Opera electromagnetic simulator gains hysteresis solver

Improving the energy conversion efficiency of electric motors and related products is possibly the most important design focus for today's electrical machinery suppliers, and hysteresis effects are typically responsible for the majority of the inefficiencies that remain to be overcome.

The modelling of hysteresis effects in soft magnetic materials is a very complex problem that electromagnetic tool suppliers have largely ignored, with the result that machine designers are forced to neglect small remanent magnetic fields that are created by the pulsing or rotating actions of dynamic machinery. If hysteresis effects are considered, it is usually done by means of some post-processing prediction based on a simplistic model. Such approaches can be highly inaccurate, especially when non-sinusoidal excitation is used, and when there are pronounced non-linear effects involved - such as detent torque.

In the drive towards higher efficiencies, many machine designers are employing more efficient ferromagnetic alloy materials for laminations. Vector Fields' new hysteresis solver tool provides the means for designers to simulate accurately the dynamic performance of these materials. In conjunction with the sophisticated design-simulate-optimise capability offered by the finite element analysis tool, this provides developers with the means to fully understand the improvements that electrical steels can make, as well as to explore mechanical design ideas that minimise hysteresis effects.

Applications

The hysteresis solver is available as part of the general-purpose Opera simulation toolsuite for static and transient electromagnetic design, or in Vector Fields' application-specific tool for motor and generator design - Opera Electrical Machines Environment. Among the product sectors that can be enhanced using the tool are dynamic electrical machinery such as motors and generators, as well as actuators and transformers.

Opera's new capabilities are also expected to appeal to the specialist segment of the motor market, which manufactures hysteresis motors and brakes. The lack of commercial finite element-based hysteresis simulation tools means that developers of equipment that relies strongly on hysteretic effects have typically depended on less accurate analytic design techniques. The finite element analysis Opera system with the improved hysteresis solver now offers such companies access to an automated design platform that can not only optimise the efficiency of existing designs, but also radically expand the range of design ideas that can be easily explored.

Vector Fields' new hysteresis solver is based on actual measured BH (magnetic induction and applied field) characteristics. The turning points of the B(H) trajectory are used to predict the behaviour of arbitrary minor hysteresis loops, providing a good approximation of true physical behaviour without requiring extensive computation and additionally making only realistic demands for materials data. The tool is provided with ready-to-use characteristics for some common silicon steel materials. This library can be expanded easily, using data from a manufacturer's datasheet, or by real-world measurement using an Epstein Frame (the standardised device for measuring the magnetic properties of electrical steels).

The new hysteresis solver complements Vector Fields' DEMAG electromagnetic modelling software for simulating the characteristics of permanent or hard magnet materials. This solver helps designers to optimise equipment designs by accurately simulating both the magnetisation process and the subsequent demagnetisation effects that might be encountered.

For more information go to www.vectorfields.com/opera.php.