We can use a very similar methodology
to determine the power losses and the thermal behavior
of the converter.
You may have noticed, when I ran my script,
the second plot popped up.
In this plot, I'm showing the average power losses
of the MOSFET, in watt, over the different operating
region I simulated with my power loss simulation,
and the average power losses of my diode.
You can see that the MOSFET is losing
a bit more, with almost 16 watt by high voltage
and high current.
The diode is a bit more difficult.
We can see that actually, the power losses
are very much dependent on the current, and not so much
of the voltage.
We can re-use these tables in software
for in a specific model build-up for thermal stimulation.
You can see here I feed my voltage and current
as a desired operating region, I am recalculating the power
losses using a lookup table, and I am feeding them
in a physical network which replicates my passive cooling
system--
my heat flow, the watt generated by the MOSFET.
I have some thermal masses due to the mass of the junction.
I have a connection to the case--
the case as well as some thermal mass,
which has a connection to the heat sink.
My passive heat sink then has her convection
with the ambient temperature.
There is no active cooling.
This is simply a passive system based
on the ambient temperature.
I can quickly change to my operating region,
like around 18 volt and 1 ampere,
and then I can simulate for up to an entire day.
We can see it 3,600 second for 24 hours.
I can run-- the simulation will be instantaneous.
This is a very simple model.
But this can be incredibly powerful technique
for the engineers which are creating or assessing or sizing
the cooling system for your power converter.
We can see that our expected operating region--
we actually are going to be around 318 Kelvin
of temperature for the MOSFET and 328 Kelvin
for the diode, which is acceptable.
It's more or less 47 degrees.
So of course, it's the entire day, with a lot of current.
But it doesn't heat up too much, so we
may be fine with a passive cooling system.
I used a new probe block to get the temperature.
You can use it for any kind of physical system.
You double-click, you pick a block,
and then you get access to all the variables
that are inserted in this block.
So this is a very convenient technique
that allow you to build up a network
and avoiding to instrument everything with sensor.
This has been introduced in release 2020a.
Now, of course, if the passive cooling is not enough,
your colleagues which are working on the cooling system
may need to search for a fan to start blowing air actively
on the heat sink.
Maybe you need some heat exchanger as well.
So we provide a lot of these blocks that allow your team
to work truly on the entire engineering aspect--
not only on the power electronics,
but on the cooling--
sizing the cooling, and the cooling control.
So this is what we think when we say
that we provide truly a multi-domain simulation
environment for a multidisciplinary team
to work on.
So as a recap, we saw how you can use the function
getpowerlossSummary to create your table of power losses
from MOSFET and diode.
You can create a very fast implementation of your cooling
system using simply the power losses at different operating
point.
We have an example for this called Switching Power Supply
Thermal, if you want to take a look at it.
And we actually have a new function
as well to hide this fidelity of your switching devices.
We added MOSFET, and we parameterized the MOSFET
based on the data sheet.
But more and more, you can import existing models
that you may have in SPICE directly into Simscape using
the function subcircuit2ssc.
This will, from a netlist, automatically
create a Simscape component based on the SPICE netlist.
We pushed this that right now, we introduced SPICE models
for our switches such as the SPICE-imported MOSFET,
and we provide some selection off-the-shelf
for certain type of MOSFET such as the one from Infineon.
This is repeatable work for you as well.
So we provided the conversion assistance.
And of course, then you can validate this conversion
by generating the characteristics
and comparing with LTspice.