Analytical Methodology for Modelling of Circulating Current Loss in Synchronous Electrical Machines with Permanent Magnets

This paper describes a novel analytical methodology for modelling winding copper losses as a result of circulating currents (CC) in permanent magnet synchronous machines (PMSM). Nowadays mainly FEM method is used for precise calculation of circulating currents. However, it suffers on significant computational time required for building models and simulation of circulating current effect that makes it inapplicable for optimization purpose. The paper demonstrates the computationally efficient methodology through comparison with FEM based models for high power density PMSM with concentrated winding and validation against experimental results for a stator section at the fundamental frequency from 500 Hz to 2000 Hz. The methodology allows simulation of CC and AC Ohmic losses when machine supplied by any current waveforms, for arbitrary size and location of the conductors in the slots. A key novelty of the proposed method is the utilization of subdomain (SDM) approach in conjunction with solution of a system of ordinary differential equations (ODE) for an equivalent electrical circuit of machine windings. This approach is precise and fast but has never been used before for circulating current loss evaluation in windings of electrical machine

9th International Conference on Energy Efficiency in Motor Driven Systems

The 9th International Conference on Energy Efficiency in Motor Driven Systems (EEMODS'15) was be held in Helsinki (Finland) on 15-17 September, 2015. The EEMODS'15 conferences have been very successful in attracting distinguished and international presenters and attendees. The wide variety of stakeholders has included professionals involved in manufacturing, marketing, and promotion of energy efficient motors and motor driven systems and representatives from research labs, academia, and public policy. EEMODS’15 provided a forum to discuss and debate the latest developments in the impacts of electrical motor systems (advanced motors and drives, compressors, pumps, and fans) on energy and the environment, the policies and programmes adopted and planned, and the technical and commercial advances made in the dissemination and penetration of energy-efficient motor systems. In addition EEMODS covered also energy management in organizations, international harmonization of test method and financing of energy efficiency in motor systems. The Book of Proceedings contains the peer reviewed paper that have been presented at the conference.JRC.F.7-Renewables and Energy Efficienc

Partial discharge measurements in high voltage motors.

The work presented in this thesis is concerned with the development of an on-line technique for detecting and locating partial discharges in the stator winding of a high voltage electrical machine. This technique forms part of an on-line health monitoring strategy for the insulation of high voltage machines. Existing diagnostic techniques and partial discharge measurement systems are reviewed. The requirement for an on-line partial discharge location technique is discussed. An experimental investigation was carried out into the propagation characteristics of partial discharge pulses within a model stator winding. This allowed identification of the main propagation characteristics which were used as the basis for the development of a partial discharge location technique. In the development of a location technique, a means of on-line detection of discharge signals at the motor terminals is required. A study was therefore made on the use of the Rogowski coil for the non-invasive measurement of partial discharges. A partial discharge location system was developed based on the correlation of partial discharge pulses detected at the two ends of a motor phase winding. The performance of the location system was investigated by injecting artificially generated discharge pulses into the model stator winding. Further verification of the ability of the technique to locate the position of discharges was done by injecting high voltage discharges. The final part of the research work was to develop a theoretical model to predict the propagation behaviour of partial discharge pulses in the stator winding of an electrical machine . The effect of electromagnetic propagation through the endwinding region is incorporated in the model of two adjacent coils in a winding

HASTECS: Hybrid Aircraft: reSearch on Thermal and Electric Components and Systems

In 2019, transportation was the fastest growing sector, contributing to environmental degradation. Finding sustainable solutions that pollute less is a key element in solving this problem, particularly for the aviation sector, which accounts for around 2-3% of global CO2 emissions. With the advent of Covid-19, air traffic seems to have come to a fairly permanent halt, but this pandemic reinforces the need to move towards a "cleaner sky" and respect for the environment, which is the objective of the Clean Sky2 program (H2020 EU), the context in which the HASTECS project has been launched in September 2016

Proceedings of the 8th International Conference EEMODS'2013 Energy Efficiency in Motor Driven Systems

This book contains the papers presented at the eighth international conference on Energy Efficiency in Motor Driven Systems EEMODS 2013 EEMODS 2013 was organised in Rio de Janeiro, Brasil from 28 to 30 October 2013. This major international conference, which was previously been staged in Lisbon (1996), London (1999), Treviso (2002), Heidelberg (2005), Beijing (2007), Nantes (2009) and Washington DC (2011) has been very successful in attracting an international and distinguished audience, representing a wide variety of stakeholders in policy implementation and development, manufacturing and promotion of energy-efficient motor systems, including key policy makers, equipment manufacturers, academia and end-users. Potential readers who may benefit from this book include researchers, engineers, policymakers, energy agencies, electric utilities, and all those who can influence the design, selection, application, and operation of electrical motor driven systems.JRC.F.7-Renewables and Energy Efficienc

Duality derived topological model of single phase four limb transformers for GIC and DC bias studies

Geomagnetic disturbances brought about by solar activity cause geo-electric fields in the Earth that drive geomagnetically induced currents through the earthed neutrals of transformers and through power transmission networks. The flow of these currents causes the magnetic cores of transformers to half-wave saturate. Saturated transformers pose problems for power system operators since they can cause harmonics, transformer heating, mal-operation of protection relays, generator heating and vibration, and consume a large reactive power that can cause voltage collapse. Network studies of slow transient phenomena such as transformer half-wave saturation require appropriate models with parameters that represent the transformer transient state aptly. In this thesis a novel duality derived reversible model is developed of a single phase four limb transformer. The test transformers' non-step lap butt type core joints are shown to be problematic and the model is developed further to include the core joints. Due to the irregular core stacking method joint parameter determination is at best an approximation and the model is reduced to a duality compliant equivalent pi model for accuracy reasons. The pi model parameters and saturation characteristics are determined through laboratory testing and a complete pi model is presented. An understanding of a single phase transformer's physical behavior to slow transients is undertaken through the use of appropriately developed test circuits. Search coils are used extensively to understand the transformer core's behaviour through flux mapping of the core and stray flux in the surrounding air space when the transformer saturates. Three phase testing is included using a three phase bank of test transformers. The electrical measurements of waveforms are analysed and fast Fourier transforms carried out to obtain the harmonic components. The effect on a motor load of the distortion caused by transformer half-wave saturation is determined. A novel method of determining the effective core joint area of the problematic non-step lap butt type core joints is developed and a joint utilization factor is proposed that can be used in the absence of transformer manufacturer design information about this joint type in other transformer models

Energy: A continuing bibliography with indexes, issue 19

A bibliographical list of 1339 reports, articles, and other documents introduced into the NASA scientific and technical information system from July 1, 1978 through September 30, 1978 are presented