Unlisted Slot Shapes
The tremendous amount of experimental and theoretical work that Cyril Veinott did, years ago, resulted in practical and accurate leakage reactance equations for may types of motor slot shapes. This knowledge was merged into the Vica software so that a designer can
“pick and choose” from a variety of rotor slots and stator slots and thereby have an accurate Fortran representation of the important slot leakage reactances that partially determine the performance of a motor. This makes the Vica software superfast compared to using finite element methods.
Of course, he included commonly used shapes and this usually suffices for a designer, but we know that there are shapes out there that do not exactly match one of the available slot diagrams. To get the leakage reactances in those cases, we either
1 use an approximately matched shape, or
2 we use finite element magnetostatic analysis, or
3 we divide the shape into horizontal strips and do an approximate calculation based on the magnetic reluctance of each strip, or
4 seek some other approximation
At 123cad.net we can analyze your special slot shape to get parameters of equations for leakage reactance that you can put into the enhanced version of Vica30, right on the worksheet along with any other custom user equations for losses, temperature rises, optimizing, and so on. These reactance equations will replace the slot leakage equations that are standard. These equations for self leakage reactance and, if a double cage, mutual reactance between top and bottom cages. The equations will contain variables for the slot dimensions as well so that you can optimize your design to the best dimensions.
Does accuracy suffer with this approach, compared to all the fancy finite element based motor packages out there? It is debatable, especially considering “Is it accurate enough?” Ease of use is as important as computer running time, and using Vica30 certainly is easier than the finite element based packages, and much lower priced as well.