Search Results

Induction machines (IM) are considered work horse for industrial applications due to their rugged, reliable and inexpensive nature; however, their low power density restricts their use in volume and weight limited environments such as an aerospace, traction and propulsion applications. Given recent advancements in additive manufacturing technologies, this paper presents opportunity to improve power density of induction machines by taking advantage of higher slot fill factor (SFF) (defined as ratio of bare copper area to slot area) is explored. Increase in SFF is achieved by deposition of copper in much more compact way than conventional manufacturing methods of winding in electrical machines. Thus a design tradeoff study for an induction motor with improved SFF is essential to identify and highlight the potentials of IM for high power density applications and is elaborated in this paper.

This paper will present a multi-domain (electrical and thermal) model of a three phase voltage source converter and its implementation in Modelica language. An averaged model is utilised for the electrical domain, and a power balance method is used for linking the DC and AC sides. The thermal domain focuses in deriving the converter losses by deriving the analytical equations of the space vector modulation to derive a function for the duty cycle of each converter leg. With this, the conduction and switching losses are calculated for the individual switches and diodes, without having to model their actual switching behaviour. The model is very fast to simulate, as no switching events are needed, and allows obtaining the simulation of the electrical and thermal behaviour in the same simulation package..

Induction machines (IM) are considered work horse for industrial applications due to their rugged, reliable and inexpensive nature; however, their low power density restricts their use in volume and weight limited environments such as an aerospace, traction and propulsion applications. Given recent advancements in additive manufacturing technologies, this paper presents opportunity to improve power density of induction machines by taking advantage of higher slot fill factor (SFF) (defined as ratio of bare copper area to slot area) is explored. Increase in SFF is achieved by deposition of copper in much more compact way than conventional manufacturing methods of winding in electrical machines. Thus a design tradeoff study for an induction motor with improved SFF is essential to identify and highlight the potentials of IM for high power density applications and is elaborated in this paper.

It is desired to reduce stator end winding length and mass to reduce associated resistive losses, increase efficiency and power density of an induction motor. With recent advancements in additive manufacturing technology, it is possible to deposit copper conductive paths and insulation layers in a selective controlled manner. This enables more compact end winding designs. The objective of this paper is to present a topology optimization based approach for design of stator end winding to minimize its overall length, volume and mass. Design approach and parametric study results for a representative stator design are presented in this paper. By reducing length of end winding, efficiency and power density of the induction motor can be increased enabling benefit realization for weight critical aerospace applications, incorporation in electric vehicle market and potentially reducing rare-earth dependency.

Over the past decade, fuel cell systems have begun to appear as both primary and auxiliary power sources for aircraft. Fuel cells enable quiet electric aircraft with endurances that exceed equivalent battery powered vehicles, but have been limited to efficient fixed-wing aircraft due to low fuel cell power-to-weight ratios. This paper begins by discussing polymer electrolyte membrane fuel cell (PEFC) advancements at United Technologies Corporation (UTC) that have resulted in a significant increase in both the power-to-weight and power-to-volume ratios of fuel cell systems. As a result of these advances, UTC PEFC systems can now enable longer endurance missions for smaller UAVs as well as be considered for electric aircraft requiring vertical takeoff and landing capability. The move into vertical takeoff for electric aircraft is of particular interest as capabilities such as hover, perch and stare, and runway independence are enabled.

The application of a production-oriented high-power CO2 laser system for the welding of auto underbody components is reported. Sheet metal sections, varying in thickness from 0.060-0.135 in, are welded at speeds up to 500 in/min at 6 kW. An overview of recent developments in laser welding is presented along with a discussion of the laser deep-penetration weld phenomenon. A comparison is made between laser and electron-beam welding performance.

An analytic framework for process planning activity has been formulated and incorporated as the basis of a generative computer process planning system. The system uses full geometric design data and produces, under interactive control, detailed operation sheets with dimensioned workpiece drawings. The major elements of the system technology are process decision models, machining analysis and optimization models, a special process planning language, and man-machine communication by interactive graphics.

The advancement of both sensory and unmanned technology, combined with increased utilization of autonomous platforms in complex teaming scenarios, has created a need for practical design space exploration tools to aid in the synthesis of effective System-of-Systems (SoS). The presented work describes a modular, flexible, and extensible framework, referred to herein as the Technologies and Teaming Evaluation (TATE) framework, for straightforward identification of high-quality SoS, which may include both manned and autonomous elements, through quantitative evaluation of system-level and SoS-level attributes against a set of user-defined reference tasks.

This paper presents a demonstrator developed in the European CleanSky2 project MISSION (Modelling and Simulation Tools for Systems Integration on Aircraft). Its scope is the development towards a seamless integrated, interconnected toolchain enabling more efficient processes with less rework time in todays, highly collaborative aerospace domain design applications. The demonstration described here, consists of an open, modular and multitool platform implementation, using specific techniques to achieve fully traceable (early stage) requirements verification by virtual testing. The most promising approach is a model based integration along the whole process from requirements definition to the verified, integrated (and certified) system. Extending previous publications in this series, the paper introduces the motivation and briefly describes the technical background and a potential implementation of a workflow suitable for that target.