Power Electronics chapter01

8/19/2019 Power Electronics chapter01

1/37

1

1

Power

Electronics

CHAPTER 1

In t roduct ion


2/37

2

2

Power

Electronics

Power electronic circuit vs electronic circuit

Resistor Capacitor Inductor Transistor Diode

Different circuit design methodologies used


3/37

3

3

Power

Electronics

work

power

(energy)

used

heat energy

sweat tired

power consumption

work

power

(energy)used

heat energy

Fan/heat sink

power consumption

Battery discharged

How to work with less power consumption High efficiency required

Human beings

Electronics


4/37

4

4

Power

Electronics

Electronic circuit is working

I

V

+

-

0

0

I

V

0 P

How to design circuits with less power consumption and high efficiency

Power electronics circuit


5/37

5

5

Power

Electronics

Why power electronics so important

Rapidly increasing energy

demand

Energy crisis & energy security

Environmental issues Wide usage of portable devices


6/37

6

6

Power

Electronics

High efficiency is essential.

Power Electronics Circuits

Pin Pout

Ploss

Ploss / Pout

0.5

1

heat

Power

Electronic

circuit

lossout in P P P

lossout

out

in

out

P P

P

P

P


7/377

7

Power

Electronics

Input

source

Output

load

dc-dc

converter

ac-ac

converter

ac-dc

rectifier

dc-ac

inverter

Power electronic

circuits

Power Electronic Circuits

DC

AC

DC

AC


8/378

8

Power

Electronics


9/379

9

Power

Electronics

Vdc Vo

How realized ?

Simple AC-DC Converter

Vdc VoRload?

Io = 10 A

= 50 V

= 100 V

50V, 10A,500W

+ 50 V -

Rconv = 5

Io = 10 A

= 50 V

= 100 VRload = 5

Simplest way is using resistive voltage divider

dc-dc

converterac-dc

rectifier

controllabledc

uncontrollabledc

raw ac

input


10/3710

10

Power

Electronics

Most of loads have dynamic characteristics

The resistance of the converter should change accordingly, with load condition changed.


Vdc Vo

+ 50 V -

Rconv : 5 1

Io : 10 A 50 A

= 50 V

= 100 V

Rload : 5 1

3

2

1

Converter should behave as a series/adjustable resistor


11/3711

11

Power

Electronics

iD +

-

vDS

A transistor can work as a variable resistor

RDS


vDS [V]

iD [mA]

RDS1

RDS2

RDS3

RDS4

Controlling gate voltage of a transistor can change resistor RDS

iD +

-

vDS

Characteristic curve of transistor


12/3712

12

Power

Electronics

Vdc

controller

Vo

Vo.ref

Rload

Transistor operates in linear-mode

• Gate voltage control by feedback system

Change effective resistor

Only applied at low power levels

Linear regulator

AC-DC Converter with Linear Regulator

Io = 10 A

= 50 V

= 100 V

+ 50 V -

Pin = 1000 WPout = 500 W

Ploss = 500 WHigh power loss

in linear circuit

dc-dc

converterac-dc

rectifier

controllabledc

uncontrollabledc

raw ac

input


13/3713

13

Power

Electronics

Switching Circuit based AC-DC Converter

vDS [V]

iD [mA]

vDS [V]

iD [mA]

Switch open:

iD = 0

Switch closed:

vDS = 0

Ideal switch consumes zero power

In both cases:

P = VDS iD = 0

iD +

-

vDS

iD +

-

vDS

A transistor can work as a switch

idealized

trioderegion

Cut-offregion

14


14/3714

14

Power

Electronics

on-time of S1

Rload

Io = 10 A

Vo = 50 V

Vdc

100 V

+

-

+

-

Switching regulator

Vs

+

-

Vs Vdc Vdc

S1

S2

S1 ON S2 ON S1 ON

AC-DC Converter

Ts

dc-dc

converterac-dc

rectifier

controllabledc

uncontrollabledc

raw ac

input

D = duty cycle

=Ts

15


15/3715

15

Power

Electronics

The switching operation can change the dc voltage level

AC-DC Converter

Vs

Vdc Vdc

S1 ON S2 ON S1 ON

Vs,avg = DVdc

Ts

increased dc

voltage levellonger duration

sT

dc s

s

avg s DV dt V T

V 0

,

1

DC component of Vs = average value

16


16/3716

16

Power

Electronics

Addition of LC low-pass filter to remove high freq. components of V s

Rload

Io = 10 A

Vo = 50 V

+

-

+

-

+

-

S1

S2

LC low-pass

filter

Vs

Vdc

100 V L

C

Vs Vdc Vdc

Vo = Vs,avg + vripple

S1 ON S2 ON S1 ON

AC-DC Converter

DC negligible

17


17/3717

17

Power

Electronics

Rload

Ideally no converter losses with switching approach

Io = 10 A

Vo = 50 V

+

-

+

-

+

-

S1

S2 Vs

Vdc 100 V L

C

Ideally speaking,

Switch – no losses

L, C – no losses

AC-DC Converter

Ideally Ploss = 0

Pin = 500 WP

out

= 500 W

18


18/3718

18

Power

Electronics

Linear vs Switching circuit

Linear regulator

Large size and heavy weight

High power losses

Used in labs or very lowpower applications

Switch-Mode Power Supply

(SMPS)Switching regulator

Small size and light weight

Very low power losses

Used in most electronics

19


19/3719

19

Power

Electronics

Components of Power Electronic Circuits

- Semiconductor switch: energy flow control from input to output

- Inductor & capacitor: energy transmitter and filter for remove ripple component

- Transformer: voltage gain control of input & output and galvanic isolation

20


20/3720

20

Power

Electronics

1 2 1

Rload Vo

+

-

+

-

+

-

S1

S2

Vs Vdc

100 V

L

C

AC-AC Converter

S4

S3

Vdc

-Vdc

2 Vs modeMode 1: S1 & S4 ON

Mode 2: S2 & S3 ON

Vs = Vdc

Vs = -VdcVs,avg = Vo

dc-ac

inverterac-dc

rectifier

controllableac

uncontrollabledc

raw ac

input

21


21/3721

21

Power

Electronics

control input port

Controller

raw input source

(DC or AC)

regulated output

(DC or AC)

Raw power

Uncontrolled magnitude

Uncontrolled frequency

Conditioned power

Controllable magnitude

Changeable frequency & phase

Power

input port

Power

Electronic

Circuits

High efficiency

Very

important

Power Electronics Systems

Power/Energy processing

measurement

reference

Power electronics process and control electrical power/energy flow bymanipulating voltage and current in optimal form suited for loads

Power

output port

22


22/37

22

22

Power

Electronics

Applications – Charger & PMIC


23/37

24


24/37

24

24

Power

Electronics

Applications – Display

25


25/37

25

25

Power

Electronics

Applications

Elevator HVDC Transmission

26


26/37

26

26

Power

Electronics

Applications - Trains

KTX Sancheon (2010)

Maglev (Magnetic Levitation) train

Subway

27


27/37

27

27

Power

Electronics

Applications – EV/HEV

28


28/37

28

28

Power

Electronics

Applications – New renewable energy systems

29


29/37

29Power

Electronics

Applications – New renewable energy systems

30


30/37

30Power

Electronics

Electronic Switches

switches ON short circuit

switches OFF open circuit

instantaneous transition

Ideal switch model

Desirable practical switch

1) Higher allowable current and lower on-resistance when switch is on

2) Higher blocking voltage across switch when switch is off

3) Faster transition between on-off states

4) Lower power consumption to drive switch


31/37

32


32/37

32Power

Electronics

Diode

i-v curveidealized i-v curve

reverse recovery current

limits high-frequency operation

reverse recovery time

Fast recovery diode (FRD) Schottky diode

Idealized

forward voltagedrop VF = 0

on-resistance Rd

= 0

Metal-silicon than PN junction

Small VF and little reverse

recovery, but small reverseblocking voltage

uncontrolled-on & uncontrolled-off switch

unidirectional current-flow & unidirectional voltage blocking

switching

33


33/37

33Power

Electronics

Thyristor (SCR: Silicon Controlled Rectifier)

SCR turned on v AK > 0 & gate current applied

Once SCR is on, it keeps on with no gate current (it works as diode) pulse gate current

SCR turned off SCR current goes down to minimum level (almost 0)

Highest current and voltage rating, but slow switching frequency

High power level applications only

controlled-on & uncontrolled-off switch


switching

34


34/37

34Power

Electronics

MOSFET

MOSFET turned off vGS = 0

MOSFET turned on vGS applied with 5V/15V

No power loss to drive MOSFET

on-state resistance r DS(on) increases rapidly with blocking voltage rating

limited to small blocking voltage switch

High switching frequency (typically a few hundred kHz)

voltage controlled switch

controlled-on & controlled-off switch

unidirectional current-flow, but possible reverse current flow through body-diode

unidirectional voltage blocking

body diode: useful

for rectifier &

inverterapplications

switching

35


35/37

35Power

Electronics

BJT

BJT turned off base current iB = 0

BJT turned on sufficient base current provided (even a few ampere)

considerable power loss to drive BJT

small on-state voltage Vce(sat) (typically 1 ~ 2 V) low conduction loss Slower switching speed than MOSFET

Rarely used as electronic switch after invent of IGBT, only used for linear regulator

current controlled switch

controlled-on & controlled-off switch


switching

36


36/37

36Power

Electronics

IGBT(Insulated Gate Bipolar Transistor)

MOSFET

No power loss

(Good)

high power loss

(Bad)

high RDS(on) with

high blocking

voltage (Bad)

Small on-state

voltage drop(Good)

BJT IGBT

IGBT turned off vGE = 0

IGBT turned on vGE applied with 5V/15V

No power loss to drive IGBT as MOSFET

small on-state voltage Vce(sat) low conduction loss as BJT

Higher current and voltage ratings than MOSFET

Slower switching frequency than MOSFET (typically a few ten kHz)

voltage controlled switch

37

S it h l ti


37/37

Power

Switch selection

Power Electronics chapter01

Documents

Transcript of Power Electronics chapter01