0885-8993 (c) 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TPEL.2018.2856534, IEEE Transactions on Power Electronics 1 Load Control for the DC Electrical Power Distribution System of the More Electric Aircraft Sandro G¨ unter, Member, IEEE, Giampaolo Buticchi, Senior Member, IEEE, Giovanni De Carne, Member, IEEE, Chunyang Gu, Member, IEEE, Marco Liserre, Fellow, IEEE, He Zhang, Member, IEEE, Chris Gerada, Senior Member, IEEE Abstract—The More Electric Aircraft (MEA) concepts aims at increasing the amount and the power of the electrical subsystems on the next generation of aircrafts. One of the major challenges in this framework is that the electric power is generated by means of electrical generators connected to the jet turbine shaft. In order to satisfy the peak power demand and overload conditions, the generators are oversized, increasing weight and total cost of operation. Possible solutions to this problem is to decrease the size of the generator and to provide the peak power with storage systems. As an alternative, load disconnection during peak demand (load-shedding) can be enforced with solid- state switches. This paper presents a different approach: by modifying the DC voltage of the distribution, the load can be controlled. In order to achieve this objective, a precise on- line identification algorithm is proposed. Theoretical analysis is performed and simulation results on a study-case distribu- tion system are reported, highlighting how the proposed load identification and control method effectively manages a power curtailment condition without load-shedding or storage systems. Power Hardware in the Loop simulations on a DC microgrid with a multi-port power converter confirm the simulation analysis. Index Terms—DC-DC power converters, aircraft power sys- tem, load modeling, multi-port power converters I. I NTRODUCTION The More Electric Aircraft initiative aims at increasing the penetration of the electrical systems into the aircrafts, in order to decrease the weight and increase the overall efficiency and reliability [1]. Already now, the newer aircrafts, the Boeing 787 and the Airbus A380, have an increased amount of electrical systems, and the tendency seems to be growing. Although even actual aircrafts feature some amount of electrical power, this is often limited to the electronics (flight systems, entertainment systems) or to auxiliary systems, like lighting or anti-icing. The core systems of the actuation still rely on hydraulic power. S. G¨ unter, G. Buticchi (corresponding author), C. Gu, H. Zhang and C. Gerada are with the University of Nottingham Ningbo China (UNNC), 199 Taikang East Road, 315100 Ningbo, China (e-mail sandro.gunter@nottingham.edu.cn, buticchi@ieee.org, chunyang.gu@nottingham.edu.cn, he.zhang@nottingham.edu.cn, chris.gerada@nottingham.edu.cn). G. De Carne and M. Liserre are with the University of Kiel, Kaiserstr. 2, 24143 Kiel, Germany (e-mail gdc@tf.uni-kiel.de, ml@tf.uni-kiel.de). C. Gerada is also with The University of Nottingham, Nottingham, NG7 2RD, UK (e-mail chris.gerada@nottingham.ac.uk). This work was supported by the Ningbo Science & Technology Beauro under Grant 2013A31012, China NSFC Grant 51650110507 and by the Euro- pean Research Council (ERC) under the European Unions Seventh Framework Program (FP/2007-2013)/ERC Grant Agreement 616344 - HEART and the German Federal Ministry of Education and Research (BMBF) within the Kopernikus Project ENSURE (03SFK1I0). The power density and the reliability of the hydraulic actuators are known to be high, however, the oil distribution system is bulky and prone to leaks, and this counterbalances the advantages of the actuators. Another relevant issue of the hydraulic distribution system is that a bleed valve on the main engine usually powers the main oil pump and this deterio- rates the efficiency of the main engines [2]. Other systems that normally rely on the bleed air, like the environmental conditioning, can be substituted by a compressor powered by the electric system, like it has been done on the Boeing 787. With an increased on-board power generation, the problem of power distribution arises. Considering that the aircraft is an isolated systems with generators and loads, the distribution system can be considered as a micro-grid on-board. Different paradigms are possible, depending on the amount of power electronics installed and of the characteristics of the actuator. These have been standardized in the MIL-STD-704F as con- stant voltage / constant frequency, constant voltage / variable frequency and DC distribution. In a DC distribution, a power electronics interface controls a high-voltage DC supply from the generator; the system is then designed to operate with DC voltage. Step down power converters to supply LV buses or loads are needed. This solution simplifies the actuation system, since standard voltage source inverters (VSI) can be adopted instead of AC/AC (back-to-back or matrix-based). Voltage levels of ±270 V are contemplated by the standard. With the increase of the electrical power penetration, higher voltage levels will be adopted: 230/400V are already con- templated by the double-voltage systems in MIL-STD-704F. At the moment, AC systems are used to power the large commercial aircraft, while DC systems are mostly used for military applications. Both solutions have advantages and dis- advantages: DC systems feature a lower number of conversion stages, while variable frequency AC do not need rated-power electrical drives connected to the generators. Nevertheless, a motor drive connected to the generator can be used to start the turbine engine without the air turbine starter (ATS), eliminating the need of the bleed valve [3]. One of the major challenges of the MEA is to increase the installed electrical power without oversizing the electrical generator. In fact, if the generators are sized to supply the peak power, the weight saving benefits would be lost. Some solutions [4] involve the use of storage systems to perform peak shaving, employing batteries or supercapacitors to supply the loads during the high demand phase. In common practice,