A QUASI-STATIC MODELLING APPROACH OF AIRBORNE POWER SYSTEMS

Abstract Modelling the whole power system of an airborne system requires very high computational capacity. This paper presents a possible approach to overcome this obstacle when considering new technology and topologies in airborne systems. Using Step-down and step-up voltage converters are described as fictive DC/DC transformers. This approach makes it possible to reduce the complexity of power system models of tentative systems to such extent that the resulting computational tool can be used for studies of the system performance during entire flight missions and/or for optimisation

A quasi-static modelling approach of electromechanical actuators

Abstract This paper presents a suggested modelling approach of an electromechanical actuator, where the performance of involved semiconductor devices and tentative motors as PM, transversal, torus, and switched reluctance electrical machines are condensed into look-up tables. Current and voltages are then described in form of quasi-static rms values quantities, and the actuator mechanical outputs in momentary forces and velocities. The proposed modelling approach is considered to be one ingredient in future build-up of models of entire MEA aircrafts. Design of the electric power systems of a More Electric Aircraft (MEA) comprises dimensioning of several electromechanical actuator systems. During flight the effective mechanical outputs of the actuators vary considerably slower than the voltages and currents in the corresponding electrical machines and semiconductor devices. To facilitate modelling of the whole system and decrease simulation time it is feasible to separate the high and low frequency behaviour of these components For a general transducer T em = T me = BB 0 l , where B 0 B is the effective magnetic flux density and l is the effective length of the winding wire subjected to B 0 . The fundamental feeding angular frequency ω e is assumed to be considerably higher than the mechanical angular frequencies. This means that one can regard time varying rms values of voltages and currents on the electrical side and related time varying torque and angular values on the mechanical side. The torque and counter EMF constants are t = r 2 T me and e = r 1 T me , respectively, and are normally specified by the electrical machine producer. An equivalent circuit can now be drawn according t

Abstract 25 TH INTERNATIONAL CONGRESS OF THE AERONAUTICAL SCIENCES ANALYSIS OF A FEASIBLE PULSED-POWER SUPPLY SYSTEM FOR AN UNMANNED AERIAL VEHICLE

power supply of electric energy weapons such as high-power microwave and laser weapons. Aspects of electric power generation, energy storage, distribution and pulse-conditioning systems for the power supply of directed energy weapons in Unmanned Aerial Vehicle are addressed in this paper. A trend in aircraft design is to electrify more parts of the aircraft via the concept of More Electric Aircraft (MEA) and its technology which allows for increased electric power consumption. Thus, MEA technology enables the power supply of weapons and protection systems that are using electric energy. Among these devices directed energy weapons such as high-power microwave (HPM) and laser weapons are feasible. Such systems require high power pulsed electric energy with, thus imposing new requirements of on-board power supplies. In the demonstrated concept it is important to analyze power losses and efficiency as well as weight and volume in order to evaluate the possibility to adapt the system in an UAV.

OPTIMIZATION AND CHARACTERISATION BY FINITE ELEMENT METHOD OF AN ELECTROMECHANICAL ACTAUTOR FOR MORE ELECTRIC AIRCRAFT APPLICATIONS

The future More Electric Aircraft (MEA) technology focus on increasing the use of electrical equipment to a larger extent, e.g. replacing conventional hydraulic and pneumatic actuators with electromechanical or electro hydrostatic actuators to reduce weight, cost and maintenance. Advances in enabling technologies of electric power generation, distribution, and utility equipment have made the use of electric actuators more competitive. Electric actuation can be based on Electro Hydrostatic (EHA), ElectroMechanical (EMA), or Magnetostrictive Actuator (MA) concepts. In this paper the experiences from a performed electromechanical actuator demonstrator program are presented together with a motor optimization method intended for future programs. The described actuator demonstrator is designed for an Unmanned Aerial Vehicle (UAV) application. The important key design criteria’s for the demonstrator have been reliability, redundancy, torque density, and reduced maintenance

Abstract 25 TH INTERNATIONAL CONGRESS OF THE AERONAUTICAL SCIENCES SIMULATION AND ANALYSIS OF A NEW HIGH POWER DENSITY GENERATOR

When high power electrical machines are required, an increase in the mechanical frequency and/or number of poles is suggested. The analyzed electrical machine produces a high torque density due to a concentrated winding arrangement, in combination with the increased width of the stator teeth. It is a permanent magnet synchronous generator, [1] and is intended for operation at high speed and high power applications. The large crosssectional area of the magnetic core flux paths is one of the reasons of the generators good performance. In this paper the impact on output power and losses by increasing number of poles and generated input speed is treated. New soft magnetic material also is addressed. The feasibility of using key parameters of the involved electrical machine, estimated by FEM-analyses and condensed into a quasistatic model, [2] is also addressed in this paper. These extracted parameters constitute a platform for a scaleable model.

25 TH INTERNATIONAL CONGRESS OF THE AERONAUTICAL SCIENCES

stresses the need of robust, low weight systems with low losses. New hard and soft magnetic materials have made it feasible to work with high speed and high frequency. Applications of new soft magnetic materials and hard magnetic materials like NeFeB magnets have enabled high density power generation systems. A new concept comprising a high speed PM-generator system and a magnetic amplifier control is presented. Magnetic amplifiers are used in the power supply of the Electronic Flight Control System in the Swedish "Gripen " fighter-aircraft. This technology is attractive in More Electric Aircraft (MEA) systems due to the possibility to achieve a compact, robust and a highly reliable system with low losses. Applications of new soft magnetic materials, such as amorphous magnetic alloys, have enabled the use of magnetic amplifier (magamp) technology in the design of competitive electric power converters. This paper presents a studied design on a 20-40 kW generator system including a +/- 270V controlled output, performed by magnetic amplifier technology. This work addresses the power generator, and the power converter. High speed PM-generators are offering high power density