Full Authority Digital Electronic Control Research Articles

Tízéves a teljes hatáskörű digitális elektronikus hajtómű-szabályozó rendszerek fejlesztése a BME VRHT-n

A gázturbinás hajtóművek napjainkban már szinte kizárólagosan digitális elektronikus szabályozó rendszerrel (Full Authority Digital Electronic Control, FADEC) rendelkeznek, jobb pontosságuk, kisebb méretük, tömegük és karbantartásigényük miatt. A BME VRHT jogelődjén 2009-ben indult meg a TKT-1 gázturbinás sugárhajtómű megalkotását és üzembe állítását követően a szabályozórendszer tervezése. A cikk bemutatja a fejlesztés főbb állomásait a kiinduló, valamint további típusokon (Deutz T216, PD-60R), a különféle alkalmazott szabályozási törvényszerűségeket (fordulatszám, hajtómű nyomás- és teljesítményviszony). Továbbá bemutatjuk azokat az algoritmusokat is (PID, lineáris kvadratikus és csúszómód-szabályozások), amelyeket FADEC-rendszereinkben kidolgoztunk.Munkánk egyik legnagyobb eredménye, hogy a gázturbinás sugárhajtómű próbapadján ezeketaz algoritmusokat valós körülmények között is le tudjuk ellenőrizni.

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

The forced commutated controlled series capacitor (FCSC) rectifier has been recently proposed to power stand-alone variable-voltage variable-frequency generation systems, such as the full authority digital electronic control (FADEC) system, in more electric aircraft. The employment of this rectifier helps to meet increasing power demand requirements while maintaining low current harmonic levels without the need for bulky filters. The FCSC rectifier is controlled to maintain resonance with line frequency variation by inserting variable capacitive reactance in series with the variable-frequency generator's inductive reactance. Unity power factor operation with nearly pure sinusoidal converter input currents is thus achieved, for better utilization of the generator. The FCSC rectifier operation with a variable dc on-board load is analyzed in this paper, including a description of the principle modes of operation of the circuit. The enhancement in circuit's output voltage and output power achieved by replacing the conventional diode bridge rectifier with the FCSC rectifier is also demonstrated. Both rectifiers are analyzed numerically using Saber/Synopsys over a wide range of operating voltages and frequencies. Results are experimentally verified using 1-kW laboratory test rig.

Forced Commutated Controlled Series Capacitor Rectifier for More Electric Aircraft

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 are not welcomed in the aerospace industry. This paper proposes a circuit, named forced commutation controlled series capacitor (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 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 1-kW test circuit.

Design and Test Evaluation of Full Authority Digital Electronic Control System for an Auxiliary Power Unit

A helicopter auxiliary power unit (APU) is initially equipped with a hydro-mechanical control system (HMC). Because HMC's complex structure is difficult to be modified to realize sophisticated control algorithms and the APU is faced with the need for performance improvement, it is urgently necessary to carry out digital control modification of HMC. Based on the analysis of control laws of the original HMC and differences between HMC and digital control system, key techniques involved in the digital control system are studied, such as overall structure, control laws and fuel system based on electric fuel pump, and finally a full authority digital electronic control system (FADEC) is developed for APU. Functions, performances and key techniques of the FADEC system are evaluated on test rig, and the test results show functions of original control system are enhanced and performances of APU are improved more effectively under the control of the designed FADEC compared with the original HMC.

Powerplant Reliability Issues and Wear Monitoring in Aircraft Piston Engines. Part II: Engine Diagnostic

This paper introduces a method to efficiently monitor the status of a piston engine during flight. ECUs (Electronic Control Units) make it possible to fly safely without emergencies or urgencies with random electronic failures of components and connections. The same can be easily done on older engines by adding a reliable digital monitoring system and an automated calibration of the carburetors. In fact, their reliability is several order of magnitude inferior to modern turboshafts. In modern engines with FADEC (Full Authority Digital Electronic Control) as the “on” button is pressed the sensors and actuators are checked. The CPUs will then run start-up during the cranking phase (engine running without ignition). If everything is all right, then the engine starts and the post start checks are also performed. During flight, the ECU checks CPUs, sensors and actuators. Therefore, the electronic system can be monitored with high reliability without much effort. The sensors may crosscheck the engine situation and may output very reliable early diagnosis of incoming failures. Statistical data on spare parts are invaluable for monitoring application, signaling weak or not-lasting components and failure modes. This is another advantage of automotive piston engines conversions to aircraft use.

On the Real-Time Estimation of Disk Temperature Spatial Distributions in Aeroengines

This paper presents a novel approach to real-time modeling of disk temperature distribution using proper orthogonal decomposition (POD). The method combines singular value decomposition (SVD) techniques with a series of low-order transfer functions to predict the disk's thermal response over a typical flight. The model uses only typically available full authority digital electronic control (FADEC) measurements to predict temperature with accuracy of ±30 K over the whole flight cycle. A Kalman filter has also been developed based on a single temperature measurement, and the location of the measurement has been assessed in order to select the most appropriate target for instrumentation. Points all around the front and back of the disk have been assessed, and the best practice result is found to be near the center of the disk neck. This represents a compromise between matching the fast dynamic response of the rim, with the slower dynamics of the cob. The new model has been validated against an independent flight simulation.

A High Temperature Frequency Signal Conditioning Unit for Aeronautical Rotating Systems

This paper covers the development and testing of a high temperature signal conditioning unit capable of sensing wide dynamic range signals from rotating sensors. The unit includes a current peak detector block, a digital pulse generator, ESD (electrostatic discharge) protection and generates an output current proportional to the peak value of the applied input signal. The digital data from the unit can be directly utilized by the FADEC (Full Authority Digital Electronic Control) system or the EHMS (Engine Health Monitoring System) on an aeroengine. The mixed signal unit presented in this paper was designed and fabricated on 1 $\mu\text{m}$ silicon-on-insulator (SOI) CMOS (complementary metal oxide semiconductor) technology and has been shown to function up to 235 $^{\circ}$ Celsius with very high linearity of the output signal. This is the highest operating temperature of an integrated signal conditioning unit developed for a civil aircraft. The mixed signal unit was mounted on a high temperature hybrid module and helps reducing the weight of the aeroengine by several kilograms.

Analysis on Aeroengine Digital Electronic Control

Control technology of aeroengine has made remarkable development in recent 20 years. In order to meet the needs of high performance, high precision propulsion system control, based on computer technology, microelectronic technology and control theory, the control technology is from traditional hydraulic mechanical control to digital electronic control. Digital electronic control has been a huge success from limited function to the full authority control and from the development test to practical application. In the future it will have more widely application and development in the field of military and civilian aircraft control. This paper mainly discusses the full authority digital electronic control. It shows that the digital electronic engine control has wide application prospect and high application value.

Design and Assembly of High Temperature Distributed Aero-engine Control System Demonstrator

This paper covers the development of a distributed high temperature electronics demonstrator for integration with sensor elements to provide digital outputs that can be used by the FADEC (Full Authority Digital Electronic Control) system or the EHMS (Engine Health Monitoring System) on an aircraft engine. This distributed electronics demonstrator eliminates the need for the FADEC or EHMS to process the sensor signal, which will assist in making the overall system more accurate and efficient in processing only digital signals. This will offer weight savings in cables, harnesses and connector pin reduction. The design concept was to take the output from several on-engine sensors, carry out the signal conditioning, multiplexing, analogue to digital conversion and data transmission through a serial data bus. The unit has to meet the environmental requirements of DO-160 with the need to operate at 200°C, with short term operation at temperatures up to 250°C. The work undertaken has been to design an ASIC based on 1.0μm Silicon on Insulator (SOI) device technology incorporating sensor signal conditioning electronics for sensors including resistance temperature probes, strain gauges, thermocouples, torque and frequency inputs. The ASIC contains analogue multiplexers, temperature stable voltage band-gap reference and bias circuits, ADC, BIST, core logic, DIN inputs and two parallel ARINC 429 serial databuses. The ASIC was tested and showed to be functional up to a maximum temperature of 275°C. The ASIC has been integrated with other high temperature components including voltage regulators, a crystal oscillator, precision resistors, silicon capacitors within a hermetic hybrid package. The hybrid circuit has been assembled within a stainless steel enclosure with high temperature connectors. The high temperature electronics demonstrator has been shown to operate from −40°C to +250°C. This work has been carried out under the EU Clean Sky HIGHTECS project with the Project being led by Turbomeca (Fr) and carried out by GE Aviation Systems (UK), GE Research – Munich (D) and Oxford University (UK).

Trends in Automotive Packaging

The long-term trend in automobiles has been increasing electronics content over time. This trend is expected to continue and drives diverse functional, form factor, and reliability requirements. These requirements, in turn, are leading to changes in the package types selected and the performance specifications of the packages used for automotive electronics. Several examples will be given. This abstract covers the development of a distributed high temperature electronics demonstrator for integration with sensor elements to provide digital outputs that can be used by the FADEC (Full Authority Digital Electronic Control) system or the EHMS (Engine Health Monitoring System) on an aircraft engine. This distributed electronics demonstrator eliminates the need for the FADEC or EHMS to process the sensor signal, which will assist in making the overall system more accurate and efficient in processing only digital signals. This will offer weight savings in cables, harnesses and connector pin reduction. The design concept was to take the output from several on-engine sensors, carry out the signal conditioning, multiplexing, analogue to digital conversion and data transmission through a serial data bus. The unit has to meet the environmental requirements of DO-160 with the need to operate at 200°C, with short term operation at temperatures up to 250°C. The work undertaken has been to design an ASIC based on 1.0 μm Silicon on Insulator (SOI) device technology incorporating sensor signal conditioning electronics for sensors including resistance temperature probes, strain gauges, thermocouples, torque and frequency inputs. The ASIC contains analogue multiplexers, temperature stable voltage band-gap reference and bias circuits, ADC, BIST, core logic, DIN inputs and two parallel ARINC 429 serial databuses. The ASIC was tested and showed to be functional up to a maximum temperature of 275°C. The ASIC has been integrated with other high temperature components including voltage regulators, a crystal oscillator, precision resistors, silicon capacitors within a hermetic hybrid package. The hybrid circuit has been assembled within a stainless steel enclosure with high temperature connectors. The high temperature electronics demonstrator has been demonstrated operating from −40°C to +250°C. This work has been carried out under the EU Clean Sky HIGHTECS project with the Project being led by Turbomeca (Fr) and carried out by GE Aviation Systems (UK), GE Research – Munich (D) and Oxford University (UK).

Design of Fault Tolerant Control Laws for Jet Engines

Full Authority Digital Electronic Control (FADEC) system is common in all modern jet engines. In jet engine, the simplest control system is to produce desired engine thrust by changing the fuel flow. Since in flight engine thrust measurement is practically not possible, engine low pressure shaft rotational speed (N1/NL), engine pressure ratio (EPR), or exhaust jet temperature (EJT) has been effectively used as an indicator of the engine thrust. In this paper, the model used is twin spool turbofan engine. If any fault occurs in N1 sensor, the entire engine operation will be affected. Since there exists a unique aerodynamic relationship among the spool speeds, if any fault occurs in N1 sensor, engine thrust can be controlled with a certain amount of degradation using high pressure spool speed (N2/NH).Both soft and hard failures are detected using kalman filter, range, rate and comparison techniques. The effectiveness of the proposed approach is demonstrated by means of simulations.

9.2.1 Developing Product Lines in Engine Control Systems: Systems Engineering Challenges

AbstractRolls‐Royce is developing a Full Authority Digital Electronic Control (FADEC) product line for helicopter and light turboprop applications. This is driven by market demand to reduce the proportional cost of control systems relative to the engine, and to field applications in timescales that preclude traditional clone‐and‐own approaches. The goal is to develop reusable control system architectures, requirements, and verification evidence, which can be used on a variety of applications. Key challenges include addressing military and commercial constraints with the same architecture, designing in flexibility for future applications, and leveraging global company capability in processes, tools, and supply chain strategy. This paper describes Rolls‐Royce's experience adapting existing software product line principles to apply at the control system (hardware and embedded software) level in light of certification guidelines from DO‐178B and ARP4574A. Lessons learned from moving through the “V” life cycle provide insight into how Systems Engineering adds value in this context.

飛行推進統合制御対応航空エンジン制御装置の研究

The Integrated Flight and Propulsion Control (IFPC) for a highly maneuverable aircraft and a fighter-class engine with pitch/yaw thrust vectoring is described. Of the two IFPC functions the aircraft maneuver control utilizes the thrust vectoring based on aerodynamic control surfaces/thrust vectoring control allocation specified by the Integrated Control Unit (ICU) of a FADEC (Full Authority Digital Electronic Control) system. On the other hand in the Performance Seeking Control (PSC) the ICU identifies engine's various characteristic changes, optimizes manipulated variables and finally adjusts engine control parameters in cooperation with the Engine Control Unit (ECU). It is shown by hardware-in-the-loop simulation that the thrust vectoring can enhance aircraft maneuverability/agility and that the PSC can improve engine performance parameters such as SFC (specific fuel consumption), thrust and gas temperature.

2214 環境適合型次世代超音速推進システムの分散制御システム検討

This paper describes feasibility study of distributed control system for "Environmentally Compatible Propulsion System For Next-Generation Supersonic Transport (ESPR Project)". The control system possesses advanced control functions, such as performance seeking control, stall margin control, tip clearance control, etc., which can significantly improve fuel consumption rate, hence can suppress CO2 emission. Since the control system will be so complicated, the conventional FADEC (Full Authority Digital Electronic Control) system will not be able to handle those tasks. A distributed control system with smart sensors and actuators will be preferable to such a complicated control system. The result shows the proposed control system architecture and an example of smart sensor.

Aspects of aircraft engine control systems R&D

The FADEC (full authority digital electronic engine control) technology in Japan has matured substantially within the TRDI's JEC-series FADEC R&D programs. The aspects of engineering practice described in this paper have been addressed by the Third Research Center, TRDI (Technical Research and Development Institute), in the R&D process of the JEC-series aircraft engine control systems. It is shown that the analysis of rotor speed fuel control systems as non-linear servomechanisms has contributed the improvement of control performance, and that the incorporation of the derivative term within the afterburner control loop has decreased the interaction between the low-pressure rotor speed and the exhaust gas temperature. Furthermore, current important topics are described, that are absorbing the group's research effort, in accordance with the TRDI's objectives.

Engine Control Reliability and Durability Improvement Through Accelerated Mission Environmental Testing

The integration of aircraft control systems for future weapon systems will require the engine control system to meet the mission reliability of the flight control system. This will be accomplished through system redundancy and verified by accelerated environmental testing. Combined environment reliability testing (CERT) will assure control system structural integrity and reliability growth of engine-mounted digital electronic controls. Pratt & Whitney, under contract to the U.S. Navy, has recently completed a 10,000-hr CERT program. Dual full authority digital electronic controls (FADEC), connected by a fiber optic data link, were subjected to environmental tests simulating a composite F-14 mission profile. The FADEC units were also exposed to periodic high vibration levels which would be experienced after foreign object damage and salt spray testing to simulate aircraft carrier environment. The test results are reported herein providing insight not only into the reliability and durability of digital electronic controls but also into the equipment and procedures required for testing of future military and commercial engine control systems.

CFM International Tests its First Full Authority Digital Electronic Control for CFM56–5 Engine

Engine testing has begun in Evendale, Ohio using the first Full Authority Digital Electronic Control (FADEC) for the CM56–5 high bypass turbofan, the engine for the new Airbus Industrie A320.

F-14 Aircraft and Propulsion Control Integration Evaluation

Since 1976, the U.S. Navy in conjunction with Pratt and Whitney Aircraft (PWA) has been actively engaged in developing the technology base for on engine, dual redundant, fault tolerant, full authority digital electronic control (FADEC) systems with the capability of aircraft control integration for application to the next generation Navy aircraft. Navy contracts were awarded in 1981 to PWA and Grumman Aerospace Corporation (GAC) to identify the operational benefits of the F-14 Aircraft with a dual-redundant FADEC interfaced to an Advanced Fuel Management Systems (AFM) and integrated with the F-14 aircraft control system. This paper presents the FADEC/F-14 integration evaluation performed by PWA and discusses the benefits of the FADEC/F-14 integrated system. These include improvements in reliability, mission abort, survivability, maintainability, cruise fuel consumption, engine weight, diagnostics and fault recording, inlet and engine air flow matching and propulsion control accuracy.