The construction and simulation of a permanent magnet DC motor using CST EM STUDIO™ (CST EMS) is demonstrated. CST EMS offers an extremely user-friendly interface with powerful CAD and parameterization features. Non-linear materials are taken into account in the magnetostatic simulations. Figure 1 shows the components of the motor which were all constructed in CST EMS. A Visual Basic for Applications (VBA) macro was developed to allow any rotor configuration to be automatically generated based on standard design parameters.
The stator iron was a hollow cylinder, a primitive shape in CST EMS with the non-linear iron material characteristics. The permanent magnets are segments of radially magnetized ferrites. The rotor is also based on a cylinder primitive which has the shaft and slots cut away. The double-layer winding was created as a 3D polygon for which the coordinates were provided as a text file. The commutator does not have to be modeled. Different current distributions are correctly taken into account by rotating the rotor. The complete geometry is shown in Figure 2....
Two typical modes of operation can be modeled:
Figure 3 shows the tetrahedral mesh used for the simulation.
Figure 4 shows the flux density in both contour and vector forms on a user-defined cut-plane for the load operation case. Other quantities may be derived from the magnetic field quantities via post-processing templates in conjunction with parameterization.
Features which are an extremely powerful aid for the setup and simulation of permanent magnet motors include: