• Proceedings of the KIEE Conference
• /
• 대한전기학회 2004년도 하계학술대회 논문집 B
• /
• pp.761-763
• /
• 2004

Due to the high peripheral speed of the rotor and the relatively high conductivity of the magnets used, rotor eddy current loss can be substantial. On the basis of the coupled FEM and analytical method, this paper deals with the rotor loss analysis in permanent magnet high-speed machine with 3-phase rectifier.

• The Journal of Korea Robotics Society
• /
• 제5권4호
• /
• pp.309-317
• /
• 2010

This paper proposes an efficient measurement system for the velocity and direction of the wind using the dual rotor wind power generator in vessel. Conventional digital measurement system recognizes the direction and the velocity of the wind using the electric compass or synchronous motor and Vane probe method using hall sensors. But each system has its own short-comings: the synchronous motor has a larger measurement error than the magnetic compass and magnetic compass is weak for the external disturbances such as fluctuation of the vessel. To compensate these short-comings, this paper proposes a new compensation algorithm for the fluctuation errors according to the external interference and the unexpected movement of the vessel along the roll and pitch directions. The proposed system is implemented with the dual compasses and a synchronous motor. The proposed independent power generation system can be operated by itself and can raise the efficiency of the wind power generation systems of 30 ~ 400 W installed along the vertical and horizontal axes. The proposed system also realizes the efficient and reliable power production system by the MPPT algorithm for the real-time recognition of the wind direction and velocity. An advanced switching algorithm for the battery charging system has been also proposed. Effectiveness of the proposed algorithm has been verified through the real experiments and the results are demonstrated.

• Journal of Magnetics
• /
• 제20권2호
• /
• pp.148-154
• /
• 2015

48-V ISG (Integrated Starter Generator) system has attracted attention to improve the fuel efficiency of ICE (Internal Combustion Engine) vehicle. One of the key components that significantly affects the cost and performance of the 48-V ISG system is the motor. In an ISG motor, the core and copper loss make the motor efficiency change because the motor has a broad driving operated range and more diverse driving modes compared with other motors. When designing an ISG motor, the selection of an electrical steel sheet is important, because the electrical steel sheet directly influences the efficiency of the motor. In this paper, the efficiency of the ISG motor, considering core loss and copper loss, is analyzed by testing different types of electrical steel sheets with respect to the driving speed range and mode. Using the results of a finite element method (FEM) analysis, a method to select the electrical steel sheet is proposed. This method considers the cost of the steel sheet and the efficiency according to driving mode frequency during the design process of the motor. A wound rotor synchronous machine (WRSM) was applied to the ISG motor in this study.

• Journal of Electrical Engineering and Technology
• /
• 제11권4호
• /
• pp.801-809
• /
• 2016

The electrically excited synchronous generator (EESG) is applied in wind turbine systems recently. In an EESG control system, electrical torque is affected by stator flux and rotor current. So the control system is more complicated than that of the permanent-magnet synchronous generator (PMSG). Thus, the higher demanding of the control system is required especially in case of wind turbine mechanical resonance. In this paper, the mechanism of rotor speed resonant phenomenon is introduced from the viewpoint of mechanics firstly, and the characteristics of an effective damping torque are illustrated through system eigenvalues analysis. Considering the variables are tightly coupled, the four-order small signal equation for torque is derived considering stator and rotor control systems with regulators, and the bode plot of the closed loop transfer function is analyzed. According to the four-order mathematical equation, the stator flux, stator current, and electrical torque responses are derived by torque reference step and ramp in MATLAB from a pure mathematical deduction, which is identical with the responses in PSCAD/EMTDC simulation results. At last, the simulation studies are carried out in PSCAD software package to verify the resonant damping control strategy used in the EESG wind turbine system.

• The KSFM Journal of Fluid Machinery
• /
• 제14권1호
• /
• pp.5-10
• /
• 2011

MTG(Micro turbine generator) operating at 400,000 rpm is under development and the impact test rig to measure the dynamic stiffness and damping coefficient of air foil bearing for high speed rotor is presented in this study. The stiffness and damping coefficient of air foil bearing depending on the rotational speed can be measured easily and effectively by using the simple configuration of impact test rig which is composed of air gun, gap sensors and high speed motor. The estimation results of stiffness and dampling coefficient using least square estimation method is presented as well.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• 제53권11호
• /
• pp.753-759
• /
• 2004

This paper presents a modeling and simulation of a fuzzy controller for maximum power extraction of a grid-connected wind energy conversion system with a link of a rectifier and an inverter. It discusses the maximum power control algorithm for a wind turbine and proposes, in a graphical form, the relationships of wind turbine output, rotor speed, power coefficient, tip-speed ratio with wind speed when the wind turbine is operated under the maximum power control. The control objective is to always extract maximum power from wind and transfer the power to the utility by controlling both the pitch angle of the wind turbine blades and the inverter firing angle. Pitch control method is mechanically complicated, but the control performance is better than that of the stall regulation method. The simulation results performed on MATLAB will show the variation of generator's rotor angle and rotor speed, pitch angle, and generator output.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 한국소음진동공학회 2002년도 추계학술대회논문초록집
• /
• pp.379.2-379
• /
• 2002

The support bearing requires high DN to raise specific energy efficiency for the state of the art rotating machine with high speed. Especially for the system has a big rotor(750 kgf) with high speed(about one mi i lion DNs) such as the pulsed generator, tin selection of the bearing and lubrication method are very important. (omitted)

• Journal of Electrical Engineering and Technology
• /
• 제13권2호
• /
• pp.849-857
• /
• 2018

This paper aims is to study the effect of photovoltaic generation penetration and STATCOM on the transient stability of a single machine infinite bus (SMIB) system based on the rotor angle stability. The influence of STATCOM and PV penetration can be seen through damping oscillations, so that the generator remains stable with the rest of the system for various fault conditions. The simulation results obtained make it possible to efficient identify harmful and beneficial impact of increasing the PV penetration and the existence of STATCOM capability. The system model is created in MATLAB/ SIMULINK software.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• 제51권8호
• /
• pp.391-397
• /
• 2002

This paper presents a modeling and simulation of a PI controller for maximum power extraction of a grid-connected wind energy conversion system with a link of a rectifier and an inverter. It discusses the maximum power control algorithm fnr a wind turbine and proposes, in a graphical form, the relationships of wind turbine output, rotor speed, power coefficient, tip-speed ratio with wind speed when the wind turbine is operated under the maximum power control. The control objective is to always extract maximum power from wind and transfer the power to the utility by controlling both the Pitch angle of the wind turbine blades and the inverter firing angle. Pitch control method is mechanically complicated, but the control performance is better than that of the stall regulation method. The simulation results performed on MATLAB will show the variation of generator's rotor angle and rotor speed, pitch angle, and generator output.

• Proceedings of the KIPE Conference
• /
• 전력전자학회 2001년도 전력전자학술대회 논문집
• /
• pp.38-41
• /
• 2001

Switched reluctance generators(SRGs) attract much attention in the generator because of high efficiency, simplicity, and ruggedness. They require rotor position information In determine the turn-on and turn-off angle, but the rotor position sensor is less tolerant of extreme environmental conditions, such as high temperature or dust, so the position sensor is limited and undesirable. This paper describes a new approach to estimate the rotor position from the measured terminal voltages and currents of the SRG. The proposed method is based on the instantaneous inductance of the SRG. The proposed method is verified by computer simulations and experiments.