9. File exports

9.1. GT-ISE loss map and circuit simulation files

GT-PowerForge offers functionalities with GT-ISE, the Integrated Simulation Environment of GT-Suite.

9.1.1. Loss map

Loss map refers to the converter losses generated in the performance analysis space.

All the loss maps are a function of the imposed temperature (cold source, sink, case or junction), depending on the selected variant in the performance map inputs.

In addition, depending on the converter topology, electrical independent variables are listed below:

• DCConverterPowerForge

  • Non-isolated DC/DC: U_HV, U_LV and I_LV

  • Isolated DC/DC: U_DC Primary , U_DC Secondary and I_DC Secondary

• InverterPowerForge

  • 3 phase DC/AC: U_DC, U_AC, I_AC and cos φ

• MotorGeneratorMap

  • Machine with controls: U_DC, Speed and Torque

The .pfloss file can be imported into the template, in the Main tab (e.g. InverterPowerForge template):

The imposed temperature can be specified in the “Thermal behavior” tab or linked to an external model:

9.1.2. Circuit simulation files

Most of the designs evaluated can be exported and used in GT-ISE by selecting the option illustrated below:

This option will construct a .zip file that contains everything needed to run a GT-ISE simulation. The procedure to create a model in GT-ISE is detailed below:

1. Open GT-ISE (Ensure version corresponds to the version of the downloaded zip).

2. Click the “PowerForge Design Import” button on the Utilities tab (see picture below).

3. Select the downloaded zip file and the location to save the generated model.

4. [Optional] Check the “Verbose” option if you wish to see more detailed log while importing.

5. [Optional] Check the “Close GTM after import” option if you do not wish to see the model open in GT-ISE after import.

6. Click “Import”. The log window will show import progress. Close window when completed.

9.2. PLECS™ and PSIM™ circuit simulation files

Generates ready-to-use circuit simulation files for industry-standard software.

9.2.1. How to use PSIM files

1. Unzip the archive contents into a directory. Do not open the files directly within the zip archive!

2. From PSIM, open the ‘generate-files.script’ file (“File” > “Open…”) which will generate all schematic files

3. Go back to the directory where the archive contents were unzipped

4. Open the newly-generated ‘MainCircuit.psimsch’ file with PSIM

PSIM will auto-detect XML device description files as long as they remain in the same directory as .psimsch files. You can also import them to a PSIM device database using the “Device” > “Import Device from XML file” menu option of PSIM’s device database editor (PcdEditor) accessible from PSIM via “Utilities” > “Device Database Editor”. The device reference will then be available for “IGBT (database)” or “MOSFET (Eon) (database)” elements from PSIM’s Thermal Module.

Note that, unlike PowerForge, PSIM feeds back voltage drops computed by its Thermal Module into the electrical circuit simulation. Because the simulation runs open-loop, this may lead to a significantly altered operating point.

9.2.2. How to use PLECS files

1. Unzip the archive contents into a directory. Do not open the files directly within the zip archive!

2. Open the .plecs file with PLECS

PLECS will auto-detect XML thermal description files as long as they remain in the same directory as .plecs files.

To evaluate loss and validate waveforms, we advise using the steady-state analysis feature of PLECS. Once the file has been opened, go to “Simulation” > “Analysis Tools” and choose “steady state analysis”. In some cases, this steady-state analysis might have convergence issues: if this happens, a normal simulation can be performed instead.

When using a MOSFET as ‘synchronous rectifier’, the split of reverse current between paralleled MOSFET & diode symbols cannot be properly simulated in PLECS. A very small Vf in the diode symbol is used to ensure all reverse current flows through the MOSFET symbol. The i < 0 half of the voltage drop curve for this MOSFET symbol is pre-computed by PowerForge as the result of both channel and diode conducting in parallel, however all resulting power loss will be assigned to the MOSFET symbol. This means there may be significant power loss and junction temperature differences with PowerForge when using a MOSFET with a separate anti-parallel diode chip.

If the HV filter is 1st-order (e.g. “C filter”) and the LV filter is 2nd-order (e.g. “LC filter”) the HV bus is modeled as a controlled current source. HV filter voltage ripple may slightly differ from PowerForge. Similarly, if the HV filter is 2nd-order (e.g. “Damped LC filter”) and the LV filter is 1st-order (e.g. “L filter”) the LV bus is modeled as a controlled voltage source. LV filter current ripple may slightly differ from PowerForge.

9.2.3. Known issues common to PSIM & PLECS exports

In paralleled flying capacitor configurations (n_cell(fc)>1 and n_cell(par)>1), as no control loop is considered, inductor currents or flying capacitor voltages may be unbalanced in some cases. As a consequence, the semiconductor loss may differ from PowerForge.

PowerForge assumes the macrocell HV/DC voltages to be constant when computing waveforms for the LV/AC side of the circuit. Similarly, it assumes the macrocell LV/AC currents to be ripple-free (constant/sinusoidal) when computing waveforms for the HV/DC side of the circuit. This is not the case in PSIM & PLECS, therefore waveforms might differ from PowerForge in designs with high ripple.

9.3. FEMM finite-elements simulation files

9.3.1. Description

Generates as well FEMM magnetics simulation files to validate the calculation done within the design. These files help to validate:

• inductance value,

• DC winding resistance.

The export .zip file contains a set of files:

• .fem files: describing the inductors’ geometry and the materials,

• .lua files: ready-to-run scripts to perform simulations and extract data of interest,

• readme.txt: how to use help file.

9.3.2. How to use the .fem files

Once FEMM.exe has been launched go to “File” > “Open…”. The file can be evaluated using “Analysis” > “Analyze”. To view magnetic field, current, etc. go to “Analysis” > “View Results” and select the desired plot in the “View” menu. For further information, refer to the FEMM documentation.

To compare the design results with the simulation results, you may want to compute resistance and inductance with FEMM. This is easily done using the included .lua scripts: go to “File” > “Open Lua Script” and select the desired inductor. A console will open where the computed values are displayed.

9.3.3. Notes about .fem export

• The inductance value computed with FEMM takes leakage into account and should therefore be slightly higher than in PowerForge.

• The simple L inductance model has no associated geometry and therefore results in an empty .fem file.

• If no magnetic element is present in the subsystem, no .fem file is exported.

9.4. Excel report

Generates and download an .xlsx file that contains information on a design, including:

• Conversion stage specifications,

• System and sub-system level user inputs and results,

• If applicable, information about the design results.

A second worksheet includes a bill of materials, containing for all power components involved in the design:

• Reference and manufacturer,

• Main characteristics,

• Quantity and cost (as estimated by PowerForge from user-provided inputs).