• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.2
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• pp.22-31
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• 2005

A design study was conducted for a new concept aircraft(Canard Rotor/Wing: CRW) that has the capability of dual mode flight, a rotorcraft and a fixed wing mode. The CRW can show a vertical take off/landing and a high speed/efficiency cruise performance simultaneously. It is not surprising to develop a new sizing code for this class of aircraft because conventional sizing codes developed solely for either the rotary wing or the fixed wing aircraft are not adequate to design a dual mode aircraft operated both by the rotary wing through tip jet effux and the fixed wing lift. Thus, a new design code was developed based on the conventional sizing code by adding some features including rotor performance, duct flow, and engine flow analysis, hence could eventually predict the performance of reaction driven rotor, the flight performance and the flight characteristics. The various design parameters were investigated to find their influences on the flight performance then, a small UAV(Unmanned Aircraft Vehicle) of 1500 lbs class was optimally designed to have minimum weight using the developed sizing code.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.2
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• pp.105-114
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• 2008

In this study, the sizing and performance analysis program is developed for the canard rotor wing(CRW) aircraft which operates in dual modes (fixed wing mode and rotary wing mode). The developed program is verified for both fixed wing and rotary wing modes using the existing aircraft data and the design optimization formulation is made to perform the reconnaissance mission. For the canard rotor wing aircraft optimization , multi-objective function is constructed to consider both the fixed wing mode and rotary wing mode the weighting factor. For six design cases with different weighting factors and different design constraints, the optimization is performed and improved rotor design results are derived.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.4
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• pp.467-472
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• 2020

The superconducting synchronous generator is one of the breakthrough elements for direct-drive wind turbines because it is light and small. Normally the superconducting one has copper armature windings in the stator and superconducting field windings on the rotor. The high resistance of the armature can make large copper losses, comparing with the conventional generators with a gear box. One of the solutions for the large copper losses could be a fully superconducting generator. But the high magnetic fields from the superconducting field windings on the rotor also make high perpendicular magnetic fields on the superconducting tapes in the armature windings. We have proposed a fully superconducting synchronous generator with dual field windings. It could immensely decrease the circumferential component of the magnetic field from the field windings at the armature windings. In this paper, we conceptually designed 3 types of superconducting synchronous generators. The first one is the fully superconducting one with conventional structure, which has superconducting armature windings in the stator and superconducting field windings on the rotor. The second one is the one with dual superconducting field windings and superconducting armature windings between them. The last one is the same as the third one except the structure of the armature. If the concentrated armature windings are superconducting ones with cryostats, then they cannot be installed within the span of 2 poles. So, we adopted 3 phases windings within 4 poles system. It makes more AC losses but can be manufactured really.

• The KSFM Journal of Fluid Machinery
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• v.15 no.2
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• pp.63-68
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• 2012

This paper deals with the aerodynamic analysis and structural test under estimated loading condition for small composite blade, which is utilized in dual rotor wind turbine system. Firstly, the front and rear blades of dual rotor wind turbine system were modeled using reverse engineering method. And using finite volume method, the aerodynamic forces were analyzed at the rated and cutout wind speed to identify the pressure distribution on blades. And then, the full scale structural tests were conducted according to load and strength based methodology in IEC 61400-2 to identify the structural integrity of composite blade.

• New & Renewable Energy
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• v.1 no.4 s.4
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• pp.55-59
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• 2005

In this paper, a new drive system(SHS) for hybrid electric vehicle is proposed. As dual rotor hybrid electric vehicle using planetary gearsets, the SHS has the advantages of both series and parallel systems. The output speed and torque of SHS can be determined at specific point regardless of the engine's operating point. When the size of generator which is used in SHS is same as in THS, the SHS has more activities of engine control due to the ability that is operated in lower speed range. To maximize the performance of system, we carried out optimization for the three parameters that are engine, motorl and motor2. As the result of the optimization, we confirmed the SHS is more preferable to THS in fuel consumption and acceleration area.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.97-104
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• 2008

Most of engine control systems for helicopter turboshaft engines are equipped with dual sensors. For the system with dual redundancy, analytic methods are used to detect faults based on the system dynamical model. Helicopter engine dynamics are affected by aerodynamic torque induced from the dynamics of the main rotor. In this paper an engine model including the rotor dynamics is constructed for the T700-GE-700 turboshaft engine powering UH-60 helicopter. The singular value decomposition(SVD) method is applied to the developed model in order to detect sensor faults. The SVD method which do not need an additional computation to generate residual uses the characteristics that the system outputs in direction of the left singular vector if an input is applied in direction of the right singular vector. Simulations show that the SVD method works well in detecting and isolating the sensor faults.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.10
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• pp.1481-1487
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• 2017

This paper proposes a sensorless speed control algorithm for parallel-connected dual Surface-mounted Permanent Magnet Synchronous Motors fed by a single inverter. For stable parallel operation of synchronous motors with a single inverter, each motor has to be constantly kept in the synchronization state regardless of load torque. If the master motor with the larger load is controlled, the synchronous state will be maintained. Therefore, detection of the master motor is essential. Conventionally, the master motor is determined by comparing the rotor position error from the relation between the back-EMF for torque angle and the flux position. consequently, the position sensor is deemed essential for finding the rotor position. In this paper, we proposed a method that decides the magnitude of the load from the power angle of two motors due to the load variation and selects the motor to control through the sign function for the sensorless speed control without the position sensor. The results of simulation and experiment conducted verify the efficacy of the proposed method.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1048-1057
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• 2015

This paper proposes a sensorless speed control algorithm for parallel-connected dual Surface-mounted Permanent Magnet Synchronous Motors (SPMSMs) fed by a single inverter. For stable parallel operation of synchronous motors with a single inverter, each motor has to be constantly kept in the synchronization state regardless of load torque. If the master motor with the larger load is controlled, the synchronous state will be maintained. Therefore, detection of the master motor is essential. Conventionally, the master motor is determined by comparing the rotor position error from the relation between the back-EMF for torque angle and the flux position; consequently, the position sensor is deemed essential for finding the rotor position. The parallel sensorless speed control method proposed in this paper uses no position sensor, instead it compares the flux-axis current from the connection between the back-EMF for torque angle and current in unbalanced load conditions. The results of simulation and experiment conducted verify the efficacy of the proposed method.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2376-2384
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• 2018

To reduce the size and cost of motor driving systems, several methods for driving multiple parallel-connected motors with a single inverter have been proposed. However, dual PMSMs driven by a single inverter, unlike induction motors, have a problem with instability due to system resonance caused by disturbances such as load imbalance and tolerances between two motors. To drive dual SPMSMs fed by a single inverter, this paper proposes an active damping algorithm to effectively suppress resonance by using one-sided sensorless speed control and position difference estimation. By deriving rotor position difference from d-q current differences between two motors, the proposed method is affected less by position difference estimation errors and is simpler than dual sensorless position estimation.

• Journal of Magnetics
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• v.21 no.3
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• pp.399-404
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• 2016

This paper presents a new permanent magnet (PM) assisted topology for a recently introduced brushless wound rotor synchronous machine (BL-WRSM) [1]. The BL-WRSM had a dual-inverter configuration for generating a composite magneto motive force (MMF) with a fundamental component and a subharmonic component. The subharmonic component of the MMF is used for brushless excitation of the rotor. In this paper, additional PMs were introduced on the rotor of the BL-WRSM, making it a hybrid BL-WRSM. We also discussed the flux weakening operation for the hybrid BL-WRSM. The hybrid BL-WRSM offered advantages for starting the machine and provided better performance under full-load conditions. The finite element method (FEM) was used to analyze the performance of the hybrid BL-WRSM, and we compared its performance with BL-WRSM. Finally, prototypes were built with and without the PM-assistance, and experiments were conducted to demonstrate their performance.