The thesis describes iron core model of a resistance spot welding transformer. The proposed model considers eddy currents, hysteresis, and the saturation effect of a magnetic field in a laminated iron core. The model is based on the presumption that the domain magnetic structure of the grain oriented electrical steel sheet can be neglected and modelled with the classical model, which presume homogeneous magnetic structure of the steel sheet. In order to consider the influence of the eddy currents on the magneticfield in the iron core, the cross-section of lamellas is divided into slices so that the presumption of the homogeneous magnetic field in the virtual slice is adequately fulfilled. From Amperes law and Faraday's Law of induction, the equation of magnetic field for each slice in the lamella is obtained. Hysteresis properties of the magnetic steel sheet in the equation ofmagnetic field are modelled by simple scalar hysteresis model. Iron core losses are calculated by separation losses into hysteresis losses and eddy current losses. Since the iron core model proposed in this work considers the influence of eddy currents on the distribution of the magnetic flux density, the excess losses are neglected. A good agreement of calculated and measured results confirms that excess losses can be ignored in this case. The proposed iron core model of the resistance spot welding transformer is simple, computationally effective, and based on parameters that can be easily obtained from data sheet. Since the iron core model is easy to integrate into the circuit model of the transformer, it is applicable for the design of control algorithms as well as a rough optimisation of blade thickness, air gap width, and the dimensions of the transformer's core.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 261784576The principal investigator and members of the research project group have actively participated in the programme, editorial and organising committee of the professional conference »SPOT 2012 – Innovative Electric Energy Converters«, which was held at the 13th and 14th June, 2012 in Nova Gorica. All partners of the applied research project have been included in the organisation of the conference, TECES as the main organiser and UM-FERI with others as co-organisers. The purpose of the conference was to provide an insight into the Slovenian electrical industry in the field of electric energy converters, to identify development challenges of the Slovenian economy and strengthen mutual development cooperation of companies and research organisations in order to make Slovenian products competitive in the rapidly changing field of electric energy converters. The event attracted 157 participants. More information is available at the website http://spot-2012.teces.si
F.35 Other
A device for monitoring of a welding transformer has been developed in the scope of the project. The device is mounted on welding transformer. Its main goal is the recording of welding transformer critical operational parameters. Based on the recorded data, it is possible to monitor operating conditions of the transformer and changes of parameters due to the aging. The recorded data help to find reasons for failures in cases of defects. The monitoring of transformer’s operational parameters is one of the key points which can help to find weaknesses in transformer’s design and to improve the design of new transformers. The device for monitoring of welding transformers is a completely new product which could fill the market niche. The device prototype already passed all laboratory tests. Technical documentation has been submitted to the company Bosch with the goal to protect the invention by patent. The patent application is being prepared.
F.06 Development of a new product