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Electromagnetic design software speeds system development

Cobham Technical Services’ Opera electromagnetic design software is aiding in the development of a contactless distributed power supply system for modular automation components, by a team lead by Hans-Peter Schmidt at The University of Applied Sciences in Amberg, Germany.

The contactless power system is being developed by the university’s Faculty of Electrical Engineering and Information Technology under a publicly funded research programme, and is about to move from design concept to prototype evaluation. During this process the software was used to evaluate the coupling efficiency of different system layouts, perform basic field measurements and assess the effect of various types of magnetic shielding on eddy currents.

Principally intended for industrial control and instrumentation applications, where it will be used for powering and communicating with remote I/O sensors and actuators, the system uses magnetic induction to facilitate the transfer of power and data between an input coupling device and a number of physically separate devices distributed along the length of a ‘backbone’.

It essentially comprises a ferrite backbone with an E-shape cross-sectional geometry and a coil wound around its central pillar – which can easily be incorporated in an industry-standard DIN rail – together with a power input coupling device and a number of pick-up modules, all incorporating wound E-shape ferrite cores that can be positioned anywhere along the length of the backbone.

Two types of contactless power system are presently being investigated. One places the ferrite backbone in an aluminium DIN rail; the other is essentially free-standing. The basic electrical test setup involves a variable waveform generator, power amplifier, current transducer, wideband oscilloscope and power meter. Considerable effort has gone into determining the optimum air gap, excitation voltage and frequency, and in assessing the effect of various conducting backplane materials, such as µ-metal foil, to suppress eddy currents.

Currently, the system is capable of achieving up to 90 per cent power transfer efficiency with ten pick-up modules, each demanding between one and two Watts, and data transfer rates of up to two Mbps. It is envisaged that these performance figures will increase by at least an order of magnitude as the project progresses over the next year.

Commenting that the nature of the contactless power system makes it a very interesting simulation subject, Chris Riley, technology manager for Cobham Technical Services, said: ‘I don’t know of anyone else using Opera for this type of research, and it is very pleasing to see such a close correlation between predicted and measured results – many of the basic air gap measurements, for example, agree to within two per cent, which is an excellent figure.’


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