Our first task is going to be to model the converter
and calculate the most efficient operating region.
The converter is split up in three parts
with the power supply, the converter itself, and the load.
We can see here how this has been represented in Simulink
using three different subsystem and some connection
between them.
But before jumping into the model,
let me quickly go over some way that we
can represent physical system with our solution.
A lot of you may be familiar in using Simulink equation
to write them and solve the ODEs directly using the block
diagram in Simulink.
Some of you may already know Simscape
which is our platform for physical network
and connecting components together.
And the system level equation is generated automatically
by combining together all these different components in one go.
Lastly, if you have measurement of your system,
you can always import them and derive a data-driven model
usually called black box model.
And the nice thing about having all these three possibilities
and more is that you can combine them.
You are not forced to stay in one kind of solution mode.
You can have part of your model as an identified model,
some of it as a physical network, and some of it
as equation in Simulink.
Let's take a look at our SEPC model.
As we saw on the slide, we have a view of our system.
The converter should work with a frequency of 100 kilohertz,
so medium height.
The LEDs, on the other end, are going to work at 20 kilohertz.
The power supplies 12 volt. The operating region
of the LEDs, by specification of Texas Instrument.
are between 17, more or less, and 2.5 volt.
So if I open up my SEPC converter.
I'm going to notice that I have four different systems.
Three of them gray out.
I'm using what is called variant sub system.
Here I have my controlled converter,
which is a perfectly ideal converter, which
is just represented with some kind of time constant.
And always keep the voltage at the right level at the output.
So this can be incredibly useful for system level simulation
because it's very fast.
On the other end, I have other variant of my implementation.
I have a steady state converter.
I have an average SEPC.
And I have my SEPC circuit, which
I am going to focus right now.
If I look inside, I see that I have
all the typical components, such as inductances and capacitors.
And I've linked, actually, the datasheet
which is present online, directly to my model.
So it's easier for me to find, again, the right documentation.
Just a quick excuses on the differences between inductances
is the foundation library.
If I open up, I see I have only two parameters, more or less,
and the source code so that I can go and see
which kind of equation are implemented under the hood.
So please allow me to start from this component,
change it if I want, and have my own version of the inductance.
I always define any kind of equation using the Simscape
language.
On the other hand, I'm using the datasheets
provided by Simscape Electrical, the dedicated
toolbox for electrical and power system.
In this case, you can see I have tolerance,
I could even apply a random tolerance for my system
if I want to perform some kind of Monte Carlo analysis
based on the tolerance by changing.
I can set operating limits in my inductance.
I can set fault. So I can break down my inductances
when I want, how I want.
And all of this allow me to increase the level of fidelity
of my simulation and do more.
But as you can see, this time you
don't have access to the source code.
Let's go back to my SEPC subsystem
and look at this small rectangular here.
These are test harnesses.
Let's open up one of them.
In this test harness, I'm doing a step between 0%
and 61% of my circuit.
And I'm measuring the output, comparing with some measurement
that I've taken on my oscilloscope.
So I'm simulating for 700 millisecond the switch
linear system.
So I'm simulating all the switches at 100 kilohertz.
And you can see that the simulation time is quite fast.
This is happening because I'm using
ODN, which is a software can be forced to act a certain point.
In combination with a special PVM
block that you can retrieve as well
in using your models from these files
that you're going to get access to after the seminar.
The entire project would be available to you.
So in this case, in this PVM, we are generating our carrier wave
and we are simulating at a certain frequency this kind
of impulse in order to force time step
to take the appropriate step at the right point of my carrier
wave.
If we look, then, at the simulation result with the time
step present, for instance the diode current,
we can see that we are actually--
they can time step up only when needed
by the simulation and no more.
So we're really simulating the entire 100 kilohertz switches.
We are doing that in a very efficient way.
We are only switching when it's necessary.
There is one time in the middle which
is the point of my support of my carrier wave.
And the current is modeled as a switched linear system.
This is great.
It allowed me to simulate quite fast.
And I can then compare how my model
is compared to the reality.
We can see that I have captured most of the element
quite accurately, rising time, the settling time
voltage, and then the slowing down time when I shut off
my PVM.
Very well.
But this is not going to be my modeling of choice.
Because I want to investigate efficiency.
In order to investigate efficiency,
I will need to work with actual physical devices,
optical MOSFET physical devices model If I go in it,
except this time I'm using the Simscape Electrical
PVM because it's connected to our actual n channel MOSFET.
This can be parameterized by a parameter
that you can find in datasheet.
And with the right click, you could access multiple options.
You can either change the block choice
or if you don't want the threshold base model,
or you want to add a thermal part to it,
you could do it by accessing and right clicking on this menu.
Or you could use it to generate basic characteristics.
This case is going to do under the hood automatically
instrument these MOSFET with this parameter
and generate automatically a typical plot that we
can find on a data sheet here for my MOSFET.
If I open up the actual data sheet
and scroll down to search for the plot,
I can then just graphically compare it and see
if it matches yes or now.
We can see that we are doing quite a good job here
is the 8 voltage line which is settling down around a bit more
than 10 ampere after around 2 or 3 voltages.
We can see here that we have very similar behavior
by our MOSFET.
You could actually use certain tool from the File Exchange
to import directly this kind of plot into Simulink.
And then use them to better parameterize your model
as well.
Let's go back to our model and look at a second test harness.
First I need to close the one I used to simulate and compare it
to my measurement.
And afterwards, I would like to open up
the one called Efficiency Test.
In this case, I am simulating a closed loop model.
I want my model to reach a certain voltage.
That's why I have a very simple PID block here.
And I changed the value of the resistor
to get a specific current going in
so that I can create a grid of specific voltage
from 12 to 30 volt and a specific rate of current from 0
to 2 ampere.
And in creating, I create more or less hundreds
of operating points that I would like to test.
And I instrument my model to stop the simulation if I
reach the appropriate voltage.
Afterwards, when I simulate it and I can simulate in parallel
using the parallel computing toolbox to gain even more time,
I could use functions such as Get Efficiency
to define which components are going
to be to load and feed them the simulation result.
So I can get the efficiency of my converter
at any operating point based on the load.
I can do the same for the power dissipated.
And I actually prepared this as a script and saved my result.
If I run this, I will load already
my result showing you the kind of map
that you can actually create.
Here we have my converter operating region,
the one defined by Texas Instrument
that we can see that it actually working around
very high efficiency, with the point up to 92% maybe 93%.
And we can see how the converter behaves
in the rest of the operating region.
So these are the kind of things that you can instrument
your model using functions such as Get Efficiency
to analyze your circuit and see where and how you
should operate your converter.
If you are not happy, you can change your parameters
such as inductance capacitor.
You let it run again, hopefully in parallel,
because it will speed up a lot this kind of investigation,
and recreate automatically these kind of maps.
Let's go back to our presentation.
What we saw now is a Simscape as a platform
to model a physical system.
In particular, we saw Simscape Electrical
in action, which is the toolbox in addition to Simscape
to model electrical circuit and power system.
Simscape offers Simscape language in order for you
to start from the basic blocks and make your own block
so that to capture exactly the kind of behavior
you want to represent.
Very brief excuses on what's new in Simscape Electrical.
We have two blocks now and more are coming, such as the stepper
motor and the battery which have been pre-parameterized
using value from the industry.
We can see the batteries.
You can put the battery in your system
and automatically pick up some of the cell
available on the market pre-parameterized
at different temperature levels.
So this is going to really speed up
the development of your electrified system
if you're looking into batteries.
We have added even more possibility to generate fault,
not only at the component level but you
can do fault during dynamic load,
do delta connected, y connected, and so on.
So we are really investing a lot to be able to break your model,
make it foldable whenever you want and however you want.