Tubular permanent magnet actuators: cogging forces characterization

Tubular permanent magnet actuators are evermore used in demanding industrial and automotive applications. However, these actuators can suffer from large cogging forces, which have a destabilizing effect on the servo control system and compromise position and speed control accuracy. This paper focuses on the identification of the cogging forces by means of finite element software, where an approach is introduced within the 2D finite element analysis to model the linear tubular permanent magnet actuator compared to conventional axisymmetrical models. This gives that the contribution of the stator teeth and finite length of the ferromagnetic armature core to the total cogging force can be separately analyzed. The cogging force predictions is characterized and the effectiveness of the new method is verified comparing the results of the tubular structure in both the axisymmetrical model and 2D finite element model, normally used for rotary machines

Power from the people - Human-powered small-scale generation system for a sustainable dance club

Most Human-Powered Energy-Harvesting Systems are used to power ubiquitously deployed sensor networks and mobile electronics. These systems scavenge power from human activity or derive limited energy from ambient heat, light, or vibrations. In this article, systems that use human power by walking or running are analyzed, where an alternative system has been designed and implemented that generates energy from people dancing in a club environment

Optimization in Electromagnetics with the Space-Mapping Technique

Abstract: Purpose – Optimisation in electromagnetics, based on finite element models, is often very time-consuming. In this paper, we present the space-mapping (SM) technique which aims at speeding up such procedures by exploiting auxiliary models that are less accurate but much cheaper to compute. Design/methodology/approach – The key element in this technique is the SM function. Its purpose is to relate the two models. The SM function, combined with the low accuracy model, makes a surrogate model that can be optimised more efficiently. Findings – By two examples we show that the SM technique is effective. Further we show how the choice of the low accuracy model can influence the acceleration process. On one hand, taking into account more essential features of the problem helps speeding up the whole procedure. On the other hand, extremely simple auxiliary models can already yield a significant acceleration. Research limitations/implications – Obtaining the low accuracy model is not always straightforward. Some research could be done in this direction. The SM technique can also be applied iteratively, i.e. the auxiliary model is optimised aided by a coarser one. Thus, the generation of hierarchies of models seems to be a promising venue for the SM technique. Originality/value – Optimisation in electromagnetics, based on finite element models, is often very time-consuming. The results given show that the SM technique is effective for speeding up such procedures

Passive and active constant force-displacement characteristics and optimization of a long-stroke linear actuator

In applications such as vibration isolation, gravity compensation, pick and place machines, etc., the applicability of commercial low force passive devices is limited and hence would benefit from an improved and preferably variable force level. This paper presents and investigates such a long stroke constant-force versus displacement actuator topology, where analytical and equivalent circuit models are detailed and compared with comprehensive three dimensional (3D) finite element analyses. Furthermore, the optimization of such an actuator by means of aggressive output space mapping is considered. This technique employs a combination of a single analytical equation and a 3D finite element model. Specifically, the optimization is applied to obtain a passive and active force level of 200 N and 300 N, respectively, where the force- displacement response is constant over 60% to 90% of the total stroke

Small-scale urban Venturi wind turbine: Direct-drive generator

There is a growing interest for the use of small-scale wind turbines at buildings. In most situations the deployment of existing (small = 5kW) wind turbines will not be very successful due to the fact that they are not adapted to the complex wind environment. Several novel wind turbines have been developed to be able to extract a large amount of energy from these urban environments. This paper concerns a new horizontal Venturi wind turbine (2.0m diameter), which has a comparable power per rotor cross-sectional area in respect to various other wind turbines, due to its direct-drive generator. This direct-drive external rotor permanent magnet brushless generator system has been selected for this application due to its power density, where a total system efficiency of =80% has been achieved over a large speed range

Hybrid shipping for inland navigation : loss analysis of an aluminum direct-drive high performance 11,OOONm permanent magnet machine

Hybrid electric ship propulsions are becoming a leading/emerging area of research, prompting investigation in hybrid propulsion system design and demonstration of concept vessels. With respect to ship design and operation, minimizing costs associated with fuel consumption and maintenance are key objectives. As such, new, and existing, ships are subject to regulatory requirements, especially regarding emissions and energy efficiency. Hybrid electric propulsion is a promising approach in addressing these concerns. Particularly for inland vessels that require a high degree of manoeuvrability and are continuously travelling upstream and downstream. In this work, a Permanent Magnet propulsion motor with 350kW at 300rpm, hence around 11,000Nm, will be discussed. With this motor a quiet mode is available with reduced emission during electric cruising and dynamic positioning