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To improve the pulse width modulation (PWM) harmonic suppression effect of the three‐phase VSI‐fed PMSM system, this paper proposed a novel random switching period (RSP)‐Space Vector Pulse Width Modulation (SVPWM) technique for the three‐phase power converter. First, the proposed technique replaces the 10‐bit linear feedback shift register pseudorandom number generator (LFSR‐PRNG) with a Tiny Mersenne Twister (MT)‐PRNG to quickly generate high‐quality pseudorandom number sequences. Then, to reduce the sampling error caused by the current ripple, this paper analyzes the sampling timing under different modulation techniques. Based on the interrupted update mechanism of the Infineon AURIX‐TC264, the variable frequency sampling of the RSP‐SVPWM technique is implemented to ensure the best sampling of the motor phase current. Finally, the simulation and experimental results show that the proposed technique can effectively disperse PWM harmonic energy. Meanwhile, the RSP‐SVPWM technique based on variable sampling frequency effectively improves the phase current quality of the PMSM system. The proposed technique shows great potential for suppressing PWM harmonics in integrated PMSM systems. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

A nonlinear multivariable highly coupled system that is susceptible to both internal and external perturbations is the permanent magnet synchronous motor. A new reaching law‐based control approach that combines a sliding‐mode disturbance observer and an enhanced two‐vector model predictive current control is suggested in order to enhance the dynamic performance of the permanent magnet synchronous motor and its robustness to system disturbances. First, a new reaching law is developed in this paper to resolve the conflict between the traditional reaching law's chattering of the system and the reaching time of the sliding‐mode surface. This new reaching law not only makes the system's response more rapid but also reduces chattering; second, taking into account the possibility of systems with internal parameter uptake and external load disturbance, a sliding‐mode disturbance observer based on t is developed. Finally, the q‐axis current obtained from the speed sliding‐mode control rate is added to the model predictive current control, and an optimal duty cycle model predictive current control based on space vector modulation is designed because the traditional two‐vector model predictive current control is to optimize the duty cycle and voltage vectors separately, and the switching frequency is not fixed. The method suggested in this research may successfully suppress the sliding‐mode control system chattering and increase the resilience and dynamic response performance of the speed control system, according to simulation findings compared to the traditional reaching law and traditional duty cycle. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Aiming at the current control steady‐state error caused by sampling delay, parameters mismatch of direct‐drive permanent magnet synchronous motor (PMSM). This paper proposed a method of dual model predictive control (MPC) of direct‐drive PMSM based on sliding mode disturbance observer (SMDO). Deadbeat predictive current control (DPCC) is used for current loop, a SMDO is proposed to observe the system disturbance, the estimation is compensated to DPCC by feedback to decrease the current control steady‐state error. For speed loop, MPC with an internal model control observer (IMCO) can observe and compensate the load disturbance feedforward. The experimental results show that, the dynamic response speed of the proposed strategy is fast, the speed recovery time after sudden load torque is short, and the anti‐load disturbance performance and current tracking performance are effectively improved. © 2024 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Compared to the model predictive control (MPC) technique, the modulated MPC (M2PC) method applies multiple voltage vectors in order within one switching cycle, enabling a fixed switching frequency and better motor control performance. However, the M2PC technique suffers from a significant computational burden and imprecise allocation method of the vector action time, affecting the control performance. To address these two issues, this paper proposes an improved M2PC method that utilizes the information of projection of the reference vector on the selected voltage vectors for efficiently selecting the optimal active vectors and also accurately calculating their action time. Compared to the conventional M2PC, the proposed technique demonstrates both excellent dynamic performance with reduced execution time by 15.3% and superior steady‐state performance in terms of lower torque/speed ripple as well as fewer current harmonics. Those benefits have been proven by the results of a 2.5k rpm permanent magnet synchronous motor drive. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Aiming at the problem of difficulties in heat dissipation for a permanent magnet synchronous motor (PMSM) with high power/torque density, the effect of motor length‐to‐diameter ratio (r0) on the selection of cooling water channels is investigated from the perspective of the geometric parameters of the PMSM in this paper. First, the 3‐D fluid–solid coupled heat transfer models of three actual motors with the length‐to‐diameter ratios of 0.27, 0.81 and 2.04 are established. Every model is calculated under spiral, axial and circumferential cooling water channels, respectively. The cooling effect, cooling energy loss and motor thermal balance are compared and analyzed. Then the optimal cooling water channel for each of three motors is confirmed. Further, the motor temperature rise and fluid differential pressure are plotted. The threshold of motor length‐to‐diameter ratios is determined at which the overall performance of the axial and circumferential cooling water channel is highly similar. The general conclusions of selection of cooling water channels for PMSMs with different geometry shape are summarized. Finally, a prototype with r0 = 0.27 is fabricated and tested, verifying the validity of the fluid–solid coupling simulation analysis. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents a strategy for direct‐driving a turbine with an external rotor high‐speed permanent magnet motor. It is used to improve the large footprint, low efficiency, high maintenance costs, and high vibration risk of turbines. Combining the characteristics of the working conditions of pipeline gas transmission, this paper takes a 200 kW, 10 000 rpm external rotor high‐speed permanent magnet motor as an example. This paper analyzes the eddy current losses in the rotor due to the armature magnetomotive force generated by the stator fundamental and harmonic currents. To reduce eddy current losses in permanent magnets, a circumferentially segmented pole structure is proposed for theoretical comparison and FEA with common surface‐mounted pole structures under different loads and work angles. The results confirm that the circumferentially segmented pole can effectively reduce the eddy current loss of the permanent magnet rotor. The effect of variations in the pole arc coefficient on eddy current losses in permanent magnets is also analyzed. Finally, the temperature field simulation of the motor is carried out under consideration of wind mill losses. By setting up three comparison groups with different conditions, this paper analyses the influence of the temperature and flow rate of the gas on the temperature rise and heat dissipation of the motor in a high‐temperature gas environment. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of the loss distribution and magnetic saturation on the efficiency performance, which includes the location of maximum efficiency point, the size of high‐efficiency region and the value of maximum efficiency, for an interior permanent magnet synchronous motor (IPMSM). The loss expressions considering magnetic saturation are first proposed and then the efficiency‐losses function model of the IPMSM is constructed. The efficiency performance of the motor is analyzed quantitatively. The general principle is summarized including adjusting the location of maximum efficiency point, expanding the size of high‐efficiency zone and improving the maximum value of efficiency from the perspective of loss distribution and magnetic saturation. Two IPMSMs with different magnetic circuit characteristics are designed to verify the correctness of the analytical method by finite‐element analysis (FEA). Finally, prototypes are manufactured for the experiment and measurement results are given for validations. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In order to improve the dynamic and steady‐state performance of the finite control set model predictive torque controlled surface‐mounted permanent magnet synchronous motor drive system, a novel finite control set model predictive torque control (FCS‐MPTC) with different dynamic and steady‐state control schemes is proposed in this paper. When the SMPMSM drive system operates at transient state, the optimal basic voltage vector of inverter is the vector that minimizes torque tracking error, the proposed FCS‐MPTC achieves fast dynamic response based on the optimal torque control. When the system operates at steady state, the relative importance of torque to the stator flux amplitude is calculated based on the quantitative analysis of minimum staggered errors between motor torque and stator flux amplitude control objectives, then the priority weighting factors based on the relative importance are determined online adaptively, the optimal control of motor torque and stator flux amplitude is achieved simultaneously. Finally, the comparison of the experimental results of proposed FCS‐MPTC with different control methods is implemented and research conclusion is shown. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The high‐temperature electric‐actuated valve widely adopts the split structure, and the valve stem drives the opening and closing of the valve after passing through the high‐temperature packing and sealing structure. However, the transmission chain is too long, which cannot meet the pursuit of small volume and lightweight in the nuclear industry. In this paper, a novel integrated structure of high‐temperature direct drive electric‐actuated valve canned permanent magnet synchronous motor (DDEAV‐CPMSM) is proposed. The structure omits the dynamic sealing structure composed of stuffing box, pressure plate and pressure sleeve, as well as the transmission structure of gears and couplings, and the reliability is significantly improved. This paper focuses on the calculation of the dimension parameters, thermal load design, and electromagnetic vibration of DDEAV‐CPMSM, and compares it with the integrated structure of the induction motor to explore the optimal topology of the high‐temperature electric‐actuated valve. Aiming at the problem of serious heat generation in limited space, it is difficult to simulate the running time of high‐temperature valve. Based on the magneto‐thermal coupling method, a 3D temperature field model considering high‐temperature heat source, canned sleeve eddy current loss, and hydraulic friction loss is established. The steady‐state temperature distribution of the system at high temperature and the transient temperature change law of valve opening and closing are analyzed, and the minimum time of secondary start‐up and the maximum running time under fault conditions are further studied, to provide a theoretical basis for the application of DDEAV‐CPMSM. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper is aimed at improve accuracy of angular position synchronization control of Permanent Magnet Synchronous Motor driving system. Traditional PID controller could not meet requirement due to poor dynamic characteristics. The Global Fast Terminal Sliding Mode Control (GFTSMC) has good ant‐disturbance ability, could make system more robust and realize synchronization control of angular position. But due to error in load torque observation, system state convergence error will be caused, which will reduce the accuracy of synchronization. In this paper, fractional‐order differentiation is used to replace the nonlinear part of GFTSMC, constructed Fractional Order Differentiation—GFTSMC (FOD‐GFTSMC) controller to improve accuracy of synchronization. Theoretical analysis will be used to demonstrate that this control strategy could improve convergence accuracy of system state, reduces error of synchronization, and some experiments will be carried out to verify that this kind of controller has high synchronization accuracy, fast dynamic response ability and strong robustness. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The low‐speed and high‐torque modular fault‐tolerant permanent magnet motor has the strong fault‐tolerant ability, and can make the motor output torque act on the load directly, and the system has the highest transmission efficiency, which is especially suitable for ship propulsion. In the electric ship direct‐drive propulsion system, the motor is the core of the power system. Because the motor is directly connected with the load, the intermediate buffer mechanism is canceled, so the smooth operation of the motor is put forward to higher requirements. Especially in some fault‐tolerant operations, the unbalanced radial force generated by the asymmetric operation may cause the motor to vibrate greatly, which will reduce the operational life of the motor and even bring new faults. In serious cases, the whole transmission system will be damaged. Therefore, it is necessary to study the vibration of the fault‐tolerant motor under different operating conditions. In this paper, the module combined stator fault‐tolerant permanent magnetic synchronous motor for ship direct‐drive propulsion is taken as the research object. Based on the Maxwell tensor method, the radial force wave expressions of the motor during regular operation and fault‐tolerant operation are derived, and the harmonic order and frequency, which have a significant influence on vibration are summarized. The radial force of the motor under different operating conditions with different control strategies is calculated by the finite element method, and the harmonic components are analyzed by the two‐dimensional Fourier transform. On this basis, the vibration of the motor and the mechanical strength of the rotor support frame are analyzed. The research results of this paper provide some reference for the subsequent vibration reduction strategies of fault‐tolerant motors. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Abstract in order to study the torque ripple of permanent magnet synchronous motor for electric vehicle, the method of modular poles instead of single pole is adopted to reduce the torque ripple. The modular poles consist of three kinds of permanent magnets with different remanence and are arranged in a sinusoidal distribution. The pole arc length and position of each magnetic pole are calculated according to the cutting area of sinusoidal air gap flux density wave. By changing the cutting area of sinusoidal air gap flux density wave, the optimal pole arc coefficient of each permanent magnet was determined, and the magnet pole combination with the smallest torque ripple value is obtained. The results show that the sine degree of back electromotive force is improved obviously, the cogging torque is decreased greatly, and the motor with modular poles has obvious effect on torque ripple suppression. The torque of the motor with different kinds of magnetic pole combination is more stable than that of the motor with the same kind of magnetic pole combination. In this paper, the method of using modular poles instead of single pole to reduce torque ripple is of positive significance, which provides a reference for the subsequent performance optimization of electric vehicle motor. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In this paper, a novel doubly salient PM motor based on parallel path magnetic technology (PPMT) is presented. PPMT is an advanced magnetic control technology, which can be applied to linear and rotary actuators. First, the fundamental principle of the PPMT prototype is elaborated, and then a comprehensive research and analysis of PPMT motor is carried out, with particular emphasis on machine topology, operation principle and electromagnetic performance. The equivalent no‐load PM magnetic circuit model is established and equations for calculating the main PM flux are derived. Besides, a dual‐stator 6‐pole PPMT motor prototype has been developed to valid the analysis. According to the similarity of topology and operation principle, comparison between the FSPM machine and PPMT machine is conducted, which leads to the conclusion that the PPMT motor has lower cogging torque, lower torque ripple and better sine back EMF waveform, the PPMT motor is more suitable for servo applications compared to FSPM motor. Finally, to improve the power density of PPMT motor, FE parametric modeling method for designing the three coupled stator parameters, which are the PM width, the stator yoke width and the second airgap length is given out. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Fractional slot concentrated winding (FSCW) is a kind of winding structure with few‐slots/coils multi‐poles. FSCW has the potential value of high torque density due to its short end‐winding and high slot fill ratio and is widely used in low‐speed direct‐drive application situations. However, compared with integral slot winding (ISW), the back EMF coefficient of FSCW is smaller, which leads to smaller output torque under the same condition. To improve the back EMF coefficient of FSCW, equidirectional toroidal winding (ETW) is proposed and applied to the dual rotor slotless axial flux permanent magnet motor (AFPM), in which the unit structure is three slots/coils two poles, and the ideal back EMF coefficient is the same as that of ISW. In this paper, firstly, the structure of ETW is introduced and its operating principle is analyzed. Then, compared with the AFPM with ISW, the open circuit and load characteristics of the AFPM with ETW under two conditions of the same wire gauge and the same coil width are analyzed respectively. The back EMF coefficient and output torque of ETW‐AFPM are similar to that of ISW‐AFPM under the same coil width. The back EMF coefficient and output torque of ETW‐AFPM are a little lower than that of ISW‐AFPM under the same wire gauge. Finally, the experimental results also validate the feasibility of AFPM with ETW and the correctness of the analysis results. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In this paper, an improved auto disturbance rejection controller (ADRC) is applied to permanent magnet synchronous motor (PMSM) speed control system. Specifically, the improved ADRC is proposed to solve the defect that the nonlinear function of traditional ADRC is not differentiable at the piecewise point. In addition, considering that there are numerous parameters to be optimized in ADRC, an improved moth‐flame optimization (MFO) is proposed to obtain ADRC parameters, and adaptive inertia weight coefficient and optimization mechanism based on the fusion of refraction operation and chaotic search are proposed to improve the convergence speed and optimization accuracy for MFO. Simulation and experimental results show that the improvement strategies proposed in this paper can increase the optimization performance for MFO algorithm effectively so that obtained more appropriative ADRC parameters. The improved ADRC can effectively improve the tracking control performance of PMSM speed control system. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Hybrid excited machine (HEM) is a novel type of machine which has attracted much attention as it is able to adjust the flux linkage flexibly and ensure the wide speed range operation. In this paper, a novel brushless HEM with permanent magnet (PM) located in rotor is further researched. By supplying specific armature currents, the sub‐harmonic component magnetomotive force (MMF) in stator MMF would be generated and utilized to realize the brushless hybrid excited operation. Firstly, the generation principle of the sub‐harmonic component is derived analytically. Secondly, during the brushless hybrid excited operation, the influence of the stator current amplitude ratio m$$ m $$ is quantitatively studied. Thirdly, based on 2D finite element analysis (FEA), the electromagnetic performance of the brushless HEM is analyzed under different operation statuses over a wide speed range. At last, the experiment is performed based on a 6 kW brushless HEM prototype machine, and the correctness of the theoretical analysis and FEA results are validated by the test. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

According to the air‐gap flux density (AGFD) and the thickness of the permanent magnet (PM) in the direction of magnetization, this paper proposes a modified analytical model for the sine pole‐shaping surface‐mounted permanent magnet motor (SPMM) under parallel magnetization. The construction of the model also involves the Carter coefficient formula, the principle of magnetic‐circuit equivalence, and the distributed magnetic‐circuit method, which are used to deal with such influential factors as stator slotting, interpolar magnetic leakage, edge effect, and magnetic‐circuit saturation. Then, a finite‐element model is established to verify the analytical model through simulation. The results show that the fundamental amplitude of AGFD of the modified sine pole‐shaping motor is respectively 6.4 and 0.15% higher than that of the simplified sine pole‐shaping motor and the eccentric pole‐shaping motor, and that the total harmonic distortion of AGFD the former is respectively 67.2 and 11.1% lower than that of the latter, thereby causing an increase in average torque of the sine pole‐shaping motor and a decrease in its radial electromagnetic harmonics and torque ripple. Experiments show that both the modified analytical and finite‐element model are accurate. And, the proposed analytical model which does not need ergodic scanning as the eccentric pole‐shaping method can further optimize the electromagnetic performance of the motor. It can not only improve the motor design but also provide reference for the optimal design of high‐quality PM motors. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The high‐temperature canned electric‐actuated valve permanent magnet synchronous motor (CEAV‐PMSM) directly drives the valve load, which is prone to eccentricity operation, causing greater system vibration and shortening the valve operating life. In order to analyze the electromagnetic and structural characteristics of CEAV‐PMSM under different eccentricity faults, this paper uses analytical methods to derive the magnetic field distribution of the motor under normal and eccentricity conditions. Then, the Maxwell Stress Tensor method is used to derive the expression of the radial electromagnetic force under normal and eccentricity conditions, and the order of space–time harmonics that have a greater impact on CEAV‐PMSM are summarized. After that, the electromagnetic performance comparison of the three pole‐slot combinations under different eccentricity conditions, and the harmonic orders during eccentricity is analyzed by Fourier transform to obtain the optimal pole‐slot combination, which verified the correctness of the analytical calculations. In addition, the influence of different eccentricity conditions on the radial force density and unbalanced magnetic pull are studied. On this basis, the vibration response of the motor under eccentricity is analyzed, and the influence of the canned sleeve on the vibration performance of the motor is discussed. Finally, the modal analysis of CEAV‐PMSM is carried out to prevent the occurrence of resonance under eccentricity, which provides some references for reducing the vibration and noise of the canned electric‐actuated valve. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The electric power propulsion is becoming the important development direction of ship propulsion technology recent years, as it is conducive to the realization of automation, intelligence, reduced noise, enhanced propulsion efficiency, high power density, flexible arrangement, and energy saving. The good fault‐tolerant capacity and robustness of the fault‐tolerant permanent magnet motor (FTPMM) make it a potentially highly effective and economical propulsion motor in the electric power propulsion ship than other alternatives. In this paper, the structure and mathematical model of FTPMM are analyzed and the improved sliding mode observer (SMO) is constructed according to the deviation between the observed currents and actual currents. Combined with model reference adaptive control (MRAC) method and the phase‐lock loop (PLL), the switch function is replaced by the continuous Sigmoid function to reduce the chattering and finally the rotor position estimated accuracy is improved. When the motor winding open‐circuit and short‐circuit fault occur, the current vector fault‐tolerant control strategy is introduced into the improved SMO algorithm, and the rotor position is estimated accurately under faulty conditions. Finally, the proposed improved SMO position estimation algorithm under healthy and faulty conditions is verified in Matlab/Simulink. The FTPMM position sensorless technology would play a critical role in the electric power propulsion ship, and may have a profound impact on the high‐performance advanced ships and green shipping industry as well. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Compared with multi‐phase single‐module permanent magnet motors, three‐phase multi‐modularized permanent magnet motors have stronger fault tolerance ability, widely used in aerospace, ship propulsion, and other special fields. Especially in ship direct‐drive propulsion, low speed and high torque modular combined stator fault‐tolerant permanent magnet motor (MCS‐FTPMSM) has high torque density, and fault‐tolerant operation conditions may appear in actual operation, so it is essential to analyze the temperature of the fault‐tolerant motor accurately. This paper analyzes the temperature of MCS‐FTPMSM under different operating conditions and determines the longest operating time of the motor under different fault‐tolerant operating conditions based on the 3D electromagnetic‐temperature bi‐directional coupling method. Among them, the loss of the motor is calculated by the 3D electromagnetic field, which is added to the 3D temperature field as an excitation, and then the material properties in the 3D electromagnetic field are updated according to the calculated temperature distribution. The cyclic iteration method is used to make the calculated temperature deviation less than the given error value. When analyzing the electromagnetic loss of the motor, the field‐circuit coupling method is adopted to consider the influence of the current time‐harmonics of the controller on the loss of the motor during actual operation. Finally, the 12kw100r/min 3 × 3 modular prototype was tested. By comparing the results of experiments, one‐way coupling method (OWCM) and bi‐directional coupling method (BDCM), it is found that the electromagnetic‐thermal bi‐directional coupling can more accurately predict the temperature of the fault‐tolerant motor. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper proposes a simple and efficient method to weaken the cogging torque of the direct‐drive permanent magnet motor with inner enhance force (IEF‐DDPMM). It is characterized by adjusting the relative position of the inner and outer permanent magnets so that the cogging torque generated by the inner and outer air‐gaps is opposite in phase, thus eliminating or weakening a certain order of cogging torque. For IEF‐DDPMM, the expression of cogging torque and the variation law of cogging torque with the staggered‐pole angle are derived by the analytical method. The relationship between optimal staggered‐pole angle and the pole‐slot combination is analyzed. The influence of staggered‐pole on average torque and torque ripple is analyzed. Finally, the commercial finite element software ANASYS‐Maxwell is used for simulation, and the simulation results are consistent with the analytical results. The results show that the cogging torque of IEF‐DDPMM is the linear superposition of cogging torque from inner and outer parts; choosing a suitable staggered‐pole angle can effectively weaken the cogging torque and reduce the torque ripple. Besides, the average torque reduction caused by the staggered‐pole method can be compensated by adopting the internal power factor angle compensation strategy. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper proposes an analytical no‐load magnetic field model taking account of the curvature coefficient to compute the no‐load magnetic field of parallel direct‐driven conjoined permanent magnet synchronous motor (PDC‐PMSM). The shortcomings of the 3‐D finite element method are avoided, such as the time‐consuming and sensitive to finite element meshes. As well as, putting forward the design method of the motor. A 2‐D subdomain model of PDC‐PMSM can be obtained by segment 3‐D model at the average radius, which is quasi to linear permanent magnet synchronous motor. Based on Maxwell's equations, the Poisson's equations in the permanent magnet (PM) subdomain and the Laplace's equations in the subdomain between air gap and PM are calculated under no‐load condition. The radial and tangential flux density of each subdomain are obtained by the Fourier's series, hyperbolic functions, separation of variables, and the boundary condition. Better yet, the curvature coefficient is introduced to reduce the error between the analytical magnetic field in the planar model and the tubular model. The analytical no‐load magnetic field model is established more accurately. The expression of curvature coefficient and back‐electromotive force are derived. One prototype is manufactured for simulation and experimental study. The accuracy and feasibility of the proposed model are verified by the prototype test. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In the field of ship propulsion, highly reliable propulsion motor is one of the key factors for the stable operation of the drive system. This paper proposes a new modular stator low‐speed high‐torque fault‐tolerant permanent magnet motor (MCS‐PMFTSM) for the direct‐drive ship propulsion system. The unequal‐span winding is used for enhanced fault‐tolerant as well as modular operation of the motor. Each module is isolated electrically and mechanically, while the maintenance procedure is greatly simplified by the structure that uses external radiation installation. Introducing the new structure and operating principle of the MCS‐PMFTSM, the basic size equation of the motor is derived followed by the analysis for the selection of the number of poles and slots. The rotor structure of the motor is then optimized using the genetic algorithm. The finite element method is used to analyze the motor performance under normal and various fault‐tolerant conditions. In addition, the electromagnetic vibration of the proposed motor is also examined under different operating conditions. Finally, a 12 kW 100 r/min 3 × 3 modular prototype is developed to experimentally validate the excellent performance of the proposed motor under both normal and fault‐tolerant operating conditions. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Halbach array has been more frequently used in the field of electromagnetism in recent days because of some unique advantages such as the self‐shielding and sinusoidal field distribution. In order to reduce the impact of the high order harmonic content of the air‐gap flux density of the interior permanent magnet synchronous motor (IPMSM) on the performance of the machine, a new non‐uniform Halbach array structure is proposed in this paper. Firstly, an equivalent analytical model is established to analyze the influence on the air‐gap flux density. At the same time, the interior permanent magnet synchronous motor model is built by using the finite element analysis. Then, the relationship between the air‐gap flux density and the four design parameters (the thickness of the permanent magnet, the magnetization angle, the angle of the permanent magnet, and the proportion of auxiliary magnetic poles) is analyzed by using the Taguchi method orthogonal experiment. The total harmonic distortion (THD) of air‐gap magnetic fields and its fundamental harmonic amplitude are employed as the evaluation criteria. Finally, the effectiveness of this optimization method is verified by comparing the harmonic content of the air‐gap flux density before and after the optimization. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The fractional slot concentrated winding structure effectively solves the difficulty of low‐speed and high‐torque permanent magnet (PM) machines with a large number of poles and slots, but it also brings a wealth of magnetomotive force (MMF) harmonic. The winding function method is used to compare and analyze the stator MMF distribution and harmonic content of the fractional slot PM machines with different pole and slot combinations, and the cogging torque waveform and torque ripple are calculated by the finite element method. The influence of pole and slot combination on radial force and vibration modes of fractional slot PM machines is studied. The main vibration mode can be determined from the lowest order of radial force harmonics. The results show that in a fractional slot PM motor, the radial force is the main cause of noise and vibration, rather than the cogging torque and torque ripple. The dominant radial force is mainly produced by the interaction of rotor field harmonics and armature reaction field harmonics, and the vibration and noise will significantly increase with the decrease of the dominant vibration mode order, which largely depends on the pole and slot combination. This paper provides a certain reference for the selection of pole and slot combination in the electromagnetic design process of low speed high torque fractional slot PM motors. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This is a survey paper focusing on permanent magnet motors with variable field capability. The synchronous motors, which have been applied to somewhat limited fields, have garnered attention as attractive electric drives. Due to a connection with rare‐earth magnet and power electronics‐based flexible control, current permanent magnet synchronous motors have achieved the best position in terms of high power and torque densities, high efficiency and flexible control capability. In order to satisfy the diverse demands of users, a motor is requested to ensure high‐efficiency operation at multiple operating points on the speed–torque plane. It is well recognized that maximum efficiency is attained under the condition that the copper loss is equal to the fixed loss, mainly composed of iron loss, at a given operating point. This is why permanent magnet synchronous motors should have the capability of adjusting the field excitation, similar to the direct current shunt motors. In this paper, recent trends of research and development of variable field permanent magnet motors are overviewed from the standpoint of design and control. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

To enhance the torque of short‐time duty permanent magnet (PM) dual‐redundancy brushless DC motors (DR‐BLDCM) and avoid the motor overheating under a fixed outer diameter and length, a design method based on the optimization of split ratio and stator magnetic density (Bm) considering thermal limitations is presented. The global thermal limitation of DR‐BLDCM is set by limiting loss density. The local thermal limitation of the winding is set by limiting current density. The thermal limitations are taken as the boundary of torque enhancement design optimization. Both the cold backup and hot backup DR‐BLDCM are studied in this paper. By researching the relationship between torque, split ratio, and Bm, the optimal combination of split ratio and Bm are calculated analytically. The influences of thermal limitations on the maximum torque and the optimal combination are analyzed, and the principle to determine the optimal combination is obtained. The analytically calculated results are verified by finite element simulation, and the error is less than 6.82%. A prototype is manufactured based on analytical design results. The error between the calculated and measured copper loss is 6.96%. The verification results show that the proposed optimization method can fully enhance the torque of DR‐BLDCM under the condition of fixed overall dimension and thermal limitations. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents a gain tuning method of the load torque compensator for direct speed control based on finite control set model predictive control (FCS‐MPC). In this method, the transfer function between the error in predicted speed and the load torque is constructed and used for gain parameter tuning of a load torque observer‐based prediction error correction. By using the proposed method, the stability and the responsiveness of FCS‐MPC with a load torque compensation can be improved without a fully simulating the electric drive systems and experiments. The simulation and experimental results obtained with a permanent magnet synchronous motor, fed by a two‐level three‐phase voltage source inverter, show that the tracking performance of the direct speed control tuned by the proposed method was excellent under load torque conditions. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Since it can be difficult to directly estimate the temperature of permanent magnets (PM) in high‐density permanent magnet motor rotors, this paper proposes a method based on lumped parameter thermal networks (LPTN) for online estimation of PM temperature. Firstly, a parameter model is established that contains a four‐node thermal network model and a loss model. For the online estimation, an extended Kalman filter algorithm with fading factor is used to dynamically update the thermal network parameter model in order to estimate the PM temperature. The simulation and experimental results show that the parameter model can quickly converge to a value that is close to the true value. Therefore, this online estimation method for PM temperature can accurately monitor the PM temperature online without increasing the required motor hardware; thus not affecting the motor operation. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

In‐wheel motors (IWMs) are one of the most important key technologies to be used by electric vehicles, hybrid electric vehicles, and fuel cell vehicles. To meet the limitations of the space within the wheel rim, unsprung mass, and drive without a multispeed transmission, IWMs need to be designed to simultaneously have high torque per volume and power per mass and wide high‐efficiency operation region. In addition, it is obligatory to meet the requirements of torque output capacity, speed capacity, torque ripple, peak efficiency, power output capacity, etc. In this paper, a direct‐drive surface‐mounted permanent magnet in‐wheel motor (DSPMIWM) is synthetically optimized. Above design demands are accounted for simultaneously by selecting some of them as the design objectives and setting the others as constraints. Firstly, simplified design equations of the DSPMIWM, which can reduce the number of design variables, are established. The size parameters of the DSPMIWM are classified by constants, indirect design parameters, and direct design parameters. The direct design parameters are selected as optimal design variables. Then, a synthetically optimal design of the DSPMIWM is executed by employing the Kriging method combined with the Latin Hypercube sampling and Genetic Algorithm. Compared with an existing mature design, the torque per volume, power per mass, and high‐efficiency operation region of the studied IWM are still improved while all constraints are met. Finally, the effectiveness of the proposed synthetically optimal design procedure is verified by finite element analysis. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The line start permanent magnet synchronous motor (LSPMSM) can be used for direct‐on‐line (DOL) starting, so it is easily affected by voltage unbalance. Based on the finite element method (FEM) and analytical method, the influence of voltage unbalance on the steady‐state performance of LSPMSM is studied in this paper. A two‐dimensional finite element model is built, and the armature current, losses and torque ripple as a function of the phase voltage unbalance rate (PVUR) are obtained. The influence mechanism of voltage unbalance on the steady‐state performance of a motor is demonstrated. Finally, a prototype of LSPMSM is manufactured and tested. By comparing the experimental data with the simulation data, the accuracy of the calculation model is verified, and the correctness of the research is proved. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

Permanent magnet synchronous motor (PMSM) drive systems have been increasingly applied in all kinds of high‐power AC drives because of their inherent advantages of good performance, rapid dynamic response, as well as high reliability and efficiency. Precise control of the system traditionally depends on the shaft encoder, but the presence of the encoder could result in increased cost and volume, reduced reliability, etc. Therefore, the development of sensorless control techniques is important to avoid the above issues by the elimination of the sensor. Based on the running process of the motor, sensorless control techniques can be classified into four categories: initial position detection methods (IPDMs), low‐speed control strategies, mid‐high‐speed control strategies, and full‐speed control strategies. The fundamental principles, their advantages and disadvantages, the control precision, and the application range of these strategies on surface and interior permanent magnet synchronous motors (SPMSMs, IPMSMs) are described in detail in this paper. Finally, the development trend of PMSM sensorless control technologies is discussed. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]