Adaptive Selective Compensation for Variable Frequency Active Power Filters in More Electrical Aircraft R. P. VENTURINI University of Padova Italy P. MATTAVELLI, Senior Member, IEEE CPES, Virginia Tech P. ZANCHETTA, Member, IEEE M. SUMNER, Senior Member, IEEE University of Nottingham Nottingham, UK The work presented here investigates an adaptive current controller for active power filters for aircrafts power networks, which compensate selected load current harmonics. The attention is focused on the load current harmonic compensation when the fundamental frequency varies over a wide range (typically between 360 Hz and 800 Hz as in new generation aircrafts) and the harmonics produced by distorting loads (such as the 5th and the 7th) are above the achievable current loop bandwidth. Compared with previously reported resonant controllers, this work proposes an adaptive leading angle compensation in the resonant filter, which–by compensating the variable process delay–is potentially able to guarantee the theoretical current control stability when the selected frequency is up to the Nyquist frequency. However, the presence of intermodulation, i.e., distortion introduced due to the compensation of frequencies approaching the Nyquist limit, introduces an additional distortion, which limits the maximum compensation frequency. Experimental results are presented to demonstrate the effectiveness of the proposed system. Manuscript received August 4, 2008; revised April 25, 2010; released for publication May 7, 2011. IEEE Log No. T-AES/48/2/943819. Refereeing of this contribution was handled by M. Veerachary. A preliminary version of this paper was presented at the 4th International Conference on Power Electronics, Machines and Drives 2008 (PEMD 2008), York St. John University College, York, UK, April 2—4, 2008. Authors’ current addresses: R. P. Venturini, DEI, University of Padova, Via Gradenigo 6B, 35131 Padova, Italy; P. Mattavelli, Center for Power Electronics Systems (CPES), Bradley Department of Electrical and Computer Engineering, Virginia Tech, 668 Whittemore Hall (0179), Blacksburg, VA 24061, E-mail: (pmatta@vt.edu); P. Zanchetta and M. Sumner, Power Electronics Machines and Control (PEMC) Research Group, University of Nottingham, University Park, Nottingham, UK. 0018-9251/12/$26.00 c ° 2012 IEEE I. INTRODUCTION Electrical power is consumed in aircrafts by avionics, lighting, galleys, fans, and increasingly by entertainment systems. There is also a trend towards the implementation of the so-called more electric aircraft (MEA) using more electric power to drive aircraft subsystems that conventionally have been driven by a combination of mechanical, hydraulic, pneumatic, and electrical systems [1]. Electrically powered actuation is becoming more attractive due to technology advances in bespoke equipment among which are electrical motors, magnetic materials, electronic control circuits, and power devices. Power electronics converters are required to control electrical power and are necessary, for example, for actuator motor drives and to convert variable frequency (360—800 Hz) in the next generation of civil aircraft to a constant frequency supply bus for various loads or to a dc supply bus. Modern aircraft power system are complex networks [1—3], including ac variable frequency buses, two or more dc buses (one low voltage, typically 28 V and one higher voltage) connected to the ac buses through active rectifiers and through a bidirectional dc-dc converter between them. Although the presence of electrically powered equipment is desirable for weight and fuel cost reduction, the increase of electrical systems on board, and above all the presence of power electronic subsystems, brings severe challenges to aircraft power system distribution [1—2]. Flight control systems, electric actuated brakes, electric anti-icing, environmental systems, electromechanical valve control, utility actuators, air-conditioning, flight entertainment systems, fuel pumping, etc., all need decentralized static power conversion above all in a variable speed variable frequency generation system. Consequently, MEA power distribution networks appear in the form of multi-converter power electronic systems. Furthermore, ac-dc conversion for avionics installations has been traditionally implemented by uncontrollable diode bridge rectifiers. They have the advantage of a good reliability and reduced cost, but generate a high amount of harmonic currents and have a poor input power factor. The more the installed power of airborne systems increases, the more the power of rectification loads becomes a significant fraction of the total [3]. Due to the large presence of these distorting loads, of constant power loads, widespread devices interconnections, and relatively large grid impedances, at least compared with the conventional power distribution systems, power quality issues such as harmonic pollution, voltage dips and swells, and grid stability are difficult to address, especially considering that in the new generation aircrafts the fundamental frequency varies over a wide range. To overcome this IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS VOL. 48, NO. 2 APRIL 2012 1319