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정재헌,안다훈,김기현,최영만,김명현,이학준,박재현,김현준,류지흔,김효영,권대갑 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10
The magnetically levitated system, so called maglev system, has been researched and developed with the purpose of vacuum compatibility in the semiconductor industry. In the maglev system, the back electromotive force is inevitably generated when the system moves. The back electromotive force causes force/moment disturbances. Especially, the moment disturbances have negative effect on controlling the rotational motions (θ x , θ y , θ z ) whose control bandwidth is low. Therefore, the back electromotive force causes rotational motion errors. The rotational motion errors should be suppressed since they prevent high speed motion of the maglev system due to the rotational motion allowance of sensors. The rotational motion errors are suppressed by compensating the back electromotive force. In this paper, the back electromotive force, the cause of the rotational motion errors, is mathematically found in terms of the mover velocity and element of force-current matrix. A maglev system without the compensation was simulated and the rotational motion errors due to back electromotive force were found. Then, a feedforward compensated system using a mathematically modeled back electromotive force was simulated. It was verified that the feedforward compensation method with the modeled equation could be useful for suppressing rotational motion errors.
An Improved Flux Estimator for Gap Flux Orientation Control of DC-Excited Synchronous Machines
Xu, Yajun,Jiang, Jianguo The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.2
Flux estimation is a significant foundation of high-performance control for DC-excited synchronous motor. For almost all flux estimators, such as the flux estimator based on phase locked loop (PLL), DC drift causes fluctuations in flux magnitude. Furthermore, significant dynamic error may be introduced at transient conditions. To overcome these problems, this paper proposes an improved flux estimator for the PLL-based algorithm. Filters based on the generalized integrator are used to avoid flux fluctuation problems caused by the DC drift at the back electromotive force. Programmable low-pass filters are employed to improve the dynamic performance of the flux estimator, and the cutoff frequency of the filter is determined by the dynamic factor. The algorithm is verified by a 960V/1.6MW industrial prototype. Simulation and experimental results show that the proposed estimator can estimate the flux more accurately than the PLL-based algorithm in a cycloconverter-fed DC-excited synchronous machine vector control system.
An Improved Flux Estimator for Gap Flux Orientation Control of DC-Excited Synchronous Machines
Yajun Xu,Jianguo Jiang 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.2
Flux estimation is a significant foundation of high-performance control for DC-excited synchronous motor. For almost all flux estimators, such as the flux estimator based on phase locked loop (PLL), DC drift causes fluctuations in flux magnitude. Furthermore, significant dynamic error may be introduced at transient conditions. To overcome these problems, this paper proposes an improved flux estimator for the PLL-based algorithm. Filters based on the generalized integrator are used to avoid flux fluctuation problems caused by the DC drift at the back electromotive force. Programmable low-pass filters are employed to improve the dynamic performance of the flux estimator, and the cutoff frequency of the filter is determined by the dynamic factor. The algorithm is verified by a 960V/1.6MW industrial prototype. Simulation and experimental results show that the proposed estimator can estimate the flux more accurately than the PLL-based algorithm in a cycloconverter-fed DC-excited synchronous machine vector control system.
자동차 공기 블로워용 영구자석 동기 전동기의 위치 추정 오차 보정
신창필(Changphil Shin),이경진(Kyeongjin Lee),이우택(Wootaik Lee),박정희(Jeong-Hee Park),박용선(Yongsun Park) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
In this paper, a novel correction method of position estimation error is proposed to estimate the rotor position of the permanent magnet synchronous motor (PMSM) in conjunction with Hall-effect sensors. The position estimation error is an unavoidable problem in asymmetric placement of the permanent magnet or the sensors, and causes current harmonics and a degradation of the entire drive performance. The method includes a vector cross-product for two unit vectors of back-electromotive-force (EMF) with respect to stator and rotor quantities. and calculates and corrects position estimation error. A performance improvement of the proposed drive system is validated in several experimental results at the steady state and transient state. compared with a conventional drive system with the Hall-effect sensors alone.
Ji Hyung Kim,Thanh Dung Le,Do Jin Kim,Chang-Jin Boo,Young-Sik Jo,Yong Soo Yoon,Kyung Yong Yoon,Yoon Hyuck Choi,Haigun Lee,Ho Min Kim Institute of Electrical and Electronics Engineers 2016 IEEE transactions on applied superconductivity Vol.26 No.4
<P>In general, a metallic stabilization layer is overcoated on the outermost layer of a second-generation high-temperature superconducting (2G HTS) wire to stably transfer current against thermal and magnetic disturbances. Stabilizer thickness T-s is one of the key issues in an HTS synchronous machine (HTSSM) application because it strongly affects the electrical output performance of the machine and the stable operation and reliable protection of the HTS field coil. In this paper, a design and characteristic analysis for manufacturing a 1.5-MW-class HTSSM was performed using a 2-D analytical design code and a 3-D finite-element method. Various T-s values were considered in the HTS field-coil design to investigate their effects on the stability and protection of the HTS coil and the back-electromotive force of the machine. The design parameters are also discussed to determine suitable T-s for the 2G HTS wire.</P>
Kumar, Sunil,Zhao, Wenliang,Du, Zhentao S.,Lipo, Thomas,Kwon, Byung-Il IEEE 2015 IEEE transactions on magnetics Vol.51 No.11
<P>This paper focuses on the design and the analysis of an ultrahigh speed axial-flux permanent magnet (AFPM) machine for an aerospace flywheel energy storage system. The superiority of the proposed AFPM machine is the material-efficient PM shape, which contributes to obtain a sinusoidal back electromotive force (back EMF) and, hence, reduces the torque pulsations of the machine such as torque ripple. The harmonics present in back EMF have a large influence on iron loss and torque pulsations, which are always unacceptable in the applications involving the speed as high as 1 000 000 r/min. Analytical modeling is first performed to determine the PM shape for the proposed models. Then, the advantages of the proposed models are verified by comparing with the basic model with the conventional ring-shaped PMs using the 3-D finite-element method. The results show that the proposed models have a nearly ideal sinusoidal back-EMF waveform that significantly reduces the torque ripples compared with the basic model.</P>
Back EMF Design of an AFPM Motor using PCB Winding by Quasi 3D Space Harmonic Analysis Method
장대규,장정환,장건희 대한전기학회 2012 Journal of Electrical Engineering & Technology Vol.7 No.5
This paper presents a method to design the waveform of a back electromotive force (back EMF) of an axial flux permanent magnet (AFPM) motor using printed circuit board (PCB) windings. When the magnetization distribution of permanent magnet (PM) is given, the magnetic field in the air gap region is calculated by the quasi three dimensional (3D) space harmonic analysis (SHA) method. Once the flux density distribution in the winding region is determined, the required shape of the back EMF can be obtained by adjusting the winding distribution. This can be done by modifying the distance between patterns of PCB to control the harmonics in the winding distribution. The proposed method is verified by finite element analysis (FEA) results and it shows the usefulness of the method in eliminating a specific harmonic component in the back EMF waveform of a motor.
역기전력을 활용한 영구자석 전동기의 동적 편심 검출 방법
강경진(K. J. Kang),장건희(G. H. Jang),송정용(J. Y. Song),서보성(B. S. Seo) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.10
We develop a method to detect the dynamic eccentricity of a permanent magnet (PM) motor by monitoring back electromotive force (BEMF). We derive the mathematical equations of BEMF induced in a tooth and a phase due to dynamic eccentricity of a PM motor. We find that the dynamic eccentricity can be detected by monitoring main harmonic ±1 components of the BEMF induced in a tooth. We also perform the experiment to validate the proposed method by using a PM motor with 8 poles and 12 slots.
Hanlin Shen,Xin Luo,Guilin Liang,Anwen Shen 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6
A complete current loop decoupling control strategy based on a sliding mode observer (SMO) is proposed to eliminate the influence of current dynamic coupling and back electromotive force (EMF) in the vector control of permanent magnet synchronous motors. With this strategy, current dynamic decoupling and back EMF compensation can be simultaneously achieved. Unlike conventional methods, the proposed strategy can avoid the disturbances caused by the parametric variations of motor systems and maintain the advantages of proportional integral (PI) controllers, which are robust and easy to operate. An improved SMO, which uses a special PI regulator other than a linear saturation function as the equivalent control law in the boundary layer of a sliding surface, is proposed to eliminate the estimated errors caused by the quasi-sliding mode and obtain a satisfactory decoupling performance. The stability and parameter robustness of the proposed strategy are also analyzed. Physical experimental results are presented to verify the validity of the method.
Back EMF Design of an AFPM Motor using PCB Winding by Quasi 3D Space Harmonic Analysis Method
Dae-Kyu Jang,Jung-Hwan Chang,Gun-Hee Jang 대한전기학회 2012 Journal of Electrical Engineering & Technology Vol.7 No.5
This paper presents a method to design the waveform of a back electromotive force (back EMF) of an axial flux permanent magnet (AFPM) motor using printed circuit board (PCB) windings. When the magnetization distribution of permanent magnet (PM) is given, the magnetic field in the air gap region is calculated by the quasi three dimensional (3D) space harmonic analysis (SHA) method. Once the flux density distribution in the winding region is determined, the required shape of the back EMF can be obtained by adjusting the winding distribution. This can be done by modifying the distance between patterns of PCB to control the harmonics in the winding distribution. The proposed method is verified by finite element analysis (FEA) results and it shows the usefulness of the method in eliminating a specific harmonic component in the back EMF waveform of a motor.