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In order to realize the low vibration design, variable leakage flux permanent magnet (VLF-PM) motor is investigated and purposefully optimized. Firstly, the variable flux characteristics of the VLF-PM motor are studied in detail. Then the electromagnetic vibration characteristics of the VLF-PM motor under different operating conditions are analyzed. On this basis, key electromagnetic force harmonics caused by the vibration at typical operating conditions and torque performances are selected to be optimized. By the adoption of multi-objective optimization, low radial electromagnetic force (REF) and high output torque can be achieved. Both simulation and experimental results verify the effectiveness of the reduced vibration design of LCF-PM motors, which provides a potential research path for the low vibration design of PM motors, especially multi-mode PM motors. [ABSTRACT FROM AUTHOR]

In this article, a dual-mechanical-port flux-switching permanent magnet (DMP-FSPM) motor is studied for achieving high-efficiency design and optimization. The key of this study is to propose an optimization design approach for broadening high-efficiency region, where the motor efficiency fitting curve and the speed–torque envelope curve are combined. First, the efficiency function is established according to the motor power and loss equation. Then, high-efficiency region boundary points are obtained by combination of the fitted efficiency curve and speed–torque envelope curve. Next, the efficiency of representative operating points is determined and optimized to realize the broadening of motor high-efficiency region. Finally, the effectiveness of the proposed method and the studied DMP-FSPM motor is verified by the study results and experiment test. [ABSTRACT FROM AUTHOR]

This article proposes a robust optimization method for hybrid permanent magnet (HPM) machines, aiming to eliminate the influence of permanent magnets (PMs) asymmetric uncertainties. Exemplified by a 12-slots/10-poles (12s10p) HPM machine, the optimization method is specifically clarified. First, uncertainties of two types of PMs are comprehensively analyzed and the worst combination of these uncertainties are estimated. Then, the design of experiments (DOEs) technique is utilized to take samples, and the corresponding performance of samples with and without consideration about uncertainties are simulated by finite element analysis (FEA), respectively. After that, a dual-level kriging surrogate model is constructed. And the difference of the two levels, as a quantitative index of robustness, is added as an additional optimization objective. Finally, a multi-objective optimization algorithm non-dominated sorting genetic algorithm (NSGA-II) is carried out. The optimization results indicate that the proposed method can effectively reduce the additional torque tipple brought from asymmetric uncertainties of PMs. In addition, a prototype is manufactured and tested to further verify the method. [ABSTRACT FROM AUTHOR]

In this article, based on flux modulation theory, torque characteristics improvement method is proposed for double-stator vernier permanent magnet (DS-VPM) motor. Also, the detailed torque production mechanism of DS-VPM motor is derived. Based on theoretical analysis results, key design parameters which possess significant influence on motor torque characteristics are selected to be further optimized purposefully. Non-dominated sorting genetic algorithm is then adopted to obtain increased output torque and reduced torque ripple of inner, outer, and total DS-VPM motor. Besides, based on finite-element analysis, motor performances before and after optimization are compared in detail. Finally, a prototype motor is built and corresponding experiments are carried out. Both theoretical analysis and experimental results verify the effectiveness of the proposed torque characteristics improvement method, which provides a potential research path for the design optimization of high-performance VPM motors. [ABSTRACT FROM AUTHOR]

This article proposes a method to suppress the torque ripple of the traditional V-shaped permanent magnet vernier motor (V-PMVM) from the perspective of shifted air-gap permeance distribution. On the basis of such method, a shifted permeance V-PMVM (SPV-PMVM) is presented and compared with the traditional V-PMVM. First, the generation mechanism of cogging torque as the major source of the torque ripple is explained based on the magnetic field modulation (MFM) principle. Moreover, the cogging torque expression of the SPV-PMVM is derived considering the shifted permeance design. Then, by means of the detailed and comprehensive analysis method, the key parameters of shifted permeance are optimally determined at low cogging torque and torque ripple. Finally, the SPV-PMVM and V-PMVM performances are evaluated by using the finite element method (FEM). The comparison results indicate that, based on the shifted permeance design method, the torque ripple is suppressed effectively while the desired torque output capability is maintained. [ABSTRACT FROM AUTHOR]

In this article, a parallel-series magnetic circuit multi-permanent magnet (M-PM) motor is designed and optimized considering magnet characteristic variation effects, where two kinds of permanent magnets (PMs) are utilized as co-magnetic. Based on the equivalent magnetic circuit method, the detailed design method for the M-PM motor is illustrated. Considering the various operation conditions in potential electric vehicle applications, the B–H curves of two PMs of different typical operation conditions are obtained. Then, a multiobjective optimization method is newly proposed which not only focuses on the magnet characteristics variation effect but also considers output torque, torque ripple as well as antidemagnetization capability under three typical operation conditions. The performances of the initial motor and optimal motor are compared under typical operation conditions. Finally, a prototype machine is built and tested. Both theoretical analysis and experimental results verify the validity of the motor and the proposed design optimization method. [ABSTRACT FROM AUTHOR]

In this article, a flux-controllable permanent magnet (FC-PM) motor has been designed and optimized to achieve the optimal torque component distribution under different flux leakage conditions. The FC-PM motor can realize flexible adjustment and control of air-gap magnetic field by a reasonable flux bridge design, which further broadens the speed range of the motor effectively. The focus of the research is to analyze and optimize the torque characteristics in combination with typical operation conditions. First, a motor topology is proposed and then the mechanism of flux leakage and the distribution of torque characteristics are studied. Then, according to different flux leakage operation conditions, an optimization method considering the torque component distribution is newly proposed. Based on the proposed optimization method, the optimal motor can be obtained. Finally, the performance of the optimal motor is analyzed and compared with the initial motor. The comparison results indicate that, based on the proposed optimization method, the torque output capability is improved effectively, while the desired leakage flux adjustment range is maintained. [ABSTRACT FROM AUTHOR]

This article proposes a method to improve the electromagnetic torque of the I-shaped flux-switching permanent magnet (FSPM) motor considering the flux density harmonic reduction ratio. First, based on the harmonic torque contribution, the harmonics for research are selected. The corresponding flux density harmonic reduction ratio is calculated by comparing the flux density of the rotor yoke with the air gap side. Then, the comprehensive reduction ratio incorporating the selected harmonics is further obtained. Moreover, the FSPM motor is optimized for the reduction ratio and the electromagnetic torque. The characteristics related to the flux density harmonic reduction ratio and other basic performances are evaluated, including magnetic field and flux distribution, no-load back-electromotive force, and so on. Finally, the simulation results verify the effectiveness and rationality of the reduction ratio method. It reveals that the proposed method of the flux density harmonic reduction ratio offers a new perspective to analyze and improve the output performances of the FSPM motor. [ABSTRACT FROM AUTHOR]

In this article, a robust optimization design method considering magnet material uncertainties is proposed for permanent magnet (PM) machines. The key of this method is to improve the machine design robustness to resist the uncertainties influence from PM material, including material diversity, manufacture error, and assembly accuracy. To verify the proposed optimization method, a double PM machine is selected as an example. During the implementation of optimization design, first, the robust optimization model is constructed based on the analysis of PM uncertainties. Then, the Kriging surrogate model and non-dominated sorting genetic algorithm II (NSGA-II) are adopted to solve the optimization model. Finally, to verify the effectiveness of the method, the machine performance and corresponding reliability are evaluated, and a prototype is manufactured and tested. Both simulation and experimental results indicate that the proposed robust optimization method can effectively reduce the influence of magnet material uncertainties on PM machine performance. [ABSTRACT FROM AUTHOR]

In this article, an optimization design method of power factor is proposed for vernier permanent magnet (VPM) machine, in which the key is to analyze and investigate the power factor from the perspective of air-gap flux harmonic modulation. To improve the design efficiency, air-gap harmonics are analyzed and serve as the crucial bridge between power factor and machine geometry. It is noted that, during the operation of the VPM machine, more attention is required for the power factor of low-speed operation area. Based on the popular new European driving cycle of the electric vehicles, three low-speed driving conditions are chosen for the optimization design. For the systematic investigation, a V-shape VPM machine is selected as an optimization example. In order to evaluate conveniently, the comprehensive power factor is defined and sensitive air-gap flux harmonics of different conditions are selected as the optimization objectives, for improving the power factor characteristics in low-speed conditions. In addition, power factor and machine performances are evaluated to validate the proposed method. Finally, the prototype machine is built and tested. Both the simulation and experimental results reveal the feasibility and effectiveness of the proposed method and investigated VPM machine. [ABSTRACT FROM AUTHOR]

In this article, a variable-saliency-ratio permanent magnet motor is designed and optimized considering driving cycles. To satisfy the demands of multi-operation conditions of EVs, a variable resistance is adopted and a new variable-saliency-ratio design concept is proposed to enhance output torque, widen speed range and lower irreversible demagnetization risk effectively. A multiobjective optimization considering driving cycles is proposed, where the design objective of saliency ratio is firstly selected and optimized with multiobjective genetic algorithm method. Then, the operation performances of the motor in different operation conditions are investigated in detail. Finally, a prototype motor is built and tested. Both the simulation and experimental results verify the validity of the proposed method. [ABSTRACT FROM AUTHOR]

In this article, a new type of flux-intensifying permanent magnet (FI-PM) motor is designed, analyzed, and optimized. It focuses on the low-speed operation condition of electric vehicles (EVs). The key characteristic of this motor is the feature of the reverse saliency, so that it not only utilizes the positive reluctance under the positive $d$ -axis current but also improves the PM operation point under maximum torque per ampere (MTPA) control strategy. The relationships among the key parameters, reverse saliency, and torque performance are analyzed and investigated. The response surface method is used to optimize the motor performances. Then, for a better presentation of the investigated motor, the motor performances are evaluated and compared with the traditional interior permanent magnet motor (IPM) in torque characteristic and irreversible demagnetization ability. Finally, for the experimental validation, the prototyped motor is manufactured and tested. [ABSTRACT FROM AUTHOR]

In this article, a robust-oriented optimization design method is proposed for the permanent magnet (PM) motors. The key of the method is to introduce the concept of parameter fluctuation into motor design process, which aims at solving the uncertainties during motor manufacturing process. The optimization design process is purposely divided into two layers. In the Layer I, except for the motor performance objectives, the influence of parameters fluctuation on motor performances is also served as the design objectives to obtain the deterministic motor structure. In the Layer II, the allowable manufacture errors caused by the parameter fluctuation and the manufacturing qualification rate of the motor with the errors are calculated and optimized simultaneously. Then, an interior PM (IPM) motor is chosen as a design example during robust optimization process. For verifying the effectiveness of the optimization design, the performances are evaluated in detail and the prototype motor is built. Finally, both theoretical analysis and experimental results validate the effectiveness of design method and the rationality of PM motor. [ABSTRACT FROM AUTHOR]

In this article, an airgap-harmonic-orientated design method is proposed, where the airgap harmonics are newly acted as the effective bridge between the three key elements of permanent magnet sources, modulators, or armature windings and the motor performances. In the proposed design method, the airgap harmonics play couple roles of design objectives and variables, which are not only served as the design variables for the motor performances, but also considered as the objectives for design parameters. For extensive investigation, a V-shape flux-modulated permanent-magnet (V-FMPM) motor is selected as a design example, which has a potential application for the electrical vehicles. In the optimization process, the sensitivity analysis of different airgap harmonics on the torque performance is conducted to select the leading airgap harmonics. Meanwhile, the sensitivity degrees of the design parameters on the leading harmonics are calculated to pick out the sensitive design parameters. Then, the performances of the V-FMPM motor are evaluated for validating airgap-harmonic-orientated design method. Finally, a prototype motor is built and tested. Both the theoretical analysis and experimental results verify the effectiveness and reasonability of the proposed design method and the V-FMPM motor. [ABSTRACT FROM AUTHOR]

The price fluctuation and the unstable supply chain of rare-earth permanent magnet (PM) have posed potential risks for further application of rare-earth PM motors. To alleviate the consumption of rare-earth PM material, a less-rare-earth PM brushless motor with two types of PM materials is proposed in this paper. The key of this motor is that the rare-earth PM is purposely combined with a non-rare-earth ferrite PM, forming the hybrid PM excitation. To design the proposed motor efficiently, a multi-objective stratified optimization strategy is proposed, where the selected five optimization objectives of output torque, PM cost, cogging torque, torque ripple, and efficiency are divided into two levels. Then, different optimization methods are skillfully combined to meet the specific design requirements. The corresponding electromagnetic performances are analyzed and compared with the baseline rare-earth PM brushless motor. Finally, several experiments of the two motors are carried out for evaluation. Both theoretical analysis and experimental results verify the feasibility and validity of the proposed motor and the optimization method. [ABSTRACT FROM AUTHOR]

In nature, to flux-modulated permanent magnet (FMPM) motors, the electromagnetic energy transmission is realized by abundant harmonics in the air-gap field. It means that, under the flux modulation effect, the harmonics in FMPM motors play an important role for motor performances. In this paper, by incorporating the concept of harmonics design into motor design process, a double-air-gap FMPM motor considering leading working harmonics is proposed and studied for potential applications of electric vehicles or electric tractors. First, the leading working harmonics are distinguished and chosen conveniently by evaluating the contributions of diverse harmonics to PM flux linkage. Then, a correlation design between the harmonic characteristics and geometric parameters is implemented based on the selected leading harmonics. In addition, the motor performances are evaluated by using the finite-element method, consisting of the air-gap harmonic analysis, no-load back-electromotive force, and torque performances. Finally, the theoretical analysis and computational results verify the effectiveness of the proposed motor. [ABSTRACT FROM AUTHOR]

In this paper, two permanent magnet flux-intensifying motors are designed and optimized to realize the characteristic ofLd>Lqand the flux-intensifying effect. Compared with the conventional interior permanent magnet motor with the characteristic ofLd< Lq, the advantages of a low irreversible demagnetization risk and a wide speed range can be obtained in the motors. To meet multiple design requirements effectively, a comprehensive sensitivity analysis method is first implemented to evaluate the influence of each design variable on the selected optimized objectives of output torque, reverse saliency ratio, and torque ripple. Second, a sequential nonlinear programming algorithm is used for realizing the multiobjective optimizations of strong-sensitive design variables. Then, the performances of the two optimal motors are analyzed and compared with the initial permanent magnet motor in detail. Finally, two prototype motors are manufactured and tested. Both the simulation and experimental results verify the validity of the new flux-intensifying motors and the optimization method. [ABSTRACT FROM AUTHOR]

An active disturbance rejection control (ADRC) controller using phase-locking loop observer (PLLO) is proposed in this paper to improve the disturbance rejection property of speed control system. First, to simplify the comparison with other controllers, a universal speed controller design method based on disturbance estimation is employed, and a unified expression for different controllers is presented. Then, several common speed controllers are compared with each other, and two PLLO-based ADRC controllers are presented. After that, considering the variations of load inertia, robustness of the proposed ADRC system to inertia variation is analyzed. Finally, to improve the tracking performance for sinusoidal speed reference, an adaptive speed control system using identified inertia is presented. Simulation and experimental results verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this study, a new sensitivity analysis based on non‐linear varying‐network magnetic circuit (VNMC) method is proposed for an outer‐rotor I‐shaped permanent magnet flux‐switching motor. By integrating concept of sensitivity analysis into the non‐linear VNMC method, the whole design efficiency can be improved effectively by using the comprehensive sensitivity method and sequential non‐linear programming algorithm. In the optimisation process, two design objectives are selected, including machine output torque and torque ripple. Based on the sensitivity analysis, the parameters possessing the significant influence on the design objectives can be selected purposely, thus the overall amount of calculation is obviously reduced. After the determination of the sensitive parameters, the rest of optimisation can be realised efficiently by the non‐linear VNMC method. Finally, a prototype motor is manufactured and tested. Both theoretical analysis and experimental results confirm the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper proposes a new V-shaped permanent magnet vernier (V-PMV) motor for potential applications in direct-drive system. By utilizing the V-shaped PM topology and suitable pole–slot ratio, not only the flux leakage can be reduced effectively which is inevitable in traditional surface-mounted and spoke-type vernier permanent magnet (VPM) motor, but also the utilization of air-gap magnetic field harmonics can be improved. Moreover, dummy slots are employed on the inner edge of rotor, so that the torque ripple can be reduced. To fairly estimate electromagnetic performances of the proposed V-PMV motor, an existing flux-concentrating VPM motor is selected purposely and designed with the same size for comparative analysis by using the finite-element method. The simulation results indicate that the V-PMV motor can offer the advantages of high PM utilization, and low cogging torque and torque ripple. [ABSTRACT FROM AUTHOR]

In this paper, a multimode design method is proposed for motor design under multiple operation conditions. Based on the driving cycles in electric vehicles, five typical operation conditions and the corresponding five driving modes are determined for the multimode design. To investigate the method conveniently, a flux controllable stator permanent magnet (SPM) memory motor is selected and taken as a design example. In the design process, by using the sensitivity analysis method, the significance of the parameters in various driving modes are evaluated effectively. Based on the motor driving demands, the whole optimization design is divided into three steps, where different optimization method is applied in each step. To verify the feasibility of the multimode design method, the operation performances of the motor in different driving modes are investigated in detail. Finally, a prototype motor is built and tested. Both the simulation and experimental results reveal that the proposed design method can offer an effective design optimization for the flux-controllable SPM memory motor, where multimode operations are indispensable. [ABSTRACT FROM PUBLISHER]

This paper investigates an optimal split ratio for a brushless dual-rotor flux-switching permanent magnet (BDR-FSPM) machine. Based on the design theory of conventional FSPM machine, the split ratio of the BDR-FSPM machine is deduced and redefined. And the crucial factors which have close relationship with the split ratio are determined, consisting of power split ratio, magnetic loading, PM pole width, and stator pole width. To conveniently explore the optimal split ratio, the response surface method is purposely utilized for conducting optimization, where the magnetic loading and output torque are chosen to be the objectives. In addition, considering the application requirement of hybrid electric vehicles, the concept of power allocation is proposed and integrated into the optimization process of split ratio. Then based on the optimal split ratio, the machine performances are analyzed in detail, including air gap flux density, back-electromotive force (EMF), coupled-EMF, and torque performances. Finally, a prototyped BDR-FSPM machine is manufactured and tested to verify the validity of the proposed split ratio optimization and machine design approach. [ABSTRACT FROM AUTHOR]

This paper designs and compares two outer-rotor flux switching permanent-magnet (FSPM) motors, in which the two different PM topologies of the V-shape magnet and I-shape magnet are adopted respectively in their stator structures, namely, V-FSPM motor and I-FSPM motor. First, the design principles and motor topologies are introduced. Second, by using the comprehensive sensitivity method and sequential nonlinear programming algorithm, the two motors are optimized efficiently before comparison, where the torque and torque ripple are selected as the design objectives. And then based on the finite element analysis (FEA) method, the motor performances are evaluated in detail, such as back EMF, torque characteristics, and efficiency. To extensively explore the advantages of the two motors, the comparison work involving output torque, torque ripple, and PM usage efficiencies are further implemented under three different conditions. Finally, the two prototyped motors are manufactured and tested, respectively. The theoretical analysis is verified by the FEA results and experimental results, which reveals that both of the two motors can be interesting and potential candidates for the in-wheel traction applications. [ABSTRACT FROM AUTHOR]

In this paper, an outer rotor flux-switching permanent-magnet (FSPM) motor incorporating the concept of stator permanent-magnet motor into outer-rotor motor is investigated. Similar to the traditional FSPM motors, the torque ripple of the motor is relatively high. In order to realize the torque ripple reduction effectively, a new systematic multi-level design and control scheme is proposed to coreduce the torque ripple of the proposed motor. In motor design level, by adopting the design of experiments method and the response surface method, the lower cogging torque with desirable high output torque and efficiency can be obtained. In motor control level, the optimization model based on the iterative learning control method is proposed, wherein the optimal compensating torque can be produced to further suppress the torque ripple. Finally, a prototype motor is manufactured for evaluation. Both simulation and experiment results verify the validity of the proposed method. [ABSTRACT FROM AUTHOR]

This paper proposes a brushless double mechanical port flux-switching permanent-magnet motor for potential application in hybrid electric vehicles. To realize the design objectives of high-torque capability, low-torque ripple, and low-magnetic coupling between the inner and outer motors, a new multilevel design optimization method is proposed to conduct a multiobjectives optimization. First, by adopting the comprehensive sensitivity approach, the whole optimization design process is divided into three levels: nonsensitive level, mild-sensitive level, and strong-sensitive level. Then, to improve the whole design efficiency, the response surface method and multiobjective genetic algorithm are applied in the mild-sensitive level and strong-sensitive level, respectively. Based on the proposed design method, a compromise design among the three design objectives is considered and realized. Finally, a prototype motor is built to verify the validity of the proposed design method and motor operation. [ABSTRACT FROM PUBLISHER]

This paper proposes an outer-rotor V-shaped permanent magnet flux switching (V-PMFS) motor for potential applications in in-wheel direct drive system. However, the cogging torque and torque ripple of the outer-rotor V-PMFS motor are relatively high, which may lead to mechanical vibration and acoustic noise, especially in low speed operation. To improve the overall performances of the outer-rotor V-PMFS motor, a multi-objective optimization method based on multi-level design method is proposed. According to the effect of the design variables on the optimization objectives, sensitivity analysis method is used to divide the design variables into two levels. Then, the two levels of design variables are optimized with two different optimization methods. After optimization, electromagnetic performances between initial and optimal motors are compared. Finally, a prototype motor is manufactured and tested. Both electromagnetic performance analyses and experimental results verify the validity of the proposed optimization method. [ABSTRACT FROM PUBLISHER]

This paper proposes a new brushless double mechanical port flux-switching permanent magnet (BDMP-FSPM) motor for plug-in hybrid electric vehicles applications. The key is to highly integrate two rotors and single stator into one motor frame, which is based on the concept of incorporating the double-rotor motor into a stator-permanent-magnet motor. In addition, by combining the non-contact magnetic planetary gear with the proposed motor, the new resulting electric continuous variable transmission system can not only realize the required speed and torque transmission, but also manage the power split and combination in various driving cycles. The electromagnetic performances of the proposed motor are analyzed by using the finite-element method, such as magnetic field distribution, coupled back-EMF, torque performances, torque-speed curves, and power-speed curves. Experimental results of the BDMP-FSPM prototype are also given to verify the validity. [ABSTRACT FROM AUTHOR]