Modelling Wolfspeed Power Modules

KonstandinKotsis

Hello all,

I am using 2 power modules from Wolfspeed for a bi-directional full bridge DC-DC converter. The power module I am using is the CAS120M12BM2 but since this model does not seem to be available on LTspice, in my spice model I am using the CAS175M12BM3.
The main objective of modelling this full bridge converter is mostly to:

1. Get a better understanding of its operation.
2. Become better acquainted with the Wolfspeed Spice models.
3. Get a better understanding on how to model the parasitics of the system.
4. Understand how these parasitics influence the performance of the power modules.

Therefore, whether I use the CAS120, CAS175 or any other WS Spice model, does not really matter to me as long as I figure out how to model and/or include the parasitics correctly.

I have read the following application notes from Wolfspeed:

1. Wolfspeed Power Module SPICE Models User Guide
2. Power Module Baseplate Capacitance and Electromagnetic Compatibility

The second document gives a description on the modeling of the baseplate capacitances in which I am currently not very interested.

The first document describes how to make use of the power module spice models and gives some direction on how to include some parasitics in the model (for example editing the SpiceLine 2 attribute of the component). However there are still a few details that I have not been able to find in the document or extract while reading it.

Question 1: Is there a list and a description of all the parameters included in the model of the power module?

Question 2: Are these parameters and their influence enabled by default whenever I use a certain model or should I call them in the SpiceLine 2 attribute in order to "enable/activate" them?

Question 3: Can I edit any of these parameters simply by calling it and editing it in the SpiceLine 2 attribute of the component or should I edit them in the .LIB file of the component?

In the document(1) I am reading that Cds, and Cgd are modeled with dependence on Vds, and Cgs is modeled with dependence on Vgs. When I read the .LIB file I can find the function (.func Cxx(V)) used to describe this behaviour.
This function looks little bit like this:

.func Cgs(V) {table(V,-5.000,5.298,-4.750,4.915,-4.500,4.606,-4.250...)}. In this function, and functions that are structured similarly to this one, are the given values the values of Cgs, or whichever parameter is being described by the function?
The values of V, are those given in another table in the .LIB file or are this actually the values of the source that I will be using in the spice model?

Question 4: If I want to model these parasitic capacitances or components whose value depends on the voltage across them, where can I extract his information from?

I would really appreciate any help and advice.

Thank you in advance.

Kosta Kotsis

BlakeNelson

I hope that this answered your question. I will close this discussion for now but if you have a follow up question, please "Start a New Discussion" and we would be glad to support you further.

Blake