Dual three-phase PMSMs are ideal for steer-by-wire (SBW) systems due to high power density and inherent fault tolerance. However, short-circuit faults create coupled highcurrent fields that induce irreversible demagnetization. This study systematically evaluates four interior permanent magnet (IPM) rotor topologies (U-type, V-type, Spoke-type, and I-type) within a 12-slot/8-pole framework under an electro-thermal sequential mapping methodology. Results indicate that while fixedtemperature $\left(80^{\circ} \mathrm{C}\right)$ analysis suggests high resistance for both Utype and V-type rotors, actual loss-induced thermal gradients alter the reliability hierarchy. The V-type topology maintains the highest back-EMF retention (96.69%) and torque retention $(98.81 \%)$ under a peak operating temperature of 111.98° C. Its flux barriers provide a high-reluctance shielding path that diverts the transient demagnetizing magnetomotive force (MMF). Conversely, the Spoke-type exhibits extreme vulnerability (85.76% retention) due to flux-focusing at inter-pole bridges, and the U-type suffers from the highest inrush current (41.72 A) and thermal peak $\left(115.92^{\circ} \mathrm{C}\right)$. Thus, the V-type topology is proven optimal for highreliability SBW applications.

Effective thermal management of the rotor is crucial for high-speed permanent magnet motors seeking to enhance power density. This paper proposes spiral water cooling to effectively mitigate the rise in rotor temperature resulting from significant rotor eddy current losses in fractional slot concentrated winding motors. This advanced cooling structure consists of a hollow shaft with multiple spiral ducts on its surface and a rotor hub constructed from a high thermal conductivity material, joined together through the interference fit. By employing the spoke-type rotor in the prototype, the rotor hub comes into direct contact with the heat sources from other rotor components, thereby achieving exceptional heat dissipation capabilities. The three-dimensional computational fluid dynamics model is utilized to investigate the fluid flow characteristics of the spiral water cooling and elucidates the impact of parameters such as rotational speed, coolant flow rate, and duct size on the convective heat transfer coefficient of the cooling structure. In addition, the advantages of spiral water cooling are illustrated by comparing the cooling performance of spiral water cooling and hollow shaft cooling with different cooling media. On this basis, the temperature distribution of each component of the prototype is forecasted. Experiments and simulations definitively proved the effectiveness of the proposed rotor cooling structure and the accuracy of the calculation results.

Due to their compact dimensions, high torque density, high efficiency, and superior flux-weakening capabilities, permanent magnet synchronous machines with tooth-coil winding (TC-PMSMs) are highly suitable for low-power electric transportation applications. This study incorporates the actual duty cycle of an electric motorcycle in the optimization of the slot number for the drive machine. The proposed methodology addresses the shortcomings of conventional design strategies, which typically consider only a limited set of operating points, leading to suboptimal round-trip efficiency under real driving conditions. Firstly, the influence of slot number on torque output, electromagnetic losses, and flux-weakening performance is examined for 10-pole TC-PMSMs using finite element analysis. Subsequently, the optimal slot number is identified by integrating the real duty cycle of the drive motor into the evaluation. To verify the accuracy and effectiveness of the analytical results and design approach, prototypes of stator assemblies with varying slot numbers were fabricated and experimentally tested.

This paper proposes a resonance damping and harmonic suppression control method without capacitor voltage sampling for LCL-equipped HSPMSM drives with a capacitively coupled active damper. The proposed method only needs to sample the motor current, and the resonance damping and harmonic suppression are achieved through the state feedback of the motor current. The proposed method can effectively suppress the resonance of the LCL filter and reduce the harmonics of the motor current, which not only saves the sensors but also has a better harmonic suppression effect compared with the method based on capacitor voltage sampling. The proposed method has been experimentally demonstrated to reduce the motor current harmonics by more than 30%.

Tooth-coil permanent magnet synchronous machines (TC-PMSMs) are commonly used in wind power generation and wheel-hub propulsion applications. These machines operate at low speeds and have a large number of poles and slots, providing various pole/slot combinations as options. Typically, these combinations have similar performances, making it challenging to choose the best one from different perspectives. This study focuses on 32-pole TC-PMSMs with different slot numbers to understand how key electromagnetic and thermal performance indicators vary with slot numbers. Using the finite element method, parameters such as torque density, cogging torque, inductance, flux-weakening capability, losses, and temperature rise are evaluated and compared. Prototypes of the wheel-hub TC-PMSM are manufactured and tested on a back-to-back test rig, to validate the analysis results. The findings and conclusions derived from this research can assist in determining the optimal slot number or narrowing down the selection range of competitive pole/slot combinations during the scheme comparison stage.

The slender shape of the driving machine leads to a low rigidity and large axial thermal elongation of the motorized spindle, which deteriorates the machining precision. To solve these problems and pursue a more compact size, this paper investigates the feasibility of using a tooth-coil permanent magnet synchronous machine in a high-speed spindle, replacing the original motor that has the conventional distributed winding. Comprehensive performance and behavior of machines with distributed and tooth-coil windings are comparatively analyzed, in terms of the essential torque ripples, winding inductances, electromagnetic losses, rotor integrity, and heat dissipation of the spindle. Thorough numerical simulation results indicate that the newly designed tooth-coil winding solution shows significant advantages over the original design, regarding high rotor rigidity, low torque ripples, reduced electromagnetic losses, and reduced shaft thermal elongation. Prototypes and test setups for the high-speed tooth-coil machine are built, where preliminary measurements are carried out to validate the analysis results and system design.

Considering the price of rare earth permanent magnets and its supply crisis, this paper proposes the design of a permanent magnet assisted synchronous reluctance motor with permanent magnets embedded in the rotor magnetic flux barrier. The Finite element method is used to analyze and compare the electromagnetic performance of PMa-SynRMs with different rotor topologies. The results show that the V-type rotor structure has the largest output torque; the multi-layer magnetic barriers can effectively increase the reluctance torque.

Aiming at the characteristics of poor anti – disturbance ability and speed ripple of traditional proportional integral (PI) controller, a novel speed controller for permanent magnet synchronous motor (PMSM) is proposed in this paper, which uses a novel sliding-mode control (SMC). To improve the chattering problem of traditional SMC, a high-order approaching law super-twisting algorithm (STA) is applied. Considering the internal and external disturbance of motor driver system such as motor parameter drifts and load torque changes, a disturbance estimator based on extended state observer (ESO) is proposed, and it is used for the feed-forward compensation of current. The composite super-twisting intergral sliding mode controller (ST-ISMC) with nonlinear ESO is tested by simulation, and the comparative results varify that the proposed controller has the higher control accuracy, smaller speed ripple and stronger robustness.

In this article, an optimized sampling mechanism for full-state feedback current control (FSFCC) of LCL-equipped high-speed permanent magnet synchronous motor drives is proposed. First, the full-state current control structure is introduced and it indicates that the control performance suffers from the sampling harmonic components caused by the pulsewidth modulation. Then the sampled capacitor voltage and the inverter current are analyzed theoretically with different sampling trigger times. Based on the harmonic analysis, an optimized sampling mechanism is developed and the current ripple is much reduced compared with the conventional method. Finally, the effectiveness of the proposed method is validated by the experimental results at 100 kr/min.

In this article, an efficient multi-objective optimization strategy for the Halbach array permanent magnet synchronous machine (PMSM) is developed by taking into consideration the nonlinear B-H behavior of soft magnetic materials. Based on the harmonic modeling (HM) technology, the electromagnetic performances (EPs) of the Halbach array PMSM can be computed. To specifically model the local magnetic saturation, the stator teeth are separated into several annular layers, and each tooth is further divided into several regions along the tangential direction. Then, the parameters of the Halbach array PMSM are optimized utilizing combined nonlinear semi-analytical model (SAM) and non-dominated sorting genetic algorithm II (NSGA-II). To validate the effectiveness and accuracy of the developed optimization scheme, a Halbach array prototype is then manufactured in accordance with the optimization results. The multi-objective rapid optimization strategy developed in this article, which includes but is not limited to Halbach array permanent magnet (PM) machines, serves as a reference for the design and optimization of various PM machines.

Fractional slot concentrated winding machine is a promising solution for wheel-hub propulsion. However, there are so many pole/slot combinations for such machine especially when with larger number of poles. Such combinations usually have similar electromagnetic performance, thus it is difficult to select the most rational and optimal combinations from numerous candidates. This paper takes a 50kW high torque density wheel-hub motor as an example to make a comprehensive comparison of different pole-slot combinations. The common pole-slot combinations are screened by inherent performance and design specifications. Performance comparisons are then carried out to determine the appropriate combination for the prototype. Finally, prototypes are manufactured to verify the analysis results.

Facing the energy crisis, Flywheel Energy Storage System (FESS), representing the physical energy storage technology, has great application prospects in the energy storage market owing to its high conversion efficiency. In practical applications, the structure of Flywheel Energy Storage Array Systems (FESAS) is mostly used. Although traditional allocation strategies for arrays are straightforward and easy to implement, they often fall short of optimal allocation. This paper proposes the utilization of the Particle Swarm Optimization (PSO) algorithm for power command allocation, along with an improvement in its parameters. Refering to the motor loss, we construct evaluation guidelines and compare the effects of different allocation strategies for grid-connected applications. The final results of the simulation demonstrate the feasibility and efficiency of the method proposed in this paper.

新工科及工程教育对电机学课程的授课内容、授课方法及考核评价方式提出了更高的要求.本文通过对当前课程教学中存在的不足进行具体剖析,探索多学科交叉背景下电机学课程教学改革的路径;基于课程特点和工业应用的需求,从课程内容设置、授课方法和考核评价机制进行了深入的教学改革和探索.实践表明,所做的教学改革探索显著提升了学生理论应用于工程实践的能力,并在一定程度上启发了学生的工程思维.

Permanent magnet synchronous motors (PMSMs) are widely applied in industry, and proportional integral (PI) controllers are often used to control PMSMs. Aiming at the characteristics of the poor anti-disturbance ability and speed ripple of traditional PI controllers, a novel composite speed controller for PMSMs is proposed in this paper that uses a novel sliding mode control (SMC). To improve the chattering problem of traditional SMC, a high-order approaching law super-twisting algorithm (STA) is applied. Considering the internal and external disturbance of motor driver systems, such as motor parameter drifts and load torque changes, a disturbance estimator based on an extended state observer (ESO) is proposed, and it is used for the feed-forward compensation of the current. The composite super-twisting integral sliding mode controller (ST-ISMC) with a nonlinear ESO is tested by simulations and experiments, and the comparative results verify that the proposed controller has the higher control accuracy, smaller speed ripple and stronger robustness.

In response to the rising price of permanent magnets and the shortage of rare earth resources, this paper designs a permanent magnet assisted synchronous reluctance motor. In consideration of the copper consumption and material utilization of the armature winding, a fractional slot concentrated winding is selected as the armature winding. After the same constraints on stator structure, armature current, permanent magnet quantities, and rotor silicon lamination stress, six different rotor topologies are compared using the finite element method. The results show that the V1-type rotor structure has outstanding performance.

This letter proposes a general single-sensor active damping framework for LCL-equipped high-speed permanent magnet synchronous machines. By the proposed method, arbitrary damping assignment and stability for the LCL resonance within the Nyquist frequency are achieved with only the inverter-current feedback or motor-current feedback. Moreover, the simplified analytical expression between the physical parameters and the damping performance enables automatic tuning for different drive systems.

In this article, a novel dynamic-decoupled active damping current controller is proposed for an LCL-equipped high-speed permanent magnet synchronous machine. Compared with the conventional stationary current-control method for the LCL-type system, the proposed method is established in the synchronous rotating frame for improving the current transient performance. When taking the controller into the synchronous coordinate, there are two following challenges: first, the synchronous resonance frequency varying in a wide range because of the synchronous coordinate transformation, and second, eliminating the coupling between the ${dq}$ coordinate. To address these issues, an improved synchronous capacitor-current-feedback active damping method is designed based on arbitrary pole assignment and is significantly effective for the LCL resonance within the Nyquist frequency. Moreover, a novel dynamic-decoupled motor-current controller is proposed to eliminate the coupling between the ${dq}$-axis motor current. The gain selection method is discussed to acquire sufficient phase margin and gain margin. Finally, the effectiveness of the proposed method is verified by driving the tested motor to 72 kr/min.

This article proposes a discrete-time dynamic-decoupled current controller for an LCL-equipped high-speed permanent magnet synchronous machine with only the motor currents measured. The controller is designed in the synchronous coordinate based on a complex $\boldsymbol{z}$-domain transfer function. The main contribution of the proposed current controller is the robust dynamic decoupling performance to achieve better transient behavior. Moreover, an effective coefficient selection method is developed to acquire sufficient phase margin and gain margin, even with the system parameters varying $\boldsymbol{\pm 50\%}$. Additionally, the stable region of the LCL resonance with the proposed method is discussed. Finally, the effectiveness of the proposed method is verified by driving the tested motor to 100 kr/min.

This article proposes an improved position sensorless drive method for interior permanent magnet synchronous machines (IPMSM) in medium- and high-speed regions, which relies on the fully discretized extended back-electromotive force (EEMF) model and online inductance identification. First, the fully discretized EEMF model is developed for constructing position observers, which overcomes the accuracy deterioration of the conventional Euler-discretized model with the speed increasing. And then, an online inductance identification method for IPMSM, which utilizes the inherent pulsewidth modulation (PWM) current ripple of the voltage source inverter (VSI), is proposed to improve the position estimation accuracy. Compared with the traditional parameter identification method, the proposed method does not require the additional signal injection, therefore, the undesirable torque fluctuation and additional voltage occupancy due to signal injection are avoided. Benefiting from the fully discretized EEMF model and the estimated inductances, the improved rotor position estimation of IPMSM can be achieved. Finally, the proposed method is verified by simulations and experiments.

The zero-sequence inductance is a vital parameter for the performance analysis of permanent magnet machines, especially under faulty conditions or in open-winding machines. This paper focuses on the zero-sequence inductance calculation of fractional slot concentrated winding permanent magnet synchronous machines (FSCW-PMSMs), and reveals the variation regularity of this kind of inductance and its various components against pole/slot combinations, using the winding function and finite element methods. Moreover, based on the analysis of 36-slot FSCW-PMSMs with different pole numbers, the dependency of each inductance component on the pole/slot combination is discussed in detail. To validate the regularities, experimental measurements of zero-sequence inductance are implemented in the prototype of the 36-slot stator. It is found that the regularities are independent of specific slot or pole numbers, which provide guidelines for optimum pole/slot combination selection, to mitigate the problems caused by zero-sequence current.