Thomas Baumgartner

Modelling the valuesphere and the ecosphere: Integrating the decision makers’ perspectives into LCA

Methods for Life Cycle Impact Assessment have to cope with two critical aspects, the uncertainty in values and the (unknown) system behaviour. LCA methodology should cope explicitly with these subjective elements. A structured aggregation procedure is proposed that differentiates between the technosphere and the ecosphere and embeds them in the valuesphere. LCA thus becomes a decision support system that models and combines these three spheres. We introduce three structurally identical types of LCA, each based on one coherent but different set of values. These sets of values can be derived from the Cultural Theory and are labeled as ‘egalitarian’, ‘individualistic’, and ‘hierarchic’. Within Life Cycle Impact Assessment, a damage oriented assessment model is complemented with both a newly developed precautionary indicator designed to address unknown damage and an indicator for the manageability of environmental damages. The indicators for unknown damage and for manageability complete the set of indicators judged to be relevant by decision makers. The weights given to these indicators are also value-dependent. The framework proposed here answers the criticisms that present LCA methodology does not strictly enough separate subjective from objective elements and that it fails to accurately model environmental impacts.

Novel high-speed, Lorentz-type, slotless self-bearing motor

Active magnetic bearings are a preferred choice for supporting rotors spinning at high-speed due to low friction losses and no wear. However, the rotational speed in previous bearing topologies has been limited by complex rotor constructions, high rotor losses, or position control instabilities at high speed. This paper presents a novel Lorentz-type, slotless self-bearing motor concept which overcomes most limitations of previously presented high-speed AMBs. An analytical model for motor torque and bearing forces is presented and a design for 500 000 rpm is verified with FE simulations, showing exceptionally low negative stiffness cross coupling. Finally, a prototype system is described.

Analysis and Measurement of Three-Dimensional Torque and Forces for Slotless Permanent-Magnet Motors

Slotless windings, both skewed and rhombic, are widely used in industry. In addition to the drive torque, possibly undesirable transverse torques and forces are generated. An analytical derivation of the torque and force components in all three directions is detailed in this paper for the skewed and the rhombic windings. It is shown that, for some winding configurations, alternating transverse torque components are generated, which may compromise stable operation in applications where, for example, magnetic or gas bearings are involved. Finite-element method results, which enable the transverse torque for various winding geometries to be quantified, are also included. Finally, the theoretical results are verified by measurements.

Analysis and measurement of 3D torque and forces for permanent magnet motors with slotless windings

Slotless windings, skewed and rhombic, are widely used in industry. Beside the drive torque, possibly undesired transverse torques and forces are generated, which have not been analyzed previously. An analytical derivation of the torque and force components in all three directions is detailed in this paper for the skewed winding. It is shown that for some winding configurations alternating transverse torque components are generated, which may compromise stable operation in applications where for example magnetic or gas bearings are involved. Moreover the windings are analyzed with regard to a potential use as active magnetic radial bearings in high-speed applications. Finally, measurements are presented to verify the theoretical results.

High-speed magnetically levitated reaction wheel demonstrator

Reaction wheels (RWs) for small satellites with active magnetic bearings allowing for ultra-high-speed operation show advantages in angular momentum density over ball bearing RWs with limited speed according to scaling laws developed in this paper. A reaction wheel demonstrator design based on a novel dual hetero/homoploar, slotless, self-bearing, permanent-magnet synchronous motor concept with a rotational speed of 250 000 rpm is investigated. The design includes the rotor dynamics, mechanical stress analysis, electromagnetics, power electronics and control, and the sensor concept. The experimental setup ready for experimental verification is presented.

Trajectory prediction for low-cost collision avoidance systems

In this paper, a novel algorithm for estimation, filtering and prediction of glider and light aircraft trajectories based on GPS measurements is introduced. The algorithm uses Interacting Multiple Model (IMM) filters to detect specific maneuvers such as turning, circling or straight flight. An integrated wind model allows for quick estimation of local wind fields and helps achieving consistent prediction quality in windy conditions. The algorithm is shown to perform well compared to algorithms currently used in the FLARM® collision avoidance system, particularly in windy conditions.

Analysis and design of an ultra-high-speed slotless self-bearing permanent-magnet motor

Active magnetic bearings (AMB) enable contactless operation and can therefore be used for supporting rotors spinning at high speeds. However, the rotational speed in conventional reluctance-force-based AMB topologies is limited which is mainly due to high rotor losses and achievable force control bandwidths. In this paper, a prototype of a self-bearing motor designed for rotational speeds of up to 500 000 revolutions per minute (rpm) is presented. Due to the employed AMB, the motor can be operated in high-purity or vacuum environments. An analytical mechanical and electrical bearing model is introduced and verified by measurements. Furthermore, a bearing inverter system is designed and its controller performance is shown. Closed-loop system measurements of a spinning levitated rotor at 400 000 rpm verify the functionality of the overall system. To the authors knowledge, this is the world record speed for magnetically-levitated electrical drive systems.

Trajectory Prediction for Light Aircraft

In this paper, a novel algorithm for estimation, filtering, and prediction of trajectories of light aircraft and gliders based on Global Positioning System measurements is introduced. The algorithm uses interacting-multiple-model filters to detect specific maneuvers such as turning, circling, or straight flight. An integrated wind model allows for quick estimation of the local wind field and helps to achieve consistently good prediction accuracy in windy conditions. The algorithm is shown to perform well compared with legacy algorithms currently used in a collision avoidance system.

Modelling the Valuesphere and the Ecosphere

Methods for Life Cycle Impact Assessment have to cope with two critical aspects, the uncertainty in values and the (unknown) system behaviour. LCA methodology should cope explicitly with these subjective elements. A structured aggregation procedure is proposed that differentiates between the technosphere and the ecosphere and embeds them in the valuesphere. LCA thus becomes a decision support system that models and combines these three spheres. We introduce three structurally identical types of LCA, each based on one coherent but different set of values. These sets of values can be derived from the Cultural Theory and are labeled as ‘egalitarian’, ‘individualistic’, and ‘hierarchic’. Within Life Cycle Impact Assessment, a damage oriented assessment model is complemented with both a newly developed precautionary indicator designed to address unknown damage and an indicator for the manageability of environmental damages. The indicators for unknown damage and for manageability complete the set of indicators judged to be relevant by decision makers. The weights given to these indicators are also value-dependent. The framework proposed here answers the criticisms that present LCA methodology does not strictly enough separate subjective from objective elements and that it fails to accurately model environmental impacts.