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In an interior permanent magnet synchronous motor (IPMSM) with segmented skewed poles, the armature reaction magnetic field (AR-MF) changes nonlinearly due to the saturation of the rotor magnetic barrier. Meanwhile, this varies under different excitation currents. As a result, it is difficult to be calculated by means of analytical methods. In this paper, the calculation model of AR-MF of IPMSM is first established by vector superposition method, without considering the saturation effect of rotor and the slotting effect of stator. In the second step, the virtual magnetic field of the rotor is introduced to quantitatively calculate the influence of local inhomogeneous saturation on the AR-MF. The latter is derived by combining both the subdomain method and equivalent magnetic circuit method. The complex relative permeance is also introduced to establish the AR-MF accounting for the stator slotting effect. To validate the AR-MF calculation method proposed, an 8-pole 48-slot IPMSM with segmented skewed poles is considered as a case study, showing a comparison by both with finite element (FE) results and the electromagnetic torque measured on a test bench. The model proposed in this paper shows high accuracy and fast computation with respect to FE analysis. [ABSTRACT FROM AUTHOR]

This paper presents a novel design concept for Synchronous Reluctance (SynRel) machines aimed at reducing the torque ripple. Two general sizing approaches based on the homothetic scaling principle are defined and compared. An in depth analysis on the torque ripple, for a wide range of scaled geometries, evaluated by finite element, has been carried out at different operating conditions. A further analysis is performed on 4 scaled geometries that have been optimized starting from 4 random rotor geometries. It is shown that the main rotor geometrical variables converge to similar values for all scaled machines. The accuracy of the proposed model is then validated by comparing the FE simulated torque ripple waveforms with the experimental data carried out, for a range of operating conditions, on a machine prototype. The outcome of this work is a fast and accurate scaling technique for the preliminary design of SynRel machines with reduced torque ripple. [ABSTRACT FROM AUTHOR]

A close functional and structural integration of passive elements is required to improve the power density of motor drives. Such power-dense motor drives are prerequisites in aerospace and automotive applications. This article presents a permanent magnet motor with an integrated filter inductor, which not only eliminates inductor losses but also removes its associated weight and volume. The motor with an integrated filter uses motor's inherent magnetics in order to use it as a filter inductance instead of adopting an external inductor option, which is traditionally placed outside the motor. A vector-controlled model, taking modulation and switching effect into account, has been developed by using MATLAB/Simulink tool. To experimentally validate the concept of the motor with an integrated filter inductor, the winding connections of an existing motor are modified. The comparative analysis, between the traditional and integrated motor drive systems, is carried out in terms of the magnitude of switching component, total system losses, weight, and volume. The total losses in the motor with integrated filter are reduced by 34.2% at 2100 r/min and 3-N·m load, when compared to the motor with traditional filter inductor, whereas, its weight and volume in the motor with integrated filter inductor are eliminated completely. [ABSTRACT FROM AUTHOR]

For the high-speed permanent magnet synchronous motors (HSPMSMs), their magnetic fields are more complicated with the rotating magnetization and harmonics considered. Furthermore, there are interaction effects on motor iron loss from high frequency, temperature, and compressive stress. In order to obtain the accurate HSPMSM iron loss calculation model, different iron loss models are proposed, in this article, considering these physical factors, and the iron loss model considering the interaction effect of the multiphysics factors is given. The magnetic field, temperature field, and stress field are analyzed for HSPMSM by finite-element method (FEM). Then, the proposed models are employed to calculate the iron loss of the silicon steel sheet and the prototype. The accuracy of the proposed iron loss model, which can consider the interaction effect of the multiphysics factors, is verified by the experimental test measurements on the prototype. [ABSTRACT FROM AUTHOR]

Metallic sleeves are widely used to ensure the mechanical integrity of rotors in high-speed permanent magnet (PM) synchronous machines (HSPMSM). However, in traditional high-speed rotors, the PMs which are very weak in tensile stress cannot be well protected by sleeves. Furthermore, the material properties of both the sleeves and PMs cannot be fully used. As a result, the high-speed running range of the machines are limited by the mechanical strength for a given rotor size. In this paper, taking a 230-kW 35-kr/min prototype as an example, the mechanical strength issues of the rotor are investigated by analytical method and finite element analysis (FEA). In order to overcome the unbalanced protective effect of the sleeve and make fully use of the materials, an optimal sleeve, as well as an improved rotor structure, is presented. The comparison results show that the optimized sleeve has well balanced protective effect to the PM as well as good utilization of materials, with a resultant increase in maximum speed of nearly 40% with respect to the prototype. [ABSTRACT FROM AUTHOR]

The rotor structure of synchronous reluctance machines (SynRel) is conventionally retained mechanically by iron ribs. In this paper, a novel structure for high-speed synchronous reluctance rotor is presented. The novelty of this paper is the proof of a concept of SynRel machine without iron ribs. Structurally, the rotor iron lamination segments are embedded in an adhesive resin material with high temperature resistance and mechanical strength. Three four-pole SynRel machines have been designed with the target of improving motor torque, and compared for different ribs configuration. It has been shown that the proposed motor performs enhanced torque, power factor, and efficiency with respect to conventional SynRel with iron ribs. An extensive sensitivity analysis of the ribless rotor geometry is carried out, followed by both mechanical analysis and experimental over speed test to guarantee its robustness above the operating speed range. The manufacturing procedure of this novel rotor is introduced. Finally, the experimental results on both SynRel prototypes are presented, showing the increase in torque, power factor, and efficiency of the proposed solution. This paper is a first step toward the definition of a viable and novel solution of SynRel machines with improved performance. [ABSTRACT FROM AUTHOR]

This paper deals with the high accurate current set-points solution for interior permanent-magnet synchronous motors (IPMSM) in wide-speed range applications. Considering voltage and current constraints, the operating regions can be divided into maximum torque per ampere, maximum current, field weakening, and maximum torque per voltage regions, which requires solving different nonlinear functions in real time to obtain optimal current set-points. Traditional methods including curve-fitting methods and polynomial approximation (PA) methods are not easy to obtain these solutions, especially involving magnetic saturation problems. In this paper, Newton–Raphson algorithm for improving the control accuracy of the current set-points is proposed. Meanwhile, parameters influence including magnetic saturation and resistive voltage drop is fully investigated. Compared with PA method, the proposed method is able to converge to accurate solutions in few numbers of iterations with reduced execution time, which can be easily implemented on an off-the-shelf digital signal processor. Both simulation results and experimental results on an 8-kW IPMSM rig are conducted showing good agreement with the expected results. [ABSTRACT FROM AUTHOR]

This paper presents a validation of the novel motor-shaped rotational inductor. To validate the concept, 12 slots 2 poles rotational inductor is tested at different supply frequencies and rotor speeds. Experimental results have shown that the iron losses reduce as the rotor speed increases to the synchronous speed of the stator supply. The performance of the integrated rotational inductor is also compared with traditional EE core inductor in terms of total losses, synchronous inductance, copper resistance, and total harmonic distortion (THD). The total loss-to inductance ratio of the rotational inductor is reduced by 22.5% when rotor is rotating at 18 kRPM and supply frequency is held at 300 Hz. A significant reduction in copper resistance-to-inductance is also noticed when supply frequency is varied from 0 Hz to 20 kHz. Furthermore, the synchronous inductance and voltage and current's %THD of rotational inductor is found to be superior to EE core inductor. [ABSTRACT FROM AUTHOR]

The longitudinal end effect of the double-sided permanent magnet linear synchronous motor (DS-PMLSM) causes a large end force. To overcome this drawback, this paper proposes a novel DS-PMLSM structure, in which the upper or lower primary component is shifted by a certain distance. First, the end-force model of the DS-PMLSM is established, based on which, the influences of the staggered structure on the fundamental and higher order end-force components are analyzed. Following this, the DS-PMLSMs with different slot–pole combinations are divided into four categories, and the design principles of possible winding arrangements are discussed. Furthermore, the staggered structures are applied to four slot–pole combinations, namely 21-, 15-, 20-, and 16-pole/18-slot. The back electromotive forces, detent forces, thrusts, and normal forces of the four combinations are analyzed and compared through the finite-element method. The electromagnetic and output characteristics of the novel DS-PMLSM are also compared with the traditional DS-PMLSM prototype to verify the effect of the proposed structure on suppressing the end force. [ABSTRACT FROM AUTHOR]

This article describes the development of an exact analytical model for predicting magnetic field distribution within active parts of a dual-rotor (DR) permanent magnet (PM) synchronous machine with a Halbach array. The model is based on the accurate solution of Laplace’s and Poisson’s partial differential equations (PDEs) using a method of separation of variables. The model also allows the calculation of the DR machine flux linkage, back electromotive force (bEMF), and electromagnetic torque at on load and cogging torque at a no-load condition. The model can be used at the initial stage of designing a DR PM machine for the estimation of electromagnetic parameters and the optimization of machine geometry. [ABSTRACT FROM AUTHOR]

Phase-shift or pole-shift method can reduce the detent force of the double-sided permanent magnet linear synchronous motor (DS-PMLSM) dramatically. However, this method causes a decrease in thrust and an increase in normal force simultaneously. To overcome this drawback, a novel slot-shift structure whose slots on the two sides of the primary component are staggered by an optimal distance is proposed in this paper. The models of the detent force including the end force and cogging force is established theoretically, and then verified by finite element analysis. The windings in the upper primary and the lower primary are arranged differently to improve the average thrust. The thrust characteristics of the DS-PMLSM under different shifted distances are analyzed and compared in detail. Furthermore, the primary component employing two kinds of core laminations is proposed to reduce both the dc component and ripple of the normal force. Finally, a DS-PMLSM prototype is tested, and the experimental results are compared with the analytical results to verify the effectiveness of the theoretical and simulation research. [ABSTRACT FROM AUTHOR]

This paper proposes an integrated method of three-phase ac excitation and high-frequency voltage signal injection (HFVSI) for sensorless controlled starting of brushless synchronous machines (BSM) used as starter/generator in variable frequency ac power systems of civil aircraft. Fixed 400 Hz of the three-phase ac power is adopted both for the ac excitation and HFVSI in the initial starting process to eliminate the bulky rotor position sensor for BSM. The resulting 6th sequence harmonic voltage determined by the rotating rectifier is utilized as the HFVSI into the field-winding of main generator without any extra high-frequency signal injection. The rotor position is estimated by the high-frequency response signals extracted from the armature windings of main generator. Due to the nonlinear rotating rectifier linked in the HFSI chain, a novel frequency-insensitive asynchronous demodulation strategy is proposed in this paper for rotor position estimation. Furthermore, the initial rotor position detection is calibrated by polarity decision of the induced currents of the armature windings within the establishment procedure of field current of the main generator at standstill. The effectiveness of the ac excitation and feasibility of rotor position estimation for sensorless starting control of BSM are validated by the simulation and experimental results. [ABSTRACT FROM AUTHOR]

This paper deals with a comparative study between reluctance (REL), permanent magnet assisted reluctance (PMAREL), and surface mounted permanent magnet (PM) synchronous machines with rotor eccentricity. Static, dynamic, and combined eccentricity cases are considered. For the sake of generality, this comparison is carried out at different levels of air-gap flux density, as different current angles, different PM materials, and different number of magnetic poles. Additionally, different stator windings arrangements, i.e, distributed and fractional slot concentrated windings are taken into account. Besides, different rotor geometries of REL and PMAREL machines are included. As a case of study, 36-slot machine is analyzed, considering three flux barriers per pole; however, the study can be applied to any machine geometry. Due to the structural criticality of the rotor iron ribs of the REL machines, the impact of the eccentricity on the mechanical stress acting on those ribs and the deformation of the rotor is studied. [ABSTRACT FROM AUTHOR]

Synchronous reluctance machine has high flux density fluctuations in the iron due to the high harmonics results from the rotor anisotropy. Thus, an accurate computation of the iron losses is of paramount importance, especially during the design stage. In this paper, a nonlinear analytical model considering the magnetic iron saturation and the slotting effect is proposed. The model estimates accurately the iron losses at a wide range of operating speed. In addition, the accuracy of the nonlinear model when the machine is highly saturated, i.e., when it works along the maximum torque per ampere (MTPA) trajectory, is presented and verified. The model presented is general and can be applied to other configurations. A 36-slot four-pole machine, with three flux-barriers per pole is considered as a case study. Finite element analysis is used to validate the results achieved by means of the nonlinear analytical model. Furthermore, an experimental setup is built to validate the simulation results. [ABSTRACT FROM AUTHOR]

This paper investigates a novel rotor configuration of a permanent-magnet synchronous machine (PMSM) in which a saliency modulation rotor end is added to the machine rotor to improve the self-sensing capability. The saliency-based self-sensing control method is widely adopted for position estimation at stand-still and low speed range. However, the performance is heavily affected by saturation effects for conventional PMSMs, because the machine saliency variates with increased fundamental stator flux under loaded operation. The proposed scheme provides an additional space anisotropic to the rotor. Saliency modulation of the rotor end is electrically asynchronous with the machine fundamental reference frame. Hence the tracked machine saliency provided by the rotor end is no longer affected by saturation effects. In addition, for medium and high speed ranges, the rotor end saliency can be modulated with the fundamental voltage and the rotor position can be tracked without superposed injection. A genetic algorithm optimization environment joined with finite element analysis allows obtaining optimized rotor end geometry for better position signal quality. The expected self-sensing performance is validated by experimental results. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of the slot/pole (S/P) combination on inter-turn short-circuit (SC) current in fault-tolerant permanent magnet (FT-PM) machines. A 2-D sub-domain field computational model with multi-objective genetic algorithm is used for the design and performance prediction of the considered FT-PM machines. The electromagnetic losses of machines, including iron, magnet, and winding losses are systematically computed using analytical tools. During the postprocessing stage, a 1-D analysis is employed for turn–turn fault analysis. The method calculates self- and mutual inductances of both the faulty and healthy turns under an SC fault condition with respect to the fault locations, and thus SC fault current, considering its location. Eight FT-PM machines with different S/P combinations are analyzed. Both the performance of the machine during normal operation and induced currents during a turn–turn SC fault are investigated. To evaluate the thermal impact of each S/P combination under an inter-turn fault condition, a thermal analysis is performed using finite element computation. It is shown that low-rotor-pole-number machines have a better fault tolerance capability, while high-rotor-pole-number machines are lighter and provide higher efficiency. Results show that the influence of the S/P selection on inter-turn fault SC current needs to be considered during the design process to balance the efficiency and power density against fault-tolerant criteria of the application at hand. [ABSTRACT FROM AUTHOR]

The automated design of synchronous reluctance (SyR) motors based on multiobjective genetic optimization and finite-element analysis is considered in this paper. Three types of barrier shapes are considered, all described by an effective limited set of input variables. The three solutions are investigated to establish which of the geometries can give the best torque output and also which one represents the best compromise between output performance and computational time. The analysis presented in this paper shows that SyR motors designed automatically can give a good performance and can be designed in a reasonable time, and it is also shown that not all design degrees of freedom are useful in terms of motor performance. Two prototypes of automatically designed machines have been fabricated and experimentally compared with a third prototype designed according to state-of-the-art design principles. [ABSTRACT FROM PUBLISHER]

In this paper, a simple and robust method for parameter estimation at rotor standstill is presented for interior permanent magnet (IPM) synchronous machines. The estimated parameters are the stator resistance through dc test, the $dq$ inductances using high-frequency injection, and the permanent magnet flux by means of a closed-loop speed control maintaining rotor stationary. The proposed method does not require either locking the rotor or additional/special power supplies. The validity of the suggested method has been verified by implementation on two IPM motor prototypes. Finally, the estimated parameters have been compared against results obtained through finite-element simulations and with machine magnetic characterization, separately performed, to validate the method's effectiveness. Saturation and cross-saturation effects are taken care of through amplitude modulation and cross-axis current application, respectively. [ABSTRACT FROM AUTHOR]

This paper describes a brushless dc (BLDC) drive with a single sided matrix converter (SSMC) for an electrohydrostatic actuation system in aerospace application. The use of an SSMC with a BLDC motor is novel and is used to achieve operation without a microprocessor. A simple hysteresis current control strategy is implemented to control motor torque. The multiphase SSMC provides high reliability and fault tolerance with the penalty of more power devices. A five-phase SSMC prototype is built. The experiment results are presented to verify the drive performance. [ABSTRACT FROM AUTHOR]