• Journal of Electrical Engineering and Technology
• /
• v.7 no.4
• /
• pp.564-569
• /
• 2012

This paper proposes a hybrid-excited linear synchronous motor (LSM) that has potential applications in a magnetically levitated vehicle. The levitation and thrust force characteristics of the LSM are investigated by means of three-dimensional (3-D) numerical electromagnetic FEM calculations and experimental verification. Compared to a conventional LSM with electromagnets, a hybrid-excited LSM can improve levitation force/weight ratios, and reduce the power consumption of the vehicle. Because the two-dimensional (2-D) FE analysis model describes only the center section of the physical device, it cannot express the complex behavior of leakage flux, which this study is able to predicts along with levitation and thrust force characteristics by 3-D FEM calculations. A static force tester for a hybrid-excited LSM has been manufactured and tested in order to verify these predictions. The experimental results confirm the validity of the 3-D FEM calculation scheme for the description of a hybrid-excited LSM.

• Progress in Superconductivity and Cryogenics
• /
• v.20 no.4
• /
• pp.55-59
• /
• 2018

Currently, the development of industry makes needs larger electric supply. Providers must consider the efficiency about losses and reliability of the system. In this case, DC power system can save electrical energy; long-distance transmission line losses. Relevance to switch technology with a voltage-source converter (VSC) in AC-DC conversion system have been researched. But, protection device of DC-link against fault current is still needed to study much. VSC DC power system is vulnerable to DC-cable short-circuit and ground faults, because DC-link has a huge size of capacitor filter which releases extremely large current during DC faults. Furthermore, DC has a fatal flaw that current zero crossing is nonexistence. To interrupt the DC, several methods which make a zero crossing is used; parallel connecting self-excited series LC circuit with main switch, LC circuit with power electronic device called hybrid DC circuit breaker. Meanwhile, self-excited oscillator needs a huge size capacitor that produces big oscillation current which makes zero crossing. This capacitor has a quite effective on the price of DCCB. In this paper, hybrid self-excited type superconducting DCCB which are using AC circuit breaker system is studied by simulation tool PSCAD/EMTDC.

• Structural Engineering and Mechanics
• /
• v.36 no.3
• /
• pp.381-399
• /
• 2010

A fuzzy hybrid control technique using a semi-active tuned mass damper (STMD) has been proposed in this study for mitigation of wind induced motion of a tall building. For numerical simulation, a third generation benchmark is employed for a wind-excited 76-story building. A magnetorheological (MR) damper is used to compose an STMD. The proposed control technique employs a hierarchical structure consisting of two lower-level semi-active controllers (sub-controllers) and a higher-level fuzzy hybrid controller. Skyhook and groundhook control algorithms are used as sub-controllers. When a wind load is applied to the benchmark building, each sub-controller provides different control commands for the STMD. These control commands are appropriately combined by the fuzzy hybrid controller during realtime control. Results from numerical simulations demonstrate that the proposed fuzzy hybrid control technique can effectively reduce the STMD motion as well as building responses compared to the conventional hybrid controller. In addition, it is shown that the control performance of the STMD is superior to that of the sample TMD and comparable to an active TMD, but with a significant reduction in power consumption.

• Journal of Electrical Engineering and Technology
• /
• v.1 no.2
• /
• pp.185-191
• /
• 2006

In this paper, a novel stator hybrid excited doubly salient permanent magnet (SHEDS-PM) brushless machine with a special magnetic bridge is proposed for the first time. The originality of this machine is purposely to add a magnetic bridge in shunt with each PM pole, which not only maintains the stator lamination in its entireness, but also amplifies the effect of DC field flux on PM flux. An equivalent magnetic circuit is presented to clarify the novelty. Based on the 2-D finite element analysis, the static characteristics of the SHEDS-PM machine, namely phase flux linkage, back-EMF, cogging torque, winding inductance and static torque are deduced. The corresponding results on a prototype machine illustrate that the proposed machine is promising for application to electric vehicles.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2002.10a
• /
• pp.338-345
• /
• 2002

This paper presents a hybrid control strategy for seismic protection of a benchmark cable-stayed bridge, which is provided as a testbed structure for the development of strategies for the control of cable-stayed bridges. In this study, a hybrid control system is composed of a passive control system to reduce the earthquake-induced forces in the structure and an active control system to further reduce the bridge responses, especially deck displacements. Lead rubber bearings and ideal hydraulic actuators are used fur the passive and active control systems. Bouc-Wen model is used to simulate the nonlinear behavior of lead rubber bearings and an H₂/LQG control algorithm is adopted as an active control algorithm. Numerical simulation results show that the performance of the proposed hybrid control strategy is superior to that of the passive control strategy and slightly better than that of the active control strategy. The proposed control method is also more reliable than the fully active control method due to the passive control part. Therefore, the proposed hybrid control strategy can effectively be used to seismically excited cable-stayed bridges.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.75.4-75
• /
• 2001

This paper designs the robust hybrid controller for the multi degree-of-freedom system having uncertainty caused by modeling error and disturbances. The controlled plant is the construction which has an active dynamic vibration absorber on the top and is excited by the El Centre earthquake at the base. The active controller designed by the LQR(Linear Quadratic Regulator) and H-infinity control theory. The robustness of the hybrid H$\infty$ controller is compared with that of the hybrid LQ controller from computer simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.574-577
• /
• 2004

This paper presents a hybrid system combining lead rubber bearings and hydraulic actuators controlled by a $\mu-synthesis$ method for seismic response control of a cable-stayed bridge. A hybrid system could alleviate some of restrictions and limitations that exist when each system is acting alone because multiple control devices are operating. Therefore, the overall control performance of a hybrid system may be improved compared to each system, however the overall system robustness may be negatively impacted by active device in the hybrid system or active controller may cause instability due to small margins. Therefore, a $\mu-synthesis$ method that guarantees the robust performance is considered to enhance the possibility of real applications of the control system. The performances of the proposed control system are compared with those of passive, active, semiactive control systems and hybrid system controlled by a LQG algorithm. Furthermore, an extensive robust analysis with respect to stiffness and mass matrices perturbation and time delay of actuator is performed. Numerical simulation results show that the performances of the proposed control system are superior to those of passive system and slightly better than those of active and semiactive systems and two hybrid systems show similar control performances. Furthermore, the hybrid system controlled by a f-synthesis method shows the good robustness without loss of control performances. Therefore, the proposed control system could effectively be used to seismically excited cable-stayed bridge which contains many uncertainties.

• Bulletin of the Korean Chemical Society
• /
• v.18 no.2
• /
• pp.156-161
• /
• 1997

Aqueous 6-hydroxyquinoline in the first excited singlet state undergoes protonation to the imine group first in 15 ps, then in the time scale of 40 ps deprotonation from the enol group and finally, however, quickly as in 11 ps electron rearrangement to change into a resonance hybrid structure of quinoid-prevailing forms. Despite the fact that the decay time constant is smaller than the formation time constant, fluorescence from excited protropic zwitterion is observed to assign its maximum at 510 nm. The electron rearrangement is basically an intramolecular charge transfer from the deprotonated oxygen atom to the positively charged iminium ring without any notable change in nuclear geometry, producing a zwitterionic quinoid structure with much a smaller electric dipole moment than the zwitterionic protropic species. This photoproduct formed by consecutive excited state proton and electron transfers shows a smaller dipole moment in S1 than in S0 and a hypsochromic shift although its S1 state has (π, π*) character.

• Journal of Power Electronics
• /
• v.12 no.4
• /
• pp.615-622
• /
• 2012

The switching frequency of the power electronic devices used in large synchronous motor drives is usually kept low (less than 1 kHz) to reduce the switching losses and to improve the converter power capability. However, this results in a couple of problems, e.g. an increase in the harmonic components of the stator current, and an undesired cross-coupling between the magnetization current component ($i_m$) and the torque component ($i_t$). In this paper, a novel complex matrix model of electrically excited synchronous motors (EESM) was established with a new control scheme for coping with the low switching frequency issues. First, a hybrid observer was proposed to identify the instantaneous fundamental component of the stator current, which results in an obvious reduction of both the total harmonic distortion (THD) and the low order harmonics. Then, a novel complex current controller was designed to realize the decoupling between $i_m$ and $i_t$. Simulation and experimental results verify the effectiveness of this novel control system for EESM drives.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.4
• /
• pp.647-651
• /
• 2007

In order to investigate the excited-state intramolecular proton transfer (ESIPT) process of dihydroxyanthraquinones (DHAQ; 1,5-DHAQ and 1,8-DHAQ) in organic-inorganic hybrid matrices, transparent SiO2, SiO2- Al2O3, and Al2O3 matrices chemically bonded with DHAQ were prepared using a sol-gel technique. The absorption maxima of 1,5- and 1,8-DHAQ in SiO2 matrices are observed at around 420 nm, whereas those of DHAQ in both SiO2-Al2O3 and Al2O3 matrices are markedly shifted to longer wavelength compared with those in SiO2 matrix. This indicates that DAHQ forms a chemical bond with an Al atom of Al2O3. The DHAQ in SiO2 matrix shows a markedly Stokes-shifted emission which is originated from the ESIPT in DHAQ. Based on the emission lifetimes of DHAQ, the ESIPT of DHAQ was found to be strongly affected by the chemical interaction with Al atom in the Al2O3-related matrices.