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Ju Lee
Department of Electrical Engineering, Hanyang University, Seoul 04763, Korea

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Journal article
Published: 28 June 2021 in IEEE Transactions on Magnetics
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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.

ACS Style

Hyunwoo Kim; Yeji Park; Seung-Taek Oh; Geochul Jeong; Un-Jae Seo; Sung-Hong Won; Ju Lee. Study on Analysis and Design of Line-Start Synchronous Reluctance Motor Considering Rotor Slot Opening and Bridges. IEEE Transactions on Magnetics 2021, PP, 1 -1.

AMA Style

Hyunwoo Kim, Yeji Park, Seung-Taek Oh, Geochul Jeong, Un-Jae Seo, Sung-Hong Won, Ju Lee. Study on Analysis and Design of Line-Start Synchronous Reluctance Motor Considering Rotor Slot Opening and Bridges. IEEE Transactions on Magnetics. 2021; PP (99):1-1.

Chicago/Turabian Style

Hyunwoo Kim; Yeji Park; Seung-Taek Oh; Geochul Jeong; Un-Jae Seo; Sung-Hong Won; Ju Lee. 2021. "Study on Analysis and Design of Line-Start Synchronous Reluctance Motor Considering Rotor Slot Opening and Bridges." IEEE Transactions on Magnetics PP, no. 99: 1-1.

Journal article
Published: 10 May 2021 in IEEE Access
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To provide power to electrical power distribution systems cost effectively, it is necessary to understand the efficiency of large turbine generators. Stator cores, which account for 10%–15% of total generator losses, are supported by a either a dovetail key bar or a square key bar. The dovetail key bar, mainly used in large turbine generators, has a shallow depth of penetration into the stator core; consequently, the need for research related to core loss has been limited in the case of dovetail key bars. By contrast, the square key bar, which is attracting attention owing to its ease of assembly, deeply penetrates the stator core, and thus has a greater effect on core loss than the dovetail key bar. However, core losses due to the key bar design have not been examined quantitatively in the literature. This paper analyzes the core-loss changes due to the key bar. Using electromagnetic finite-element analysis, we calculate the differences in core loss between the two aforenoted key bar types, which are commonly used in large turbine generators. In addition, we propose points for consideration when designing key bars for large-capacity generators.

ACS Style

Dae-Il Song; Junghwan Ahn; Young-Joon Nam; Ju Lee; HyungKwan Jang. Open-Circuit Core Loss of Large Turbine Generators Considering the Influence of Key Bar Design. IEEE Access 2021, 9, 70662 -70670.

AMA Style

Dae-Il Song, Junghwan Ahn, Young-Joon Nam, Ju Lee, HyungKwan Jang. Open-Circuit Core Loss of Large Turbine Generators Considering the Influence of Key Bar Design. IEEE Access. 2021; 9 ():70662-70670.

Chicago/Turabian Style

Dae-Il Song; Junghwan Ahn; Young-Joon Nam; Ju Lee; HyungKwan Jang. 2021. "Open-Circuit Core Loss of Large Turbine Generators Considering the Influence of Key Bar Design." IEEE Access 9, no. : 70662-70670.

Journal article
Published: 29 March 2021 in IEEE Access
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With the trend towards the miniaturisation and electrification of automotive components, the electric oil pump (EOP) is generally designed as an integrated powerpack in which a motor and an electronic control unit (ECU) are combined into an integrated system, with the electronic components of the ECU exposed to harsher temperature environments. The critical weakness of the traditional design is short-circuit failures, and the most common protection method is Vds monitoring. However, this method cannot predict the accurate protection current, indicating that the fault detection level and short-circuit current (SCC) may change depending on the operating temperature and load condition to which the devices are subject. In this case, switching devices can be destroyed or deteriorated if they are unexpectedly placed outside of the protection range. This study proposes an online short-circuit protection method in which the optimal fault threshold can be controlled in real time, in accordance with changes in temperature and load conditions. To this end, this study investigates the cause of fluctuations in SCC and analyses the protection range and qualification time for SCC through worst-case analysis. To determine the optimal fault threshold, the SCC waveform is estimated through circuit analysis and a method of estimating Rdson(Tj), which is the cause of SCC fluctuation, is proposed based on simulation and experimental data. Finally, according to Rdson(Tj), optimal thresholds are derived and the proposed methods are experimentally-verified. It is found that the SCC could be predicted and managed within the protection range by the proposed new protection method.

ACS Style

Youngwoo Noh; Wonkyu Kim; Ju Lee. Online Short-Circuit Protection Strategy of an Electric Powerpack for Electric Oil Pump Applications. IEEE Access 2021, 9, 52292 -52309.

AMA Style

Youngwoo Noh, Wonkyu Kim, Ju Lee. Online Short-Circuit Protection Strategy of an Electric Powerpack for Electric Oil Pump Applications. IEEE Access. 2021; 9 (99):52292-52309.

Chicago/Turabian Style

Youngwoo Noh; Wonkyu Kim; Ju Lee. 2021. "Online Short-Circuit Protection Strategy of an Electric Powerpack for Electric Oil Pump Applications." IEEE Access 9, no. 99: 52292-52309.

Journal article
Published: 04 March 2021 in Energies
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Owing to the development of electric vehicles (EVs), research and development are underway to minimize torque ripple in relation to vibration and noise in EV motors. Although there are various ways to reduce torque ripple, this study analyzes the torque ripple, cogging torque, total harmonic distortion (THD), and magnetic flux density distribution for the three rotor shapes of interior permanent magnet synchronous motors, which are widely employed in EVs. To reduce the torque ripple while retaining the required average torque, the barrier shape is optimized, and wedge skew is applied. First, regarding the rotor barrier shape, torque ripple is primarily reduced by designing the rotor barrier shape with the response surface method, which is an experimental design method. Additionally, the wedge skew shape considering the bidirectional rotation and fabrication was applied to the stator shoe as a step and analyzed using three-dimensional finite element analysis. When designing the wedge skew, the layer subdivision according to the axial length, wedge skew diameter, and wedge skew position was analyzed and improved. The torque ripple reduction method in this paper can be applied not only to motors for EVs or Hybrid EVs (HEVs) but also all types of permanent magnet synchronous motors.

ACS Style

HyungKwan Jang; Hyunwoo Kim; Huai-Cong Liu; Ho-Joon Lee; Ju Lee. Investigation on the Torque Ripple Reduction Method of a Hybrid Electric Vehicle Motor. Energies 2021, 14, 1413 .

AMA Style

HyungKwan Jang, Hyunwoo Kim, Huai-Cong Liu, Ho-Joon Lee, Ju Lee. Investigation on the Torque Ripple Reduction Method of a Hybrid Electric Vehicle Motor. Energies. 2021; 14 (5):1413.

Chicago/Turabian Style

HyungKwan Jang; Hyunwoo Kim; Huai-Cong Liu; Ho-Joon Lee; Ju Lee. 2021. "Investigation on the Torque Ripple Reduction Method of a Hybrid Electric Vehicle Motor." Energies 14, no. 5: 1413.

Journal article
Published: 18 February 2021 in IEEE Access
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As research into technology for autonomous vehicles becomes ever more intensive, the need for redundant system designs, as a solution for fail-operational functionality, has also increased. Redundant systems are those involved in maintaining normal operation even when one or more components fails. In particular, in electric power steering (EPS) systems, redundancy is achieved by applying dual-winding (DW), permanent magnet synchronous motors (PMSMs) and dual electronic control units (ECUs). In this study, the torque and efficiency of DW-PMSMs is analysed based on the manner in which the currents in each winding mechanism are combined. It was found that the PMSMs have maximum torque and efficiency when the current ratio was the same between DWs. A diagnostic strategy is proposed whereby the phase current ratio of dual lanes is not matched. The proposed diagnostic process includes the selection of the optimal fault threshold of the current difference between two ECUs and a method for distinguishing which of these was a failure for disagreement. In addition, depending on whether or not failure detection has occurred, a current compensation control method is proposed for reverting to normal operation or for failure operations. The dual-lane system was fabricated and the proposed solutions were experimentally verified.

ACS Style

Youngwoo Noh; Wonkyu Kim; Ju Lee. The Optimal Current Ratio Control of Redundant Electric Drive Systems and Diagnostic Strategies for Disagreement. IEEE Access 2021, 9, 32115 -32130.

AMA Style

Youngwoo Noh, Wonkyu Kim, Ju Lee. The Optimal Current Ratio Control of Redundant Electric Drive Systems and Diagnostic Strategies for Disagreement. IEEE Access. 2021; 9 ():32115-32130.

Chicago/Turabian Style

Youngwoo Noh; Wonkyu Kim; Ju Lee. 2021. "The Optimal Current Ratio Control of Redundant Electric Drive Systems and Diagnostic Strategies for Disagreement." IEEE Access 9, no. : 32115-32130.

Journal article
Published: 02 December 2020 in Electronics
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There are complex physical phenomena for the interpretation of a molded case circuit breaker (MCCB) in a distribution system. Most of the studies of MCCB interruption phenomena were conducted with numerical analysis and experiments. This traditional approach may help improve the performance of the MCCB itself, but it is difficult to find connectivity with other systems. In this paper, the circuit model is proposed and the interruption phenomenon of MCCB is analyzed. The interruption of the MCCB is divided into three sections to deal with physical phenomena occurring in each area. A simplified model is proposed considering the characteristics of each section. Based on this model, the circuit model is proposed. To implement the features of each section, the calculation of physical phenomena is carried out, and this is expressed in the circuit model with resistance and zener diode. Comparing the results of the simulation with the experimental results is as follows. For 7-plates (basic state), the error rate is −5.6% in section II and 16.8% in section III. For 1-plate, the error rate is 36.5% in section II and −17.0% in section III. This case shows much difference from the simplified model in this paper, resulting in the largest error rate. The 7-plates and 5-plates cases, which are available in the general MCCB owing to the shortest distance from the arc, represent a relatively small error rate. Using the proposed circuit model, it is expected that the entire system, including the interruption phenomenon, can be interpreted as a single circuit model.

ACS Style

Kun-A Lee; Young-Maan Cho; Ho-Joon Lee. Circuit Model and Analysis of Molded Case Circuit Breaker Interruption Phenomenon. Electronics 2020, 9, 2047 .

AMA Style

Kun-A Lee, Young-Maan Cho, Ho-Joon Lee. Circuit Model and Analysis of Molded Case Circuit Breaker Interruption Phenomenon. Electronics. 2020; 9 (12):2047.

Chicago/Turabian Style

Kun-A Lee; Young-Maan Cho; Ho-Joon Lee. 2020. "Circuit Model and Analysis of Molded Case Circuit Breaker Interruption Phenomenon." Electronics 9, no. 12: 2047.

Journal article
Published: 04 November 2020 in Energies
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As international regulations of motor efficiency are strengthened, the line-start synchronous reluctance motor (LS-SynRM) is being studied to improve the efficiency of the electrical motor in industrial applications. However, in industrial applications, the power factor is also an important performance index, but the LS-SynRM has poor power factor due to the saliency characteristic. In this paper, the rotor design of LS-SynRM is performed to improve the efficiency and power factor. First, the barrier design is performed to improve the efficiency and power factor using the response surface method (RSM). Second, the rotor slot design is performed according to the length of bar for synchronization. Lastly, the rib design is performed to satisfy the power factor and the mechanical reliability. The final model through the design process is analyzed using finite element analysis (FEA), and the objective performance is satisfied. To verify the FEA result, the final model is manufactured, and experiment is performed.

ACS Style

Hyunwoo Kim; Yeji Park; Seung-Taek Oh; HyungKwan Jang; Sung-Hong Won; Yon-Do Chun; Ju Lee. A Study on the Rotor Design of Line Start Synchronous Reluctance Motor for IE4 Efficiency and Improving Power Factor. Energies 2020, 13, 5774 .

AMA Style

Hyunwoo Kim, Yeji Park, Seung-Taek Oh, HyungKwan Jang, Sung-Hong Won, Yon-Do Chun, Ju Lee. A Study on the Rotor Design of Line Start Synchronous Reluctance Motor for IE4 Efficiency and Improving Power Factor. Energies. 2020; 13 (21):5774.

Chicago/Turabian Style

Hyunwoo Kim; Yeji Park; Seung-Taek Oh; HyungKwan Jang; Sung-Hong Won; Yon-Do Chun; Ju Lee. 2020. "A Study on the Rotor Design of Line Start Synchronous Reluctance Motor for IE4 Efficiency and Improving Power Factor." Energies 13, no. 21: 5774.

Journal article
Published: 09 September 2020 in IEEE Transactions on Magnetics
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In this paper, a process for reducing electromagnetic vibration and noise by changing the shape of the stator is presented. Although the fundamental wave of the airgap 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 electromagnetic performance as much as possible while optimally reducing 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 analysis was proven its validity through finite element analysis.

ACS Style

In-Jun Yang; Seung-Hyeon Lee; Kang-Been Lee; Ju Lee; Won-Ho Kim; Ik-Sang Jang. A Process to Reduce the Electromagnetic Vibration by Reducing the Spatial Harmonics of Air Gap Magnetic Flux Density. IEEE Transactions on Magnetics 2020, 57, 1 -6.

AMA Style

In-Jun Yang, Seung-Hyeon Lee, Kang-Been Lee, Ju Lee, Won-Ho Kim, Ik-Sang Jang. A Process to Reduce the Electromagnetic Vibration by Reducing the Spatial Harmonics of Air Gap Magnetic Flux Density. IEEE Transactions on Magnetics. 2020; 57 (2):1-6.

Chicago/Turabian Style

In-Jun Yang; Seung-Hyeon Lee; Kang-Been Lee; Ju Lee; Won-Ho Kim; Ik-Sang Jang. 2020. "A Process to Reduce the Electromagnetic Vibration by Reducing the Spatial Harmonics of Air Gap Magnetic Flux Density." IEEE Transactions on Magnetics 57, no. 2: 1-6.

Journal article
Published: 26 April 2020 in Journal of the Korean Physical Society
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For increased product competitiveness, the development of generators of the same size, but with more outputs, is in the spotlight. This development trend has resulted in the magnetic flux density inside the generator being increased. The magnetic flux of the generator flows through the stator core, which is supported by the key bar. Increased magnetic flux density leads to a higher voltage in the key bar, which reduces the reliability of the generator. In this paper, we report on an electromagnetic field analysis of the key bar voltage and the verification of the result by the using the factory test. We also suggest a point to consider when designing a key bar.

ACS Style

Dae-Il Song; Ju Lee. Electromagnetic Field Analysis of the Dovetail Key Bar Voltage in a Generator. Journal of the Korean Physical Society 2020, 76, 757 -761.

AMA Style

Dae-Il Song, Ju Lee. Electromagnetic Field Analysis of the Dovetail Key Bar Voltage in a Generator. Journal of the Korean Physical Society. 2020; 76 (8):757-761.

Chicago/Turabian Style

Dae-Il Song; Ju Lee. 2020. "Electromagnetic Field Analysis of the Dovetail Key Bar Voltage in a Generator." Journal of the Korean Physical Society 76, no. 8: 757-761.

Journal article
Published: 30 March 2020 in IEEE Transactions on Applied Superconductivity
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This paper describes a study on an design of IPMSM (Interior Permanent Magnet Synchronous Motor) for reliability of demagnetization characteristics-based rotor. The IPMSM in this paper is located at a lower part of a railway vehicle and has a totally enclosed type structure so heat does not circulate within it and its temperature rises high. In order to increase power density of the motor, a neodymium permanent magnet with high energy density is used. However, this neodymium permanent magnet has properties that demagnetization occurs at a high temperature or by a reverse magnetic field and that as a new demagnetization curve called a recoil line is drawn in the B-H characteristic curve, magnet becomes permanently demagnetized. This permanent demagnetization property decreases the torque characteristics of or power output of the motor, eventually making it impossible to drive the railway vehicle and also reducing its reliability. In order to prepare for these problems, it is definitely necessary to consider analysis of the demagnetization property in the analysis stage. Hence, this study aims to propose an analysis method of demagnetization characteristics by considering the recoil line and to establish a base capable of securing reliability of IPMSM for traction of and highlights the proposed analysis method through a performance test and temperature saturation test of the prototype.

ACS Style

Geochul Jeong; Hyunwoo Kim; Ju Lee. A Study on the Design of IPMSM for Reliability of Demagnetization Characteristics-Based Rotor. IEEE Transactions on Applied Superconductivity 2020, 30, 1 -5.

AMA Style

Geochul Jeong, Hyunwoo Kim, Ju Lee. A Study on the Design of IPMSM for Reliability of Demagnetization Characteristics-Based Rotor. IEEE Transactions on Applied Superconductivity. 2020; 30 (4):1-5.

Chicago/Turabian Style

Geochul Jeong; Hyunwoo Kim; Ju Lee. 2020. "A Study on the Design of IPMSM for Reliability of Demagnetization Characteristics-Based Rotor." IEEE Transactions on Applied Superconductivity 30, no. 4: 1-5.

Journal article
Published: 02 March 2020 in IEEE Transactions on Applied Superconductivity
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ACS Style

Huai-Cong Liu; Hyun Woo Kim; Hyung Kwan Jang; Ik-Sang Jang; Ju Lee. Ferrite PM Optimization of SPM BLDC Motor for Oil-Pump Applications According to Magnetization Direction. IEEE Transactions on Applied Superconductivity 2020, 30, 1 -5.

AMA Style

Huai-Cong Liu, Hyun Woo Kim, Hyung Kwan Jang, Ik-Sang Jang, Ju Lee. Ferrite PM Optimization of SPM BLDC Motor for Oil-Pump Applications According to Magnetization Direction. IEEE Transactions on Applied Superconductivity. 2020; 30 (4):1-5.

Chicago/Turabian Style

Huai-Cong Liu; Hyun Woo Kim; Hyung Kwan Jang; Ik-Sang Jang; Ju Lee. 2020. "Ferrite PM Optimization of SPM BLDC Motor for Oil-Pump Applications According to Magnetization Direction." IEEE Transactions on Applied Superconductivity 30, no. 4: 1-5.

Journal article
Published: 28 February 2020 in IEEE Transactions on Applied Superconductivity
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Double-cage rotors are used to produce induction motors with high efficiency and high starting torque. Most often, experience constants are used in the design of the working bars of double-cage rotors. However, an error occurs, resulting in lower efficiency than actual in the characteristic analysis results. In this study, a new working bar design process is proposed using correct factor and regression, instead of using the existing experience constant when designing the working bar of the double-cage rotor. The performance of a 15-kW-class construction motor model using the existing experience constant was compared with that of the proposed design process through magnetic equivalent circuit (MEC). Finally, the finite-element method (FEM) and start-up performance tests proved the validity of the process.

ACS Style

Dong-Ho Kim; Jun-Hyuk Choi; Kwang Soo Kim; Ju Lee; Won-Ho Kim. Design Process of Working Bar of Double-Cage Induction Motor. IEEE Transactions on Applied Superconductivity 2020, 30, 1 -5.

AMA Style

Dong-Ho Kim, Jun-Hyuk Choi, Kwang Soo Kim, Ju Lee, Won-Ho Kim. Design Process of Working Bar of Double-Cage Induction Motor. IEEE Transactions on Applied Superconductivity. 2020; 30 (4):1-5.

Chicago/Turabian Style

Dong-Ho Kim; Jun-Hyuk Choi; Kwang Soo Kim; Ju Lee; Won-Ho Kim. 2020. "Design Process of Working Bar of Double-Cage Induction Motor." IEEE Transactions on Applied Superconductivity 30, no. 4: 1-5.

Journal article
Published: 04 February 2020 in IEEE Transactions on Applied Superconductivity
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This study proposes a novel rotor shape for the spoke-type per-manent magnet synchronous motor (PMSM) to improve its pow-er performance by changing permeance and increasing magnetic flux density strength in the air gap. Applying a wedge-shaped barrier to the rotor results in a reluctance change in areas of the rotor that have saturated magnetic flux density, which changes the permeance in the air gap. In addition, magnetic flux can be transmitted to the air gap to increase the air gap magnetic flux density strength. In this study, a wedge-shaped barrier was used to maximize air gap magnetic flux density and torque, thus elimi-nating the magnetic flux density saturation area that negatively affects torque. This wedge-shape barrier also changes the induct-ances. The results confirmed that average torque improves as magnetic flux density saturation area is removed.

ACS Style

HyungKwan Jang; Seung-Taek Oh; Yeji Park; Hyunwoo Kim; Ik Sang Jang; Ju Lee. Design and Analysis of a Novel Rotor Shape to Improve Power Performance. IEEE Transactions on Applied Superconductivity 2020, 30, 1 -4.

AMA Style

HyungKwan Jang, Seung-Taek Oh, Yeji Park, Hyunwoo Kim, Ik Sang Jang, Ju Lee. Design and Analysis of a Novel Rotor Shape to Improve Power Performance. IEEE Transactions on Applied Superconductivity. 2020; 30 (4):1-4.

Chicago/Turabian Style

HyungKwan Jang; Seung-Taek Oh; Yeji Park; Hyunwoo Kim; Ik Sang Jang; Ju Lee. 2020. "Design and Analysis of a Novel Rotor Shape to Improve Power Performance." IEEE Transactions on Applied Superconductivity 30, no. 4: 1-4.

Journal article
Published: 04 February 2020 in IEEE Transactions on Applied Superconductivity
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In this paper, the outer rotor permanent magnet brushless DC motor (BLDC) with halbach magnet array was studied to im-prove the power characteristics of BLDC for drones. First, the BLDC motor applied to the currently commercial drone was se-lected as the target model and improved design was carried out. Spec generation was carried out for target BLDC model and the base model was designed and manufactured. Based on the base model, am improved design was applied using the halbach mag-net array using Response Surface Method (RSM). Applying the halbach magnet array can reduce the leakage flux and improve the efficiency by reducing the iron loss of the motor. In addition, the design for reducing the weight of the motor was carried out using RSM. It was confirmed by Finite Element Analysis (FEA) that the power characteristics of the designed improved model improved compared to the target BLDC model.

ACS Style

Yeji Park; Hyunwoo Kim; HyungKwan Jang; Sang-Hwan Ham; Ju Lee; Dong-Hoon Jung. Efficiency Improvement of Permanent Magnet BLDC With Halbach Magnet Array for Drone. IEEE Transactions on Applied Superconductivity 2020, 30, 1 -5.

AMA Style

Yeji Park, Hyunwoo Kim, HyungKwan Jang, Sang-Hwan Ham, Ju Lee, Dong-Hoon Jung. Efficiency Improvement of Permanent Magnet BLDC With Halbach Magnet Array for Drone. IEEE Transactions on Applied Superconductivity. 2020; 30 (4):1-5.

Chicago/Turabian Style

Yeji Park; Hyunwoo Kim; HyungKwan Jang; Sang-Hwan Ham; Ju Lee; Dong-Hoon Jung. 2020. "Efficiency Improvement of Permanent Magnet BLDC With Halbach Magnet Array for Drone." IEEE Transactions on Applied Superconductivity 30, no. 4: 1-5.

Journal article
Published: 20 January 2020 in IEEE Transactions on Applied Superconductivity
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This paper establishes an analysis method of permanent magnet assistant synchronous motor (PMA SynRM) with asymmetric barrier. In a general motor analysis method, the inductance is calculated using the dq-axis vector diagram. In addition, the characteristics of the motor are analyzed by separating the mag-netic torque and the reluctance torque. However, in an asymmet-ric motor, the magnetic neutral plane (MNP) is shifted because the magnetic permeance is asymmetric. Therefore, it is difficult to analysis the characteristic of the asymmetric motor because it in-volves errors applying the general analysis method. In this paper, the magnetic property of the asymmetric motor is analyzed and the analysis method of asymmetric motor is proposed. To verify the proposed analysis method, PMA SynRM is designed as a conventional model. Furthermore, the magnetic torque and reluc-tance torque are separated through the proposed analysis meth-od. The validity of the proposed analysis method is verified through finite element analysis (FEA) and manufacture of the conventional model.

ACS Style

Hyunwoo Kim; Yeji Park; Seung-Taek Oh; HyungKwan Jang; Dong-Hoon Jung; Ik Sang Jang; Ju Lee. Study on Analysis Method of Asymmetric Permanent Magnet Assistance Synchronous Reluctance Motor Considering Magnetic Neutral Plane Shift. IEEE Transactions on Applied Superconductivity 2020, 30, 1 -4.

AMA Style

Hyunwoo Kim, Yeji Park, Seung-Taek Oh, HyungKwan Jang, Dong-Hoon Jung, Ik Sang Jang, Ju Lee. Study on Analysis Method of Asymmetric Permanent Magnet Assistance Synchronous Reluctance Motor Considering Magnetic Neutral Plane Shift. IEEE Transactions on Applied Superconductivity. 2020; 30 (4):1-4.

Chicago/Turabian Style

Hyunwoo Kim; Yeji Park; Seung-Taek Oh; HyungKwan Jang; Dong-Hoon Jung; Ik Sang Jang; Ju Lee. 2020. "Study on Analysis Method of Asymmetric Permanent Magnet Assistance Synchronous Reluctance Motor Considering Magnetic Neutral Plane Shift." IEEE Transactions on Applied Superconductivity 30, no. 4: 1-4.

Journal article
Published: 13 January 2020 in Energies
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In order to improve the efficiency, a line-start synchronous reluctance motor (LS-SynRM) is studied as an alternative to an induction motor (IM). However, because of the saliency characteristic of SynRM, LS-SynRM have a limited power factor. Therefore, to improve the efficiency and power factor of electric motors, we propose a line-start permanent magnet assistance synchronous reluctance motor (LS-PMA-SynRM) with permanent magnets inserted into LS-SynRM. IM and LS-SynRM are selected as reference models, whose performances are analyzed and compared with that of LS-PMA-SynRM using a finite element analysis. The performance of LS-PMA-SynRM is analyzed considering the position and length of its permanent magnet, as well as its manufacture. The final model of LS-PMA-SynRM is designed for improving the efficiency and power factor of electric motors compared with LS-SynRM. To verify the finite element analysis (FEA) result, the final model is manufactured, experiments are conducted, and the performance of LS-PMA-SynRM is verified.

ACS Style

Hyunwoo Kim; Yeji Park; Huai-Cong Liu; Pil-Wan Han; Ju Lee. Study on Line-Start Permanent Magnet Assistance Synchronous Reluctance Motor for Improving Efficiency and Power Factor. Energies 2020, 13, 384 .

AMA Style

Hyunwoo Kim, Yeji Park, Huai-Cong Liu, Pil-Wan Han, Ju Lee. Study on Line-Start Permanent Magnet Assistance Synchronous Reluctance Motor for Improving Efficiency and Power Factor. Energies. 2020; 13 (2):384.

Chicago/Turabian Style

Hyunwoo Kim; Yeji Park; Huai-Cong Liu; Pil-Wan Han; Ju Lee. 2020. "Study on Line-Start Permanent Magnet Assistance Synchronous Reluctance Motor for Improving Efficiency and Power Factor." Energies 13, no. 2: 384.

Journal article
Published: 04 November 2019 in Energies
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This study focuses on improving the power density of a spherical multi-degree-of-freedom (multi-DOF) actuator. A spherical multi-DOF actuator that can operate in three DOFs is designed. The actuator features a double air gap to reduce eddy current loss. However, a multi-DOF actuator driven by a single actuator exhibits low power density. Therefore, a Halbach magnet array is applied to improve the power density of a spherical multi-DOF actuator, and its output characteristics are compared with those of an existing spherical multi-DOF actuator via finite element analysis. Additionally, the output characteristics are analyzed based on changes in the coil pitch angle and magneto-motive force of the rotating winding. Furthermore, it is necessary for a spherical multi-DOF actuator to move to the command position. Hence, a stability analysis is performed to ensure that the spherical multi-DOF actuator is stably driven based on the command position.

ACS Style

Sooyoung Cho; Ho Joon Lee; Ju Lee. Study on Multi-DOF Actuator for Improving Power Density. Energies 2019, 12, 4204 .

AMA Style

Sooyoung Cho, Ho Joon Lee, Ju Lee. Study on Multi-DOF Actuator for Improving Power Density. Energies. 2019; 12 (21):4204.

Chicago/Turabian Style

Sooyoung Cho; Ho Joon Lee; Ju Lee. 2019. "Study on Multi-DOF Actuator for Improving Power Density." Energies 12, no. 21: 4204.

Original article
Published: 02 August 2019 in Journal of Electrical Engineering & Technology
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This paper presents a new design technique to improve the efficiency of the large turbine generator. The leakage magnetic flux at the generator end region causes the eddy current loss. The eddy current loss also occurs in the flange which supports the stator cores and outside space block at both ends of the generator. We propose a flange with the groove shape to reduce eddy current loss by decreasing the incident area of magnetic flux on the flange. The results of the three-dimensional finite-element analysis show that the proposed method can improve the generator efficiency.

ACS Style

Dae-Il Song; Ju Lee. Flange with the Groove Shape to Improve the Efficiency of Large Turbine Generator. Journal of Electrical Engineering & Technology 2019, 14, 2005 -2010.

AMA Style

Dae-Il Song, Ju Lee. Flange with the Groove Shape to Improve the Efficiency of Large Turbine Generator. Journal of Electrical Engineering & Technology. 2019; 14 (5):2005-2010.

Chicago/Turabian Style

Dae-Il Song; Ju Lee. 2019. "Flange with the Groove Shape to Improve the Efficiency of Large Turbine Generator." Journal of Electrical Engineering & Technology 14, no. 5: 2005-2010.

Journal article
Published: 18 March 2019 in IEEE Transactions on Magnetics
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This paper discusses the design of a synchronous reluctance motor designed to replace a 5.5 kW industrial induction motor. End plates are axially placed at both ends of an industrial motor to fix the lamination of the rotor. It is manufactured from magnetic materials to ensure manufacturing convenience and price advantage. With its construction from magnetic materials, a lower output of the motor due to axial flux leakage is observed. This paper analyzed the drop in output caused by the axial flux leakage in the end plate constructed of magnetic material and methods to compensate for the said output drop. The first method to improve the output degradation problem was to fabricate the end plate as a non-magnetic material. This, however, was found to be inefficient due to the need for different mass production apparatus for the new material. A new method proposed in this paper involved using the end plate constructed of magnetic material but incorporating a new shape to the end plate with the saliency ratio to resolve the decreased output problem. This method converts the magnetic flux leaked in the axial direction into reluctance torque. The 3-D FEA was performed for the validity of the method, and reliability was verified through the production and testing of the actual models.

ACS Style

Jae-Kwang Lee; Dong-Hoon Jung; Ki-Doek Lee; Wonjoon Jin; Geunho Lee; Ju Lee; Ye Jun Oh. A Study on Analysis of Synchronous Reluctance Motor Considering Axial Flux Leakage Through End Plate. IEEE Transactions on Magnetics 2019, 55, 1 -4.

AMA Style

Jae-Kwang Lee, Dong-Hoon Jung, Ki-Doek Lee, Wonjoon Jin, Geunho Lee, Ju Lee, Ye Jun Oh. A Study on Analysis of Synchronous Reluctance Motor Considering Axial Flux Leakage Through End Plate. IEEE Transactions on Magnetics. 2019; 55 (6):1-4.

Chicago/Turabian Style

Jae-Kwang Lee; Dong-Hoon Jung; Ki-Doek Lee; Wonjoon Jin; Geunho Lee; Ju Lee; Ye Jun Oh. 2019. "A Study on Analysis of Synchronous Reluctance Motor Considering Axial Flux Leakage Through End Plate." IEEE Transactions on Magnetics 55, no. 6: 1-4.

Journal article
Published: 07 January 2019 in IEEE Transactions on Applied Superconductivity
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In above paper [1], the figures were named incorrectly. The correctly named figures and explanations follow. Fig. 1. shows the magnetic flux density distribution of the motor. As shown in the figure, the magnetic flux densities are concentrated on the lip and bridge portions and are modified to show saturation. Fig. 2. is attached (b) to express the system more clearly. In the case of Fig. 4., the proposed algorithm is modified to more clearly represent and emphasize it. In Fig. 5, the longitudinal displacement part is added to graphically show how the information of the laser sensor is received in order to calculate the yaw angle. Fig. 6. shows the algorithm in more detail, making it easier to understand.

ACS Style

Jun Hui Won; Ye Jun Oh; Ju Lee; Han-Woong Ahn; Hyung Woo Lee; YonHo Cho. Corrections to “A Study on the Control Method of Lateral Displacement and Yaw Angle in Curved Driving of IRWs System” [Apr 18 Art. no. 0602505]. IEEE Transactions on Applied Superconductivity 2019, 29, 1 -2.

AMA Style

Jun Hui Won, Ye Jun Oh, Ju Lee, Han-Woong Ahn, Hyung Woo Lee, YonHo Cho. Corrections to “A Study on the Control Method of Lateral Displacement and Yaw Angle in Curved Driving of IRWs System” [Apr 18 Art. no. 0602505]. IEEE Transactions on Applied Superconductivity. 2019; 29 (6):1-2.

Chicago/Turabian Style

Jun Hui Won; Ye Jun Oh; Ju Lee; Han-Woong Ahn; Hyung Woo Lee; YonHo Cho. 2019. "Corrections to “A Study on the Control Method of Lateral Displacement and Yaw Angle in Curved Driving of IRWs System” [Apr 18 Art. no. 0602505]." IEEE Transactions on Applied Superconductivity 29, no. 6: 1-2.