3D electromagnetic design tool for rotating electrical machines

Paul Boughton

Cobham Technical Services (previously Vector Fields) is launching a 3D version of its electromagnetic design tool for rotating electrical machines - the Advanced Machines Environment. This new software combines the extreme accuracy of finite-element analysis (FEA) simulation with a design entry system that creates full 3D models of electric motors or generators within minutes. The software is an application-specific toolbox of the well-known Opera electromagnetic simulator and is said to enable users to achieve new levels of design productivity and performance.
FEA techniques simulate design concepts with supreme precision and accuracy, but it can take many hours to build a 3D model of a complex product such as a motor. The 3D Advanced Machines Environment provides a front-end to the electromagnetic simulator that speeds design entry by means of dialog boxes. Users select the form of motor or generator they want to design from a list of all common types and variants. By simply entering a list of around 10 parameters to define the mechanical geometry, material properties and electrical data, the 3D models are then created automatically. The complete design entry process can easily be performed in less than five minutes.
The 3D Advanced Machines Environment enables users to create design concepts rapidly and then simulate them with high accuracy. It can deliver significant advantages in today's market, providing a virtual prototyping tool that enables 'what-if?' investigations to be performed very efficiently.
Cobham Technical Services has been offering this software tool in a 2D form for several years, and the package has become a popular rapid design aid for motor and generator manufacturers. 2D representation can be satisfactory for many types of rotating machines because of their mechanical symmetry. However, the magnetic flux paths at the each end of a typical cylindrical motor or generator shape are slightly different to a central cross-section, and the mechanical features of some types of rotating machine can vary along their length. The extension to 3D enables developers to model entire machines, providing a comprehensive simulation that takes even marginal factors such as end winding effects and fringe effects into account.
The 3D Advanced Machines Environment comes with design templates for common rotating machinery including motor types such as AC induction, brushless, permanent magnet and switched reluctance, plus synchronous motors or generators. The new 3D version also introduces support for the fast-growing axial flux electrical machine sector - which employs a geometry that cannot be represented in 2D. Users can additionally select numerous design variants for different machine types, such as a choice of rotor styles.
If there are any unusual features that need to be incorporated into designs, users also have open access to the scripting codes that generate the models and can modify them at will to create a proprietary automated design process. A library of material properties is also included in the design software for speed, and is selected by means of a drop-down menu. Again, if users employ any special material, such as an unusual grade of steel for laminations, then a new material characteristic can be created easily and imported into the model.
The 3D Advanced Machines Environment also provides users with post-processing capabilities to simplify the analysis of results. Some commonly required manipulations of the simulation data are provided as standard, including the torque produced as a function of position. Design ideas can be trialled and optimised easily by varying the values of model parameters. Alternatively, Cobham can provide the software with a sophisticated optimisation tool. The latter option provides an intelligent approach to optimisation that will automatically select and manage multiple goal-seeking algorithms to find the best solution to a design problem.
One of the advantages of using Opera software for motor and generator design is the ability to simulate the complete drive including loads. Users have complete freedom to define the coupling to loads, including friction, load and speed dependent torques. In addition, the motor windings can be connected to a user-defined power converter comprising a voltage or current supply, switches, diodes and passive components. More complex electrical and mechanical systems can also be considered by coupling Opera electromagnetic models of motors and generators within a Simulink environment.
For more information, visit www.cobham.com/technicalservices

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