Search

A hybrid optimization method that combines parameter optimization (PO) with topology optimization (TO) is proposed for the design of a permanent magnet (PM) motor. The PM shape, configuration, and flux barrier topology were simultaneously optimized using the proposed method. The conventional hybrid method that deals with a single PM is effectively extended to deal with multiple PMs parameterized by several geometrical parameters. The use of this extension makes it possible to search for the optimal rotor structure of the multiple-PM motor, which is widely used in electric vehicles. The results obtained by the proposed method are shown superior over those obtained by conventional method. The rotor structure with double-U shaped PMs with small flux barriers near the airgap was obtained by the optimization. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Zhejiang University: Science A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel automatic design method for permanent magnet (PM) motors using a Monte Carlo tree search is presented. The optimal motor structures are determined through a tree search, in which the motors with different numbers of poles, current phase angles, PM configurations, and numbers of PMs are simultaneously considered. At the leaf nodes, parameter and topology optimizations are performed to obtain the optimal material shape and distribution. The proposed method was applied to the optimization of a 24-slot motor. It was shown to be effective in finding the optimal motor structure and geometry to maximize the average torque while considering iron loss. The proposed method can be applied not only to the design of PM motors but also to many types of electric apparatus and other systems. [ABSTRACT FROM AUTHOR]

Permanent magnet (PM) synchronous motors have become excellent alternatives for traditional induction and dc motors in numerous applications in recent years. Therefore, torque density and efficiency improvements in the development of PM synchronous motors have become a significant issue. In this study, various PM synchronous motor alternatives are proposed with both non-oriented (NO) and grain-oriented (GO) silicon steel material in the same stator in order to increase the power density and efficiency. A detailed performance comparison using 2-D/3-D finite element analysis (FEA) is completed and a feasible stator design is manufactured. The proposed design with GO material is also compared with a conventional PM motor with NO stator steel. As a result of the investigations, it is observed that the proposed motor with GO material in the stator has higher torque density and efficiency as opposed to the conventional PM motor. [ABSTRACT FROM AUTHOR]

This article introduces novel hybridization of parameter optimization (PO) and topology optimization (TO) methods. The proposed method is applied to the optimization of a permanent magnet motor. The magnet shape and topology of the flux barrier of the rotor core are optimized by performing PO and TO simultaneously. In the optimization, automatic mesh generation is adopted to improve the resolution of the shape representation. It is shown that the increase in the average torque resulting from the proposed hybrid optimization is larger than that obtained by the conventional TO in which only the topology of the flux barrier is optimized. The decomposition of the total torque to the magnet and reluctance torques suggests that the reluctance torque is effectively generated in the rotor optimized by the proposed method. [ABSTRACT FROM AUTHOR]

Accurately measuring the cogging torque, hysteresis torque, and iron losses of permanent magnet (PM) motors is a challenging task. This is especially true for sub-fractional horsepower (SFHP) variants used, e.g., in auxiliary drives for automotive fan and pump applications. Their cogging torque and hysteresis torque peak values are often in the sub-milli-Newton meter range, causing conventional measuring methods and devices to fail as especially friction impedes the measurement significantly. Moreover, their iron losses are hard to determine and usually merely estimated in the literature. This article presents an unconventional rheometer-based method to determine both 1) the cogging torque and hysteresis torque of SFHP PM motors and 2) their iron losses by evaluating the observed offset torque. Two SFHP outer-rotor PM motor topologies for fan applications are analyzed, i.e., a claw-pole motor and a salient-pole motor. The results show that, with the proposed setup, settings, and evaluation, a rheometer can successfully be used to determine the cogging torque and hysteresis torque waveforms in the sub-milli-Newton meter range and the iron losses of SFHP motors, both with excellent accuracy. [ABSTRACT FROM AUTHOR]

Condition monitoring of the stator and rotor problems such as interturn short fault (ITSF) and partial irreversible demagnetization fault (PIDF) in an interior permanent magnet synchronous motor (IPMSM) is essential for achieving high efficiency and reliability. This article presents a torque angle-based inverter-embedded technique for the online detection and identification of ITSF and PIDF. This technique monitors the deviation in the torque angle caused due to ITSF and PIDF at a certain operating point. In steady-state operation, the torque angle decreases from its original value (healthy state) due to ITSF while increases in the case of PIDF. This particular trend of torque angle is used for the detection and identification of ITSF and PIDF. In this article, the torque angle for a healthy IPMSM is first obtained using multivariate regression analysis over the entire operating region and then compared with the torque angle during operation for any potential variation. The proposed method is verified using a finite-element method-based simulation and experiment on a 400-W IPMSM. The results suggest that the proposed method can be a viable candidate for efficient ITSF and PIDF detection and identification in real time. [ABSTRACT FROM AUTHOR]

This paper presents a planar electromagnetic conveyor for a microfactory. The uniqueness of the conveyor design lies in its arrangement of overlapped two-dimensional mesh coils in matrix configuration that enables to drive a mobile part over long strokes. The conveyor architecture includes a fixed part, which consists of 5×5 matrix design that has been fabricated on a multilayer printed circuit board. An analytical model that takes into account the electromagnetic and friction effects has been developed. A conveyor prototype has been fabricated and experimentally characterized in open-loop control. Linear and planar motions, positioning repeatability error, straightness error, and rotation have been experimentally measured. From experimental results, the proposed architecture enables long linear displacement strokes ($\leqslant$ 70 mm) and rotation ($\leqslant \pm$ 12.37 $^\circ$). In addition, a 12 mm/s speed can be achieved for the mobile part at a nominal current of 0.8 A. [ABSTRACT FROM AUTHOR]

In this paper, we propose a loss calculation method considering minor hysteresis loops for permanent magnet (PM) motors driven by pulsewidth modulated (PWM) inverters. In the governing equation of the proposed method, both the effects of the major and minor hysteresis phenomena are expressed by a reaction magnetic field. This field is determined by iterative calculations of finite-element analysis (FEA) with a simple hysteresis modeling that considers the minor loops. The proposed method is applied to a PM motor, and the experimental verification is carried out. It is clarified that the minor hysteresis loops affect not only the hysteresis loss but also the eddy current loss because the skin depth varies with the differential permeability of the minor loops. [ABSTRACT FROM AUTHOR]

This paper deals with the development and implementation of an on-line technique for the identification of the stator resistance and permanent magnet flux linkage on three-phase, open-end winding, permanent magnet synchronous motor (PMSM) drives. The stator resistance and permanent magnet flux linkage are independently determined by exploiting a special current vector control strategy, which holds one of the phase currents at zero while suitably modifying the other two in order to keep the magnetomotive force unchanged. As will be demonstrated, no additional sensors or special tests are required by the proposed technique; moreover, motor electrical parameters can be on-line estimated in a wide operating range, avoiding any detrimental impact on the torque capability of the PMSM drive. Finally, the electrical machine thermal status can be also estimated from obtained values of the stator resistance and permanent magnet flux linkage. [ABSTRACT FROM AUTHOR]

In this paper, we investigate rotor and stator designs of interior permanent synchronous motors for variable speed/load applications to reduce the carrier harmonic losses caused by pulsewidth modulated inverters. The rotor core and magnet shapes are determined by automatic optimization methods with electromagnetic field analysis, which considers the inverter carrier. Appropriate stator-winding configurations are also investigated by this analysis. It is clarified that the total carrier harmonic loss can be reduced by more than 20% by optimizing both the stator and rotor shapes, whereas the other important characteristics are not deteriorated. The mechanism of carrier loss reduction is also clarified. [ABSTRACT FROM AUTHOR]

This paper proposes a design method of stator cores to modify the component ratio of space harmonics in the magnetic field due to stator windings for 12-slot 10-pole concentrated winding motors. The method inserts slit-like magnetic flux barriers in stator wound teeth. In fractional-slot concentrated winding motors, the magnetic field due to stator windings includes dominant space harmonics with a specific space harmonic that produces drive torque. These space harmonics give rise to undesirable effects that increase iron loss in cores and eddy-current loss in magnets. For 12-slot 10-pole motors with single-layer windings, the proposed method increases the driving space harmonic and decreases dominant detrimental space harmonics. This modification of the space harmonics leads to torque enhancement and efficiency improvement. The efficacy of the proposed method is determined by deriving the winding factor, estimating magnetic flux distribution and motor performance through a finite element method analysis, and demonstrating the actual motor performance of a prototype. [ABSTRACT FROM AUTHOR]

This paper describes the design process of a 10 kW 19 000 r/min high power density surface mounted permanent magnet synchronous machine for a directly coupled pump application. In order to meet the required specifications, a compact machine with cooling channels inside the slots and flooded airgap has been designed through finite element (FE) optimization. For high power density, high-speed machines, an accurate evaluation of the power losses, and the electromechanical performance is always extremely challenging. In this case, the completely flooded application adds to the general complexity. Therefore, this paper deals with a detailed losses analysis (copper, core, eddy current, and mechanical losses) considering several operating conditions. The experimental measurements of ac copper losses, as well as the material properties (BH curve and specific core losses) including the manufacturing process effect on the stator core, are presented. Accurate 3-D FE models and computational fluid dynamics analysis have been used to determine the eddy current losses in the rotor and windage losses, respectively. Based on these detailed analysis, the no-load and full-load performance are evaluated. The experimental results on the manufactured prototype are finally presented to validate the machine design. [ABSTRACT FROM AUTHOR]

An automatic shape optimization procedure that estimates the inverter carrier harmonic losses generated at cores and magnets has been developed in order to improve the performance of interior permanent magnet motors used for variable speed/load applications. In the proposed procedure, an electromagnetic field analysis coupled with armature voltage equation is iteratively carried out at each rotor shape. The input of this analysis is the theoretical inverter voltage, which is determined by both the rotor shape and the driving conditions of the motor. The proposed procedure is applied to a 100 kW-class interior permanent magnet motor, in which the carrier harmonic losses become dominant under frequent driving conditions. It is clarified that the carrier harmonic losses can be reduced by more than 10%, whereas the other important characteristics are not deteriorated. [ABSTRACT FROM AUTHOR]

This paper focuses on the application of the variance-based global sensitivity analysis for a topological derivative method in order to solve a stochastic nonlinear time-dependent magnetoquasi-static interface problem. To illustrate the approach a permanent magnet (PM) synchronous machine has been considered. Our key objective is to provide a robust design of the rotor poles and of the tooth base in a stator for the reduction of the torque ripple and electromagnetic losses, while taking material uncertainties into account. Input variations of material parameters are modeled using the polynomial chaos expansion technique, which is incorporated into the stochastic collocation method in order to provide a response surface model. Additionally, we can benefit from the variance-based sensitivity analysis. This allows us to reduce the dimensionality of the stochastic optimization problems, described by the random-dependent cost functional. Finally, to validate our approach, we provide the 2-D simulations and analysis, which confirm the usefulness of the proposed method and yield a novel topology of a PM synchronous machine. [ABSTRACT FROM AUTHOR]

The general trend toward more intelligent energy-aware ac drives is driving the development of new motor topologies and advanced model-based control techniques. Among the candidates, pure reluctance and anisotropic permanent magnet motors are gaining popularity, despite their complex structure. The availability of accurate mathematical models that describe these motors is essential to the design of any model-based advanced control. This paper focuses on the relations between currents and flux linkages, which are obtained through innovative radial basis function neural networks. These special drive-oriented neural networks take as inputs the motor voltages and currents, returning as output the motor flux linkages, inclusive of any nonlinearity and cross-coupling effect. The theoretical foundations of the radial basis function networks, the design hints, and a commented series of experimental results on a real laboratory prototype are included in this paper. The simple structure of the neural network fits for implementation on standard drives. The online training and tracking will be the next steps in field programmable gate array based control systems. [ABSTRACT FROM PUBLISHER]

Sensorless drives for permanent magnet (PM) and reluctance synchronous motors are quite interesting options in modern ac drives. Fundamental-frequency observers provide a rotor position estimate, to be used instead of that measured by delicate sensors. The estimation algorithms are based on either the extended electromotive force or active flux concepts. They feature easy implementation, although their reliability may be undermined by both corrupted measurements and parameter variations, especially in the case of anisotropic rotor structures. Through an analytical sensitivity analysis, this article investigates the influence of model uncertainty on the observed position. The substantial relationships between cause (parameter uncertainty or measurement error) and effect (position error) are validated by experimental results, which also highlights the effects of the q-axis inductance and resistance values on the electric measurement sensitivities. The resulting functions and graphic plots are useful to draw interesting considerations about the motor selection and the control design of the sensorless drive. [ABSTRACT FROM PUBLISHER]

This paper provides stress analytical models for a variable-speed simplified rotor of the surface-mounted permanent magnet synchronous motor (PMSM). The impact developed by alternator discharge on the prime motor rotor was analyzed. Parameters, such as interference fits between sleeve and magnets, rotor core and shaft, sleeve thickness, rotor heating have significant influences on the design of the shock-resistance rotor. Then the stress distribution of the actual rotor was verified by a 3-D finite element analysis model, and the critical speed of the integrated rotor was computed. [ABSTRACT FROM PUBLISHER]

In this paper, a parallel-kinematics-based micropositioning system prototype driven with four electromagnetic motors is presented. The optimal design characteristics of the system incorporate its long-range displacement capability with submicrometer level positioning precision suitable for numerous microapplications. In order to achieve a compact design with micrometer level component assembly tolerances, the movable mechanical structure of the experimental prototype has been microfabricated in the silicon material using inductively coupled plasma etching process. The 80 mm $\times$ 80 mm footprint of the prototype is able to perform millimeter level displacement strokes along both axes in the horizontal plane. The experimental results demonstrate that the micropositioning system is capable of delivering variable strokes up to 2.5 mm in the $xy$-plane. In closed-loop control the system is able to perform repeatable displacement of 2  $\mu$m with a positioning precision of 24 nm. In addition, the proposed micropositioning system design is able to carry 17.3 g of additional load during planar motion in the $xy$-plane. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel proposal to improve reliability of a spoke-type brushless direct current (BLDC) motor using ferrite permanent magnets (Fe-PMs) through a new design. First, the design process for a neodymium permanent magnet (Nd-PM) free spoke-type BLDC motor without assistant permanent magnets (PMs) is presented. The proposed motor is designed by taking into account the demagnetization phenomenon. Second, the effect of the armature reaction on the PMs is analyzed by using the finite element method (FEM) in order to evaluate the robustness of the proposed motor with Fe-PM. In addition, another proposal to avoid the demagnetization phenomenon is suggested. Finally, a prototype motor is manufactured based on the proposed motor. The output characteristics of prototype motor and the demagnetization phenomenon are verified through an experiment. [ABSTRACT FROM PUBLISHER]

The multilevel method has been presented for design optimization of electrical machines and drive systems for optimal system performances and efficiency in our previous work. For framework design of the multilevel optimization method, four techniques are presented in this paper, including the sizing equation, local sensitivity analysis, global sensitivity analysis, and design of experiments techniques. For each technique, a general and theoretical analysis procedure is presented before the application study. To demonstrate the effectiveness, a permanent magnet claw-pole motor with soft magnetic composite core and 3-D finite-element analysis model is investigated to minimize the material cost and maximize the output power while keeping the volume constant. The calculated motor performance based on this 3-D finite-element model has been verified by the experimental results. As shown, these techniques are simple to implement, and the resultant multilevel optimization framework can significantly improve the motor performance and reduce the required sample number of finite-element analysis. [ABSTRACT FROM AUTHOR]

This paper presents a comparison between two types of control algorithms for a five phase PMBLDC motor used for low power and high torque applications. It presents a fuzzy logic control (FLC) and a classical proportional integral (PI) control. Owing to the simplicity and effectiveness, the proportional integral (PI) controller is widely used in speed control of permanent magnet Brushless DC motor (PMBLDC) drive. However, the disadvantage of the PI controller is its poor capacity in dealing with system uncertainties. Simulation results are presented and analyzed for both the controllers. It is observed that fuzzy logic based controller gives better dynamic responses than the traditional PI controller. Experimental results validate the simulation results. [ABSTRACT FROM AUTHOR]

Principle of tolerance design is receiving increased research focus to determine the optimal tradeoff between manufacturing cost and quality. However, current tolerance designs are not suitable for products such as electromagnetic devices that require high reliability, i.e., a very low failure rate. In this paper, a new tolerance design named as reliability-based optimum tolerance design is formulated and performed to guarantee the high reliability of the products while maximizing manufacturing tolerances. The proposed method quantifies the reliability using reliability analysis, which reflects the tolerance in the tolerance design. To validate the proposed method, tolerance design is applied to two examples: 1) a magnetic circuit (C -core) and 2) a mass-produced interior permanent magnet motor that contains manufacturing tolerances of permanent magnet. [ABSTRACT FROM AUTHOR]

This paper investigates the dynamic demagnetization characteristics of an interior permanent magnet (PM) brushless dc motor with a stator turn fault (STF). A new algorithm, which is a finite-element method combined with a line voltage equation of the motor, is developed to analyze demagnetization under dynamic and transient states and considers an STF. The input current, circulating current, magnetic distribution characteristic, and operating property of the PM, including the irreversible demagnetization in the fault state, are analyzed using this algorithm by considering the magnetic saturation effect. The feasibility of the proposed method confirmed from the analysis results is verified via an experiment. Through this fault analysis, we can accurately check the fault phenomena and healthiness of a PM motor against the demagnetization fault for fault prevention. [ABSTRACT FROM AUTHOR]

We deal with analysis and experiments of a novel moving-coil-type synchronous permanent magnet planar motor (SPMPM) with reduced cogging force. Our previous study assumed that the equation of magnetic flux existing between a permanent magnet (PM) and core was a second-order polynomial, and the minimum cogging force was theoretically and geometrically calculated without FE analysis. In this paper, the cogging force of SPMPM with an iron core is calculated exactly using geometrical factors, which are desired for determining the magnetic flux density. The analytical results of the cogging force using the factors agree well with those obtained by FE analysis and experiment. Several methods for reducing the cogging force of the SPMPM, such as separation and arrangement of the iron core, addition of an extra core, and addition of auxiliary core teeth, are introduced in this paper. Velocity control experiments of the SPMPM with modified and unmodified cores are carried out and the results are compared with each other. The velocity ripple of SPMPM with a modified core is much smaller than that of SPMPM with an unmodified core. [ABSTRACT FROM AUTHOR]

The optimal drive current can reduce both the torque ripple and power loss in driving the permanent magnetic (PM) AC motor. This paper presents an analytical model for calculating the optimal drive current of the PMAC motor with surface mount PM rotor. Both the motors with and without the neutral line are analyzed. Theoretical analysis shows that, when the back-emf of the windings contains triple order harmonics, the neutral line of the motor can let the optimal drive current be different from the one without the neutral line, and it can also make the optimal drive current be more effective in the loss and torque ripple reduction. Two spindle motors are used in the analysis to show the influences of the optimal model presented. [ABSTRACT FROM PUBLISHER]

An equivalent dq model of three-phase flux-switching synchronous motors employing a segmental rotor is constructed and tested for predicting steady-state performance. Both the wound-field and permanent-magnet excited motors are represented. The unconventional topologies of the two types of motors present significant departure from the basic assumptions of the dq theory, even though the motors may be operated from a drive incorporating generic dq control regimes. The equivalent dq inductances and flux linkages are calculated from finite-element simulation results and applied in predicting the steady-state performance of the motor. It is found that the credibility of the dq model to predict the performance of the motors over the operating range is assured and is enhanced by incorporating dq-coupling inductances in the model. [ABSTRACT FROM PUBLISHER]

This paper deals with the magnet pole shape design of permanent magnet machines for the minimization of torque ripple based on electromagnetic field theory. On the basis of a magnetic vector potential and a two-dimensional (2-D) polar system, analytical solutions for flux density due to permanent magnet (PM) and current are obtained. In particular, the analytical solutions for mathematical expressions of magnets with different circumferential thicknesses can be solved by introducing improved magnetization modeling techniques, resulting in accurate calculations of electromagnetic torque. The analytical results are validated extensively by nonlinear finite element method (FEM). Test results such as back-emf measurements are also given to confirm the analyses. Finally, on the basis of derived analytical solutions, a reduction of torque ripple can be achieved. [ABSTRACT FROM AUTHOR]

In this paper, an adaptation of a shaded pole motor operating as a single-phase brushless PM motor is studied. After properly designing the rotor PM ring to avoid demagnetization problems, a nonlinear mathematical model for performance assessment and design improvement is proposed. The calculation of the model parameters is carried out by 2-D FEM analyses suitably corrected to also take into account 3-D effects, mainly due to different stator and rotor lengths. The procedure implemented in a numerical code makes it possible to investigate significant design aspects and determine the mechanical characteristic related to motor configurations adopted for small fan appliances. [ABSTRACT FROM AUTHOR]

Slim pump for cooling devices play an important role for cooling the electronics apparatus. This paper develops an axial-flux internal rotor type motor for the low-profile vortex pump. The integrated motor-pump structure is composed of an internal permanent magnet (PM) disc rotor and double-sided external coreless stators with windings piled up on the printed circuit board (PCB). The impeller is disposed on the periphery of the magnet and a fluid dynamic bearing (FDB) is set in the centre of the magnet to rotate relative to the centre shaft. A prototype of the axial-flux motor pump and drive circuit has been made and tested. Both simulated and experimental results show that the proposed motor would be an acceptable solution for the slim notebook (NB) applications. [ABSTRACT FROM AUTHOR]

This paper deals with theoretical analysis and design of permanent magnet (PM) synchronous motors (PMSMs) with minimized cogging force. Recently, many optimal designs for the PMSMs have been done by finite element (FE) analysis, but such analysis generally is time consuming. In this study, the equation of magnetic flux lines existing between PMs and iron cores is expressed geometrically and the cogging force is calculated theoretically without FE analysis. The form of equation is assumed to be the second-order polynomial and the virtual core is used to express the cogging force in analytical model. The cogging force can be calculated by applying the solved flux line equation and the flux density equation to the Lorentz force equation by using the Maxwell stress tensor. The theoretical analysis of minimized cogging force is applied to several prototypes such as synchronous PM planar motor (SPMPM), 2-DOF PMSM with screw motion, and axial flux PM (AFPM) brushless dc motor in this paper, and the analytical results are validated by FE analyses and experiments. [ABSTRACT FROM AUTHOR]

This paper deals with analysis and experiment of an axial flux permanent magnet (AFPM) brushless direct current (BLDC) motor with minimized cogging torque. Recently, many optimal designs for the AFPM motor have been done by finite-element (FE) analysis, but such analysis generally is time-consuming. In this study, the equation of magnetic flux lines existing between PMs and cores is assumed mathematically and the minimum cogging torque is calculated theoretically and geometrically without FE analysis. The form of equation is assumed to be a second-order polynomial in this paper. The skew angle that makes the cogging torque minimized is calculated theoretically, and the value of minimum cogging torque is confirmed by FE analyses and experiments. In the theoretical analysis, the maximum cogging torque of a proposed AFPM motor has the smallest value approximately at a skew angle of 4° and that value is about the same as those of FE analyses and experiments. Compared with the nonskewed motor, the cogging torque of the skewed motor can be decreased to over 90%, which has a value of 5% of the rated torque. Two types of stator cores, with the skew angle of 0° (nonskewed) and 4° (skewed optimally), are analyzed, manufactured, and tested experimentally in this paper. [ABSTRACT FROM AUTHOR]

This paper proposes an online method for the estimation of the stator resistance and the permanent-magnet (PM) flux in sensorless PM synchronous motor drives. An adaptive observer augmented with a high-frequency signal injection technique is used for sensorless control. The observer contains excess information that is not used for the speed and position estimation. This information is used for the adaptation of the motor parameters: At low speeds, the stator resistance is estimated, whereas at medium and high speeds, the PM flux is estimated. Small-signal analysis is carried out to investigate the proposed method. The convergence of the parameter estimates is shown by simulations and laboratory experiments. The stator resistance adaptation works down to zero speed in sensorless control. [ABSTRACT FROM AUTHOR]