Inputs

Introduction

The total number of user inputs is equal to 10.

Among these inputs, 4 are standard inputs and 6 are advanced inputs.

Operating quadrants

It defines the quadrants in the Jd-Jq plane, where the test will be carried out. By default, the only considered quadrant is the 2nd one (i.e., the grid is only defined for negative values of the current in the d axis and positive ones in the q axis). This corresponds to the motor behavior of the machine.

Options allow computing and displaying 1, 2 or 4 quadrants.

Note: Export / System LUT (Activate or PSIM) has been updated for exporting data based on 1, 2 or 4 quadrants

Among the standard inputs, the operating quadrants can be selected.

This allows defining the quadrants in the Jd-Jq plane, where the test will be carried out.

By default, the only considered quadrant is the 2nd one (i.e., the grid is only defined for negative values of the current in the d axis and positive ones in the q axis). This corresponds to the motor behavior of the machine.

The other possible values for this input are: “2nd and 3rd “, “1st and 2nd “and “all”.

Standard inputs

Current definition mode

There are 2 common ways to define the electrical current.

Electrical current can be defined by the current density in electric conductors.

In this case, the current definition mode should be « Density ».

Electrical current can be defined directly by indicating the value of the line current (the RMS value is required).

In this case, the current definition mode should be « Current ».

Maximum line current, rms

When the choice of current definition mode is “ Current ”, the maximum rms value of the line current supplied to the machine “ Max. line current, rms” ( Maximum line current, rms value ) must be provided.

Note: The number of parallel paths and the winding connections are automatically considered in the results.

Maximum current density, rms

When the choice of current definition mode is “ Density ”, the maximum rms value of the current density in electric conductors “ Max. current dens., rms” ( Maximum current density in conductors, rms value ) must be provided.

Note: The number of parallel paths and the winding connection are automatically considered in the results.

Maximum speed

The analysis of test results is performed over a given speed range, to evaluate losses as a function of speed like iron losses, mechanical losses and total losses.

The speed range is fixed between 0 and the maximum speed to be considered « Maximum speed » ( Maximum speed ).

Rotor position dependency

It defines the rotor position dependency, where the test will be carried out. By default, the rotor position dependency is set to “No” but it can be set to “Yes”. In this case the computation will be done in the Jd - Jq plane with an additional third axis corresponding to the rotor position θr.

Note: In case the rotor dependency is set to “Yes”, whatever the operating quadrant choice, the finite element computation is done over all selected quadrants (in case the rotor dependency is set to “No”, symmetries are used).

Note: Export / System LUT (Activate or PSIM) has been updated for exporting data based on the rotor position

Advanced inputs

Number of computed electrical periods

The user input “No. computed elec. periods” (Number of computed electrical periods only required with rotor position dependency set to “Yes”) influences the computation time of the results.

The default value is equal to 0.5. The maximum allowed value is 1 according to the fact that computation is done to characterize steady state behavior based on magnetostatic finite element computation. The default value provides a good compromise between the accuracy of results and computation time.

Number of points per electrical period

The user input “No. points / electrical period” (Number of computed electrical periods only required with rotor position dependency set to “Yes”) influences the accuracy of results (computation of the peak-peak ripple torque, iron losses…) and the computation time.

The default value is equal to 40. The minimum recommended value is 20. The default value provides a good balance between the accuracy of results and the computation time.

Number of computations for D-axis and Q-axis phase currents

To get maps in the J _d -J _q plan, a grid is defined. The number of computation points along the d-axis and q-axis can be Jd defined with the user input « No. comp. for current J_d , J_q » (Number of computations for D-axis and Q-axis phase currents) .

The default value is equal to 10. This default value provides a good compromise between the accuracy of results and computation time. The minimum allowed value is 5.

Number of computations for speed

The number of computation for speed corresponds to the number of points to consider in the range of speed. It can be defined via the user input “ No. comp. for speed” (Number of computations for speed) .

The default value is equal to 10. The minimum allowed value is 5.

Rotor initial position mode

The computations are performed by considering a relative angular position between rotor and stator.

This relative angular position corresponds to the angular distance between the direct axis of the rotor north pole and the axis of the stator phase 1 (reference phase).

According to the input “ Rotor initial position mode ”, the angular position can be defined either automatically using an internal computation process « Auto » (Automatic) or specified by the user « User ».

By default, the “ Rotor initial position mode ” is set to “ Auto ”.

Rotor initial position

When the “ Rotor initial position mode ” is set to “ AUTO ”, the initial position of the rotor is automatically defined by an internal computation process.

The resulting relative angular position corresponds to the alignment between the first stator phase axis (reference phase) and the direct axis of the rotor north pole.

When the “ Rotor initial position mode ” is set to “ USER ”, the initial position of the rotor taken into account for computation must be set by the user in the field « Rotor initial position ». The default value is equal to 0. The range of possible values is [-360, 360].

For more details, please refer to the section dedicated to the rotor and stator phase relative position.

Skew model – Number of layers

When the rotor magnets or the stator slots are skewed, the number of layers used in Flux Skew environment to model the machine can be modified: “ Skew model - No. of layers” ( Number of layers for modelling the skewing in Flux Skew environment ).

Note: When there is magnet step skew topology, the number of layers is defined at the design level.

Mesh order

To get results, Finite Element Modelling computations are performed (Flux software).

The geometry of the machine is meshed.

Two levels of meshing can be considered: First order and second order.

This parameter influences the accuracy of results and the computation time.

The default level is second order mesh.

Airgap mesh coefficient

The advanced user input “ Airgap mesh coefficient ” is a coefficient which adjusts the size of mesh elements inside the airgap.

When the value of “Airgap mesh coefficient” decreases, the mesh elements get smaller, leading to a higher mesh density inside the airgap, increasing the computation accuracy.

The imposed Mesh Point (size of mesh elements touching points of the geometry), inside the Flux software, is described as:

MeshPoint = (airgap) x (airgap mesh coefficient)

Airgap mesh coefficient is set to 1.5 by default.

The variation range of values for this parameter is [0.05; 2].

0.05 giving a very high mesh density and 2 giving a very coarse mesh density.

CAUTION: Be aware, a very high mesh density does not always mean a better result quality.

However, this always leads to a huge number of nodes in the corresponding finite element model.

So, it means a need of huge numerical memory and increases the computation time considerably.