbonize global transportation, the development of electric vehicles (EVs) has become one of the core strategies to address energy crises and environmental challenges [...]

In this paper, a high-torque and low-cogging-torque double-sided permanent magnet (DS-PMFM) motor is proposed. The research focuses on adopting structure of stator split-tooth and unequal-width rotor poles, enabling the motor to have high output torque, low torque ripple, and low cogging torque. It is found that the DS-PMFM motor causes a non-negligible deterioration of cogging torque and torque ripple while increasing the output torque compared with the single-sided permanent magnet (SS-PMFM) motor. Based on this, in order to achieve the comprehensive performance improvement of a high torque density, low cogging torque, and low torque ripple for the motor, research is carried out from three perspectives: pole-slot ratio, stator modulation pole split-tooth shape design, and unequal-width rotor poles design. Ultimately, the final topology is obtained through optimization. Through comparative analysis, it was shown that the torque performance of the proposed DS-PMFM motor has been effectively improved, providing effective guidance for the design of this type of motor.

Design of Coreless Axial Flux Permanent Magnet Motors for High Torque Density Through Multi-Physics Modeling and Analysis

The line-start permanent-magnet (LSPM) motor combines the direct-on-line starting of induction motors with the high efficiency of permanent-magnet (PM) synchronous motors, but conventional interior PM designs are difficult to manufacture and surface PM (SPM) designs often suffer from limited starting torque and reduced efficiency. This paper investigates consequent-pole SPM designs, in which the number of magnets is reduced by half while maintaining equal magnet volume, enabling simple rotor construction and improved starting performance. A prototype is manufactured and tested, confirming smooth synchronization under load. Efficiency is constrained by the non-sinusoidal flux distribution of the consequent-pole structure. Rotor design strategies enlarging the air gap near the iron poles are analyzed, and a finite element method analysis shows improved torque and efficiency without loss of starting capability.

Abstract Inner boost permanent magnet motor (IBPMM) can make full use of the internal space of the motor rotor, and the inner stator only runs when overloaded, so it has a high short‐term overload capacity. The split ratio of IBPMM affects the electromagnetic performances of the inner and outer stators simultaneously, so the rated efficiency, maximum overload capacity and electromagnetic load of the IBPMM are all dependent on the split ratio. In this paper, the structure and operation principle of IBPMM are explained first. Then, aiming at the problem of large error of traditional analytical method, an equivalent magnetic network (EMN) model with sliding mesh is established to consider the saturation effect, flux leakage and improve the calculation accuracy of electromagnetic performances of the IBPMM. This model is used to optimize the split ratio of IBPMM with limited copper loss and fixed permanent magnet spacing. The influences of the split ratio on rated efficiency, maximum overload capacity, electromagnetic load and input current of IBPMM under the voltage limit are analyzed. The temperature distribution of IBPMM with different split ratios are compared by transient finite element method (FEM). Finally, the accuracy of the analysis is verified by FEM and prototype experiments. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.