The hybrid variable-flux permanent-magnet synchronous machine (VF-PMSM) is an alternative candidate for adjustable speed applications. The series magnet and parallel magnet configurations are the two existing topologies for hybrid VF-PMSMs. However, they both have drawbacks that have not been fully resolved. A premium topology with high power density and magnetization regulation using acceptable current pulses is highly desired. This paper proposes a new hybrid VF-PMSM with a quasi-series magnet configuration and a passive flux barrier. After introducing the proposed topology and its operating principles, the results of a comparative study are presented comparing the magnetization characteristics and torque capabilities of the three configurations. The influences of key design variables on the machine’s performance are investigated, showing that the proposed machine can achieve a relatively high power density comparable to the series configuration, and the required magnetization current amplitude falls within acceptable limits.

Electric vehicle (EV) is a promising technology for saving fossil energy and reducing pollution. Hybrid-permanent-magnet (PM) variable-flux machine is a competitive candidate for EV propulsion since it has wide speed range and high efficiency at high-speed region. A novel hybrid-PM variable-flux machine with magnetic barriers is proposed in this paper, and a new magnet material CeFeB is used. The structure and operating principle are introduced, and different magnetization states of the machine are analyzed. The equivalent magnetic circuit model of the machine is established considering the influence of magnetic barriers, and the model is proven with good precision for the calculation of air gap flux density and PM operating point. The electromagnetic performances are analyzed, and compared with a traditional variable-flux machine. It is verified that the added magnetic barriers improve the distribution of air gap flux and load magnetization performance of the machine. The no-load back electromotive force, electromagnetic torque, speed range, and load magnetization ratio of the proposed scheme are all improved.

To overcome the inherent demerit of low power factor existing in transverse‐flux permanent‐magnet (TFPM) machines, a tubular staggered‐teeth TFPM linear machine is presented here. Linear alternator integrated with free‐piston Stirling engines could offer a great potential in a wide variety of applications ranging from solar energy generation to space power supply. The thermal behaviour of the machine is studied using a three‐terminal lumped‐parameter thermal network (LPTN) to solve the problem of temperature overestimation of the traditional LPTN. The determination of thermal resistances and thermal parameters are introduced in detail. The temperatures of various components of the machine under different load conditions are calculated by both the three‐terminal LPTN model and the numerical thermal model. Sensitivity analysis is carried out to study the influence of critical thermal parameters on the temperature rise of the machine. On this basis, the effectiveness of the forced air cooling is investigated. A prototype is fabricated and temperature experiment indicates that there is a good agreement between measurement and calculation.

This paper presents a novel staggered-teeth cylindrical transverse-flux permanent-magnet linear machine (TFPMLM), which aims to improve the power factor and force density. Due to the compact structure and high performance requirement, thermal problems should be seriously considered. The three-dimensional (3-D) temperature field model is established. The determination of convection heat transfer coefficients is discussed. Equivalent thermal conductivities of stator core and winding are given to simplify the analysis. With the thermal effect of the adhesive coatings among permanent magnets (PMs) and mover yoke taken into account, the temperature field distribution and variation rules of the TFPMLM are obtained using the finite volume method (FVM). The influences of slot filling factor and air flow velocity on the temperature field distribution are analyzed. It is found that the hottest spot of the TFPMLM appears in the middle of the end winding; and there is no risk of demagnetization for PMs.

The classical Preisach hysteresis model and its modifications are time consuming to implement due to the determination of the weight function. Another defect of the Preisach-based model is that it could only be an approximation in the absence of the congruency property. For such reasons, this paper proposes a hysteresis model identification method based on support vector regression which could be a promising alternative in practical applications. Support vector machine is attractive in regression analysis due to its strong generalization capability. A four-stage identification procedure is implemented and key techniques are introduced in detail. The penalty parameter and the kernel parameter are optimized using grid search and cross-validation method. The influences of data scaling and parameter optimization are analyzed. An identified hysteresis model of aluminum nickel cobalt alloy is evaluated and verified with the criteria of mean squared error and identified time.

Variable-flux memory machines (VFMMs) are considered as promising candidate in adjustable speed drive applications. However, the exploration of VFMMs with acceptable magnetization state (MS) regulating current and high-torque-density is still a challenging issue. This paper presents a high-torque-density VFMM of which is comparable to conventional permanent-magnet machines. The newly developed (Ce, Nd)-Fe-B Magnet with remarkable characteristics are employed in the investigated VFMM. The characteristics of the (Ce, Nd)-Fe-B magnet is firstly introduced. Secondly, a simple and superior VFMM topology with (Ce, Nd)-Fe-B magnet are evaluated in terms of torque production capability, MS regulation characteristics and overall efficiency, and compared to the benchmark machine.