Chenyi Yang

Driven by the evolution of electric drive systems in electric vehicles, aerospace, and industrial machine tools, high-speed operation has become a key direction in motor development. While progress in emerging manufacturing technologies and novel materials has partially alleviated the inherent contradiction between electromagnetic performance and mechanical strength in high-speed rotors, traditional approaches—including geometric optimization of flux bridges and center posts, macroscopic material replacement, and structural reinforcements—tend to make the multi-physics trade-offs increasingly complex. The application of dual-phase soft magnetic laminate presents a promising alternative. By achieving localized regulation of rotor characteristics, this approach effectively decouples electromagnetic performance from mechanical constraints. Although the technical merits have been verified, the existing literature lacks a systematic overview of the fabrication technologies and application status of dual-phase soft magnetic material laminate. Hence, this paper aims to provide a comprehensive review of recent fabrication approaches and development trends, thereby serving as a fundamental reference for researchers aiming to integrate this material into innovative rotor topologies.

In this article, a deadbeat predictive control (DPC) method with low measurement effort and the capability to effectively suppress torque ripple is proposed for switched reluctance machine (SRM). First, to enhance prediction model accuracy, a flux-linkage model based on second-order Bézier curves combined with full-position interval interpolation is proposed. This method only requires determining three parameters—aligned-position incremental inductance, unaligned-position incremental inductance, and unaligned-position saturation inductance to accurately describe flux-linkage characteristics. Next, Varignon’s principle is applied to analyze the mechanism by which phase current harmonics influence torque. On this basis, the beetle antennae search algorithm, which enables rapid optimization, is used to optimize the current waveform, resulting in a novel harmonic-optimized current profile. The developed enhanced DPC methodology incorporating pulsewidth modulation demonstrates significant torque ripple reduction under diverse operating conditions, minimal offline measurement requirements, and high estimation accuracy, thus providing an efficient and practical solution for achieving high-performance SRM control in industrial applications.

One significant challenge in high-speed motor design is the eddy current losses in permanent magnets (PMs), which primarily arises from distortions in the armature reaction field. The main causes of the distortions are slotting effects and current harmonics introduced by pulse-width modulation (PWM). In order to figure out how the armature reaction field influences the eddy current losses of PMs, this paper proposes a fast and accurate analytical method to calculate PM eddy current losses in surface mounted permanent magnet synchronous motors (SPMSMs) based on an improved reluctance network analysis (RNA) model of the motor and equivalent electrical network model of PMs. To overcome the limitation of conventional RNA in capturing high frequency magnetic field variations, the proposed RNA of the motor incorporates an analytical model of the armature reaction for analysis of magnetic flux density distributions. The corresponding eddy current distribution and losses in the PMs are calculated through an equivalent electrical network model. Furthermore, the impact of high-order current harmonics caused by PWM on eddy current losses is systematically investigated. The accuracy and efficiency of the proposed method are demonstrated by results from finite element analysis (FEA) and experiments. From the study results we can conclude that the high-order current harmonics caused by the PWM leads to a significant increase in PM eddy current losses, and it is necessary to consider PWM effects in losses analysis and motor design.

For synchronous reluctance motor (SynRM), parameters tends to change when the magnetic is saturated, and the characteristics are significantly nonlinear. The conventional maximum torque per ampere (MTPA) control of SynRM, which ignores the deviation terms, is subject to significant errors about current angle and leads to torque degradation. For the saturation of magnetic, relying only on finite element simulation, the accuracy of motor parameters is still not guaranteed in practical applications. In this study, an online approach of inductance parameters determination that can account for magnetic self-saturation and cross-saturation was proposed. To achieve high-precision maximum torque per ampere (MTPA) control of SynRM concerning torque degradation, this article first analyzes the factors contributing to the MTPA control error of SynRM. It then combines the identification of SynRM inductance parameters to compensate for the deviation terms online and applies the virtual signal injection method. Simulation and experimental results verify the effectiveness of the proposed parameter identification approach and high-precision MTPA control strategy considering deviation terms.

The no-insulation (NI) technique improves the stability and defect-tolerance of high-temperature superconducting (HTS) coils by enabling current redistribution, thereby reducing the risk of quenching. NI–HTS coils are widely applied in DC systems such as high-field magnets and superconducting field coils for electric machines. However, the presence of turn-to-turn contact resistance makes current distribution uneven, rendering traditional simulation methods unsuitable. To address this, a finite element method (FEM) based on the T–A formulation is proposed. This model solves coupled equations for the magnetic vector potential (A) and current vector potential (T), incorporating turn-to-turn contact resistance and anisotropic conductivity. The thin-strip approximation simplifies second-generation HTS materials as one-dimensional conductors, and a homogenization technique further reduces computational time by averaging the properties between turns, although it may limit the resolution of localized inter-turn effects. To verify the model’s accuracy, simulation results are compared against the H formulation, distributed circuit network (DCN) model, and experimental data. The proposed T–A model accurately reproduces key transient characteristics, including magnetic field evolution and radial current distribution, in both circular and racetrack NI coils. These results confirm the model’s potential as an efficient and reliable tool for transient electromagnetic analysis of NI–HTS coils.

For the switched reluctance machine (SRM) with a heavy load, the inductance of the conduction phase is nonlinear, which makes the sensorless control method based on the linear region of the phase inductance no longer applicable. Meanwhile, in the case of light or no load, the estimated rotor position will abruptly change at the connection points between neighboring segments, which has an impact on the estimation of the speed. In this article, a low-speed sensorless control method for the SRM with a heavy load is proposed. The idle-phase inductance is modeled over a wide rotor position range for position estimation, and a proportional gain decreasing type second-order generalized integrator based on a frequency-locked loop is constructed to estimate the speed while performing rotor position filtering. The effectiveness of the proposed method is experimentally verified with a 3-phase 12/8-pole SRM prototype, and the results show that the estimated rotor position and speed are accurate and smooth, which is beneficial to performance improvement of the sensorless control.

Taking the Longxian-Qishan-Mazhao fault as an example to analyze the pseudo effect of normal/inverse fault caused by strike-slip movement - 1