Showing papers by "Jin Hur published in 2022"
TL;DR: In this paper , the dynamic eccentricity fault (DEF) of the interior permanent magnet synchronous motor (IPMSM) is mainly caused by external mechanical shock, and an unbalanced magnetic force occurs because the length of the air gap is not constant, the distribution of magnetic flux density is distorted, and iron loss is increased.
Abstract: The dynamic eccentricity fault (DEF) of the interior permanent magnet synchronous motor (IPMSM) is mainly caused by external mechanical shock. In the case of DEF, an unbalanced magnetic force occurs because the length of the air gap is not constant. Noise and vibration of the motor occur due to unbalanced magnetic force. In addition, since the length of the air gap is not constant, the distribution of magnetic flux density is distorted, and iron loss is increased. As the iron loss increases, the temperature rises, and an irreversible demagnetization fault (IDF) of the permanent magnet occurs due to overheating. Therefore, in this paper, the fault mechanism of IDF due to DEF of IPMSM for electric vehicle (EV) traction is analyzed. Initially, the magnetic flux density and iron loss characteristics according to the healthy condition and DEF condition are analyzed using the finite element method (FEM). Then, the detailed iron loss analysis is performed based on the phase current waveform measured through the load test of the motor. Finally, the fault mechanism of IDF due to DEF was verified through an electric-axle load test on a manufactured motor having eccentricity.
3 citations
TL;DR: In this article , a new statistical approach was proposed to predict wind power ramp events, and evaluated the performance of prediction using empirical data, which is the observed wind power output data and wind speed data from Taebaek (South Korea) were used for analyzing ramp events and for evaluation.
Abstract: The energy industry, primarily based on the use of fossil fuels (e.g., coal and oil) is rapidly shifting toward renewable energy for securing sustainable resources. Thus, preparing for large wind power ramp events is essential to retain reliable and secure power systems. This study proposed a new statistical approach to predict wind power ramp events, and evaluated the performance of prediction. The empirical data, which is the observed wind power output data and wind speed data from Taebaek (South Korea) were used for analyzing ramp events and for evaluation. Based on the data analysis, a practical metric for evaluating the performance of wind power ramp events forecasting was developed and presented in detail. Notably, the accuracy of forecasting was evaluated through various metrics, whereas the normalized mean absolute error (NMAE) analysis demonstrated ≤ 10% values for all the analyzed months. In addition, a system review was conducted to check if the methodology suggested in this study has helped enhance the security of power systems. The results show that evaluating and considering the ramp events can improve the accuracy of wind power output forecasting which can secure the smart energy systems.
2 citations
DOI•
TL;DR: In this article , the authors compared and analyzed the output characteristics of second-generation high-temperature superconducting racetrack coils with insulation, metal-insulation (MI), non-INSulation (NI), and smart insulation (SI).
Abstract: This study aimed to compare and analyze the output characteristics of second-generation high-temperature superconducting racetrack coils with insulation, metal-insulation (MI), non-insulation (NI), and smart-insulation (SI). First, the output characteristics of each coil were experimentally validated, and circuit equations were examined to analyze these characteristics. The output characteristics were found to be affected by the turn-to-turn resistance. Circuit analysis was used to identify the nature of dependence of output characteristics on turn-to-turn resistance in addition to internal behavior and other mechanisms. In particular, an equation relating the output characteristics of the SI coil with temperature change was derived, and each coil model was simulated using the circuit equation. Then, the simulation results were analyzed, the advantages and disadvantages of each insulation method were discussed, and the validity of the simulation was confirmed. The circuit simulation proposed in this study is expected to facilitate advanced predictions in smart insulation material candidate groups.
2 citations
TL;DR: In this article , a 300-turn smart insulation (SI) coil with vanadium trioxide (V2O3) was placed in an external fluctuating magnetic field generator to allow sliding insertion through a fabricated non-rotating liquid nitrogen tank inside the stator of a 1MW superconducting rotating machine.
Abstract: Experiments and finite-element analyses were conducted to investigate the characteristics of a 300-turn smart insulation (SI) coil coated with vanadium trioxide (V2O3) placed in an external fluctuating magnetic field. The external fluctuating magnetic field generator was designed to allow sliding insertion through a fabricated non-rotating liquid-nitrogen tank inside the stator of a 1-MW superconducting rotating machine. The 300-turn SI coil was fabricated in a two-layer design with 150-turn windings in each layer. Experiments were conducted in such a manner that the SI coil did not rotate during the generation of the external fluctuating magnetic field owing to the rotating magnetic field of the stator. The SI coil with many turns showed no magnetic field delay because of the ramping time,thereby demonstrating controllability equivalent to that of a normal insulated coil. The stability of the SI coil was confirmed via repeated overcurrent tests, with and without an external fluctuating magnetic field.