Evaluating losses in Mosfet, IGBT, GTO.

To predict the losses in a drive system, the simulation has to run for many cycles. With the ever-increasing switching frequency, the total simulation time would be too long for a simulation employing dynamic Mosfet, IGBT or GTO models. Therefore the ideal switch model, with conduction and switching losses modeled are used to calculate the losses in the inverter. <br>Click to close the image

The figure above shows the modules for the fast loss prediction models. Besides the electrical nodes, each module has a thermal node that can be connected to a thermal model. In these models the turn on and turn off times can be defined from which the switching losses are calculated.

For the IGBT the IGBTMODULE4 has 4 seperate thermal nodes, one for every component. <br>Click to close the image

The thermal node has to be connected to a thermal model. The conduction and switching losses are predicted in this model. The conduction losses are calculated from the on-state volatge drop and the current through the device. The switching losses are predicted depending on the voltage accros and the curent through the device. The device parameters are depending on the temperature on the thermmal node. This block can also be used to model the Mosfet, wher yo usimply put the on-state voltage drop to zero.

For the IGBT, both VCEon and RCEon are temperature dependent. The switching losses are given in the manufacturer data-sheet and are specified for 25° Celsius and 125° Celsius. The junction temperature is simulated during the simulation and is used to adapt the parameters for the semiconductors.
Using the fast loss prediction model enables the prediction of the system behavior and prediction of the losses of the component. In an IGBT, the temperature dependent VCEon and RCEon model the conduction losses. The switching losses are calculated from the data-sheet parameters Eon and Eoff. The temperature on the heat sink is dependent on the losses. The losses are temperature dependent because VCEon and RCeon are temperature dependent.



Losses and Thermal simulation
The IGBTMODULE4 model has four thermal connections that have to be connected to a heat sink model. The temperature rise due to the conduction, switching and reverse recovery losses is modeled on this connection. Note that colors indicate which thermal node belongs to which component.
A heat sink is build from the components found in components/library/Heatsink The parameter Rth and Cth model the thermal model from junction to case. The initial temperature of the junction is modeled by the parameter Tth0. If a more detailed thermal model for the junction to case thermal path has to be build, Rth and Cth simply model the first chip-layer and the following layers are modeled by subsequent thermal models.

Overview of the parameters
The parameters for the IGBTMODULE4 are summarized in the following table.

Nominal Parameters
ParameterDefaultFunction
Vnom600Nominal voltage for which the Eon, Eoff and Err values are given
Inom100Nominal current for which the Eon, Eoff and Err values are given

IGBT Parameters
ParameterDefaultFunction
Eoff2550mJTurn off energy loss at 25 degrees Celcius
Eoff12550mJTurn off energy loss at 125 degrees Celcius
Eon2550mJTurn on energy loss at 25 degrees Celcius
Eon12550mJTurn on energy loss at 125 degrees Celcius
Vce251On-state voltage drop at 25 degrees Celcius
Vce1251On-state voltage drop at 125 degrees Celcius
Rce2525mOn-state resistance at 25 degrees Celcius
Rce12525mOn-state resistance at 125 degrees Celcius

Diode Parameters
ParameterDefaultFunction
Err2550mJReverse recovery energy loss at 25 degrees Celcius
Err12550mJReverse recovery energy loss at 125 degrees Celcius
Vd250.5On-state voltage drop at 25 degrees Celcius
Vd1250.5On-state voltage drop at 25 degrees Celcius
Rd2510mOn-state resistance at 25 degrees Celcius
Rd12510mOn-state resistance at 125 degrees Celcius

IGBTModule4x
The IGBTModule4x can be used if detailed information is available regarding the dependency of the losses on load current and gate resistance.
The are two files required, with the following format:

E_ic.dat:
ic1 EonT1 EonT2 EoffT1 EoffT2 ErecT1 ErecT2
ic2 EonT1 EonT2 EoffT1 EoffT2 ErecT1 ErecT2
.
.
icn EonT1 EonT2 EoffT1 EoffT2 ErecT1 ErecT2
E_Rg.dat:
Rg1 Eon Eoff Erec
Rg2 Eon Eoff Erec
.
.
Rgn Eon Eoff Erec

© 2018 CASPOC, All rights reserved. Home   |   Terms and Conditions   |   Legal   |   Export Compliance   |   Privacy Policy   |   Site Map