• Journal of Advanced Marine Engineering and Technology
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• v.32 no.2
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• pp.323-329
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• 2008

This paper deals with modeling and characteristic analysis of a large-powered electric ship propulsion system. Particularly, system modeling in accordance with the required shipping performance, building-up the equivalent circuit and the power analysis based on load flow have been performed. In addition, abnormal operating condition of short-circuit network is considered for investigating the safety of system components under the over-load condition. Furthermore, protective device like circuit breaker has been specified in order to make the entire system operate normally in case of short-circuit emergency.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.155-158
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• 2008

Development of Moon Explorer-1 (orbiter) is supposed to be commenced in 2017 and launched in 2020. In case of Moon Explorer-2 (lander), it would be slated to start in 2021 and launch in 2025. For this reason it is taken for granted to investigate a fundamental propulsion system for a Moon Explorer. In this paper conceptual feasibility and comparison studies are proposed for the propulsion system applicable to a Moon Explorer. Availability of monopropellant/bipropellant/electric propulsion system is compared and analysed as well with precedents overseas. As a result possible candidates for a Moon Explorer propulsion system are suggested.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.4
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• pp.49-55
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• 2013

This paper deals with the flight test of propulsion system of middle size electrically powered UAV (EAV2, Electric Aerial Vehicle 2) which is under development in KARI. EAV2 is low speed endurance type UAV whose wing span is 6.9 m, and weight is 18 kg. The UAV has flown for 22 hours in June of 2012. The flight test result showed that the propulsion system worked well suppling power for any circumstances during the test flight. Each power source worked according to the design purpose.

• Journal of the Korea Safety Management & Science
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• v.19 no.4
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• pp.309-316
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• 2017

Recently, the outboard engine system of internal combustion engine is widely used in the field of small ship propulsion. However, the internal combustion engine has serious problems of energy depletion and environmental problems, so electric propulsion methods are being studied. In this paper, we have developed important motors and controllers of electric propulsion system for small marine outboard motors. The motor design was performed through the motor characteristics analysis method, and the 30Kw system was developed through the BEMF processing circuit and the power conversion circuit by the embedded microprocessor. This study was carried out through government supported projects and achieved quantitative targets through accredited institutions.

• Journal of Aerospace System Engineering
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• v.17 no.6
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• pp.27-34
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• 2023

This paper presents the application of a magnetic gear to the electric propulsion system for an aircraft. Since high torque is required in aircraft electric propulsion systems, combining a speed reducer can amplify the torque. However, mechanical gears have issues, such as friction, vibration, and heat generation, which lead to maintenance challenges. In the case of a direct-drive motor that does not use mechanical gears, the size and weight of the motor increase to achieve high torque. This paper proposes the application of a magnetic gear to solve the maintenance issues of mechanical gears and the weight increase problem of direct-drive motors in aircraft electric propulsion systems. In this paper, a magnetic gear suitable for aircraft electric propulsion systems is designed, and it is compared with a direct-drive motor in terms of performance and the feasibility of applying the magnetic gear is verified.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.818-824
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• 2018

CFRP is often used as lightweight hull material for luxury yachts or special-service ships. An electric propulsion system is also eco-friendly, and has been trialled to equip a small vessel as its main propulsion. In this study, replacing the hull materials and propulsion system with CFRP and electric motors, we made an estimate of the effect of weight reduction and compared it to the original design, for this purpose a case study was conducted on a 45-ft yacht. When redesigning structures with CFRP, we applied the reinforcement content of the carbon fiber in the same way as the original (GC = 0.4), and when changing to the electric propulsion system, we designed motors and battery packs to achieve the same performance as the original. The result showed that CFRP and the electric propulsion system could make the structural and machinery weights 45 % and 58 % lighter, respectively. However, in terms of efficiency, it was confirmed that the electric propulsion system is practically inefficient because it requires a huge amount of battery packs for the same navigation range with diesel engines.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.4
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• pp.366-373
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• 2012

In this paper, serious changes in the electromagnetic environment with increasing power and energy capabilities for electric driving and military mission are discussed. Design and control strategies on the Electro-Magnetic Compatibility(EMC) for the series hybrid electric vehicle are proposed to minimize the effects of electromagnetic interferences.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.8
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• pp.923-929
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• 2019

The stability of the propulsion system is crucial for the autonomous vessel. Multiple power generation and propulsion systems should be provided for the stability of the propulsion system. High power generation capacity is calculated for stability, resulting in economical decline due to low load operation. To solve this problem, we need to optimize the power system. In this paper, an OPMS for electric propulsion ship is constructed. The OPMS consists of a hybrid power generation system, an energy storage system, and a control load system. The power generation system consists of a dual fuel engine, the energy storage system is a battery, and the control load system consists of the propulsion load, continuous load, intermittent load, cargo part load and deck machine load. The power system was constructed by modeling the characteristics of each system. For the experiment, a scenario based on ship operation was prepared and the stability and economical efficiency were compared with existing electric propulsion ships.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.6
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• pp.95-108
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• 2019

Electric propulsion is a type of space propulsion with a high specific impulse by accelerating propellant using electrical energy and brings about reduction of the fuel mass and launch costs of satellites so that it is being extensively studied in the world. Electric thrusters are widely used for various purposes from micro satellites to large satellites and from low Earth orbit satellites to spacecraft for exploration. Recently, satellites using full-electric propulsion have been developed, and the number of satellites with electric propulsion is also gradually increasing. In this paper, the current status and trends of research on electric propulsion in the United States, Europe, and Japan will be reported.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.1
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• pp.85-92
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• 2017

Recently, electric propulsion systems are used for unmanned surface vehicle, fish finder boat, etc. Some of these propulsion systems can be constructed of two electric motors and propellers for advanced impellent force. In this case, the speed difference generated between two propellers, namely, the synchronous error has a bad influence on the energy efficiency and course error. In this study, a synchronous control system is designed to restrain synchronous error caused by disturbance and mismatched dynamic characteristics. The control system is composed of the reference model, pre-filters, speed controllers, and synchronous controllers. The reference model is used for calculating the decoupled synchronous error and control input for each propulsion system. The pre-filters and speed controllers are designed in order that the propulsion system may follow the reference signal without overshoot and input saturation. And the synchronous controllers are designed from the viewpoint of stable and quick synchronization through root locus mothed approach. Finally, the simulation results show that the designed control system is effective for the disturbance.