IM-SQ

Case without thermal solving mode

The first option of thermal setting is to run the test with only electromagnetic computation without any thermal analysis.

This option is the default one available for all the tests.

In this case, one must define the temperatures of active components to update the corresponding material physical properties.

For Induction Machines with Squirrel cage, stator winding and squirrel cage temperatures must be defined.

Temperature of stator winding

The resulting resistance for the whole winding (considering the three parts described above) is computed as phase resistance and line-line resistance.

Temperature of the squirrel cage

Case without thermal solving mode

Below is the flow chart of computation, for tests without thermal solving mode, available for all the tests.

Table 1. Flow chart of the tests without thermal solving mode

1	Default mode of thermal setting for all the tests without thermal analysis
2	Thermal settings for the tests which have a thermal analysis are available

Case with thermal solving mode

The choice of thermal solving mode is available for the test dealing with the computation of working point defined by the line-line voltage, power supply frequency and speed. These solving modes involve interactions between electromagnetic and thermal computations.

Two scenarios are available: one with iterative process between electromagnetic and thermal computations until convergence, and the other one with only one iteration between electromagnetic and thermal computations.

1. Thermal settings to initialize the test

   For both scenarios, here is the list of thermal settings needed to initialize the test.

   Table 2. Thermal settings to initialize the test

   1	Dialog box to define thermal settings. Iterative solving mode is selecting
   2	Initial temperatures of the machine active components (Stator winding and squirrel cage) are automatically defined and equal to the external fluid temperature. These temperatures are used to initialize the electromagnetic-thermal process of computation.
   3	Definition of coolant temperatures to be considered: External fluid temperature (1) Cooling circuit fluid temperature (2)

   Note: (1) The external fluid temperature corresponds to the temperature of the fluid surrounding the machine. It is also considered as the temperature at the “infinite” for the computation of radiation from the frame to the infinite.
   Note: (2) The cooling circuit fluid inlet temperature is proposed only when a cooling circuit has been added by the user in the design environment.
2. Flow chart of thermal solving mode – Iterative process
   1. Flow chart for the thermal model solving test with iterative process is given below.

      Table 3. Flow chart for the thermal model solving test with iterative process

      0	Definition of the initial temperatures (see the list in the previous section) and working point inputs
      1	1st electromagnetic solving (Finite Element computation) with initial temperature defined in the thermal settings Losses are computed.
      2	Based on losses and speed defined by the electromagnetic working point, The thermal characterization is performed to define the temperature distribution inside the machine. The materials physical properties corresponding to the machine active components are then updated.
      3	Iterative process = loop between electromagnetic and thermal computations until the convergence on the temperature is reached (See below where can be adjusted the convergence criteria when needed)
      4	A last electromagnetic solving (Finite Element computation) with final set of temperatures is performed once the convergence on the temperature is reached (1). Electromagnetic performance and chart of temperatures are computed and displayed. The test outputs are illustrated in the sections dedicated to the considered tests.

      Note: (1) The temperatures which are considered for computed the final machine performance (step 4 in the previous flow chart) can be read in the table dealing with “Winding and Squirrel cage characteristics” of the test configuration at the beginning of result report. The same principle is applied for the squirrel cage temperature.The temperatures are also displayed in the temperature chart and table after electromagnetic results.
   2. Thermal characterization in steady state – Flow chart

      This section illustrates how the thermal characterization is performed to define the temperature distribution inside the machine from a set of losses and a working point speed

      This process corresponds to what is performed to make the thermal characterization of the machine in the test Characterization / Thermal / Steady state

      It corresponds to the second step of the previous general flow chart.

      
      

      

      
      

      The inputs of the internal process are the parameters of: Geometry, Winding, Internal cooling, External cooling, Materials, Test settings and inputs.

      Note: A 2D Finite Element model is solved to identify a thermal network which corresponds accurately to any kind of rotor or stator parts, including user parts.

      Then, the resulting network is extended with analytical computations to consider the 3D effect of the geometry.

      The solving allows to get and to display the whole chart of temperatures of the machines.

   3. Iterative process – Adjustment of the convergence criteria

      Table 4. Iterative process – Adjustment of the convergence criteria

      1	Selection of the thermal solving Iterative process in thermal settings
      2	Convergence criteria can be adjusted for reaching steady state behavior. The iterative solving is stopped once the temperature variation in the machine between two iterations is lower than the convergence criteria. A percentage close to zero gives more accurate results but takes a higher computation time. A high percentage can make the convergence shorter but decreases the accuracy of the results.

Limitation - Advice for use

Please refer to Advice for use.