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This paper deals with the fault tolerance of a five-phase flux switching machine. Short-circuit currents calculation considering inductances variation is developed. Machine behavior (torque quality, copper losses, and homopolar current) under a single short-circuit phase fault, two consecutive and nonconsecutive phases short-circuited, is simulated with a two-dimensional finite elements (2-D FE) model and validated experimentally. Then, a new method is developed to improve its performances in faulty mode, by reconfiguring reference currents. In fact, an accurate torque model is established and then used in a genetic algorithm to optimize reference currents in faulty mode. In this approach of reference currents computation, the used algorithm has multiobjectives and multiconstraints, thereby allowing choosing the appropriate fault-tolerant current solution according to our application. The torque model is considered to be more accurate and closer to the 2-D FE results in both healthy and faulty modes. Then, a comparison of machine performances in healthy, degraded, and reconfigured modes is presented. Experimental results corroborate the analysis. [ABSTRACT FROM AUTHOR]

This paper presents two short-circuit fault models of a hybrid excitation flux switching permanent magnet machine, i.e., excitation phase short-circuit and interturn short-circuit in excitation windings. Two-dimensional finite element (FE) method is used to calculate the major parameters, such as armature and excitation inductances, which are not only functions of rotor position, but also of armature and excitation currents. Moreover, in case of short-circuits, the variations of armature and excitation currents are often significant. This in turn leads to an important change in winding inductances. Therefore, in order to precisely predict machine performance under short-circuit conditions, the use of inductances versus rotor position and RMS currents is essential. With the obtained FE results, two MATLAB/Simulink-based models are established. Then, the previously mentioned short-circuits have been studied and their influences on electromagnetic performances, such as armature and excitation currents, speed and torque, armature and excitation copper losses, stator and rotor core iron losses, as well as permanent magnet (PM) eddy current losses are analyzed. Experiments have been carried out to validate the simulations. [ABSTRACT FROM PUBLISHER]

In this article, a Hybrid Excitation Synchronous Machine (HESM) is optimally designed for a specified Hybridization Ratio (HR). A new formulation of the design problem is proposed to be tackled by the Non-dominated Sorting Genetic Algorithm II (NSGA-II), while minimizing the material cost. This formulation includes a more comprehensive explanation of the key concept, HR, which considers the soft and hard saturation effects in the HESM design. The HESM model is based on a 3D nonlinear Magnetic Equivalent Circuit (MEC). For faster convergence, the number of design variables is reduced using two statistical analyses, namely Analysis of Level and Analysis of Variance (ANOVA). A HESM is optimally designed for HR = 0.5 and validated by a commercial Finite Element Analysis (FEA) software. [ABSTRACT FROM AUTHOR]

Hybrid excited (HE) machines have the synergies of high torque density and high efficiency of permanent magnet (PM) machines and excellent flux controllability of wound-field machines. The PMs and field coils (FCs) coexist in HE machines to provide excitations simultaneously, and can be coupled either in series or parallel. The topologies of HE machines are very diverse, which bring challenges in the selection and design of HE machines. Based on the partitioned stator (PS) platform, a pair of series and parallel HE machines having similar structures and PM usage are evaluated and compared to identify their merits and demerits. With the help of finite element analysis, the flux regulation, energy conversion capability, parasitic effects and irreversible demagnetization of the two kinds of the HE machines are comprehensively investigated and the guidance to the machine design is provided. A pair of prototypes are fabricated and tested to validate the analyses. [ABSTRACT FROM AUTHOR]

This paper incorporates the idea of integrated field and armature windings into the design of novel hybrid excited machines with bi-directional flux modulating effect, which results in a new hybrid-excited machine concept that is referred as dual-electrical-port dc-coil-free hybrid-excited machine (DEP-DCF-HEM). In the proposed design, dc field windings are eliminated and dc bias currents are injected into the windings to generate dc excitation field. In addition, the armature windings are divided into dual electrical ports, and zero-sequence current flows between these two ports can adjust the air-gap field effectively. Compared with existing HEMs with additional dc coils, the proposed machines can achieve both higher torque density and wider flux weakening range. The presented design principle can be utilized in a variety of configurations of DEP-DCF-HEMs. Topologies with stator permanent magnet (PM), rotor PM, and dual PM are possible designs, which are all investigated in this paper. A dual PM DEP-DCF-HEM prototype is manufactured, and experimental measurements are conducted to verify its performances. [ABSTRACT FROM AUTHOR]

With the development of more electric aircraft, higher demand for electrical energy is put forward in generation systems. The constant speed drive is eliminated in variable frequency ac (VFAC) generation systems, which makes integrated starter-generator (SG) can be realized. Considering the inherent defects of wound rotor synchronous SG systems, such as the complex starting excitation methods and rotating rectifiers, this paper proposes a VFAC SG system based on hybrid excitation synchronous machines (HESMs) for aircraft applications. The key technology of HESM-based VFAC SG system is to regulate the field current in such a way that three major modes of VFAC SG system operation for aircraft applications, namely, engine starting operation, transition mode, and generating operation, can be realized effectively. The simulation model of HESM-based VFAC SG system is built and analyzed. A prototype HESM-based VFAC SG system has been designed and developed for experimental verification. The starting operation, transition mode, and generating operation of the prototype HESM-based VFAC SG system are implemented. The feasibility of HESMs to VFAC SG system for safety-critical aircraft applications has been validated. [ABSTRACT FROM AUTHOR]

Hybrid excited (HE) machines combine the advantages of both high torque density and excellent flux regulation capability, while also having extensive applications. A novel partitioned stator HE machine employing two stators to allocate armature windings and excitations separately, is proposed in this paper. The permanent magnet (PM) pole-pair and wound field pole-pair are alternately placed on one stator to exhibit parallel magnetic paths, while the armature windings are located on the other stator. The iron-piece-rotor is sandwiched between the two stators. This machine inherits the advantages of stator-PM machine and further benefits from attractive flux regulation capability due to parallel topology. The operating principle and the slot/pole combination rule that are different from the conventional PM machine are illustrated. The two-dimensional finite element technique is used to evaluate the electromagnetic performance, confirming the mentioned advantages. A prototype is manufactured and tested to validate the predictions. [ABSTRACT FROM PUBLISHER]

Several switched flux permanent magnet (SFPM) machines with mechanically movable flux adjusting technique are proposed, analyzed, and compared for applications which demand high speed and efficiency. By using ferromagnetic pieces-–one per every stator pole or every alternative stator pole, which are named as flux adjusters (FAs) and located on the outside surface of the stator—the airgap flux density can be weakened and therefore the operation speed range and flux weakening capability can be improved. The influence of using all or alternative FAs on the open circuit results, electromagnetic performance, and torque–speed characteristics of the SFPM machine is investigated through three SFPM machines with different stator/rotor pole combinations, i.e., 12/10, 12/13, and 12/14. Moreover, although using FAs in all stator poles can significantly improve the flux weakening capability, alternative FAs can also achieve remarkable improvement although higher torque ripple is observed. Additionally, it has been found that the 12/13 combination is considered to be the most suitable candidate for alternative FAs technique. In addition to 2-D finite-element analysis (FEA) and analytical methods, 3-D FEA results accounting for the end-effect are presented. Furthermore, experiments are performed to validate the results. [ABSTRACT FROM AUTHOR]

Hybrid excitation synchronous generators are a special class of electrical machines in which the total rotor current linkage is produced by the simultaneous action of two different excitation sources: permanent-magnet (PM) excitation and field winding excitation. In the island operation, there is a need to compensate the armature reaction to keep the generator terminal voltage constant. The permanent magnet excitation is used to create the no-load excitation to the generator and the rotor winding is used as an armature reaction compensating winding. This paper studies the applicability of an armature-reaction-compensated PM synchronous generator to a marine diesel genset. This paper presents an analytical approach for the electromagnetic design of the proposed topology. Finite-element analysis and experimental measurements are performed to verify the results of the analytical approach. [ABSTRACT FROM PUBLISHER]

The stator-mounted permanent-magnet (SMPM) machines have some advantages compared with its counterparts, such as simple rotor, short winding terminals, and good thermal dissipation conditions for magnets. In this paper,. a general power equation for three types of SMPM machine is introduced first, and then, power equations considering the specific topologies are derived. Based on these power equations, theoretical comparisons are carried out between various types of the SMPM machines. In all, eight topologies have been presented and benchmarked. It reveals that the flux switching permanent-magnet (PM) machine owns higher power density than the flux reversal PM machine and the doubly salient PM machine under same outer diameter. The comparison based on the power equation has established a foundation for optimizing the SMPM machines. [ABSTRACT FROM AUTHOR]

Flux-switching permanent magnet (FSPM) motors have a doubly salient structure, the magnets being housed in the stator and the stator winding comprising concentrated coils. They have attracted considerable interest due to their essentially sinu- soidal phase back electromotive force (EMF) waveform. However, to date, the inherent nature of this desirable feature has not been investigated in detail. Thus, a typical three-phase FSPM motor with 12 stator teeth and ten rotor poles is considered. It is found that, since there is a significant difference in the magnetic flux paths associated with the coils of each phase, this results in harmonics in the coil back EMF waveforms being cancelled, resulting in es- sentially sinusoidal phase back EMF waveforms. In addition, the influence of the rotor pole-arc on the phase back EMF waveform is evaluated by finite-element analysis, and an optimal pole-arc for minimum harmonic content in the back EMF is obtained and verified experimentally. [ABSTRACT FROM AUTHOR]

This paper presents two vibration control approaches using piezoelectric inserts applied to a switched reluctance machine (SRM) in order to reduce acoustic emission. The semiactive approach, called synchronized switch damping, consists of a particular voltage processing that increases the electromechanical energy conversion of the piezoelectric insert and leads to effective vibration energy dissipation. Piezoelectric inserts can also be considered as actuators: the active technique aims at imposing an adequate force in order to compensate the structure strain originated by the electromagnetic forces. These two techniques are compared on a single-phase structure mechanically similar to that of an SRM. Advantages and drawbacks depending on the chosen technique are then discussed. [ABSTRACT FROM AUTHOR]

This paper presents the analytical, numerical, and experimental results obtained with a double excited synchronous machine (DESM) prototype designed and constructed for an electric vehicle traction system. To obtain a wide speed range, the flux-weakening technique is implemented. Analytical design, 2-D finite element method (FEM) analysis, thermal analysis, and prototype construction of the DESM are discussed, and the performances are assessed with experimental data. [ABSTRACT FROM AUTHOR]