power electronicsfaculty.iauctb.ac.ir/faculty/files/content/power... · power electronics loads:...

By: Dr. Shahram Javadi1

Power Electronics

By: Dr. Shahram JavadiDepartment of Electrical Engineering

[email protected]

By: Dr. Shahram Javadi

Syllabus Outline

1. Introduction To Power Electronic2. Power Diodes

3. Diode Rectifiers

4. Thyristors

5. Control Rectifiers

6. AC Voltage Controllers

7. Thyristor Commutation Techniques

8. Power Transistors

9. DC to DC Choppers

10. DC to AC Inverters

2


Muhammad H. Rashid

“Power Electronics”,3rd Edition,

Prentice Hall, 2004

•Text books: •Sources!!!

3


COURSE EVALUATION

COURSE WORK

(Continuous Assessment)10%

Assignment & Quiz 20%

FINAL EXAMINATION 70%

TOTAL 100%

7


Lecture 1: Introduction to Power Electronics


Power

Electrical Power Generation

Transmission

Distribution

Electronics

Deals with the study of power semiconductor switching devices and their V-I characteristics.

Electronic circuits using these power devices for power conversion and output power control for Various applications.


History of Power Electronics

Mercury arc rectifier (year 1900).

Metal tank rectifier.

Grid controlled vacuum tube rectifier.

SCR (Silicon Controlled Rectifier)• The 1st Thyristor developed by Bell labs in

1956.

• 1st Commercial grade SCR developed by

“ General Electric Co. “ in 1958.


Power Electronic Applications

Commercial Applications

Air conditioners

Central refrigeration.

UPS

Elevators

Emergency lamps

Heating systems

Domestic Applications

Cooking equipments.

Lighting & heating

Air conditioners.

Refrigerators.

Freezers.

Personal Computers.



Telecommunications

Battery chargers.

DC power supply & UPS

Mobile cell phone battery chargers.

Transportation

Traction control of electric vehicles.

Battery chargers for electric vehicles.

Electric locomotives.

Street cars & trolley buses.



Utility Systems

High voltage DC transmissions (HVDC).

Static VAR compensation.

Fuel cells.

Energy storage systems

Boiler feed water systems.


Function of Power Electronics in Utility Applications

Enabling technology providing interface between two (ac/dc) electrical systems

E.g.

Interconnection of two asynchronous ac systems

dc to ac conversion is required to connect fuel cells or photovoltaics to the utility grid

Converter

Controller

Source Load


Listing of Power Electronic Applications

Distributed generation (DG)

Renewable resources (wind and photovoltaic)

Fuel cells and micro-turbines

Storage: batteries, super-conducting magnetic energy storage, flywheels

Power electronics loads: Adjustable speed drives

Power quality solutions

Dual feeders

Uninterruptible power supplies

Dynamic voltage restorers

Transmission and distribution (T&D)

High voltage dc (HVDC) and medium voltage dc

Flexible AC Transmission Systems (FACTS): Shunt and Series compensation, and the unified power flow controller


Power Device Capabilities & Resulting Power Electronic Structures

Power Semiconductor Devices and their Capabilities Polarity of voltage blocked and direction of current conduction Switching speeds and power ratings

IGBT MOSFET

Thyristor IGCT

101 102 103 104

102

104

106

108

Thyri

stor

IGBT

MOSFET

Pow

er (

VA

)

Switching Frequency (Hz)

IGCT


History

17


Structure of Power Electronic Systems

Voltage-Link Systems

Transistors and diodes that can block voltage of only one polarity

Current-Link Systems

higher power bipolar voltage-blocking capabilities of thyristors

Solid State Switches

bidirectional voltage blockingand current conduction

AC1 AC2

AC1 AC2


Role of Power Electronics in Important Utility Applications

Distributed Generation (DG) Applications Power electronic interface depends on the source characteristics

AC

DC

DC

AC

Wound rotor

Induction Generator

Generator-side

Converter

Grid-side

Converter

Wind

Turbine

Isolated

DC-DC

Converter

PWM

Converter

Max. Power-

point Tracker

Utility

1f

Wind Power Generation with

Doubly Fed Induction Motors

Photo-voltaics Interface



Power Electronic Loads: Adjustable Speed Drives

Controller

Motor

Utility

Rectifier

Switch-mode

Converter



Power Quality Solutions for

• voltage distortion

• unbalances

• voltage sags and swells

• power outage

Load

Feeder 1

Feeder 2

Dual Feeders

Power Electronic

InterfaceLoad

Dynamic Voltage Restorers (DVR)

Uninterruptible Power Supplies

Rectifier Inverter FilterCritical

Load

Energy

Storage



Transmission and Distribution: DC Transmission

most flexible solution for connection of two ac systems

AC1 AC2

HVDC

AC1 AC2

MVDC



Transmission and Distribution: Flexible AC Transmission Systems (FACTS)

1 2 sinE E

PX

1E

2E

3E

+- 3E1E 2E

Shunt

converter

Series

converter

I

Shunt and Series Compensation

Series Compensation

Shunt Compensation

Utility

STATCOM

jX


Power Devices

Power diodes

Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET)

Bipolar Junction Transistor (BJT)

Insulated Gate Bipolar Transistor (IGBT)

Thyristors (SCR, GTO, MCT)


Applications of Power Devices


Power Diode


Diode Characteristics


Comparison between different types of Diodes

General Purpose Diodes

Fast Recovery Diodes

Schottky Diodes

Upto 6000V & 3500A

Upto 6000V and 1100A

Upto 100V and 300A

Reverse recovery time – High

Reverse recovery time – Low

Reverse recovery time – Extremely low.

25rrt s 0.1 s to 5 srrt a few nano secrrt


General Purpose Diodes

Fast Recovery Diodes

Schottky Diodes

Turn off time –High

Turn off time –Low

Turn off time –Extremely low

Switching frequency – Low

(Max 1KHz)

Switching frequency – High

(Max 20KHz)

Switching frequency – Very high.

(Max 30KHz)

0.7 to 1.2VFV 0.8 to 1.5VFV 0.4 to 0.6VFV

Comparison between different types of Diodes


BJT


BJT Characteristics


BJT Switching Times


MOSFET


n-channel Enhancement MOSFET Characteristics

Drain Characteristics

VGS1

VGS2

VGS3

Linearregion

Saturationregion

VDSVDS

ID


n-channel Depletion MOSFET

VGS

ID

+ +

G

S

D

VDS


Drain Characteristics

VGS1

VGS2

VGS3

Linearregion

Saturationregion

VDS

ID


Transfer Characteristics of MOSFET

VGS

ID

IDSS

VGS(OFF)


Switching Times of MOSFET

t

V1

VGSP

V1

VG

VT

td(on) td(off)

trtf


Semiconductor Cross-section of IGBT


IGBT


Characteristics of IGBT CM 400HA-24H

Output collector characteristics

0 2 4 6 8 10

V (Volts)CE

160

320

640

800

480I

AMPSC

V =15VGE

12

8

V =10VGE

V =7VGE

V =9VGE


Transfer Characteristics of IGBT

2 4 6 8 10 12 14

160

320

480

640

800

0

V =10VCE

T=125 Cj

0

T=25 Cj

0

VGE(TH)

VGE

I

AMPSC

I Vs V CharacteristicsC GE


Advantages of IGBT

Combines the advantages of BJT & MOSFET

High input impedance like MOSFET

Voltage controlled device like MOSFET

Simple gate drive, Lower switching loss

Low on state conduction power loss like BJT

Higher current capability & higher switching speed than a BJT. ( Switching speed lower than MOSFET)


Applications of IGBT

ac and dc motor controls.

General purpose inverters.

Uninterrupted Power Supply (UPS).

Welding Equipments.

Numerical control, Cutting tools.

Robotics & Induction heating.


DEVICE SYMBOLS & CHARACTERISTICS


Control Characteristics of Power Devices


Comparison between different commonly used Thyristors

Line Commutated Thyristors available up to 6000V, 4500A.

Ex: Converter grade (line commutated) SCR.

V / I rating: 5KV / 5000A

Max. Frequency: 60Hz.

Switching time: 100 to 400sec.

On state resistance: 0.45m.


Example of Inverter Grade Thyristor Ratings

V / I rating: 4500V / 3000A.

Max. Frequency: 20KHz.




Example of Triac Ratings

Used in heat / light control, ac motor control circuit

V / I rating: 1200V / 300A.





Example of Power Transistor Ratings

PT ratings go up to 1200V / 400A.

PT normally operated as a switch in CE config.





Example of Power MOSFET Ratings

Used in high speed power converters like inverters & choppers.

Ratings up to 1000V / 100A.

Example: MOSFET 800V / 7.5A rating.


Switching time: 1.6sec.



Example of IGBT Ratings

Used in high voltage / current & high frequency switching power applications (Inverters, SMPS).

Example: IGBT 2500V / 2400A.


Switching time: 5 to sec.



Switch applications

• Single quadrant switches

• Current-bidirectional two-quadrant switches

• Voltage-bidirectional two-quadrant switch

• Four-quadrant switches

• Synchronous rectifiers


The types of restricted switches


Some basic switch applications


A) Single-quadrant switches

The diode



• The Bipolar Junction Transistor (BJT) and

• The Insulated Gate Bipolar Transistor (IGBT)



The Metal-Oxide Semiconductor Field Effect Transistor (MOSFET)


B) Current-bidirectional two-quadrant switches

By: Dr. Shahram Javadi64MOSFET body diode

B) Current-bidirectional two-quadrant switches


C) Voltage-bidirectional two-quadrant switches


D) Four-quadrant switches


D) Three ways to realize a four-quadrant switch


E) Synchronous rectifiers


Switches comparison

Device TypeYear

made

Rated

Voltage

Rated

Current

Switching

Frequency

Rated

Power

Drive

CircuitComments

SCR 1957 6kV 3.5kA 500Hz 100s MW SimpleCannot turn-off using

gate signal

GTO 1962 4.5kV 3kA 2kHz 10s MWVery

Difficult

King in very high

power

BJT 1960s 1.2kV 400A 5kHz 1 MW DifficultPhasing out in new

product

MOSFET 1976 500V 200A 1MHz 100 kWVery

Simple

Good performance in

high frequency

IGBT 1983 3.3kV 1.2kA 100kHz 100s kWVery

Simple

Best overall

performance


Different types of Power Converters

Diode rectifiers (uncontrolled rectifiers).

Line commutated converters or AC to DC converters (controlled rectifiers).

AC voltage (RMS voltage) controllers (AC to AC converters).

Cyclo-converters (AC to AC converters at low output frequency).

DC choppers (DC to DC converters).

Inverters (DC to AC converters).


AC to DC Converter

Type of input: AC supply (fixed voltage & frequency)

Type of output: DC voltage (variable)

Line

CommutatedConverter

+

-

DC Output

V0(QC)

AC

Input

Voltage


Single Phase Diode Rectifier Circuit


Single Phase Ac-Dc Converter


Applications

Speed control of DC motor in DC drives.

UPS.

HVDC transmission.

Battery Chargers.


AC Voltage Regulators

AC

VoltageController

V0(RMS)

fS

Variable AC

RMS O/P Voltage

AC

Input

Voltage

fs

Vs

fs

Type of input: AC supply (fixed voltage & frequency).

Type of output: Variable AC RMS O/P voltage.


Single Phase Ac-Ac Converter


Applications

Speed control of ac motors.

Speed control of fans (domestic and industrial fans).

AC pumps.


Cyclo Converters

Cyclo

Converters

V , f0 0

f < f0 S

Variable Frequency

AC Output

Vs

fs

ACInput

Voltage

Type of input: AC supply (fixed voltage & frequency).

Type of output: Variable frequency ac O/P voltage.


Applications

Traction vehicles

Gearless rotary kilns.


DC Choppers

DC

Chopper

V0(dc)

-

Variable DC

Output VoltageVs

+

+

-

Type of input: Fixed DC supply voltage.

Type of output: Variable DC voltage.


Dc-Dc Converter


Applications

Speed control of DC motors from a DC supply.

DC drives for sub-urban traction.

Switching power supplies.


Inverters

Inverter

(ForcedCommutation)

AC

Output Voltage

+

-

DC

Supply

Type of input: Fixed DC supply voltage.

Type of output: AC O/P voltage.


Single Phase Dc-Ac Converter


Applications

Industrial AC drives using induction and synchronous motors.

Uninterrupted power supplies (UPS system) used for computers, computer labs.


Peripheral Effects


Induced current and voltage harmonic into supply system, and at the output of the converters.

Distortion in the output voltage.

Unwanted electromagnetic radiation.

Interference with communication circuits.

Peripheral Effects

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