Magnetics Business & Technology - Summer 2014 - (Page 24)

SOFTWARE & DESIGN Enhanced Simulator Predicts Eddy Current Effects To Model Accurate Electrical Performance Understanding eddy current effects is critical to improving the performance of many emergent electrical equipment applications, including high efficiency electric motors, generators and transformers. Cobham Technical Services has demonstrated that updates to its Opera-3d electromagnetics simulator now allow designers to model such transient effects more accurately. This fidelity of simulation gives Opera users a powerful means of exploring new design concepts and accurately predicting their impact, to bring new generations of highly optimized products to market, such as electric motors, generators, transformers, electromagnetic brakes and clutches. The finite element analysis tools of Opera-3d have been designed to model transient phenomena in electromagnetic systems. Features such as hexahedral mesh elements provide the fine resolution needed for accurately simulating the complex fields that are generated in regions where eddy currents are induced, while mesh layering improves the accuracy of capturing skin-effect in regions subject to high levels of eddy currents. Opera-3d software also incorporates an advanced time-transient solver, which employs a mix of fixed and adaptive time-stepping to ensure simulation accuracy of transient phenomena. The size of the step can be changed automatically during simulation to maintain the same level of accuracy throughout the simulation. At the start of simulation, when there are large initial transients, the solver uses short time-steps; then as the simulation progresses and the initial fast transients decrease, it progressively increases the step size until the transients have died down and the eddy currents are less significant, when it switches to a fixed duration step. Cobham has recently validated its simulation results using 'Problem 24', one of the Testing Electromagnetic Analysis Methods (TEAM) benchmarks that is endorsed by the International Compumag Society. This uses the simplified topology of a Switched Reluctance Motor (SRM), containing a single pair of rotor and stator teeth, with two stator coils. Unlike a real SRM, the stator and rotor are not laminated, allowing substantial eddy currents to be induced. The rotor is locked at a position of partial misalignment between the stator and rotor poles to increase the local saturation at the tip of the teeth, deliberately making it more difficult to predict and compute the field within the device. The physical device used for comparison purposes is driven by a step voltage applied to the series-connected stator windings. During the test, four key parameters are measured: winding current, flux in the rotor tooth, flux density in the airgap and output torque. The rotor flux is measured with a search coil and the airgap flux density with a Hall effect probe. The validation exercise was performed with and without electrical conductivity in the model, to evaluate the effect of eddy currents on simulation accuracy. When eddy currents are omitted from the analysis, the simulation results indicated that when a step voltage is applied, the rotor flux reaches its maximum at the same time as the drive current. However, this response is delayed by 0.08 seconds when eddy currents are included, because their flow opposes the change in flux linking the coil. This significant difference in transient response is most evident when looking at torque output, the effect of eddy currents delays the production of full torque by as much as 0.1 seconds. There is a high degree of correlation between the results produced by Opera-3d and the enhanced electromagnetic transient solver for the 'Problem 24' TEAM benchmark, and measurements 24 Magnetics Business & Technology * Summer 2014 from the physical device. During the first 0.08 seconds of the applied step voltage, the simulated rotor tooth flux, airgap flux density and torque output data are essentially the same as those obtained by measurement. After the initial transient, the error between the measured and simulated flux linkages is less than 2 percent. CST Studio Suite Version 2014 Released Computer Simulation Technology (CST) has released the 2014 version of the electromagnetic simulation tool, CST Studio Suite. The latest edition has been developed to improve the performance of the solvers and increase the capabilities for hybrid simulation without compromising on usability. CST Studio Suite comprises a range of electromagnetic simulation tools for high frequency, low frequency, charged particle and multiphysics applications, which are all available within a single graphical user interface. The tool is used by engineers and researchers around the world to design, simulate and optimize EM systems. Improving meshing was a major focus during the development of CST Studio Suite 2014, in order to make the mesh engines more efficient, more robust and more user-friendly. Both the hexahedral and tetrahedral mesh have been improved to reduce the cell count and help to discretize complex or low-quality CAD data. The simulation of complex systems has also been improved. Field source coupling and multiphysics simulations can be set up automatically using the new System Assembly and Modeling (SAM) wizards. SAM allows different solvers to be combined in a single simulation project and can be used to model complex systems one component at a time. CST Studio Suite fits into a wide range of CAD and EDA workflows through its import and export tools. These have been upgraded to support more file types and offer greater control of model quality. In addition, the 2014 release introduces version control. Imported CAD files can now be monitored by the software, with changes to the external data automatically reflected in the simulation model. Alongside these major changes, numerous smaller improvements have been made to both the front-end and back-end of the software in order to make modeling, simulation and results processing faster and more straightforward. "CST Studio Suite 2014 represents a significant step in the development of our EM simulation tools," said Bernhard Wagner, Managing Director, CST AG. "We have improved both the power and versatility of our solvers, and we hope that these new features help engineers and researchers in their daily work." Shipping of CST Studio Suite 2014 to existing users is expected to be completed by mid-April 2014. Submit industry news and new product press releases to Heather Williams at HeatherW@WebcomCommunications.com www.MagneticsMagazine.com http://www.MagneticsMagazine.com

Table of Contents for the Digital Edition of Magnetics Business & Technology - Summer 2014

Editor's Choice
Moving Beyond Helium in Magnetics Research
Advances in Ferrite-Integrated On-Chip Inductors Using Aerosol Deposition
A Fresh Look at Design of Buck and Boost Inductors for SMPS Converters
Research & Development
Handheld Three-Axis Magnetometers
Magnetics, Materials & Assemblies
Software & Design
Test & Measurement
Industry News
Marketplace / Advertising Index
Spontaneous Thoughts: A Different Paradigm

Magnetics Business & Technology - Summer 2014