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According to IEC 60034-1, as the industrial applications, not only efficiency but also power factor are important performance index. As a direct on line motor to replace induction motor (IM), a line-start synchronous reluctance motor (LS-SynRM) have a high efficiency but a low power factor than that of IM. In this paper, the analysis and design of LS-SynRM are performed considering the rotor slot opening and bridges for improving the efficiency and power factor. The reference machine is selected with the 2.2kW IM, the performance of reference model is analyzed based on a finite element analysis (FEA). To analyze the effect of rotor slot opening and bridges, an optimal model of LS-SynRM is designed through two step design process. First, the design of rotor slot for synchronization is performed, second, the design of barriers using the response surface method (RSM) is performed under the same condition of the stator size of IM. Based on the basic model, the performances of LS-SynRM are analyzed according to the slot opening and bridges. Furthermore, the parametric analysis is performed, and the final model is designed considering the efficiency and power factor based on the design parameters. Finally, the final model is manufactured, and the experiment is performed to verify the FEA result.

Since an existing 3-phase inner rotor torque actuator (TA) has severe torque ripples, it is not appropriate for a gimbal system that requires precise position control. Therefore, a coreless TA is considered to eliminate the core causing torque ripples. In order to compensate for several problems (e.g., problems of production structures and output degradation) when a coreless type is used, the final 2-phase outer rotor is proposed for the low vibration and high power TA in the gimbal system. To control the 2-phase TA applied to such the gimbal system, special inverter control methods, such as bi-directional drive for tilting control and control for output torque improvement, are required. The 2-phase 3-leg inverter is free of DC capacitor voltage unbalance compared to the 2-leg inverter, and is economical because it uses less power switches than the 4-leg inverter. Therefore, the 2-phase 3-leg inverter is applied to drive the 2-phase outer rotor coreless TA of a hybrid gimbal system, and it is verified through simulation.

In this paper, it is proposed to substitute the tilting operation device of hybrid multi-degree-of-freedom (DOF) system from three-phase surfaced permanent-magnet motor (SPM) to single-phase torque actuator. When performing a tilting operation with a three-phase SPM which is appropriate for continuous rotary operations, there are disadvantages such as low efficiency and difficulty in control. On the other hand, a single-phase torque actuator is suitable for sequential tilt control, and the efficiency of the actuator is higher than that of a three-phase SPM. Thus, this actuator will greatly influence the development and practical usage of multi-DOF system. This paper shows a single-phase torque actuator design, considering of magnetic saturation. In addition, the proposed method was verified by the experimental results of the manufactured torque actuator.

This paper discusses the analysis and simulation method and the test method for a two-degree-of-freedom (2-DOF) actuator torque. The previous studies on the analysis of 2-DOF motor’s tilting torque were carried out only by finite element method (FEM), not by analytic method. This paper describes the operating principles of and the processes of inducing a tilting torque and a holding torque both of which exist only in special purpose electric machines. This allowed us to establish a design process. By overcoming the limits of the 3-D FEM, this paper introduced the 2-D model analysis by considering a real coil shape. Finally, this paper manufactured and tested the 2-DOF actuator to verify the introduced analytic analysis method.

This paper proposes a novel efficiency measurement method without dynamometer. In case of small motor, the measurement of efficiency is not easy because the percentage of mechanical loss is comparably huge and the mechanical loss is not easy to be measured. In this paper, the authors proposes a method which can measure the efficiency with two test motors. This method can be useful to engineers who study small electrical motors.Key Words : Small DC motor, Measurement, Efficiency†교신저자, 정회원 : 동양미래대학교 조교수․공학박사E-mail : sagewide@dongyang.ac.kr 접수일자 : 2014년 2월 4일수정일자 : 2014년 8월 13일 최종완료 : 2014년 8월 18일 1. 서 론 소형DC모터는 산업용, 가정용 및 완구용 등 일반적으로 가장 많이 사용되는 모터이지만, 모터의 성능평가를 위한 효율측정이나 정확한 출력 측정 등을 위해서 사용할 수 있는 계측기는 실질적으로 많지 않다. 특히 모터의 기계적 출력측정을 위해서는 일반적으로 다이나모메터를 이용하게 되는데, 다이나모메터의 경우는 동력측정을 위해 토크메터를 사용하게 되며, 이 토크메터의 경우 스레인게이지 방식의 측정을 하도록 되어있어, 일정한 측정범위를 벗어날 정도로 매우 작은 출력을 내는 소형 DC모터의 경우는 다이나모메터를 이용하여 측정이 어려운 경우가 많다. 특히, 소형DC모터의 경우 측정을 위해 사용할 수 있는 측정장비는 전기적 입력이나 역기전력 측정 등 전기적 특성 치를 측정하는 것은 어렵지 않지만 출력이 작기 때문에 어느 정도 이상의 기계적 손실을 가지고 있는 기계적 출력 측정 장치를 이용하는 것은 큰 측정오차를 포함하는 결과를 가져오기도 한다[1][2]. 또한, 소형DC모터는 일반적으로 회전자가 작기 때문에 높은 속도에서 효율이 좋도록 설계된 경우가 많은데, 이런 모터를 실질적으로 사용하는 부하는 일반적으로 저속에서 구동되는 경우가 많아 회전속도범위를 변경할 수 있는 감속 기어 등을 사용하여 저속에서 구동하는 경우가 많다. 이런 기어를 사용하는 모터의 효율측정을 위해서 기계적 출력을 그대로 측정하게 되면 기어에서의 기계적 손실분을 포함하게 되어 실질적인 모터의 효율은 알기 어려운 경우가 많고, 사실상 모터의 손실보다 기어의 손실이 더 큰 상태에서 구동되는 경우도 많이 있다[3]. 소형DC모터가 사용되는 주요용도가 완구용이나 간단한 액세서리, 소형가전의 간단한 동작으로부터 전장용의 펌프, 사이드미러 동작용 모터에 이르기까지 매우 다양하기 때문에 이런 모터들을 위한 별도의 측정 장치를 구성하는 것도 용의하지 않은 일이 되며, 반면 속도의 범위는 매우 다양하고, 어느 정도 이상의 출력을 가지고 있는 경우에도 토크보다는 속도가 높은 경우가 많아 직접적인 기계적 출력을 측정하는 것이 어려운 경우가 발생한다[4].반면, 소형모터의 경우는 개별 단가가 저렴하기 때문에 시제품의 경우에도 여러 대의 모터를 만들어 그 특성을 측정할 수 있고, 각 모터가 거의 유사한 특성을 가지기 때문에 이를 활용한 다양한 모터의 특성평가가 가능하다[5].그림 1 일반적인 모터의 출력 측정Fig. 1 Ordinary output measurement of motors본 논문에서는 소형DC모터의 기계적인 출력을 측정하는 대신 같은 특성을 가지는 2개의 모터를 직결하여 전기적인 입력에 대해 전기적인 출력을 측정하는 방법으로 모터의 효율을 측정하는 방법을 사용한다. 이 경우 측정이 어려운 기계적 출력 대신 비교적 측정이 용이하고 정확하게 측정할 수 있는 전기적 출력을 측정하는 방법으로 모터의 효율을 측정할 수 있으며, 기계적 손실이나 기어의 손실에 의한 영향을 최소화 할 수 있으며, 소형모터의 측정을 위한 별도의 지그나 측정용 설비를 갖출 필요가 없어 간이측정을 위해 매우 효과적인 방법이라고 볼 수 있다.

This paper presents the design and implementation of a Bicycle Locker System. Generally DC motor has been used to control a Bicycle Locker System, but DC motor system requires frequent maintenances and its power efficiency is comparatively poor especially under heavy load conditions. In order to improve this difficulties, this paper adopts BLDC motor for a Bicycle Locker System and its motor controller is developed. The performances of locker units are compared between DC motor unit and BLDC motor unit. The motor power consumptions between two motors are discussed. Test results verify that power efficiency of the suggested BLDC drive unit is considerably improved compared to the DC drive unit with load condition.

This paper presents an parallel type Linear Induction Motor with ununiform airgap for a shallow-depth underground train with 100‰ grade and 15 m curvature. This parallel type LIM has enough gradability but has inherently ununiform airgap between center and end parts. Consequently, performance when the train passes curved section should be considered with transient analysis. Moreover, general parallel operation, 1C2M which is usually used for train operation, deteriorates LIM performance because of different line velocity between inner and outer LIMs. Transient analysis has many problems such as huge model, lots of meshes, very long calculation time, truncation error and so on. This paper has presented a novel technique using equivalent linear rotating model in order to solve these problems and has analyzed parallel type LIM by using the proposed technique. Finally, LIM performance according to independent operating control has been investigated.

To realize the multi-Degree-of-Freedom (multi-DOF) movement, researches on spherical motor have been conducted in many countries. The Spherical motor has a 3-DOF, whose shaft can not only rotate as rotary motor but also tilt in the 2-DOF space. Researches on spherical motor will greatly contribute to 3-DOF systems, because spherical motor can reduce the size and weight of 3-DOF systems. This paper studies a new type of spherical motor that has rotating coils and tilting coils. Also, the current function depending on shaft angles is proposed. Finally, the torque is calculated corresponding to different shaft angles and rotating speeds. Moreover, these performances are validated via experiments.

As the need of electric motor is increased rapidly throughout our society, the various application fields are created and the service market called robot gets expanded as well as the existing industrial market. Out of those, the joint systems such as humanoid that is servo actuator for position control or all fields which require multi-degree of freedom (multi-DOF) require the development of innovative actuator. It is multi-DOF spherical motor that can replace the existing system in multi-DOF operating system. But, multi-DOF spherical motor that has been researched up to date is at the stage which is insufficient in performance or mechanical practicality yet. Thus, first of all the research results and limitation of the previously-researched guide frame-type spherical motors were analyzed and then the feature of double air-gap spherical motor which was devised to complement that was studied. The double air-gap multi-DOF spherical motor is very suitable spherical motor for system applying which requires the multi-DOF operation due to its simple structure that does not require other guide frame as well as performance improvement due to its special shape which has two air-gaps. So, the validity of the study was verified by designing and producing it with 3D-FEM through the exclusive jig for multi-DOF spherical motor.

Since robot industry growing, the machine that could move with multi-DOF has been studied in many industrial fields. Spherical motor is one of the multi-DOF machine that doesn't need gear for multi-DOF motion. Unlike conventional motor, spherical motor can not only rotate on the shaft axis (rotating motion), but tilt the shaft with 2-DOF motion (positioning motion). In the typical type of spherical motor, one coil took part in positioning motion and rotating motion at the same time. As the result, the control algorithm was complex. To solve this problem, this study proposed a novel type of coil on the stator. The coils were separated for positioning motion and rotating motion. Thus the linkage flux of rotating coil didn't be affected the positioning angle. In this paper, comparing the back-EMF of typical and novel type was conducted and the driving experiment was carried out as the positioning angle. From the experiment result, the performance of proposed spherical motor could be verified.

This paper presents the novel design and implementation of a switched reluctance motor with commutator. Unlike typical switched reluctance motor, this motor doesn`t require semi-conductor devices and inverter circuits for driving. Instead, the brushes and commutator can make rotating field for driving the switched reluctance motor. Moreover, because this motor has no magnet, the total cost for manufacturing the motor is very cheap. In order to verify the usability of the proposed motor, the authors manufactured the prototype motor, and showed the torque-speed curve of the motor.

This paper presents the design and analysis of a linear actuator for vehicle Eco-Pedal system. To prevent the excessive gas consumption for fuel-efficient vehicle the electric actuator produces a counter force to the vehicle's pedal to be pressed stiffly. Major performances of the actuator are required such as a high force density and a low detent force. In this paper, the analysis and design technique of the actuator thrust is based on an analytical method, and the advisability of the design result is verified with both the result of the experiment and the result of the finite element method.

A surfaced permanent magnet spherical motor is capable of operating as three degree of freedom that used for the joints of the robot's arm, leg, and eyes. Ongoing research like new concept is essential part of motor field, it will make a great contribution in the future the overall portion of the motor, is becoming expected. The author analysis torque characteristics in spherical motor with state of rotating and positioning. And future design direction is smaller motors with equivalent or higher output. Solutions as torque and efficiency improvements are selecting the core with special processing type like powder metallurgy materials. Their special characteristic is high permeability and low eddy current losses at high speed, so improved the torque and efficiency.Key Words : Multi-D.O.F., Spherical motor, Soft magnetic composite, Torque characteristic, Permanent magnet motor*정 회 원 : 한양대 공대 전기공학과 박사과정** 정 회 원 : 동국대 공대 전자전기공학부 교수***정 회 원 : 한양대 공대 전기공학과 석박사 통합과정§ 정 회 원 : (주)삼성전자 선임연구원§§ 정 회 원 : 동양미래대 공대 전기시스템과 전임강사† 교신저자, 시니어회원 : 한양대 전기공학과 교수E-mail : julee@hanyang.ac.kr접수일자 : 2011년 9월 18일 최종완료 : 2011년 12월 9일

The Multi D.O.F spherical motor can drive rotating as well as tilting three degree of freedom with one motor. Existing three degree of freedom to drive with three motors that are connected by gears and belts, that will be too large size and big loss at gears and belts. So Reducing system size and improving efficient is using the Multi D.O.F spherical motor in three degree of freedom systems. For this reason, efficiency of Multi D.O.F spherical motor is one of the important performance indiccators. In this paper presented that how to improve the efficiency of the Multi D.O.F spherical motor. The fist of method is using the stator iron core`s material with high permeability and resistivity for reducing the eddy current loss. However, it was the disadvatages of motor-making and economic. So author propose the resonable method of reducing the eddy current loss in the stator iron core. That is using the rotor with double-air gap.

This paper presents a unique method for simulating permanent magnet motors without time-consuming numerical methods used in the conventional magnetic circuit method. The conventional method gives us average values like torque and power over specified periods of time, but it is usually very difficult and time-consuming to obtain instantaneous characteristics like cogging torques and torque ripples. The convolution operations method we present, however, considers relative angle variations of stator magnetic circuits and rotor magnetic circuits. As a result, it makes uses of instantaneous values possible. The authors compare the new method with the coventional method and verify that calculating cogging torque values and back-emf values is possible with the proposed new convolution method.

A 3-D.O.F. spherical PM motor has 3 degrees of freedom in its motion by tilting and rotating of a shaft, which can be applied in a range of fields. The back-EMF is proportional to the field flux and angular velocity. The back-EMF constant in conventional rotating machine has a uniform value. However, in a spherical PM motor, the back-EMF constant of the coils varies according to the tilting conditions regardless of whether the angular speed is constant. Consideration of the back-EMF constant is useful for designing 3-D.O.F. spherical PM motors. In this study, the back-EMF constant of the spherical PM motor was considered carefully.

The multi-degrees of freedom surface permanent-magnet motor (Multi-D.O.F. SPM) has several degrees of freedom operations that are defined as the “roll”, “yaw”, and “pitch”. Normally, the torque that is generated to rotate a rotor includes ripples. The analysis of the torque ripples is important for improving motor performance. In terms of the electric analysis, torque ripple occurs as a result of many factors, including the rotor and stator structures, the distribution of the air-gap flux density, and the waveform of the current in the coils. In particular, the torque ripple is an important factor in the stable operation of the Multi-D.O.F. SPM. Therefore, in this work, the torque ripple was analyzed using various types of magnetization for the permanent magnet. An improved model was proposed for the Multi-D.O.F. SPM based on this analysis.

This paper presents the design and implementation of direction controllers by microstep control and dc servo control for material transport system. The perfomances of direction control systems are compared in position responses and motor power consumptions between microstep control of a step motor and dc servo control.

A permanent magnet spherical wheel motor, which consists of magnets on rotor and coils on spherical stator, is able to operate on 3-D space as using magnetic alignment torque generated from between coils and magnets. Especially the shaft can be tilted stably by optimized coil position on stator. Because, however, the spherical wheel motor has feature of 3-D structure as relative position between coils and magnets, stable holding torque for rotor position should be analyzed as function of the tilt degree of a shaft. The characteristic of stable holding torque can be changed nonlinearly by the alpha and beta degrees of a shaft. Therefore, when reference current is commanded at coils, the shaft cannot be tilted to the reference position exactly for the nonlinear characteristic. In this paper, for improving the nonlinear phenomenon of holding torque, the authors research and improve a current compensation function to increase stable operating range. Also, the compensation function was estimated by using torque ripple computed from torque simulation.

The incomplete magnetization is a frequently occurring phenomenon during the magnetizing process of magnets in precision motors because they use ring magnets which are not segmented. Even a small variance of the incomplete magnetization can make critical changes in the characteristics of motors like cogging torque profiles and the cogging torque profiles play an important part in reducing the noise and vibration of motors. So, the modeling of the incomplete magnetization area of magnets becomes a critical point in the analysis of the precision brushless dc motors. Conventionally, the modeling method of the area is to change the magnitude of the magnetization vector according to position angles in a magnet but the authors propose a novel method for modeling the incomplete magnetization area. This method is compared with the conventional method and verified by the measured cogging torque profile.

Researchers who study axial-gap type permanent magnet motors often have difficulties in analyzing the motor because the motor structure makes it difficult to define the two-dimensional (2D) finite-element model surfaces. Sometimes they try to define the surface as a cylindrical cutting surface with appropriate assumptions and sometimes they prefer three-dimensional (3D) finite-element simulations. However, the 2D analysis of the axial-gap type motor is restricted to a specified model and it is difficult to consider winding coil shape perfectly in most cases, and the 3D simulations take too long to achieve the desired results. This paper concerns the axial-gap type permanent magnet motor modeling method which can perform the transient simulation with one static 3D finite-element simulation and a winding coil mesh. This model can shorten the simulation time dramatically. To verify the feasibility, a 2phase/4phase vibration motor transient simulation was carried out and the results are well matched with the measured ones.

This paper presents a new approach to reduce windage loss of switched reluctance motor (SRM) by changing the rotor shape. To predict the performance of improved SRM rotor, the parametric finite element analyses are needed to get inductance profiles of the proposed rotor shape. The calculated values are compared with the measurement values, in order to evaluate a validity of the proposed method.

Conventionally, when we need to know about the dynamic characteristics of motors, the moving band method has been the first considerable technique. In this paper, we have investigated the moving material method that moves the property of the material in moving area elements of BLDC motors, instead of moving mesh elements of the rotor. From this method, we can reduce the demanded HDD memory for FEM analysis and the calculation time with same results.

Previous researches have been conducted on the multi-degree of freedom operation motor, a new mechanism for power conversion out of the existing motor from early in 2000. Various types of structure have been suggested to operate more than two-degree of freedom (DOF) from one point of action and control methods have been studied appropriately for each structure. This led to overall improvement in interpreting the multi-degree of freedom for drive motor and the ability to interpret the operating characteristics, but few applications have been development practically. On the other hand, UAV systems like a multi-copter and drone, which is the biggest issue recently, are considered to be the field of applications that can maximize the effects if applying the multi-degree operation motor being studied now. This paper investigates the generic technology and suggests a new hybrid type multi-degree of freedom operation motor with increased tilting torque, improved practicality, and easy control in the commercialization stage that requires more than two-degree of freedom for application to the driving motor. In other words, rotational driving and tilting driving were separated electromagnetically to improve manufacturability and ease control and the characteristics of various tilting operating actuators were discovered for increasing the tilting torque. Finally, such a suggested hybrid type multi-degree of freedom operation motor was designed, manufactured, and tested to verify its performance. At the same time, the necessity of multi-degree of freedom operation motor in the multi-copter system, a field of application expected was discovered and the system modeling was conducted.

The flat-type vibration motor has an axial-gap structure. Analyzing axial-gap motors with the two-dimensional (2-D) finite-element method is very difficult because we have to define the analysis surface as a cylindrical surface. In order to simulate the flat-type vibration motor, we have developed new equations of calculation for the torque of the motor, which is uses a 2-D grid model. We have measured the load torque of the vibration motor which is used for the motion transient analysis. The simulated vibration characteristic is compared with experimental value

This paper describes the effect of pulsating current generated by back-electromotive force (BEMF) current of switch-off phase in flux-reversal machine (FRM) which is driven by 120deg square wave voltage sources. A two-dimension time-stepped voltage source finite element analysis using a direct convergence method is proposed to analyze an electromagnetic field and the BEMF current. To prove the propriety of the proposed analysis method, we build the prototype FRM and a digital signal processor (DSP) installed controller as a set for the experiment

The real brushless DC motor has different permanent magnet pole magnetization levels due to the influence of the magnetizer geometry. Therefore, this paper discusses the influence of change in the magnetic parameter on brushless DC motor performances. As a result, the unbalanced magnetic force acting on the rotor, cogging torque and torque ripple are examined for spindle motor with unsymmetric magnetization distribution.

This paper describes the effect of eddy currents generated in the rotor steel shell of an exterior-rotor type permanent magnet brushless DC motor of which the rotor is revolving at a high speed. A two dimensional time-stepped finite element method is used to analyze the electromagnetic field and compute motor performance. The conductivity of the rotor steel shell is modified to consider the transverse edge effect. As a result, the effect of eddy currents is shown by comparing the analysis results between when the proposed method is used and when the method it is not.

This paper presents the optimal design method of synchronous reluctance motor (SynRM) for the high torque and power factor. It is difficult to design optimal barrier shape of rotor by analytical method because of leakage flux between barriers and saturation in the core. Therefore, the optimal design of SynRM including rotor structure is proposed in this paper by using finite element method (FEM) and simulation design of experiment (DOE). Finally, the characteristics of optimal model are compared with those of the worst one

Due to the mechanical angle error between two brushes and commutation patterns on the rotor PCB, a fatal defect-starting failure-could be detected in the vibration motor. In order to eliminate this failure, we have developed a new winding method, double winding, to make a 4-phase vibration motor with only 2 bunches of coil. By this winding method, we could eliminate the starting failure successfully and save the manufacturing cost

The cogging torque of the flux-reversal machine (FRM) may cause some problems like noise and vibration of the motor. By FEM analysis of the cogging torque of FRM, a noticeable feature was found that the rotor teeth width increases, phase and magnitude of the cogging torque varies. So, the rotor teeth pairing method is proposed for reducing the cogging torque of FRM. In this method, we made a rotor which has two different tooth widths and measured the cogging torque of the motor. From the result, we can see that the simulation result is well matched with the measured result and the proposed method is feasible.

In the flat-type vibration motor, which is usually used in folder-type mobile phones, the air-gap flux from the magnet is in the axial direction. Accordingly, it is very difficult to get the torque using 2D FEM simulation. Also, because 3D FEM simulation takes so long time to get the result, the dynamic characteristics simulation using 3D FEM is not applicable for engineers who want to develop vibration motors in a short period. So, in this paper, we use 2D FEM simulation with an improved method to calculate the torque of the flat-type vibration motor and compare with 3D FEM results. From this method, we can get the faster method to simulate the transient characteristics of the motor using 2D FEM.

This paper proposes the single-phase flux-reversal motor for a vacuum cleaner. The circuit parameters are determined by using both finite-element method and experimental measurements while a simulation was done by using an equivalent circuit model to derive the dynamic characteristics. Due to the inductance of the coil of high-speed drives, a phase difference occurs between the current and the electromotive force which produces a negative torque that degrades the output. Through simulation, the turn-on angle and turn-off angle that minimize the negative torque are found and simulation results will be compared with the results of the experiment.

In this paper, the torque characteristics of multi degree of freedom surfaced permanent-magnet motor (multi-D.O.F. SPM) are introduced. The multi-D.O.F. SPM can rotate a shaft while the rotor tilts to one side [1]. To decrease the torque ripple, the locus of summed wave forms of motor driving current have to be in an ellipse. Because the axis of electro motive force is generated by many numbers of currents as considering rotor position, the currents have different phase while the rotor is tilting. Therefore the phase of each current is defined as function of rotor position as using compensated phase method in this paper. The modified current is verified by comparison of analytic simulation results to experimentation results.

The multi-degree of freedom surfaced permanent-magnet motor (Multi-D.O.F. SPM) researched in this paper has characteristic of rotor tilt. Generally electromagnetic field of an electric rotating machine is analyzed by using the 2-D finite element method, because the electromagnetic features show same phenomena in the rotational axis direction. However the Multi- D.O.F. SPM should be analyzed by using 3-D finite element method for spherical structure of stator. Therefore this paper proposes useful method of 3-D electromagnetic field computation. Finally the results are verified by experimentation.

When we design an IPMSM, we start with the output and the voltage equations of the machines. The output equation has two terms which are magnetic torque and reluctance torque. The magnetic torque is related to the electric-and magnetic-loading but reluctance torque is related to one more variable which is the difference of the d-and q-axis inductance. Therefore it is very important to calculate or estimate the d- and q-axis inductance in the design procedure. In this paper, we proposed the inductance calculation method by relative permeance. The result is reasonable to the initial design.

This paper presents the torque calculation method of a new spherical robotic wrist motor capable of three degrees of freedom (DOF) motion in a single joint. The spherical motor bases its operation principle on permanent magnet BLDC motor. Prediction of the spherical motor characteristics requires the computation of the exact motor dynamics at each position and angle using 3D finite element analysis which imposes a computational burden. By only calculating Lorentz forces of the coil area mesh elements, this computational burden can be reduced

The paper presents a new method for torque ripple calculation of permanent magnet assisted synchronous reluctance motor (PMa-SynRM) by load angle curve simulations. We can directly detect the load angle of minimum torque ripple and maximum average torque by several load angle curves with different current state. The analysis results were verified by the experiment

This paper presents a new approach to reduce windage loss of SRM by changing the rotor shape. To predict the performance of improved SRM rotor, the dynamic characteristics analysis is needed using inductance profile. The calculation values are compared with the measurement ones, in order to evaluate a validity of the proposed method

The linear DC motor is very useful for the automatic door system. For simulation of the automatic door system, the precise prediction of the thrust force and the back emf is essential. We proposed an appropriate method for fast thrust force calculation of LDM and manufactured the LDM prototype. In comparison of the simulated model and the manufactured motor, the results are relatively well matched.

Instead of the moving band method, which is widely used when someone wants to perform a FEM calculation considering the rotation, a novel moving material method was proposed that makes the demand of HDD memory capacity smaller and the calculation time faster not by changing the mesh but by rotating the material properties in the magnet area. These results are especially useful to researchers who try to analyze the BLDC spindle motor considering the rotation of the outer rotor comprising a ring magnet and a back-yoke.