Forced Commutated Controlled Series Capacitor Rectifier for More Electric Aircraft

Abstract

Rising power demands in More Electrical Aircraft (MEA) put power converters for commercial airplanes under increasing pressure to fulfill current harmonic distortion regulations as specified, for example, in DO-160G. Today, the implementation of filters is seen as an effective tool for dealing with harmonics, however, their increased weight and volume is not welcomed in the aerospace industry. This paper proposes a circuit, named Forced Commutation Series Capacitor rectifier (FCSC-rectifier), which is able to maintain low individual harmonic current levels without the need for filter components. The FCSC-rectifier includes a variable capacitive line reactance that interacts in a controlled manner with the inductive line impedance. The result is that the converter input current is nearly purely sinusoidal with a power factor of almost unity. The FCSC-rectifier is to be used for stand-alone variable-voltage, variable-frequency generation systems (VFG) and can therefore power the Full Authority Digital Electronic Control System (FADEC) in an MEA. This paper shows that the FCSC-rectifier can maintain a high power factor and acceptable current harmonic levels without the use of filters, despite large voltage and frequency variations. A full description of the circuit modes of operation is presented in this paper together with simulation results showing circuit performance characteristics over a range of voltages and frequencies. Results are experimentally verified using a 1kW test circuit. Index Terms-Forced Commutated controlled Series Capacitor (FCSC), Full Authority Digital Electronic Control System (FADEC), More Electric Aircraft (MEA), current harmonics, power factor. I. INTRODUCTION he complexity of aircraft electrical loads has substantially increased in recent years with the advent of the More Electric Aircraft (MEA) [1-3]. The most safety critical system in any MEA is the FADEC (Full Authority Digital Electronic Control)system that continuously monitors and controls the ignition timing and fuel injection to the aircraft engine. FADEC control and designs have been reported in [4][5][6] with the focus being mainly on safety. Any failure within the FADEC leads to misfiring and loss of fuel injection [7-10] which would result in a catastrophic event, such as the Airbus A 400M crash in 2015 caused by FADEC failure [11]. One major area of concern is radiated and conducted EMI which could interact with the engine control

Electrical and Electronic Technologies in More-Electric Aircraft: A Review

“…Although the implementation of filters is powerful for assisting the MEA electrical power networks in fulfilling the current harmonic distortion regulations, the demerits such as weight and volume increases are presented. For the sake of not using filters in achieving the desired low individual harmonic current levels, a forced communicated controlled series capacitor rectifier (FCSC-rectifier) was proposed in [71] to maintain a high power factor and acceptable current harmonic levels in the case of large voltage and frequency variations. The effective capacitive reactance is to be matched with the generator inductive reactance, so that the above mentioned targets can be achieved without the need for additional filtering.…”

Performance Analysis of Forced Commutated Controlled Series Capacitor Rectifier for More Electric Aircraft

“…1 shows a block diagram of the three-phase FCSCrectifier circuit. A forced-commutated, series compensation capacitor is inserted between the variable voltage, variable frequency generator and the diode bridge rectifier and controlled to maintain resonance as the frequency of the supply is varied [18]. A schematic diagram of the FCSCrectifier circuit is shown in Fig.…”

“…To avoid the use of a filter and for better utilization of the generator, a new power factor correction rectifier has recently been proposed [18] to replace the conventional diode bridge rectifier normally used to energize a DC load supplied by a variable frequency, variable voltage permanent magnet (PM) generator in MEA. An example of one such load is the Full Authority Digital Electronic Control System (FADEC).…”

Robust Control for Electric Fuel Pump with Variant Nonlinear Loads Based on a New Combined Sliding Mode Surface

“…As a contrary, the fuel flow of electric fuel system can be controlled according to FADEC [6,7] (Full Authority Digital Engine Control) demands (Fig. 3), eliminating flowing back.…”