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.
For the IGBT the IGBTMODULE4 has 4 seperate thermal nodes, one for every component.
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.
Parameter | Default | Function |
Vnom | 600 | Nominal voltage for which the Eon, Eoff and Err values are given |
Inom | 100 | Nominal current for which the Eon, Eoff and Err values are given |
IGBT Parameters
Parameter | Default | Function |
Eoff25 | 50mJ | Turn off energy loss at 25 degrees Celcius |
Eoff125 | 50mJ | Turn off energy loss at 125 degrees Celcius |
Eon25 | 50mJ | Turn on energy loss at 25 degrees Celcius |
Eon125 | 50mJ | Turn on energy loss at 125 degrees Celcius |
Vce25 | 1 | On-state voltage drop at 25 degrees Celcius |
Vce125 | 1 | On-state voltage drop at 125 degrees Celcius |
Rce25 | 25m | On-state resistance at 25 degrees Celcius |
Rce125 | 25m | On-state resistance at 125 degrees Celcius |
Diode Parameters
Parameter | Default | Function |
Err25 | 50mJ | Reverse recovery energy loss at 25 degrees Celcius |
Err125 | 50mJ | Reverse recovery energy loss at 125 degrees Celcius |
Vd25 | 0.5 | On-state voltage drop at 25 degrees Celcius |
Vd125 | 0.5 | On-state voltage drop at 25 degrees Celcius |
Rd25 | 10m | On-state resistance at 25 degrees Celcius |
Rd125 | 10m | On-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:
ic1 EonT1 EonT2 EoffT1 EoffT2 ErecT1 ErecT2
ic2 EonT1 EonT2 EoffT1 EoffT2 ErecT1 ErecT2
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icn EonT1 EonT2 EoffT1 EoffT2 ErecT1 ErecT2
Rg1 Eon Eoff Erec
Rg2 Eon Eoff Erec
.
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Rgn Eon Eoff Erec