Edited by Leslie Gordon
As an engineer, I must often tailor designs for size, weight, power consumption, and other factors. My employer had been using a general-purpose electromagnetic- simulation package based on FEA techniques. We used the software in making custom permanent-magnet motors, as well as motors for consumer products such as hard-disk drives, power tools, and digital cameras. We also manufacture automotive sensors, and accessories such as seat-position motors.
But a downside to FEA is that building models can take a lot of time. And other analytic software for motor design does not provide enough accuracy and precision. So we tried Opera Electrical Machines Environment, an applicationspecific variant of a general-purpose electromagnetic FEA tool. It helps speed the building of models with ready-to-use templates for common motor types.
The software works by presenting a high-level frontend to an electromagnetic FE-based modeler, via dialog screens. Depending on the motor type and design variant users select, there are typically three dialog boxes. These define the geometry of the rotor, the stator, and allow the selection of construction materials as well as the FE mesh size. Each screen presents a number of boxes or drop-down menus for selection. For example, the rotordefinition box asks for parameters such as outer and inner radii. Once a user completes all screens and defines the excitation conditions in a few more dialog boxes, the model is ready for simulation. It used to take me about half a day to create an FEA model. The motorsimulation software lets users build a model in about 20 min.
The 2D version of the package works well for motor design. The software exploits the symmetry of a rotary motor to create a representative segment of a design and speed processing time. Of course, simulation times depend on the mesh size selected, but they usually take about 10 min to an hour on my desktop PC. This includes the postprocessing of results done according to specifications I enter.
The design cycle is not over with first results. Design optimization is critical for us because many applications target cost or performance for a given volume of space. The software lets users change parameter values manually to improve performance. An optional automatic goal seeker lets users set target values and lower and upper limits for variables. The software then determines the best fit. Finally, it exports the drawings so we can build a prototype.
The templates support the most common geometries used in rotating machinery. They are powered by a scripting language, so the code that creates models can be modified quite easily to create custom geometries. This lets users create templates that incorporate proprietary design features to optimize performance.
As with any software, there is always room for improvement. First, it would be helpful to include an “automatic reload of model data” feature that would make user-directed, interactive design explorations simpler. Also, the library should be expanded. Currently, there are only common types of permanentmagnet machines. Although the scripting language’s open format lets users modify the software to handle new configurations and make custom changes, it would be helpful if the developer added new variations as well. Another improvement (which I understand is in development) would be to extend the Environment to 3D structures as well. 3D effects can become important in short machines because end-region resistance and inductance play a significant role in predicting performance accurately.
— Sheth Nimitkumar Kiritkumar
Kiritkumar is an engineer at Magnequench, Singapore, magnequench.com