Lecture 1 introduction of Power Electronics

DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING 1
Subject: Power Electronics (BEET-601)
Lecture 1: I Introduction to Power
Electronics
Course Objective:
To acquaint with the fundamental concept of power electronics. It deals with basic theory of different
power electronics switches. It is important for the student to understand the application of power and
their operation
Definition:
A study that utilizes electronic power devices from converting one form of electric power into another
form of electric power with proper control is known as Power Electronics. In power electronics, solid-
state electronics is used that performs the action of control and convert of the electric power.
Concept of Power Electronics:
The branch of electrical engineering is sub-classified into three categories namely:
 Electronics
 Power
 Control
It is known to us that electronics generally revolves around semiconductor devices and circuits and
thus the arrival of various technologies has made electronics a crucial branch of engineering.
Now, coming to the power domain, so power is associated with the generation, transmission,
distribution, and utilization of various forms of electric power in static as well as rotating machinery.
While control deals with the response characteristics of the systems incorporating feedback mechanisms
for continuous or sampled data.
Thus, as a whole power electronics is regarded as the field that is concerned with the use of electronics
for controlling and conversion of electric power. To achieve this, the designing of such systems is done
by maintaining interaction between source and load by making use of small-signal electric control
circuits and power semiconductor devices.
Power electronics is known to be a vast as well as complex subject that is advancing with technology
and turning out cost-effective with the various inventions. Its operations are quite reliable and are
expanding in various fields like industrial, commercial, residential, military, and aerospace applications.

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Relation of Power Electronics with other Disciplines
Power electronics has emerged as an important domain of electric power engineering and shows its
close relationship with various other disciplines like semiconductor physics, circuit theory, analog, and
digital electronics. Along with these, analog and digital control systems, electrical machines and power
systems, electromagnets and electrical machines, etc.
With the advent of various technological advancements in semiconductor physics, electronic devices
and circuits along with control theory, the uses of power electronics in various fields have upgraded
significantly.

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Block Diagram of Power Electronics:
We have already discussed that majorly power electronics deals with conversion and controlling of a
large amount of electric power. This means the converter and controller are its two major components.
We know that the fundamental operation of power electronics is the processing and controlling of
electric energy by giving sufficient voltage and current so that it will be suitable for various consumer
applications. The processing or converting of electric power is achieved through a power electronics
converter also known as power converters or switching converters.
The figure below represents the block diagram of a power electronics-based system:
As it is clear from the above figure that here we are having a power electronics converter and controller
along with some interfacing units. The power converters change one form of electric power into some
other form with the use of a power semiconductor device. While power controllers are the ones that are
responsible for producing control signals relative to turning on or off of the switching devices present
within the circuit. The complete operation of the system will provide the desired signal of a particular
frequency as shown in the block diagram given above.
Here you must note that the controller acts as feedback for the system that controls the operation of the
controller depending on the feedback signals from the load.
In power electronics-based systems, there can be an AC or DC source of electric power. The DC
electric power source can be a DC generator, battery, etc. while the ac electric power source can be an

Electronics
alternator or induction generator. With the use of a controller, a signal of controlled power reaches the
load end from the source via a converter.
The converter provides ac or dc electric power according to the load with variable voltage and
frequency. Here we have said that the electric power at the output is dependent on the load and the
reason behind this is when the load is dc motor then the converter provides output as adjustable dc
voltage. But suppose we have a three-phase induction motor at the load then the output of the
converter will be adjustable ac voltage.
Further, the parameters on which load is measured like the voltage, current, etc. acts as the input signal
for the controller unit. These are known as feedback signals or controller input signals. Along with
the feedback signal, the controller is also provided with the reference input signal. The control signal
generated by the controller is an outcome of the comparison made between the feedback signal and
reference input signal and is regarded as the heart of the system. This control signal regulates the turning
on and off of the switching devices of the power converter.
In this way with proper control, the desired output is achieved at the load.
COs
CO1 Relate basic semiconductor physics to properties of power devices, and combine circuit
mathematics and characteristics of linear and non‐linear devices
CO2 Describe basic operation and compare performance of various power semiconductor
devices, passive components and switching circuits
CO3 Design and Analyze power converter circuits and learn to select suitable power
electronic devices by assessing the requirements of application fields.
CO4 Formulate and analyze a power electronic design at the
system level and assess the performance.
CO5 Identify the critical areas in application levels and derive typical alternative solutions,
select suitable power converters to control Electrical Motors and other industry grade
apparatus.
Discuss Syllabus of Power Electronics

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Power Electronic Systems
Power electronics refers to control and conversion of electrical power by power semiconductor devices
wherein these devices operate as switches. Advent of silicon-controlled rectifiers, abbreviated as SCRs,
led to the development of a new field of application called the power electronics.
Power Electronics is a branch of Electrical Engineering, which deals with power conversion from one
from to another form using Inductors, Capacitors, Semiconductor devices (Diode, Thyristor, MOSFET,
IGBT etc.). The power may be from mW (point on load applications) to MW (Power Systems).

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Goal of power electronic systems

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Applications of Power Electronics
Residential Refrigeration and freezers, Space heating, Air conditioning, Cooking,
Lighting, Electronics (personal computers, other entertainment equipment).
Commercial Heating, ventilating, and air, conditioning, Central refrigeration, Lighting,
Computers and office equipment, Uninterruptible power supplies (UPSS),
Elevators
Industrial Pumps, Compressors, Machine tools (robots), Arc furnaces, induction
furnaces, Lighting, Industrial lasers, Induction heating, Welding.
Transportation Traction control of electric vehicles, Battery chargers for electric vehicles,
Electric locomotives, Street cars, trolley buses, Subways, Automotive
electronics including engine controls.

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Utility systems High-voltage dc transmission (HVDC), Static VAR compensation (SVC),
Supplemental energy sources (wind, photovoltaic), fuel cells, Energy storage
systems, Induced-draft fans and boiler, feed water pumps.
Aerospace Space shuttle power supply systems, Satellite power systems, Aircraft power
systems.
Telecommunications Battery chargers, Power supplies (DC and UPS).

Lecture 1 introduction of Power Electronics

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