# Step-Skewed modeling of electrical machines

## Overview

- a reduced cogging torque,
- diminished vibration and noise and
- reduced harmonic distortion in the induced electromotive forces of its windings

- A
**Simple (homogenous layers)**approach allowing the easy parametrization of the layers length, the rotation angle between adjacent layers and the number of layers. - An
**Advanced (layer by layer)**method allowing the description of more complex topologies (V, W or zig-zag skewing, for instance) with a parametrization of the layers length and of the layer rotation angle on each layer.

## Example of application

This example considers the modeling of a step-skewed permanent magnet synchronous machine (PMSM), both in Flux Skew and in Flux 3D.

To compare these modules and the results yielded by them, a three-phase, eight-pole PMSM is considered. Its three-phase winding is distributed between several stator slots, with one phase per slot. Moreover, its rotor (which contains the magnets) is step-skewed: its permanent magnets are distributed into three skewed layers along the axial direction. Each layer has an axial length equal to 125 mm, and the rotation angle between them is 10°.

A simulation representing the same PMSM with step-skewed rotor has been performed in Flux 3D as well.

This behavior is not really surprising, since the Flux 3D project takes into account the flux leakage at the extremities of the machine. This effect is not taken into account in Flux Skew, since it solves a series of linked 2D finite element problems instead.

Flux Skew | Flux 3D | |
---|---|---|

Mesh generation time | 30 seconds | 1 hour |

Solving time | 25 minutes | 11 hours |

It follows from this example that Flux Skew provides results that are in overall good agreement with Flux 3D. This is achieved with a simplified project description and shortened computation times. Even so, the user should always keep in mind the underlying approximations in a Flux Skew simulation, notably while post-processing the results or when comparing them with Flux 3D or with the real device.