Power electronics incorporates fundamentals from a number of different fields,

including analog circuits, electronic circuits and devices,

control systems, power systems in applications,

magnetics design, electric machines,

and numerical simulations, just to name some of the more important ones.

In this specialization, the assumption is that you already

understand the basics of analog circuits in electronics.

What we will do is apply those basics to

the power electronics field and its applications.

We will design control systems for these switching converters.

We'll design magnetics, do some applications of interface to power systems,

and we'll do some simulation as well.

Here's a brief summary of the six courses of the specialization.

In this course, course one,

we'll start with a simulation this first week of a basic switching converter.

This week, we will also discuss the basics of how we

process electrical power with very high efficiency.

In week two, we'll discuss the basic waveforms of switching converters and how we analyze

these switched circuits to work out

the steady state or DC voltages and currents in the converter.

In week three, we will develop

some equivalent circuits that can be used to model the important

underlying or low-frequency voltages

in currents of the converter and to predict things like the efficiency.

Course two goes into more detail regarding converter circuits.

So, we'll talk about how to realize the switches in

a switching converter using power semiconductor devices,

and we'll model the losses that arise from switching,

what we call switching loss,

and understand the basic behavior of

these semiconductor devices in the power electronic switching type applications.

Here's a power MOSFET,

which is one of the workhorse devices of the field,

and some typical voltage and current waveforms

during a switching transition of that device.

We'll also discuss what's known as the discontinuous conduction mode,

and we'll look at some different converter circuits,

including those with transformer isolation.

Here's an example of

a well-known and commonly used transformer isolated circuit

known as the forward converter.

In course three, we'll discuss how to control switching converters.

So, here we have some switching converter power circuit,

and we build a feedback loop,

either analog or digital,

to control the output voltage or some other quantity of interest.

The problem in controlling these converters is that

the power converter circuits themselves are nonlinear and time-varying,

and they produce switched waveforms,

such as these, that are pretty complicated.

So, one of the objects in course

three is to develop what we call small-signal equivalent circuit

models that ignore some of the switching and undesired parts of

the waveforms and model only the

desired underlying low-frequency components of the waveforms.

In many ways, these models are similar to

the small-signal equivalent circuits that are used in

electronics courses to model

nonlinear semiconductor devices such as transistors and diodes.

Here's an example of a small-signal equivalent circuit of one of these converters.

Once we have such a circuit,

we can solve it using

conventional circuit analysis techniques to work out the transfer functions,

which we will also do in course three.

Then we will use those results to design

compensators in closed-loop regulators for these converters.

Course four treats some more advanced techniques of converter control.

The average switch modelling technique is developed,

and it's applied to spice modeling of converters,

where we can get spice to basically average

the waveforms and plot the small-signal transfer functions such as these.

Course four also treats current mode control,

which is a popular method for controlling

switching converters that in some ways simplifies

the dynamics and also lends itself to current limiting and protection of the converter.

Course four treats magnetic design in the application of power electronics.

So, there is some modeling of the basic loss mechanisms of the inductors and

transformers of switching converters and

then some discussion of how to design inductors and transformers for these applications.

Simulation as a recurring theme in this course sequence.

We will simulate a boost converter in the homework assignment for this first week,

but we won't be doing simulations throughout this specialization.

In the Capstone Project,

you will use simulation to verify your design.

For the Capstone Project of this course,

we have selected design of the power electronics of a USB Type-C interface,

which involves a bidirectional DC-DC converter that can interface

a lithium battery pack to a USB cable and provide power that goes in both directions.

So, we can both take power from the USB cable to charge batteries or

we can take power from the batteries and supply

to peripherals that are connected to the USB cable.

So, this Type-C USB cable is a bidirectional power flow and it is programmable.

So, we will design a system that can operate with five volts,

12 volts, or 20 volts,

or up to five amps transmitted on the USB cable.

So, the Capstone Project involves selection of

the bidirectional DC-DC converter circuit and design of its power stage,

design of its magnetics,

design of an analog controller for this system,

and then some simulation and design verification.

The prerequisite chain for this specialization goes like this.

This course number one is an Introduction to Power Electronics.

It is prerequisite for course number two on converter circuits,

course number two is prerequisite for the two control courses number three and four,

and it's also the only prerequisite for the magnetics course number five.

All five courses are prerequisite for the Capstone Design Project.

My colleagues and I look forward to

your participation in this specialization and to interacting with you.