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Owing to the importance of environmental issues, a prevalent global challenge, the use of permanent magnet synchronous motors has increased significantly in several industries. Motor efficiency is important because of environmental regulations. As an approach to increase the efficiency of a motor, a method has been presented to increase efficiency via a motor design. Although the design is important, the method for controlling the actually developed motor also significantly affects efficiency. As a method for controlling the existing motor, current control was adopted. Speed–torque control is widely used as a method commonly adopted in conventional motor control. As the motor control method proposed in this study, flux–torque control was employed. Although flux–torque control is not a novel technology, in the case of the control method proposed in this study, a method for interpolating values after comparison with actual data via the finite element analysis (FEA) of the motor is applied. In this study, a method for interpolating inductance among important factors for motor torque control is proposed. Therefore, regarding the proposed flux–torque control, the validity of the study was verified based on the actual data obtained from the FEA and actual manufactured motor shape. [ABSTRACT FROM AUTHOR]

In this article, a novel global search algorithm tornado optimization (TO) and its hybridization with pattern search method (PSM) are proposed to solve the multimodal optimization problem. The TO enhances the capability of global searching with two strategies: intensification strategy and diversification strategy. The hybridization with PSM supports the exact and fast convergence on adjacent optima from the points that are discovered in global search using TO. The outstanding performance of the proposed algorithm is verified by comparison with niching genetic algorithm at the two test functions, and the algorithm is applied to the optimal design of the interior permanent magnet synchronous motor for electric vehicles. [ABSTRACT FROM AUTHOR]

Due to the local inhomogeneous magnetic saturation of the core of the interior permanent magnet synchronous motor (IPMSM), the magnetic field changes nonlinearly, which makes the analytical calculation of the magnetic field difficult. Therefore, the calculation of the magnetic field mostly relies on the finite element method (FEM). However, the high computation cost of FEM restricts the efficiency of the design and analysis of IPMSM. In this article, an analytical model (AM) of slotless open-circuit air-gap magnetic field (OC-AG-MF) of IPMSM with V-shaped segmented skewed poles is derived by combining the subdomain method (SDM) and the magnetic equivalent circuit (MEC) method, and then, the AM of slotted OC-AG-MF of IPMSM with V-shaped segmented skewed poles is obtained by introducing the complex relative permeance. To show the effectiveness of the novel AM, the OC-AG-MF and cogging torque of an IPMSM with V-shaped segmented skewed poles for electric vehicles are calculated by the AM and FEM, respectively. The spatial order, amplitude–frequency characteristics, and the 3-D spatial distribution of the OC-AG-MF are analyzed. Finally, the accuracy of the AM is experimentally verified by direct measurement of OC-AG-MF and no-load back electromotive force (EMF) of the motor. The AM proposed in this article is shown to accurately calculate the radial and tangential components of OC-AG-MF of IPMSM with V-shaped segmented skewed poles considering rotor magnetic bridge saturation effect and stator slotting effect. Meanwhile, the efficiency of the design and analysis of the motor is expected to be improved due to the reduced computational effort compared to the prevalent FEM. [ABSTRACT FROM AUTHOR]

In this article, a process for reducing the electromagnetic vibration and noise by changing the shape of the stator is presented. Although the fundamental wave of the air gap magnetic flux density contributes to the average torque of the motor, other spatial harmonics which were except the fundamental wave of that cause vibration and enfeeble the output of the motor. Therefore, it is important to reduce the spatial harmonics for performance of the motor. Through the proposed process, it is possible to obtain an objective function to reduce the specific harmonics by assigning weights to each spatial harmonic. The reduction in the fundamental wave is minimized and it is possible to reduce the spatial harmonics that have an adverse impact on vibration. After the process, a model can be found that maintains the electromagnetic performance as much as possible while optimally reducing the vibration. To verify the process, the electromagnetic vibrations by a radial force of the proposed and conventional models were compared, and it was confirmed that the electromagnetic vibration of the proposed model was reduced. The validity of the analysis was proved through finite-element analysis. [ABSTRACT FROM AUTHOR]

The interior permanent magnet synchronous motor uses a barrier structure to block the magnetic flux circulating inside the rotor and to send the magnetic flux into the air gap. Although the airgap magnetic flux density can be increased through the barrier, there is the disadvantage of increased torque ripple. Thus, this study is conducted to determine whether the torque ripple could be reduced by changing the barrier shape. The problem here is that the torque inevitably decreases when the torque ripple is decreased. Therefore, in this study, a novel shape of the bridge is proposed in a model in which the torque ripple is reduced but the torque is not. The notch structure is applied to the bridge and is analyzed through finite-element method analysis. To intuitively express the relationship between the torque and the torque ripple, a torque efficiency factor is devised, and as a result, the torque is maintained but the torque ripple is reduced. [ABSTRACT FROM AUTHOR]

This article proposes a continuum-sensitivity-based method to obtain the optimal design for an interior permanent magnet synchronous motor (IPMSM). Compared with the finite difference method, the continuum sensitivity analysis shortens the computation time significantly when there are numerous design variables. We combine the continuum sensitivity with the shape constraint so that both the shape and the size can be optimized simultaneously and within a short time. This proposed design optimization method is applied to IPMSM rotor design, and its feasibility is verified. The proposed method is expected to be effective for various design problems that require the shape and the size to be optimized simultaneously. [ABSTRACT FROM AUTHOR]

This paper deals with the optimization design process of an interior-type permanent magnet synchronous motor (IPMSM) for electric compressors of air conditioners applied to electric cars and hybrid vehicles. Based on a prototype IPMSM, we identified the current level for efficiency and cogging torque using finite-element analysis (FEA). The IPMSM’s main design variables are optimized to primarily satisfy the target of efficiency and cogging torque. A second optimization design is carried out using the response surface method (RSM) for the main design variables obtained from the Taguchi method analysis. As a result, the optimization design is carried out through a two-step optimization design process using the Taguchi method and RSM. The IPMSMs are analyzed using FEA, and their validity is confirmed by comparing the test results against each step-by-step model. We validate an effective optimization design process using a two-stage design process. We conclude that the proposed approach provides an effective design method for engineers. [ABSTRACT FROM AUTHOR]

A conventional railway vehicle adopts the rigid-axle wheelset (RW) due to its inherently characteristics of automatic restoration capability without additional actuators or control. RW allows the railway vehicle to run to the center of the rail. However, there is no restoring force in independently rotating wheelsets (IRWs), if only traction torque control is applied as in RW. As a result, excessive wear and noise between the rail and the wheel are generated, and in severe cases a derailment may occur. In order for IRWs to generate restoring force, an active control strategy is needed that controls the left and right wheel torques independently. Because of this control characteristic, unlike the conventional traction motor of RW, fast torque response and precise torque control performance are required. In this paper, the design and modeling of an IRW traction motor were accomplished considering active restoring force control. A quasi-semi-closed slot structure is proposed to improve the power density and restoring torque control performance. In the next step, control simulation was performed using a static interior permanent magnet synchronous motor model considering slot harmonics. The validity of the proposed methods was verified through experiments using a dynamo. [ABSTRACT FROM AUTHOR]

In order to resolve the starting problem for position sensorless interior permanent magnet synchronous motor, an improved initial rotor position estimation method based on square-wave signal injection is presented in this paper. Instead of the conventional sinusoidal voltage injection, square-wave voltage signals are injected into stator windings to obtain magnet pole position. On the basis of saturation and saliency principle, the voltage pulse injection method was adopted to identify the magnet polarity. Detecting the magnet pole position by using the square-wave voltage injection, the error signal can be calculated without low-pass filters and time delays. The proposed method is verified via a 1.5 kW interior permanent magnet synchronous motor drive platform. [ABSTRACT FROM AUTHOR]

In this paper, a novel algorithm “firework optimization” (FO) is introduced, as well as its hybridization with generating set search (GSS). FO is an exploration algorithm, which intends to explore a vast region within the search space in order to determine regions that may contain a regional optimum. As the regions with potential are defined, GSS, the exploitation algorithm is applied to determine whether regions determined by FO contain a local or a global optimum. The validity of FO and GSS hybridization algorithm is verified using Branin and Six-Hump Camel test functions, and the hybridization algorithm is applied to an interior permanent magnet synchronous motor, in order to minimize torque ripple. [ABSTRACT FROM AUTHOR]

Optimal design and validation combined with finite-element method (F.E.M) and mesh adaptive direct search (MADS) have been performed to realize the maximum efficiency distribution of interior permanent magnet synchronous motor (IPMSM) compatible to the maximum energy consumption areas of heavy-duty electric vehicle (HD-EV). Particularly, the target energy consumption areas are specified with vehicle simulation in accordance with the real-road driving test cycles of HD-EV. The dominant electromagnetic losses and efficiency of IPMSM are numerically identified in association with F.E.M and MADS. In addition, the proposed IPMSM is optimally modeled taking the maximum torque per ampere control strategy into consideration. Furthermore, the optimally designed prototype is validated via the resultant efficiency map built-up by the dynamometer tests. [ABSTRACT FROM AUTHOR]

In this paper, a novel calculation method of references on current amplitude and current angle of a vector inverter for an interior permanent magnet synchronous motor is proposed using FEM. For a vehicle application, the current information should be calculated effectively within the driving range while satisfying limitation value of battery voltage. Moreover, the parameters related to current and voltage information have nonlinear characteristics because of high power density of traction motor. FEM is used to calculate exact solution considering nonlinear characteristics. The proposed method for current references only uses several load angle curves of traction motor by FEM according to specified current values. By using load angle curves, the driving currents information for vector inverter can be calculated and interpolated effectively including field weakening region as well as constant torque region satisfying limitation of battery voltage. [ABSTRACT FROM AUTHOR]

This paper proposes a method to minimize the cogging torque and torque ripple of an interior permanent magnet synchronous motor by adopting asymmetric barrier design and inverting lamination method. The analysis method for cogging torque and torque ripple is suggested using finite-element method. An asymmetric barrier in a permanent magnet rotor is optimally designed without permanent magnet skew. This proposed design for low cogging torque and torque ripple has an advantage over skew design from a manufacturing point of view. The proposed model is compared with the skew model and nonskew model by calculating torque characteristics to determine the more effective method to reduce torque distortion. [ABSTRACT FROM AUTHOR]

Numerical design coupled with finite-element method (FEM) has been performed for realizing the adaptive efficiency distribution of interior permanent magnet synchronous motor (IPMSM) compatible to the frequent operating range of electric vehicle. In particular, the target operating region is specified with the representative driving modes of heavy-duty vehicle in Braunschweig and Seoul. Considering various control strategies, the dominant electromagnetic losses throughout the whole operating region of IPMSM are numerically identified in association with FEM and employed as design target to minimize. Furthermore, the purposely designed prototype is experimentally validated via the resultant efficiency map built-up by static and dynamic dynamometer tests. [ABSTRACT FROM AUTHOR]

In this paper, an interior permanent magnet (PM) synchronous motor (IPMSM) with concentrated windings was designed for railway traction applications. This IPMSM was analyzed using a 2-D FEM. The results showed that the designed IPMSM has a significant PM eddy-current loss. For more accurate calculation, a 3-D FEM analysis was carried out. Further, the PM eddy-current loss was reduced without critical torque reduction by changing the position of the magnets at the rotor. Finally, frequency analysis of air-gap magnetic flux density waveforms was carried out to investigate the effect of magnet placement on the eddy-current loss. [ABSTRACT FROM AUTHOR]

Permanent magnet (PM) synchronous motors (PMSMs) have been used to drive a number of vehicles. They have high torque density, high efficiency, and a wide speed range. However, the high cost of PMs is disadvantageous. This paper presents a technique for increasing the torque density by modifying the shape of the PMs and minimizing the magnet volume. The PM characteristics such as flux density, demagnetizing force, PM energy product, and the air-gap flux density are represented by a lumped magnetic equivalent circuit when the thickness and width of the PM are increased for the same volume but with different shapes. The torque, torque ripple, core loss, magnet loss, and efficiency of three interior (IPMSM) models designed by the proposed method are compared by finite element analysis. In addition, the demagnetization of the PM due to high temperature, maximum torque load angle, and an adverse field is analyzed. Finally, the analysis result is compared with that of the experiment to verify the proposed model. [ABSTRACT FROM AUTHOR]

This paper investigates the deterioration effect of magnetic properties on the performance of an interior permanent magnet synchronous motor (IPMSM). It is well known that the magnetic property of an electrical steel sheet is deteriorated by stress, which results in a decrease in efficiency of electric machines in general. In this paper, by making good use of the deterioration of magnetic properties, the performance improvement of IPMSMs due to the reduction of leakage flux in a rotor is examined. As a result, it is verified that cogging torque can be decreased by half by deteriorating magnetic property in bridge area in a rotor without reducing average torque and increasing iron loss at load condition. [ABSTRACT FROM AUTHOR]

This paper deals with torque harmonic characteristics of interior permanent magnet synchronous motor (IPMSM) with concentrated winding. In particular, torque ripples including EMF harmonics and cogging torque are numerically investigated with the nonlinear finite element method (FEM), and torque harmonic components are identified with Fourier fast transform (FFT). In particular, the novel design methods to compensate the specified torque harmonics are proposed, and its effectiveness are clarified according to the representative control strategies for IPMSM, maximum torque per ampere (MTPA) and flux-weakening control. [ABSTRACT FROM PUBLISHER]

In this paper, a generalized theory is developed to detect eccentricity fault in synchronous machines. This theory is independent of synchronous machines configurations and structures. Using this theory, a frequency pattern is proposed for eccentricity fault diagnosis in any synchronous machine. Amplitude of the side-band components at the above mentioned frequencies is introduced as a proper index to identify eccentricity fault in synchronous machines. Here, an interior permanent magnet synchronous motor and a surface mounted permanent magnet synchronous motors are selected for modeling and analyzing. The aforementioned motors are simulated using two-dimensional time stepping finite element method. In this modeling method, non-linearity of the permanent magnets and core materials, spatial distribution of stator windings and non-uniformity of the airgap due to static and dynamic eccentricities are taken into account. By this modeling method, Stator currents are calculated for processing and feature extracting. The spectra of the aforementioned signals are computed to certificate extracted features and recognized patterns from presented theory. The simulation results are verified by the experimental results. [ABSTRACT FROM PUBLISHER]

The interior permanent magnet synchronous motor (IPMSM) is usually applied to the traction motor in the hybrid electric vehicle and the electric vehicle due to its high-power density and wide speed range. In this paper, the IPMSM with concentrated winding for a 110 cc electric motorcycle is introduced. Its design was improved for high efficiency and a wide speed operation range. The output characteristics were also analyzed according to the partial magnetic saturation of the shoe and web in many variables. Because partial magnetic saturation affects the harmonics and the eddy current loss of the permanent magnet, it was confirmed that the output characteristics of the motor significantly changed. As a result, the new shape and the design parameters for which the partial magnetic saturation was considered were obtained. Higher level efficiency and a wider operating range than with the base model were confirmed. [ABSTRACT FROM AUTHOR]

Radial force and tangential force, which deform stator core, are the main causes of vibration and noise. There are many methods to minimize such electro-magnetic exciting forces by designing of magnetic core shape. However, modification of rotor shape increases development cost of the motor. Therefore, step skewed rotor is applied to the design to reduce electro-magnetic exciting force so that both reduction of vibration and noise and cost-effectiveness of development can be achieved. In order to consider step skewed rotor in interior permanent magnet synchronous motor (IPMSM), 3-dimensional finite element analysis (FEA) is used to consider leakage flux in axial direction and overhang effect. Furthermore, deformation of stator core caused by exciting force is analyzed to explain the mechanism of reduction of vibration and noise by skewed rotor. Comparison between prototype and step skewed model is performed in terms of analysis of exciting force, deformation of stator and experimental result of vibration to verify the analysis method. [ABSTRACT FROM AUTHOR]

Integrated starter and generator (ISG) is working as starter after vehicle idle stopping and generator during vehicle driving. When ISG works as starter to operate engine, ISG produces maximum power at the operating speed 4000 rpm to remove vibration of initial starting of the engine. In that time ISG produces whine noise which can be detected inside a vehicle. There are two methods to reduce the vibration and noise. One is improving the stiffness of stator and the other is reduction of electromagnetic exciting force. Although improvement of stiffness using mechanical design is utilized effectively to reduce whine noise, the electromagnetic design using the reduction of exciting forces is more reasonable in the same motor size. Because ISG produces torque ripple, radial force and tangential force on operating condition, this paper deals with the reduction design of electromagnetic exciting forces which affect the noise and vibration. Two design variables are selected to optimize the rotor shape especially geometry of flux barrier, and response surface methodology (RSM) is applied as an optimization method. Finally, quantity of the vibration and noise of optimized model are compared with prototype model, and the noise measured in the vehicle engine bay was reduced from 27 dB(A) to 25 dB(A). [ABSTRACT FROM AUTHOR]

This paper presents various flux-barrier designs in an interior permanent magnet synchronous motor (IPMSM) for reducing torque pulsation. A conventional single-layer IPMSM model, a popular double-layer IPMSM model and two novel double-barrier IPMSM models featuring as a double pairs of flux-barrier flexibly coupled with the simplest single-layer PM, are built and compared together. The geometries of flux-barrier structure in each IPMSM model are optimized by performing response surface methodology (RSM) for minimizing torque ripple and cogging torque. The presented IPMSM models are analyzed by using finite element analysis (FEA), and the validity is confirmed by experiment. Finally, the beneficial attributes of the proposed novel double-barrier IPM designs compared with the single-layer and double-layer IPM designs are emphasized. [ABSTRACT FROM AUTHOR]

This paper presents a method to reduce torque ripple considering parameters with magnetic saturation. To estimate parameters of inductances for Interior Permanent Magnet Synchronous Motor (IPMSM), the proposed method uses recursive least square (RLS) estimation algorithm. The estimated inductances are used for calculating torque and DC link voltage. Using the torque and the DC link voltage estimators, this control method can reduce torque ripple of LPMSM because of keeping linearity of inverter output. Therefore, the torque control system can achieve precise torque control. The proposed control method is verified by computer simulation and experiment. [ABSTRACT FROM AUTHOR]

This paper presents a research on magnetic torque improvement of interior permanent magnet synchronous motor (IPMSM) for a direct drive washing machine by considering various barrier shapes. For the direct drive of washing machine, the IPMSM must have high magnetic torque at low speed in the laundry mode. However, the magnetic torque of it is decreased and torque ripple is also increased at the same time, when current phase angle is increased. By using finite element analysis (FEA), several characteristics such as d-, q-axis inductance, back electromotive force (EMF), average torque, torque ripple, and cogging torque are presented. Besides, high-temperature demagnetization which can occur in manufacturing time is considered. Finally, the analysis results are compared with experimental results to verify the proposed design. [ABSTRACT FROM AUTHOR]

This paper presents a method on a multiobjective optimal design of interior permanent magnet synchronous motor (IPMSM) with V-shaped permanent magnet rotor for high performance. In general, a design method adopting equivalent magnetic circuit is used for basic design of IPMSM. However, its use may give us wrong design result because of air-gap flux calculation method by using lumped reluctance parameters. Moreover, it has difficulty in considering arrangement of permanent magnets and barriers, but on the other hand, there exists high degree of freedom of permanent magnet rotor design of IPMSM. Therefore, finite element method (FEM) is needed for the precise design considering arrangement of permanent magnets and barriers. In order for effective V-shaped permanent magnet rotor design, Taguchi method by adopting five multiobjective functions is proposed as an optimal design method. The different optimal design results are suggested by adjusting weighting value of each objective function. Finally, the characteristics of optimal design model with V-shaped permanent magnet rotor are verified by experiment. [ABSTRACT FROM AUTHOR]

This paper deals with the determination of parameters in the motor module of advanced vehicle simulator (ADVISOR) which is an advanced vehicle simulation software. In the ADVISOR, the traction motor of vehicle is defined by efficiency map, maximum torque/speed curve and so forth. Due to the prevalence of interior permanent magnet synchronous motor (IPMSM), this paper mainly focuses on the calculation of efficiency map of IPMSM considering magnetic nonlinearity. Firstly, by means of numerical methods, the inductance and iron loss resistance are calculated. Next according to equivalent circuits, the motor characteristics including speed, torque and efficiency are investigated. Finally, the calculated efficiency result is verified by the experiment data, and all parameters are loaded and implemented in ADVISOR for testing. [ABSTRACT FROM AUTHOR]

This paper presents a design approach to an interior permanent magnetic synchronous motor (IPMSM) for the compressor of a hybrid electric vehicle operated in a 42-V battery system. The approach is to estimate the range of inductance and back-EMF to satisfy the required efficiency of IPMSM. Then, the preliminary geometry satisfying the region is decided by PM type, current density, fill factor, and so on. Last, the detailed design with optimization is performed to consider magnetic saturation and reduce cogging torque and torque ripple. At this time, the simulation results are obtained by finite element analysis and in consideration of operating temperature. In the end, the validity of the design process presented in this paper is verified by test. [ABSTRACT FROM AUTHOR]

Interior permanent magnet synchronous motor (IPMSM) is widely used for many industrial applications such as power train, compressor and home appliances due to its high power density and wide speed range. However, IPMSM have relatively high torque ripple in comparison with surface mounted permanent magnet motor. In case of IPMSM, d-axis current should be fed to use reluctance torque, and the more d-axis current is needed as the motor speed goes up. Therefore, back electromotive force (EMF) of IPMSM contains much harmonics and torque ripple tend to increase as the motor speed increase. This paper proposes a method to reduce torque ripple using harmonic injected current. Firstly dominant harmonic order of back EMF is investigated then under the consideration of harmonics, torque ripple using harmonic injected current will be compared with that of sinusoidal current by finite element analysis. [ABSTRACT FROM AUTHOR]