Computation of a Working Point (P/Sn, Pf, U, N)

Positioning and objective

The aim of the test “Working point – Sine wave – Motor & Generator – P, Pf, U, N” is to characterize the behavior of the machine when operating at the working point that is targeted by the user. This point is defined by:
  • The output power that can be either the electrical power transmitted to the stator winding if the machine is in generator operation, or the mechanical power exerted on the shaft if the machine is in motor operation. If the generator operation is targeted, the output power can be replaced by the apparent power.
  • The power factor,
  • The line-line voltage,
  • The rotating speed.

Through this test, the user can also verify whether the desired operating point is compatible with the machine. Additionally, the user can identify the appropriate reference values for the field current and the control angle needed to achieve this operating point.



“Working point – Sine wave – Motor – P, Pf, U, N” illustration

The results of this test give an overview of the electromagnetic analysis of the machine, considering its topology.

The general data of the machine, like the machine constant and power balance, are computed and displayed. The user can choose between motor and generator conventions to build the model.

The magnetic flux density is also computed in every region of the machine’s magnetic circuit to evaluate the design.

It also gives the capability to make comparisons between the results obtained from the measurements and those obtained with Altair® FluxMotor®.
Note: This feature is available in a "Beta version" meaning that it is not entirely qualified, and that the user must be careful when analyzing the results.
Note: The motor convention and motor operating mode are not available yet in the 2024.1 version of FluxMotor.

Input and output data

User inputs

The four main user input parameters are output power / apparent power, power factor lead/lag, speed and line-line voltage. In addition, the temperatures of the windings must be set.

Main outputs and results

Test results are illustrated with data, graphs, and tables.
  • Machine performance – Base speed point
    • General data
    • Machine constants
    • Power balance
    • Flux in airgap
    • Flux density in iron
  • Ripple mechanical torque
    • Working point

Curves and graphics

  • Ripple mechanical torque versus rotor angular position
  • Flux density in airgap versus rotor angular position
  • Flux density isovalues

Main principles of computation

Introduction

The aim of this test in motor / generator convention is to give a good overview of the electromagnetic potential of the machine by characterizing the working point according to the output power / apparent power, power factor, speed and voltage set by the user.

In addition, ripple torque at the working point is also computed.

To achieve such an objective, in the back end of FluxMotor, an automatic search is performed to identify the line current I, the field current IF and the control angle ψ providing the performance defined by the user.
Note: As the motor convention and motor operating mode are not yet available in the 2024.1 version of FluxMotor. From this point on, only the computing principle of the generator convention and generator operating mode are described.

In the generator operating mode, the line current can be deduced directly from the user input (output power / apparent power, power factor and line-line voltage). The research zone comprises thus two dimensions: field current and control angle. It is defined by the maximum field current, the number of computations along the field current axis and the control angle axis, all of which can be adjusted by the user in the inputs of the test.
Research zone of the P-Pf-U-N for the generator operating mode defined by maximum field current and number of computations along the field current axis and control angle axis

Within the research zone, the If-I-Psi-N test will be executed at all points (IF, ψ) to determine the performance response surfaces of the machine. Then an optimizer is used to search for the point (IF, ψ), providing the match with the targeted performance.
Performance of the machine in generator operating mode within the research zone in terms of voltage, active power and reactive power and the point (IF, ψ) providing the targeted performance

For more information, please refer to the user help guides.