Iet Electric Power Applications最新文献

Low-frequency vibration is a key performance indicator for underwater vehicles, especially in applications with strict acoustic compliance requirements. The main source of vibration in integer slot permanent magnet synchronous motors (PMSM) is various orders of electromagnetic force waves acting on the stator tooth tips. Research has shown that for surface mounted permanent magnet synchronous motors, the surface vibration of the motor casing is closely related to the tangential force acting on the stator teeth. Reducing the number of stator teeth appropriately can effectively alleviate this type of vibration. Firstly, based on the Maxwell stress tensor method, the electromagnetic force model acting on the stator teeth was derived, and the mechanism of vibration caused by tangential force was analysed. Secondly, establish a mathematical model to describe the radial vibration transmitted from the tangential force on the stator teeth to the shell through the lever effect. Then, perform finite element simulation to compare the radial and tangential vibration characteristics of motors with different numbers of teeth. The simulation results show that reducing the number of teeth can effectively reduce the surface vibration of the casing caused by tangential forces on the stator teeth while maintaining the same volume of the motor. Finally, vibration and underwater noise tests were conducted on two prototype motors of underwater vehicles with the same volume but different numbers of teeth to verify the effectiveness of this method.

Conventional permanent magnet synchronous machine (PMSM) control methods often struggle to maintain satisfactory performance due to their dependency on parametric machine models. Parameter-free control methods have garnered significant attention in addressing machine uncertainties; however, their continuous online optimisation increases computational demands and can degrade performance. Recently, machine learning (ML) approaches have emerged as a promising alternative, enabling control methods independent of machine models and parameters. These ML methods are trained offline to create computationally efficient control models without the need for continuous online optimisation. This article reviews and thoroughly investigates various ML-based control approaches for PMSM drives, including reinforcement learning (RL) and supervised ML. The fundamentals and design principles of these methods are discussed with a focus on PMSM current control. Conventional RL, robust RL and classification-type and regression-type supervised ML are implemented and compared with traditional PMSM control methods. Simulation results, quantitative evaluations, and robustness analyses reveal that supervised ML-based control methods outperform other approaches in the presence of uncertainties for electrical machines.

Bearingless motors can realise the rotor active suspension by the radial electromagnetic force, whereas the suspension force and torque ripple will increase the difficulty of motor control, which may lead to the stator and rotor collision and irreversible damage to the motor. In order to obtain the principle and variation of the suspension force ripple and torque ripple of bearingless induction motors under the condition of multi-harmonic magnetic field, the complex coupling relationship between harmonic magnetomotive force (MMF), magnetic permeance and harmonic magnetic field is clarified firstly. Based on the traditional mathematical model of the suspension force, the calculation formula of the radial suspension force is derived and the mechanism of the radial suspension force ripple is revealed. Secondly, the radial suspension force and the electromagnetic torque are calculated by the finite element method, and the torque magnetic field and the suspension magnetic field are decoupling analysed. The dynamic changes of the radial suspension force and the torque with the time are given, and the relationship among multi-harmonic magnetic field coupling, radial suspension force ripple and torque ripple is clarified. Finally, the accuracy of analytical calculation and finite element calculation is proved by experiments.

Aiming at the problems of large normal force, large electromagnetic force pulsation and high cost of permanent magnet track of permanent magnet linear motor (PMLM), this paper proposes a novel double-sided flux-concentrating and stacked-winding permanent magnet linear motor (DFS-PMLM). To seek a PMLM with high thrust density and low electromagnetic force pulsation, this paper analyses and compares various motor structures and then optimises the parameters of the proposed motor structure. During optimisation, the objective function is first determined and then a Kriging model is established. Global optimisation is then performed within the agent model using the genetic algorithm-particle swarm optimisation (GA-PSO) and nondominated sorting genetic algorithm II (NSGA-II) sequentially. Finally, the structural parameters optimised by NSGA-II are more capable of improving the performance of the motor as verified by finite element simulation. Compared to conventional motors, the DFS-PMLM achieves a thrust of 506 N, a 30.3% increase in volumetric thrust density; a thrust fluctuation of 11.8%, a 62.5% reduction and a normal force of 21 N, a 2124 N reduction. Overall, the DFS-PMLM has higher thrust density, lower normal force and lower thrust fluctuation than conventional motors.

The rapid development of DC power systems in applications such as electric aircraft and microgrids has highlighted the need for high-performance DC short-circuit protection. Solid-state circuit breakers (SSCBs), utilising power semiconductor devices, offer superior performance compared to traditional mechanical circuit breakers by providing fast arc-free interruption and improved reliability. Whereas silicon carbide (SiC) MOSFETs and silicon (Si) insulated-gate bipolar transistors (IGBTs) are widely used in these applications, their overcurrent capabilities and long-term reliability under repetitive operation remain critical research topics. This paper investigates the overcurrent capability of SiC MOSFETs and Si IGBTs and analyzes their degradation mechanisms under repetitive overcurrent cycling. Experimental results show that although the SiC MOSFET has a longer overcurrent withstand time due to its saturation characteristics, it suffers from more severe ageing behaviours. Its gate-source voltage (V_GS) was found to drop by 3.3 V, its saturation current (I_sat) dropped by 45.2 A, and its on-state voltage drop significantly increased as the number of cycles reached 250. In contrast, the Si IGBT exhibited minimal degradation in its dynamic performance under the same conditions. To understand the underlying physics of these behaviours, detailed TCAD simulation models were developed based on the real device structures. Simulations revealed a single, concentrated hotspot in the SiC MOSFET near the gate, reaching a peak temperature of ∼1000 K. The Si IGBT, however, presented two distinct hotspots: one near the gate and another near the interface between the buffer and drift regions. We propose that this distributed thermal profile in the IGBT mitigates localised stress, which explains its superior long-term reliability. Conversely, the high concentration of thermal stress in the SiC MOSFET's gate region leads to its severe ageing.

Permanent magnet linear synchronous motors (PMLSMs) are widely used in high-precision servo systems. However, the detent force negatively affects servo performance. To address this issue, a novel double-sided PMLSM with closed-secondary structure is proposed in this paper. The magnetic bridges with auxiliary windings are installed at both secondary core ends. The magnetic flux paths through bridges and primary end teeth influence end leakage flux. Therefore, the detent force is suppressed utilising this magnetic path. First, the compensation current in the auxiliary windings is designed based on detent force and back EMF in auxiliary windings. Affected by nonlinear factors, such as core saturation, significant detent force remains after applying compensation current. Thus, the compensation current is iteratively adjusted according to the residual detent force. When a staggered-tooth design is applied to the primary core, the compensation current amplitude decreases, but the detent force can still be effectively suppressed. When the secondary core is extended to 30 pole pitches, the required compensation current increases due to diminished flux bridge influence. Nevertheless, FEM verification confirms that the suppression strategy maintains effectiveness. The prototype shows detent force reduction from 3.7 to 0.8 N with optimised compensation current. Experimental results verify the method's feasibility.

Due to their inherent capability to provide short-circuit fault protection, combined with features, such as high torque density and reduced torque ripple, five-phase permanent magnet synchronous motors (PMSMs) driven by current-source inverters are highly suitable for mission-critical applications. However, unlike PMSMs, current-source inverters are more susceptible to faults. Conventional fault-tolerant techniques for mitigating open-circuit faults in current-source inverters typically assume that all the semiconductors in the affected inverter leg are faulty. In reality, the possibility of an open-circuit fault occurring in only one power switch has not been thoroughly studied. Consequently, this article introduces a fault-tolerant control (FTC) approach specifically designed to address single-switch open faults in five-phase PMSMs driven by current-source inverters. First, the paper evaluates the fault-tolerant capabilities under this particular fault condition. Then, two space vector pulse width modulation (SVPWM) strategies are developed and compared with existing SVPWM methods, focusing on winding copper losses and torque ripple. Finally, the effectiveness of the proposed FTC scheme is verified through experiments, demonstrating that this method can effectively reduce torque ripple and decrease winding copper losses.

This paper proposes a smoothed active disturbance rejection control (ADRC) strategy integrated with a hybrid sensorless algorithm to enhance the dynamic performance of a 12-stator/19-pole yokeless and segmented armature axial flux-switching permanent magnet (12S/19P YASA-AFFSPM) motor. The improved ADRC replaces the conventional nonlinear fal function with a smooth, exponentially interpolated function (efal) and employs linear error feedback to simplify tuning while maintaining robustness. A hybrid sensorless scheme, combining a pulsed high-frequency injection method for low speeds and a sliding mode observer (SMO) for medium-to-high speeds, ensures accurate rotor position estimation across the entire operational range. Experimental results demonstrate the outstanding performance of the proposed method: the rotor position error remains within ± 2°, the speed tracking error is limited to ± 5 rpm even during direction reversals and the transient speed deviation during sudden load torque changes (0–5 N m) is kept below 5% of the rated speed. The proposed approach significantly enhances dynamic response, disturbance rejection and operational robustness, validating its suitability for high-performance applications such as electric vehicles and industrial automation.

Large-capacity high voltage direct current (HVDC) transformers are the core equipment of the future power system. The design and operation of these transformers involve the interaction of multiple physical fields. The use of multiphysics simulation technology can comprehensively consider the coupling effects of various physics, which can help optimise the design scheme, improve the efficiency and reliability of the equipment, reduce the system loss and extend the life of the equipment. This paper proposes a multiphysics coupling simulation method for high-voltage DC transformers based on COMSOL multiphysics. Using this method, the distribution characteristics of the electric, magnetic, temperature and stress fields of the key components of the HVDC transformer under intermediate frequency conditions are analysed in detail. Through the analysis of the simulation results at different frequencies, the influence of frequency on the multiphysics distribution of the equipment is revealed, which provides a theoretical basis and practical guidance for the design and performance optimisation of HVDC transformers.

To improve the torque performance of permanent magnet synchronous reluctance machine (PMSRM) for electric vehicles, a novel torque-angle approximation PMSRM (TAA_PMSRM) is proposed in this article. This design utilises asymmetric permanent magnets (PMs) and inter-pole cavity to shift the axis of PM magnetic field, so as to make the peak of the PM torque component approximate to the peak of the reluctance torque component, and to increase the resultant torque without increasing the cost. And asymmetric tangential ribs are introduced to suppress torque ripple effectively. Through the parameter sensitivity analysis, the specific influence of the key structure parameters related to the PM magnetic field shift on the electromagnetic performance of the TAA_PMSRM is clarified, providing a theoretical basis for torque performance optimisation. Based on the step-by-step multi-objective optimisation design, the average torque and torque ripple are optimised while ensuring the mechanical integrity of rotor. A comparative analysis between the proposed TAA_PMSRM and the conventional PMSRM, both optimised using the same method under multiple operating conditions, confirms the torque improvement and overall performance advantages of the proposed design. Finally, a prototype of the TAA_PMSRM is fabricated and tested to validate the simulation accuracy and demonstrate its practical performance benefits.