Computation of AC losses in winding – Hybrid method

From now on, while running the test to characterize the behavior of machines, operating at a targeted “working point” by considering the “Accurate mode” of computation, there will be three options for computing or ignoring AC losses in winding:

None: AC losses are not computed. However, as the computation mode is “Accurate”, a transient computation is performed, but without representing the solid conductors (wires) inside the slots. Phases are modeled with coil regions. Thanks to that, the mesh density is lower with a lower number of nodes and a lower computation time.

FE-One phase: AC losses are computed on one phase. Only one phase is modeled with solid conductors. The two other ones are modeled with coil regions. One gets AC losses in winding, but with a lower computation time than if all the phases were modeled with solid conductors. However, this can have a little impact on the accuracy of results.

FE-All phase: AC losses are computed on all the phases. All the phases are modeled with solid conductors. This computation method gives the best results in terms of accuracy, but with a higher computation time

With the current version, a new method is available:

FE-Hybrid: AC losses in winding are computed without representing the wires (strands, solid conductors) inside the slots.

Since the location of each wire is accurately defined in the winding environment, sensors evaluate the evolution of the flux density close to each wire. Then, a postprocessing based on analytical approaches computes the resulting current density inside the conductors and the corresponding Joule losses.

The wire topology can be “Circular” or “Rectangular”.

There can be one or several wires in parallel (in hand) in a conductor (per turn).

This new method of computation is available for all the machines:

Synchronous Machines with Permanent magnets – Inner and outer rotor or Reluctance Synchronous Machines – Inner rotor, when running the test “Working point – Sine wave – Motor – I, Ψ, N” to characterize the behavior of the synchronous machines, operating at the targeted input values I, Ψ, N (Magnitude of current, Control angle, Speed).

Induction Machines with squirrel cage – Inner and Outer rotor, when running the test “Working point – Sine wave – Motor – U, f, N” to characterize the behavior of the induction machines, operating at the targeted input values U, f, N (Line-Line voltage, Power supply frequency, Speed).

This method leads to more accurate results with lower computation time. This is a good trade off between accuracy and computation time.