Changes in the Thermal Module between v2021 and v2022/v2023

Changes in the file format

In Altair PSIM v2022.x a new file format is used for thermal models. In v2021, device thermal models were stored in a proprietary binary format (.dev).

In the current release a “.xml” file is used with the following characteristics:

• Can be edited both with PcdEditor and any text editor.
• Only one device is stored per “.xml” file.
• “. dev” files cannot be edited or created.
• Saved data from a “. dev” file will be stored on a new .xml file with “_discrete” added to the file name, e.g., “CAS325M12HM2_discrete.xml”.

General changes in the Thermal Module

Package information is removed. The use of multiple discrete devices is implemented through Switch Modules, which can link Thermal Models in v2022.

Figure 1. Thermal Models in switch modules in v2022

Dimensions and weight information was removed since it was not relevant to the simulation.

Figure 2. Package and Dimensions and Weight Sections in v2021

Two new options were added to define the Electrical Characteristics curves:

• An equation instead of data points can be used to define Electrical Characteristics curves.
• Data points can be imported from a “. csv” file using the “Load Data” function for the following Electrical Characteristics curves:
  • Transistors: Eon vs. IC, Eoff vs. IC (IGBT, IGBT_DIODE, IGBT_RB) and Eon vs. IDS, Eoff vs. IDS (MOSFET_EON)
  • Diodes: Err vs. IF

Figure 3. “Equation” and “Load Data” Options in Electrical Characteristics definition

“Other Test Conditions” button is disabled for most curves, mostly due to Test Conditions not being used to calculate losses, other Test Conditions were relocated to the top of the model. While some of these Test Conditions do have an impact in the loss of a switch, PSIM uses the existing curves to calculate losses and the effects are reflected in these curves. Other Test Conditions were moved to the top level of the model. The next section includes a list of removed and changed Test Conditions.

Figure 3. “Equation” and “Load Data” Options in Electrical Characteristics definition

Device-specific changes in thermal models

Diode

• Reverse recovery energy (Err) vs Gate Resistance (RG) curve was added.
• Reverse recovery energy (Err) vs current (IF) can be defined at different VR values. Because of this, VR is removed from “Other Test Conditions...”.
• The following Test Conditions were removed since they were not used in loss calculations:
  • Reverse Blocking Voltage VR (For the reasons previously mentioned)
  • Rate of change of the current IF

Figure 4. Changes in diode model.

IGBT

• The following curves can be defined for different VCE values (also applies for IGBT_DIODE/IGBT_RB Devices). Because of this VCE is removed from “Other Test Conditions...”:
  • Transistor: Eon vs. IC, Eoff vs. IC
  • Diode: Err vs IF
• Added electrical characteristics (also applies for IGBT_RB):
  • Turn-on losses vs Temperature (Eon vs. Tj)
  • Turn-on losses vs CE Voltage (Eon vs. VCE)
  • Turn-off losses vs Temperature (Eoff vs. Tj)
  • Turn-off losses vs CE Voltage (Eoff vs. VCE)

• The following Test Conditions were removed since they were not used in loss calculations (also applies for IGBT_DIODE/IGBT_RB Devices):
  • Voltage VCE (For the reasons previously mentioned)
  • Gate Voltage VGE *

• • Gate Voltage (VGE_on and VGE_off) *
  • Reverse blocking voltage VR
  • Rate of change of the current IF

* While VGE has impact in switch losses, this model calculates losses directly from other curves.

If the datasheet includes curves for different values of VGE a separate thermal model file needs to be created per VGE value.

• Gate resistance (RG_on and RG_off) were moved from the “Other Test Conditions” menu to the top level of the model.

Figure 5. Changes in IGBT model.

MOSFET_EON

• Removed electrical characteristics curves, these are replaced by the Eon vs IDS curves defined for multiple values of VDS:
  • Eon_VDS@IDS1
  • Eoff_VDS@IDS1
  • Eon_VDS@IDS2
  • Eoff_VDS@IDS2

• The following curves can be defined for different VDS values, therefore VDS is removed from “Other Test Conditions”:
  • Transistor: Eon vs. IDS, Eoff vs. IDS
  • Diode: Err vs IF

• The following Test Conditions were removed since they were not used in loss calculations:
  • Gate Voltage VGS*

• • Gate Voltage (VGS_on and VGS_off) *
  • Voltage VDS (For the reasons previously mentioned)
  • Current IDS
  • Reverse blocking voltage VR
  • Rate of change of the current IF

* While VGS has impact in switch losses, this model calculates losses directly from other curves.

If the datasheet includes curves for different values of VGS a separate thermal model file needs to be created per VGS value.

• Gate resistance (RG_on and RG_off) were moved from the “Other Test Conditions” menu to the top level of the model.

Figure 6. Changes in MOSFET_EON model.

MOSFET:

• The following Electrical Characteristics were removed since they are not used in loss calculations:

Figure 7. Changes in MOSFET model.