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ABSTRACT: This study describes the design and testing of a dual-lane electric drive for a prototype, electromechanically actuated, nose wheel steering system for a commercial aircraft. The drive features two independent motor controllers, each operating one-half of a dual three-phase motor, resulting in an actuator capable of full performance following an electrical fault. An isolated communications link between controllers allows parameter consolidation to identify faults and to synchronise outputs, ensuring even load sharing. A selection of results is presented from motor dynamometer performance analysis and from fully loaded output tests, performed on a hydraulic load rig at Airbus, UK.
Electrical Systems in Transportation, IET. 10/2011;
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ABSTRACT: Research is increasingly focusing on the incorporation of electromechanical actuators into future More Electric Aircraft. For an actuator to be feasible in a commercial aircraft, the most critical design factor is attaining the strict safety requirements. The electrical drives used in More Electric technologies must also be suitable for the conventional power supply and control arrangements of aircraft, otherwise feasibility of a new technology may be reduced. This study discusses the generic design requirements for electromechanical actuators from a safety perspective, including the application of fault-tolerant electric drives. Later, two prototype electromechanical actuators, developed by the authors are discussed, comparing the different topologies.
IET Electric Power Applications 02/2011; · 1.17 Impact Factor
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ABSTRACT: Grid-connected wind turbine doubly fed induction generators (DFIGs) are sensitive to dips in supply voltage, so-called “grid faults”. Fault ride through systems must be designed to manage the large and potentially dangerous fault currents in both stator and rotor circuits. However, DFIG fault response has been only partially or summarily treated in contemporary literature. This paper presents a detailed analytical analysis of wind turbine DFIG grid-fault response. The physical behavior of the machine is presented through a description of the flux-linkage response and later developed with analytical solutions of the generalized DFIG machine equations operating under fault conditions showing that the frequencies of the decay components of current deviate from pure dc and rotor speed due to magnetic drag effects. The analysis is experimentally verified and evaluated using a 7.5-kW test facility.
IEEE Transactions on Energy Conversion 01/2011; · 2.27 Impact Factor
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ABSTRACT: This paper presents a comparative investigation of the performance characteristics of a directly connected photovoltaic (PV) pumping system and a scheme utilizing a constant voltage maximum power point tracking algorithm. A simple and accurate model is developed for each individual component of the system based on its measured characteristics and the system is simulated numerically. System performance is analyzed and energy utilization efficiency is calculated for different weather conditions. A detailed comparison identifying the advantages and drawbacks of each technique is presented. Experimental results obtained using a 1080-Wp PV array connected to a 1-kW permanent magnet dc motor-centrifugal pump set show very good agreement with the numerical simulation of the systems.
IEEE Transactions on Sustainable Energy 11/2010;
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ABSTRACT: This paper considers existing More Electric technologies in commercial aircraft, observing recent technologies adopted by aerospace and discussing the reasons restricting the application of other designs. Fault tolerant drives are considered, assessing where reliability may affect application in aerospace. Failure conditions and design issues are proposed which will present challenges in the evolution of laboratory prototypes to actual aerospace hardware. Results are presented from fault tolerant drives, highlighting some of these design considerations.
Electrical Machines (ICEM), 2010 XIX International Conference on; 10/2010
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ABSTRACT: Doubly fed induction generator (DFIG) technology is the dominant technology in the growing global market for wind power generation, due to the combination of variable-speed operation and a cost-effective partially rated power converter. However, the DFIG is sensitive to dips in supply voltage and without specific protection to “ride-through” grid faults, a DFIG risks damage to its power converter due to overcurrent and/or overvoltage. Conventional converter protection via a sustained period of rotor-crowbar closed circuit leads to poor power output and sustained suppression of the stator voltages. A new minimum-threshold rotor-crowbar method is presented in this paper, improving fault response by reducing crowbar application periods to 11-16 ms, successfully diverting transient overcurrents, and restoring good power control within 45 ms of both fault initiation and clearance, thus enabling the DFIG to meet grid-code fault-ride-through requirements. The new method is experimentally verified and evaluated using a 7.5-kW test facility.
IEEE Transactions on Energy Conversion 10/2010; · 2.27 Impact Factor
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ABSTRACT: This paper considers the electrical actuation of aircraft wing surfaces, with particular emphasis on flap systems. It discusses existing hydraulic and electrohydraulic systems and proposes an electrical alternative, examining the potential system benefits in terms of increased functionality, maintenance, and life-cycle costs. This paper then progresses to describe a full-scale actuation demonstrator of the flap system, including the high-speed electrical drive, step-down gearbox, and flaps. Detailed descriptions of the fault-tolerant motor, power electronics, control architecture, and position sensor systems are given, along with a range of test results, demonstrating the system in operation.
IEEE Transactions on Industry Applications 07/2010; · 1.66 Impact Factor
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ABSTRACT: This paper describes the design and testing of a dual-lane electric drive for the operation of a prototype, electromechanically actuated, nose wheel steering system for a commercial aircraft. The drive features two fully independent motor controllers, each operating one half of a three-phase motor to produce an actuator capable of full operation in the event of an electrical fault. An isolated communications link between the controllers allows for consolidation of parameters to identify faults and synchronise outputs to ensure even load sharing. A selection of results is presented from motor dynamometer performance analysis and fully loaded output tests on an Airbus hydraulic test rig at Filton, UK.
Power Electronics, Machines and Drives (PEMD 2010), 5th IET International Conference on; 05/2010
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ABSTRACT: Solar-powered aircraft require electric drives for the main propulsion system. It is critical that these drives provide both very high efficiency and low mass. This paper discusses the relative merits of different machine topologies based upon maximizing efficiency, taking into account power-electronic losses, motor losses, mass, and size penalties. Laminated machines are usually limited in their efficiency at light load because of their iron losses. This paper shows how, by combining a high pole number with an ultralow loss lamination material, these machines can be more efficient than other more complex arrangements which have been adopted by others. A demonstrator machine has been built and predicted efficiencies have been validated by test. It has then been used to propel a solar plane to over 60000 feet and extend the aircraft flight-endurance world record from 30 to 84 h.
IEEE Transactions on Industrial Electronics 02/2010; · 5.16 Impact Factor
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ABSTRACT: The behaviour of searching maximum power point tracking (MPPT) algorithms utilizing direct duty ratio perturbation control is shown to exhibit nonlinear phenomena, including slow scale bifurcations and chaos like behaviour, when applied to a dc photovoltaic (PV) system. The performance characteristics of a dc photovoltaic water pumping system, in which the searching MPPT algorithm is applied at the frequency of the PWM signal of the converter, are examined. The nonlinear behaviour of the system is analyzed and the effects of different parameters on system performance are discussed.
Power Engineering, Energy and Electrical Drives, 2009. POWERENG '09. International Conference on; 04/2009
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ABSTRACT: Many algorithms for maximum power point tracking (MPPT) of photovoltaic (PV) systems have been proposed. However, the application of these algorithms to dc pumping systems is not well covered in the literature. In this paper, the performance of directly connected dc PV pumping systems is compared to that of systems using three different low cost MPPT algorithms, namely a constant voltage algorithm, a perturb and observe (P&O) algorithm, and an incremental conductance (INC) algorithm. Using MPPT, the load power increases reducing the PV array size and the overall cost of the system.
Power Electronics, Machines and Drives, 2008. PEMD 2008. 4th IET Conference on; 05/2008
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ABSTRACT: This paper examines fault tolerant power converter topologies and develops a technique for producing data to compare the reliability of topologies. The various states of fault-tolerant systems are modelled, following which reliability curves and failure rate data is constructed.
Power Electronics, Machines and Drives, 2008. PEMD 2008. 4th IET Conference on; 05/2008
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ABSTRACT: Fault ride-through (FRT) is required for large wind farms in most power systems. Fixed speed wind turbines (FSWTs) are a diminishing but significant sector in the fast-growing wind turbine (WT) market. State-of-art techniques applied to meet grid requirements for FSWT wind farms are blade pitching and dynamic reactive power compensation (RPC). Blade pitching is constrained by the onerous mechanical loads imposed on a wind turbine during rapid power restoration. Dynamic RPC is constrained by its high capital cost. These present technologies can therefore be limiting, especially when connecting to smaller power systems. A novel alternative technology is proposed that inserts series resistance into the generation circuit. The series dynamic braking resistor (SDBR) dissipates active power and boosts generator voltage, potentially displacing the need for pitch control and dynamic RPC. This paper uses a representative wind farm model to study the beneficial effect of SDBR compared to dynamic RPC. This is achieved by quasi-steady-state characterization and transient FRT stability simulations. The analysis shows that SDBR can substantially improve the FRT performance of a FSWT wind farm. It also shows that a small resistance, inserted for less than one
IEEE Transactions on Power Systems 09/2007; · 2.68 Impact Factor
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ABSTRACT: This paper discusses the design of a fault-tolerant electric motor for an aircraft main engine fuel pump. The motor in question is a four-phase fault-tolerant motor with separated windings and a six-pole permanent magnet rotor. Methods of reducing machine losses in both the rotor and stator are introduced and discussed. The methods used to calculate rotor eddy current losses are examined. Full three-dimensional finite-element (FE) time stepping, two-dimensional (2-D) FE time stepping, and 2-D FE harmonic methods are discussed, and the differences between them and the results they produce were investigated. Conclusions are drawn about the accuracy of the results produced and how the methods in question will help the machine designer
IEEE Transactions on Industry Applications 10/2006; · 1.66 Impact Factor
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ABSTRACT: This paper considers the electrical actuation of aircraft wing surfaces, with particular emphasis upon flap systems. It discusses existing electro-hydraulic systems and proposes an electrical alternative, examining the potential system benefits in terms of increased functionality, maintenance and life cycle costs. The paper then progresses to describe a full scale actuation demonstrator of the flap system, including the high speed electrical drive, step down gearbox and flaps. Detailed descriptions are given of the fault tolerant motor, power electronics, control architecture and position sensor systems, along with a range of test results, demonstrating the system in operation
Electric Machines and Drives, 2005 IEEE International Conference on; 06/2005
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ABSTRACT: This paper discusses the design of a fault tolerant electric motor for an aircraft main engine fuel pump. The motor in question is a four phase fault tolerant motor with separated windings and a six pole permanent magnet rotor. Methods of reducing machine losses in both the rotor and stator are introduced and discussed. The methods used to calculate rotor eddy current losses are examined. 3D finite element, 2D finite element time-stepping and 2D finite element harmonic methods are discussed and the differences between them and the results they produce investigated. Conclusions are drawn about the accuracy of the results produced and how the methods in question helps the machine designer
Electric Machines and Drives, 2005 IEEE International Conference on; 06/2005
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ABSTRACT: This paper discusses the design and testing of an aircraft electric fuel pump drive. The drive is a modular, four-phase, fault-tolerant system which is designed to meet the specification with a fault in any one of the phases. The motor employed has a permanent-magnet rotor with the magnets arranged in a Halbach array to maximize the air-gap flux density. Exceptionally high electric loadings are obtained by flooding the entire motor with aircraft fuel, which acts as an excellent cooling agent. Theoretical results are compared with test results gained in conditions approaching those found in an aircraft. Tests are carried out on the unfaulted drive and with one of several fault scenarios imposed. The electrical and thermal performance of the drive is assessed, showing how the flooded fuel cooling has excellent performance without introducing significant drag on the rotor.
IEEE Transactions on Energy Conversion 01/2005; · 2.27 Impact Factor
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ABSTRACT: In safety-critical applications fault-tolerant electric drives and motors can be used. To avoid compromising the reliability of the drives and isolated motor windings, the control hardware must also be fault tolerant. In this work control hardware is separated into lanes, each with a designated power supply, electric drive, motor phase winding and position feedback sensor, all packaged into a single assembly. For a system to operate with a faulted lane, lanes must be able to cross-compare data and determine whether a lane has failed. A demonstrator controller drive has been produced for a multiple lane actuator with the ability to detect a failed lane and continue operation. For the first time, current shaping is implemented on a working prototype to produce instantaneous torque control, even in the event of a fault. This permits rated torque at all rotor positions when stationary and when rotating slowly and rated mean torque at high speeds, when the inertia of the system lets the drive ride through torque dips caused by the faulted phase.
Power Electronics Specialists Conference, 2004. PESC 04. 2004 IEEE 35th Annual; 07/2004
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ABSTRACT: This paper presents a method of adjusting the gains of a PI speed controller adaptively to give the minimum integral absolute error between the speed demand and the output response for a brushless DC drive. A feedforward neural network, trained using a genetic algorithm, adjusts the controller gains to improve the speed response to changes in speed demand and load. Experimental results demonstrate how the gain values vary with speed demand and load set point.
Industrial Electronics, 2004 IEEE International Symposium on; 06/2004
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ABSTRACT: The aerospace industry is currently considering a constant voltage, variable frequency supply for aircraft power systems. This variable frequency system is based on a generator directly driven from the aero-engine, in which the frequency is dependent on engine speed. A number of safety critical loads are placed on this system, and it is essential that failure of any one load does not affect the operation of another. The paper develops the concept of fault tolerant input converters for an electric fuel pump. The converters always act as a unity power-factor load, and can tolerate a range of failures, whilst maintaining both the operation of the pump and minimal impact on the electrical supply. Two converter types are proposed and compared for this application. The operation of these two unity power factor converters from a variable frequency supply is demonstrated. The effect of faults in the selected converters on converter operation and the supply itself is then discussed.
IEE Proceedings - Electric Power Applications 12/2003; · 0.55 Impact Factor
