• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.42-51
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• 2022

An eVTOL aircraft, which is required to operate with low pollution/low noise in urban environments, mostly use battery-powered electric propulsion systems as power sources, not traditional propulsion systems such as reciprocating or turbine engines. Accordingly, certification preparation for the electric propulsion system and securing the safety of the electric propulsion system, are important issues. In the U.S., special technical standards equivalent to FAR Part 33 were issued to certify electric engines, and in Europe, various special conditions were established to certify electric propulsion systems. Thus, in Korea, the technical standards for the electric propulsion system for eVTOL aircraft must also be prepared in line with the U.S. and Europe. In this paper, SC E-19, the technical standard of the electric/hybrid propulsion system (EHPS) in special conditions, was analyzed. Additionally, securing the safety of the electric propulsion system of the aircraft are proposed, through the collaboration of SC E-19 technical standards with the existing aircraft safety evaluation procedure ARP 4761. Finally, through a case study of the Ehang 184 electric propulsion system, it has been confirmed that the proposed safety assurance method is applicable at the aircraft level.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.5
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• pp.391-403
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• 2013

Propeller aircraft propelled by an electric propulsion system is gaining a renewed interest because of ever-increasing environmental concern on harmful emissions emitted from conventional jet engines and national energy security. Traditional aircraft sizing methods are not readily applicable to electric propulsion aircraft that utilize a variety of alternative energy sources and power generation systems. This study showcases an electric propulsion aircraft sizing exercise based on a generalized, power based sizing method. A general aviation aircraft is propelled by an electric propulsion system that comprises of a propeller, a high temperature super conducting motor, a Proton Exchange Membrance(PEM) fuel cell system fuelled with hydrogen, and power conditioning equipment. In order to assess the impact of technology progression, aircraft sizing was conducted for two different sets of technology assumptions for electric components, and the results were compared with conventional baseline aircraft.

• Journal of Aerospace System Engineering
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• v.15 no.3
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• pp.20-29
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• 2021

As the feasibility of urban air mobility (UAM) service using electric vertical take-off and landing (eVTOL) aircraft increases due to aircraft electrification, distributed propulsion, and artificial intelligence technologies, the U.S. and European aeronautical societies have been improving their certification system and regulations for the type certification of eVTOL. The improved certification system is expected to be ready in the near future, after the European Union Aviation Safety Agency (EASA) proposed the VTOL Special Condition, SC-VTOL in 2019. However, the current domestic certification system is still insufficient to properly respond to eVTOL. This study investigated the development trends of foreign eVTOL and certification systems, identified considerations to improve the domestic certification system, and proposed the measures for type certificates and type certificates validation of eVTOL based on the comparison between SC-VTOL and Korea airworthiness standards (KAS).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.554-559
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• 2017

Recently, the global attention is focused on the development of the renewal aero-propulsion systems proved in the air pollution, the noise, the great operational cost, safety and risks. Especially, various study are conducting for the development of the advanced high power to weight ratio aircraft through the significant reduction of fuel consumption and upgrade of the propulsion efficiency, using the alternative propulsion system developments such as hydrogen and solar power system. The hybrid propulsion system can be the representative propulsion system which get the power sources by combining the merits of two or more power sources. In this study, the advancement trends, characteristics, design method which can be applied to the renewal future UAV development.

• 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 Aerospace System Engineering
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• v.15 no.1
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• pp.32-39
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• 2021

Electric propulsion aircraft are being actively researched in the aviation field in recent years to solve environmental and noise problems caused by existing gas turbine engine. In particular, research on a thrust motor as a core component of an electric power propulsion system and an inverter for driving it is actively being conducted. In this paper, a motor with high specific power is selected to determine characteristics of aircraft that are sensitive to weight and volume. Power loss of the inverter is then simulated. In the simulation, the selected motor and power device were modeled using PSIM, a power electronics analysis tool. Inverter power loss according to switching frequency was then analyzed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.183-186
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• 2011

In this paper, we present some results of power analyses, and weight estimation on electric propulsion systems for Personal Air Vehicles(PAV) applications. When hybrid electric propulsion is adopted, its power performance using fuel cells and batteries is inferior to that of internal combustion engines for 1,000 kg PAV. However, hybrid electric propulsion systems may replace IC engines when energy density and power density is over $0.75kW{\cdot}hr/kg$and 2.5 kW/kg, respectively.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.6
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• pp.1-8
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• 2010

In this paper, we present some results of technical surveys, power analyses, and weight estimation on electric propulsion systems for 1-ton class Personal Air Vehicles(PAV) applications. When hybrid electric propulsion is adopted, its power performance using fuel cells and batteries in inferior to that of internal combustion engines. However, hybrid electric propulsion systems may replace IC engines when energy density and power density reach 0.75 kW$^*$hr/kg and 2.5 kW/kg, respectively.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.55-57
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• 2020

최근 항공기 분야에서는 기존 내연기관이 아닌 배터리를 이용한 전기 추진 방식(Electric Propulsion)에 대한 연구가 활발하다. 특히 완전 전기 추진 시스템에서는 모든 전력을 배터리로부터 입력받는다. 배터리는 잔존용량에 따라 배터리의 출력전압의 크기가 변하는 특성을 갖는다. 이러한 특성은 전동기 상전류의전고조파 왜율(THD)에 영향을 준다. 본 논문에서는 배터리 잔존용량에 따른 상전류 맥동을 분석하였고, 배터리 동작 특성에 맞추어 상전류 THD 조건을 만족하고 최대 효율로 인버터를 동작하기 위한 스위칭 주파수 선정 알고리즘을 제안하였다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.908-909
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• 2015

본 논문은 항공기 추진용 전동기에 대한 논문으로 전동기 내부에 블레이드가 삽입되는 특징으로 인해 매우 얇은 요크폭과 항공기 시스템 효율을 위해 가볍게 설계해야 한다는 점을 제약조건으로 갖는 Ring-type PMSM 설계에 관한 논문이다. 본 논문에 언급되는 전동기의 경우 내부에 삽입되는 블레이드로 인해 내부 요크 폭이 매우 얇다는 제약조건에서 어떠한 전동기 타입이 적절한지 검토하였고, 네오디움(NdFeB) 자석을 사용하여 높은 자속밀도로 고출력을 얻는 동시에 높은 도전율과 얇고 넓은 자석 형상에 따라 발생하는 손실을 저감하기 위한 설계를 진행하였고 유한요소해석을 통해 감자를 고려하여 전자기적 성능을 확인하였다.