On-Off Controller Error While Driving Mosfet Thermal Block in PSIM

Alper Ozden

I want to do thermal analysis on the mosfets of a converter I designed. I defined the parameters of the mosfet I will use to PcdEditor and entered the label values in the "mosfet (database)-thermal" block. However, the "on-off controller" block that I have to use to drive the "Mosfet database" block  does not work properly I'm afraid. It says that this mosfet is an "ideal mosfet" and then I need to change the I/O Signal Type to "control the ideal switch"; As you know, this makes the gate voltage entering the mosfet 0V and 1V and this problem prevents the mosfet from working properly.  Due to the Vgg(+) and Vgg(-) values I entered in the Mosfet database (thermal) section, the mosfet cannot enter full transmission and cutting. Simple methods such as raising the on off controller output with an opamp or directly multiplying it with a multiplier block do not work. What do I have to do now?

I would be very happy if you could reply as soon as possible. Thanks in advance.

Rhonda_20369

Hi, Alper,

For the "On-off controller", both input and output are logic levels, not voltage levels. Therefore, the voltage values are 0 and 1.

In the MOSFET (database) model's parameter dialog, you must enter the real engineering values of Vgg+ and Vgg-. 

You have encountered the problem "Due to the Vgg(+) and Vgg(-) values I entered in the Mosfet database (thermal) section, the mosfet cannot enter full transmission and cutting."

This means some of the parameters in your MOSFET model are incorrect.

Please double check with the datasheet for the gating threshold and other characteristic curves.

You may send your thermal model file (the .xml file) and the datasheet here, and we can check the curves together.