Advanced PFC

7/31/2019 Advanced PFC

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11/11/2003 Advanced Techniques in PowerFactor Correction

1

Advanced Techniques in Power FactorCorrection (PFC)

Prof. Dr. Javier Sebastin

Grupo de Electrnica Industrial

Universidad de Oviedo (Spain)


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2

Outline

Introduction

Using a simple resistor to comply with the IEC 61000-3-2 in Class A

Using an inductor to comply with the IEC 61000-3-2 in Class A and in

Class D

Exploring the use of isolated Resistor Emulators as the only

conversion stage for medium-speed response applications

High-efficiency post regulators used to improve the transient

response of Resistors Emulators

Very simple single-stage PFCs

Very simple current shaping techniques for very low-cost applications


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3

Outline

Introduction



Class D








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4

Cheap & reliable Input current with astrong harmonic content

Current

Focusing the problemIntroduction (I)

Electronic

circuitry

Power supply

DC/DC

converter

Line

Electronic load


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5

Load

Electronicload

Line impedance

Line

Load

Load

Introduction (II)

Current

Input

voltage

Distorted


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6

Power Factor (PF)

PF=Input power

Input voltage, rms X Input current, rms

THD=(Input current, rms)2 - (Its 1ST harmonic, rms)2

Its 1ST harmonic, rms

Introduction (III)Quantifying the problem

Total Harmonic Distortion (THD)

Each individual harmonic

Europeanregulations

Word used to describethe problem


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7

Introduction (IV)

Power Companies will:

High PF

No harmonics

Electronic equipment

manufacturers will:

Low cost

Reliability

Conflict of interest

Regulations aboutharmonics in the line


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8

Electronicload

Line impedance

Line

Electronicload

Electronicload

ActiveFilter

Introduction (V)Starting solving the problem (I)

Using active filters


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9

Introduction (VI)Starting solving the problem (II)

Modifying the electronic load Power Factor Correctors

Inputcurrent

Either

or

Electronic

circuitry

Power supply

DC/DC

converter

Electronic load

NewdevicesLine

Power Factor Corrector


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10

Introduction (VII)

However:the value of the Power Factor is notimportant.

According to the European Regulations, only the value

ofeach individual harmonic is important.

We should use words such as Low-Frequency

Harmonic Reduction and Low-Frequency

Harmonic Reducer instead of Power Factor

Correctionand PowerFactorCorrector.


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11

Focusing the courseIntroduction (VIII)

Line

Single-Phase

Three-Phase Conversion

AC/DC

AC/AC

Power

High power

Low-medium power(230V,


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12

What is the right choice in PFC?

It strongly depends on the application. There is notmagic solutions.

It depends on:

The regulations that must be applied The type of equipment

The output power

The input voltage range

The output voltage

The dynamic response needed

The main objective in the design

Introduction (IX)


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13

ClassA

YesBalanced3 equipment?

Portabletool?

No

Lightingequipment?

No

PC or TV &P


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14

Harmonic Class A [A] Class D [mA/W]

3 2.3 3.4

5 1.14 1.9

7 0.77 1.0

9 0.40 0.511 0.33 0.35

13 0.21 0.296

15 n 39 2.25/n 3.85/n

Introduction (XI)

Harmonic limits for Class A and Class D

Very Important!!

Limits in Class A are absolute values [A]

Limits in Class D are relative values [mA/W]


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15

Harmonic Limits in

Class A [mA]

Limits in

Class D [mA]

3 2300 340

5 1140 190

7 770 1009 400 50

11 330 35

13 210 29.6

15 n 39 2250/n 385/n

Introduction (XII)

Example #1: a 100 W (low-power) converter

Limits in Class A are less strict for low-power applications


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16

Harmonic Limits in

Class A [mA]

Limits in

Class D [mA]

3 2300 1700

5 1140 950

7 770 5009 400 250

11 330 175

13 210 148

15 n 39 2250/n 1925/n

Introduction (XIII)

Example #2: a 500 W (medium-power) converter

Limits in Class A and in Class D become more

similar for medium-power applications


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17

Introduction (XIV)

Battery

Example #1: a 100 W (low-power) batterycharger (Class A)

Linecurrent

Linevoltage

This waveform complies

with the regulations!!!

PF = 0.46 and

THD = 193.1%

Very cheap systems for low-frequency harmonic attenuation

can be used to obtain this type of waveform


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18

Introduction (XV)

Example #1: a 100 W (low-power) TV set (Class D)

Linecurrent

Linevoltage

A slightly more complex system

must be used (it is still very simple)

Linevoltage Line

current

PF = 0.748 and

THD = 88.8%

It does not comply with

the regulations


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19

Introduction (XVI)

Example #2: two 500 W (low-power) pieces ofequipment

The advantages of being Class A vanish at 500 W

Linevoltage Line

current

PF = 0.748 and

THD = 88.8%

Linevoltage

Linecurrent

PF = 0.705 andTHD = 100.5%

Class AClass D


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20

Introduction (XVII)

The complexity of the systems for low-frequency

harmonic attenuation increases with the power

Linevoltage

Linecurrent

PF = 0.705 and

THD = 100.5% PF = 0.963 andTHD = 28.1%

Linecurrent

Linevoltage

Example #3: same Class, different power


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21

Introduction (XVIII)

Influence of the input voltage range (I)

European range: 190 Vac 265 Vac

American range: 85 Vac 130 Vac

Universal range: 85 Vac 265 Vac

Two ranges (American and European), but a

mechanical switch permitted for changing therange


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22

Introduction (XIX)Influence of the input voltage range (II)

Electronic

circuitryLine

Power supply

DC/DC

converter

Electronic load

PFC

Single range (either European or American) and simple system for

low-frequency harmonic attenuation (PFC)

Moderate change in the input voltage of the DC/DC converter

Slight penalty in efficiency

Simple PFC with

single range


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23

Introduction (XX)

Electronic

circuitryLine

Power supply

DC/DC

converter

Electronic load

PFC

Universal range and simple PFC

Large change in the input voltage of the DC/DC converter

Significant penalty in efficiency

Complex PFCs which guaranty constant input voltage are interesting

Complex PFC with

universal range

Influence of the input voltage range (III)

I d i (XXI)


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24

Introduction (XXI)

Is it compatible with the

use of simple PFC?

Electronic

circuitry

Power supply

DC/DC

converter

Electronic load

Electronic

circuitry

Power supply

DC/DCconverter

Electronic load

230V

110V

Power supply for single

range without PFC

Power supply for double

range without PFC

Two ranges selected by a switch

Influence of the input voltage range (IV)

I d i (XXII)


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25

Introduction (XXII)

Simple PFC placed

on the DC side 110V

230V

Power supply

DC/DC

converter

SimplePFC

SimplePFC

110V

230V

Power supply

DC/DCconverter

Simple

PFCSimple PFC placedon the AC side

Influence of the input voltage range (V)

Two ranges selected by a switch and PFC

I t d ti (XXIII)


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26

Current

Introduction (XXIII)

Electronic

circuitryLine

Power supply

DC/DC

converter

Electronic load

Electronic

circuitryLine

Power supply

DC/DCconverter

as

Electronic load

ResistorEmulator

Current

Changing the place of the DC/DCconverter Resistor Emulator concept

I t d ti (XXIV)


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27

Introduction (XXIV) Using only a Resistor Emulator (I)

Line

Power supply

DC/DCconverteras

ResistorEmulator

Output

Current

Line

Power supply

DC/DC

converterOutput

Current

Energy stored at high voltage

(325 V DC) small size

Energy stored at the outputvoltage the size depends onthe voltage

It is not a good solution for low-voltage

(


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28

Introduction (XXV) Using only a Resistor Emulator (II)

Power

Line

Power supply

DC/DC

converterOutput

Current

Voltage

Line

Power supply

DC/DCconverter

as

Resistor

Emulator

Output

Current

VoltagePower

No devices to store

energy at 100 Hz

Energy stored here

The converter is in charge of

cancelling the output rippleLittle (or no) power processed at

specific moments the outputripple depends on the capacitor

It is not a good solution when

low output-ripple is needed

I t d ti (XXVI)


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Introduction (XXVI) Using only a Resistor Emulator (III)

Power

Line

Power supply

DC/DCconverter

as

ResistorEmulator

Output

Current

Voltage

Line

Power supply

DC/DC

converterOutput

Current

Voltage

Power

No devices to store energy at 100 HzEnergy stored here

The converter can get energy from the

capacitor to maintain the output voltage

when the output current changes

Little (or no) power processed at

specific moments no energyavailable to maintain the output

voltage when the output current

changesIt is not a good solution when fast

transient response is needed

Introduction (XXVII) I th f f t t i t


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11/11/2003 Advanced Techniques in PowerFactor Correction 30

Introduction (XXVII) In the case of fast transient responseneeded:

Power supply

Electronic

circuitryLine

Simple orcomplex

PFC

DC/DCconverter

Two separate

stages

Electronic

circuitryLine

Power supply

Simple

PFCsection

DC/DC

converter

section

One integrated

stage

A DC/DC converter

(or section) is needed

DC/DCconverter

DC/DC

converter

Introduction (XXVIII)


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Cost

Size

Weight

Efficiency

Only comply with the regulations

High Power Factor and low Total Harmonic

Distortion (for marketing reasons)

Introduction (XXVIII)

What are the design priorities?

They also determine the right choice


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Outline

Introduction

Using a simple resistor to comply with the IEC 61000-3-2 in

Class A


Class D







Using a resistor (I)


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Using a resistor (I)

Looking for the simplest solution (I)

Line

Power supply

DC/DC

converter

(120 W)200 mF

4 X 1N4007

Capacitor voltage

Input current Class D

Using a resistor (II)


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Using a resistor (II) Looking for the simplest solution (II)

Input currentOrder Measured [A] Limits Class D [A]

1 0.542 -

3 0.527 0.4085 0.498 0.228

7 0.457 0.12

9 0.407 0.06

11 0.351 0.042

13 0.294 0.036

15 0.239 0.031

17 0.192 0.027

19 0.155 0.024

21 0.132 0.022

23 0.121 0.02

25 0.117 0.018

27 0.115 0.017

29 0.112 0.016

31 0.105 0.015

33 0.097 0.014

35 0.087 0.013

37 0.079 0.012

39 0.073 0.012The compliance is very far

0 5 10 15 20 25 30 35 400

0.2

0.4

0.6

Harmonic order

Input current [A]

Limits in Class D

Simulated

Using a resistor (III)


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Using a resistor (III) Looking for the simplest solution (III)

What about a Class A piece of equipment?

Line

Battery Charger

DC/DC

converter

(120 W)200 mF

4 X 1N4007 Battery

Capacitor voltage

Input current Class A

Using a resistor (IV)


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Using a resistor (IV) Looking for the simplest solution (IV)

Input current

It does not comply, but it

is very near to comply

Order Measured [A] Limits Class A [A]

1 0.542 -

3 0.527 2.35 0.498 1.14

7 0.457 0.77

9 0.407 0.4

11 0.351 0.33

13 0.294 0.21

15 0.239 0.15

17 0.192 0.13219 0.155 0.118

21 0.132 0.107

23 0.121 0.098

25 0.117 0.09

27 0.115 0.083

29 0.112 0.078

31 0.105 0.073

33 0.097 0.068

35 0.087 0.064

37 0.079 0.061

39 0.073 0.058

0 5 10 15 20 25 30 35 400

0.5

1

1.5

2

2.5

Harmonic order

Input current [A]

Limits in Class A

Simulated

Using a resistor (V) L ki f h i l l i (V)


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Using a resistor (V) Looking for the simplest solution (V)

Order Measured [A] Limits Class A [A]

1 0.528 -

3 0.5 2.3

5 0.448 1.14

7 0.378 0.77

9 0.3 0.4

11 0.225 0.33

13 0.164 0.21

15 0.128 0.1517 0.115 0.132

19 0.113 0.118

21 0.109 0.107

23 0.1 0.098

25 0.087 0.09

27 0.076 0.083

29 0.07 0.07831 0.067 0.073

33 0.066 0.068

35 0.063 0.064

37 0.058 0.061

39 0.053 0.058

Line

Battery Charger

DC/DC

converter

(120 W)100 F

4 X 1N4007

Let us change the value of the bulk capacitor

Capacitor voltage

Input current

Almost compliance

with 100 mF

Using a resistor (VI) L ki f h i l l i (VI)


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Using a resistor (VI) Looking for the simplest solution (VI)

However, the value of the bulk capacitor cannot be

freely chosen because:

Hold-up time requirements

Input voltage range of the DC/DC converter

Another solution must be found

Using a resistor (VII)


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Using a resistor (VII)

The simplest solution: to add a resistor

Electronic

circuitry

Class A

Line

Power supply

DC/DC

converter

DC side

Electronic

circuitryClass A

Line

Power supply

DC/DC

converter

AC sideR

R

Using a resistor (VIII)


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@ 230V ac, R =1.5 Wiinput peak = 4.12 A

Presistor= 1.85 W

Using a resistor (VIII)

Order Measured [A]with R=0

Measured [A]with R=1

Measured [A]with R=1.5

LimitsClass A [A]

1 0.542 0.539 0.538 -

3 0.527 0.52 0.516 2.3

5 0.498 0.484 0.474 1.14

7 0.457 0.433 0.416 0.77

9 0.407 0.372 0.347 0.4

11 0.351 0.304 0.273 0.33

13 0.294 0.237 0.2 0.21

15 0.239 0.173 0.135 0.15

17 0.192 0.12 0.084 0.132

19 0.155 0.084 0.056 0.118

21 0.132 0.067 0.053 0.107

23 0.121 0.066 0.057 0.098

25 0.117 0.067 0.058 0.09

27 0.115 0.065 0.052 0.083

29 0.112 0.058 0.041 0.078

31 0.105 0.047 0.029 0.073

33 0.097 0.036 0.021 0.068

35 0.087 0.028 0.02 0.064

37 0.079 0.025 0.022 0.061

39 0.073 0.026 0.024 0.058

Cbulk = 200 mFPconverter= 120 W

Using a resistor (IX)I f i h i


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@ 230V ac, R =1.5 Wiinput peak = 4.12 APresistor= 1.85 W

Using a resistor (IX)

Cbulk = 200 mFP

converter= 120 W

Input-current waveform with a resistor

Capacitor voltage

Input current

Capacitor voltage

Input current

@ 230V ac, R =0 Wiinput peak = 6.37 A

Using a resistor (X)


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Using a resistor (X)Design procedure

Obtain the resistor

(from graphs)

Use the simplestmethod

Othermethod must

be used

Choose bulk

capacitor

Input power

Calculate losses @ full

power, 190 Vac

Acceptablelosses?

NO YES

Using a resistor (XI)


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50 100 150 200 250 300

1

2

3

4

R [ ]

Output power [W]

Using a resistor (XI)Value of the resistor needed to complywith the IEC 61000-3-2 in Class A as afunction of the input power (bulk capacitor

inmF per watt as parameter)

0.5 F/W1 F/W

2 F/W

Using a resistor (XII)Ab l t l t f ll


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11/11/2003 Advanced Techniques in Power

Factor Correction

44

Using a resistor (XII)Absolute power losses at fullload and minimum line voltage(maximum line current)

Output power [W]

Power losses [W]

50 100 150 200 250 300

5

10

15

20

25

1 F/W

2 F/W

0.5 F/W

Using a resistor (XIII)Relative power losses (P /P at


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Factor Correction

45

Using a resistor (XIII)Relative power losses (PR/Poutput) atfull load and minimum line voltage(maximum line current)

Output Power [W]

Relative losses [%]

50 100 150 200 250 300

2

4

6

8

10

0.5 F/W

1 F/W

2 F/W

Using a resistor (XIV)D i l


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Factor Correction

46

g ( )Design example:Poutput=150W, C=150mF (1mF/W)

50 100 150 200 250 300

1

2

3

4

R [ ]

Output power [W]

1 F/W

2.5 W


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Using a resistor (XVI)Power limits for this solution


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Factor Correction

48

g ( )Power limits for this solution

Output Power [W]

Relative losses [%]

50 100 150 200 250 300

2

4

6

8

10

1 F/W

Veryinteresting Not sointeresting

Using a resistor (XVII)Using this solution for Universal line


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Factor Correction

49

Power lossesstrongly increase at

low line voltage

g ( )

Pconverter= 120 WCbulk = 200 mFR=1.5 W

Using this solution for Universal linevoltage range

Line

Quantity

@ 230V @ 110V

iinput peak 4.12 A 5.09A

iinput RMS 1.11 A 1.853 A

Plosses resistor 1.85 W 5.15 W

Line

Power supply

DC/DCconverter

PconverterCbulk

4 X 1N4007

R

Using a resistor (XVIII) Adaptation for operation in two ranges (I)


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Factor Correction

50

g ( ) Adaptation for operation in two ranges (I)

DC/DCconverter

Electronic

circuitry

Class A

Line

Power supply

R/2

R/2

DC side

230V

110V

AC sideElectronic

circuitry

Class A

DC/DC

converter

Power supply

Line

R

230V

110V

Different operation (AC side & DC side)

Using a resistor (XIX) Adaptation for operation in two ranges (II)


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Factor Correction

51

g ( ) Adaptation for operation in two ranges (II)

Electronic

circuitry

Class A

DC/DC

converter

Power supply

Line

R

230V

110V

iinput 230V

AC sideElectronic

circuitry

Class A

DC/DC

converter

Power supply

Line

R

230V

110V

iinput 110V

Both iinput 110V and iinput 230V passing through R

Using a resistor (XX) Adaptation for operation in two ranges (III)


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Factor Correction

52

Adaptation for operation in two ranges (III)

DC side

DC/DC

converter

Electronic

circuitry

Class ALine

Power supply

R/2

R/2

230V

110V

iinput 110V

DC/DC

converter

Electronic

circuitry

Class ALine

Power supply

R/2

R/2

230V

110V

iinput 230V

iinput 110V passing through R/2and iinput 230V passing through R (better)

Using a resistor (XXI)Adaptation for operation in two ranges (IV)


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Factor Correction

53

Adaptation for operation in two ranges (IV)

DC/DC

converter

Electronic

circuitry

Class A

Line

Power supply

R/2

R/2

230V

110V

110V

Electronic

circuitry

Class A

DC/DC

converter

Power supply

Line

R230V

110V

110V

Example:

Pconverter = 120 W

Cbulk = 2 X 400 F (series)R=1.5

Plosses resistors = 3.15 W

(total)

Plosses resistor= 5.27 W

Using a resistor (XXII)Adaptation for operation in two ranges (V)


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Factor Correction

54

Impractical due to the fact that the power losses strongly

increase at low line voltage

Power R C losses

@ 230V

losses

@ 190V

losses

@ 110V

losses

@ 85V

100 W 1.6 W 2x220 mF 1.3 W 1.6 W 3.8 W 5 W

200 W 3.6 W 2x440 mF 8.5 W 11.5 W 29 W 50 W

Adaptation for operation in two ranges (V)

Electronic

circuitry

Class A

DC/DC

converter

Power supply

Line

R230V

110V

C

C

Using a resistor (XXIII)Adaptation for operation in two ranges (VI)


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Factor Correction

55

Better results with the resistor split into two resistors

Adaptation for operation in two ranges (VI)

DC/DC

converter

Electronic

circuitryClass A

Line

Power supply

R/2

R/2

230V

110V

C

C

Power R C losses

@ 230V

losses

@ 190V

losses

@ 110V

losses

@ 85V

100 W 1.6 W 2x220 mF 1.3 W 1.6 W 2.1 W 3.1 W

200 W 3.6 W 2x440 mF 8.5 W 11.5 W 16 W 25 W

Using a resistor (XXIV)Experimental results (I)


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Factor Correction

56

Line

R/2

R/2

230V

110V

C

C

1 A/div

@ 230V, 100W

2 A/div

@ 110V, 100W

@ 230V, 100W,2x0.82 , 2W

0

0.5

1

1.5

2

2.5

11 19 317 15 23 35273

Harmonic Order

Input current [A]

Limits inClass A

Measured

Experimental results (I)

Pconverter = 100 W

C = 2 X 100 F (series)

R = 2x0.82

Using a resistor (XXV)Experimental results (II)


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Factor Correction

57

Line

R/2

R/2

230V

110V

C

C

2 A/div

@ 230V, 200W

2 A/div

@ 110V, 200W

Experimental results (II)

Pconverter = 200 W

C = 2 X 200 F (series)

R= 2x1.8

@ 230V, 200W,2x1.8 , 10W

0

0.5

1

1.5

2

2.5

11 19 317 15 23 35273

Harmonic Order

Input current [A]

Limits inClass A

Measured

Using a resistor (XXVI) Conclusions of the use of a resistor to


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Factor Correction

58

comply with the IEC 61000-3-2regulations in Class A

This is the simplest possible solution Low-cost and low-size solution

Very interesting for low-power (P


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Factor Correction

59

Outline

Introduction


Using an inductor to comply with the IEC 61000-3-2 in Class A

and in Class D

Exploring the use of isolated Resistor Emulators as the onlyconversion stage for medium-speed response applications





Using an inductor (I)Another very simple solution: to add an inductor


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Factor Correction

60

Another very simple solution: to add an inductor

Electronic

circuitry

Class A

Line

Power supply

DC/DC

converter

DC side

Electronic

circuitry

Class A

Line

Power supply

DC/DC

converter

AC side

L

L

Using an inductor (II)


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Factor Correction

61

@ 230V ac, L = 2 mHiinput peak = 3.84 A

Order Measured [A]with L=0 mH

Measured [A]with L=1 mH

Measured [A]with L=2 mH

LimitsClass A [A]

1 0.542 0.552 0.545 -

3 0.527 0.531 0.515 2.35 0.498 0.493 0.459 1.14

7 0.457 0.438 0.384 0.77

9 0.407 0.374 0.299 0.4

11 0.351 0.303 0.214 0.33

13 0.294 0.232 0.138 0.21

15 0.239 0.167 0.079 0.15

17 0.192 0.11 0.046 0.132

19 0.155 0.067 0.039 0.118

21 0.132 0.042 0.04 0.107

23 0.121 0.036 0.036 0.098

25 0.117 0.037 0.028 0.09

27 0.115 0.037 0.02 0.083

29 0.112 0.032 0.017 0.078

31 0.105 0.025 0.016 0.073

33 0.097 0.019 0.016 0.068

35 0.087 0.016 0.014 0.064

37 0.079 0.015 0.011 0.061

39 0.073 0.015 0.009 0.058


Using an inductor (III)Input-current waveform and harmonic


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Factor Correction

62

Input current waveform and harmoniccontent with an inductor

Capacitor voltage

Input current

Example:


L = 2 mH

0 5 10 15 20 25 30 35 40

0

0.2

0.4

0.6

Input current [A]

Limits in Class D

Simulated

Harmonic order

@ 230V, 120 W@ 230V, 120 W

Harmonic order

0 5 10 15 20 25 30 35 400

0.5

1

1.5

2

2.5

Input current [A]

Limits in Class A

Simulated

It complies

It does not

comply

Comparing input-current waveform withUsing an inductor (IV)


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Factor Correction

63


Comparing input current waveform withan inductor and a resistor for Class Aequipment

@ 230V ac, R =1.5 Wiinput peak = 4.12 A

Presistor= 1.85 W

Capacitor voltage

Input current

@ 230V ac, L = 2 mHiinput peak = 3.84 A

Capacitor voltage

Input current

Comparing input-current waveforms withUsing an inductor (V)


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Factor Correction

64

0

5

10

10 ms0

C = 200 F

C = 800 F

Comparing input current waveforms withdifferent bulk capacitor values

Slightly influence of

the capacitor value

340 V

288 V

8.38 A

C = 200 F10 ms 20 ms0

Capacitor

voltage

Input current

0

312 V

300 V

7.55 A

C = 800 F

10 ms 20 ms0

Capacitor

voltage

Input current

L = 3.3 mH

Pconverter

= 400 W

Using an inductor (VI)Looking for the most restrictive harmonics (I)


65/268


Factor Correction

65

3 5 7 9 11 13 15 17 19

0.5

1

1.5

22.5

3

3.5

Harmonic Order

@ 230V, 100 W,

1.7 mH & 47 mF

Input current [A]

Limits inClass A

Simulated

20 ms-5

0

5

3.85 A

10 ms0

Input current [A]

Time

g ( )

Example: 100 W,1.7 mH & 47 F

Harmonics 13th-17thare the most restrictive

at low power

Using an inductor (VII)Looking for the most restrictive harmonics (II)


66/268


Factor Correction

66

Example: 600 W,7.8 mH & 330 F

Harmonics 3rd-5th are

the most restrictive at

high power

g ( )

0.5

1

1.5

2

2.5

3

3.5

3 5 7 9 11 13 15 17 19

Harmonic Order

@ 230V, 600 W,

7.8 mH & 330 mF

Input current [A]

Limits inClass A

Simulated

-10

0

108.68 A

10 ms 20 ms0

Input current [A]

Time

Using an inductor (VIII)Value of the minimum inductor needed to comply


67/268


Factor Correction

67

100 200 300 400 500 600

2

4

6

8

L [mH]

Output power [W]

0.5 F/W

2 F/W

p ywith the IEC 61000-3-2 in Class A as a functionof the input power (bulk capacitor inmF per wattas parameter)

Using an inductor (IX)Comparing the influence of the bulk capacitor for


68/268


Factor Correction

68

Comparing the influence of the bulk capacitor forthe case of the inductor and the resistor

0.5 F/W

2 F/W

100 200 300 400 500 600

2

4

6

8

L [mH]

Output power [W]

50 100 150 200 250 300

1

2

3

4 R [ ]

Output power [W]

0.5 F/W

1 F/W2 F/W

Lower inductor values with

high bulk capacitor values

Erratic influence of the

value of the bulk capacitor

Design procedureUsing an inductor (X)


69/268


Factor Correction

69

Design procedurefor Class A

Obtain the inductor

(from graphs)

Use this method

Other

method mustbe used

Choose bulk

capacitor

Input power

Calculate the inductor

size

Acceptablesize?

NOYES

Using an inductor (XI)Design example:


70/268


Factor Correction

70

100 200 300 400 500 600

2

4

6

8

L [mH]

Output power [W]

0.5 F/W

2 F/W2.7 mH

g pPoutput=200 W, C=100mF (0.5mF/W)

Using an inductor (XII)What about the inductor size?


71/268


Factor Correction

71

We must know the maximum peak value of the input current (at full

load and minimum line voltage) determine the gap and number ofturns

We must know the maximum RMS value of the input current (at full

load and minimum line voltage) determine the wire size (diameter)and losses

Input power[W]

L [mH] Ipeak [A] IRMS [A]Equivalent

ferritecore size

Power losses(%)

200 2.7 5.33 @ 230V6.07 @ 190V

1.6 @ 230V1.88 @ 190V

E30/15/7 0.8

Using an inductor (XIII)Inductor size and losses for different


72/268


Factor Correction

72

power levels

Input power[W]

L [mH]Equivalent

ferritecore size

Power losses(%)

100 2 E20/10/5 0.53

200 2.7 E30/15/7 0.8

300 3.4 E42/21/15 0.3

400 4.4 E42/21/15 0.66

500 6.8 E42/21/20 0.57

600 7.8 E42/21/20 1.66

Using an inductor (XIV)Magnetic materials for the inductor (I)


73/268


Factor Correction

73

10 100 1000 10000 100000

0.5

1

1.5

2

B [T]

H [A/m]

B [mT]10 100 1000 10000

0.01

0.1

1

10

100

Plosses [kw/m3]

g ( )

Silicon steel laminationcore (instead of ferrite)

Example: RG11

High induction levels(1.4 T) are possible

Magnetic materials for the inductor (II)Using an inductor (XV)


74/268


Factor Correction

74

DC-side or AC-side inductor?Using an inductor (XVI)


75/268


Factor Correction

75

Line current

with DC-side

inductor

Capacitor voltage

with DC-side inductor

Time

with AC-side

inductor

with AC-side

inductor

DC-side inductor

AC-side

inductor

Exactly the same result if the converter is

working in strong DCM

Example: Cbulk = 200 mF, L = 2 mH, Pconverter= 120 W

Using an inductor (XVII)What about complying with the IEC


76/268


Factor Correction

76

0 5 10 15 20 25 30 35 40

0

0.2

0.4

0.6Input current [A]

Limits in Class D

Simulated

Harmonic order

@ 230V, 120 W


Low-frequency harmonics are the most significant ones

A considerable increase in the inductance value is needed

61000-3-2 regulations in Class D?

Looking for the minimum value of L toUsing an inductor (XVIII)


77/268


Factor Correction

77

3 5 7 9 11 13 15 17 19

0.1

0.2

0.3

0.4

0.5

Harmonic Order

@ 230V, 100W, 41mH & 200mF

Input current [A]

Limits in

Class D@ 100W

Simulated

-2

-1

0

1

21.42 A

0 10 ms 20 ms

Input current [A]

Time

Looking for the minimum value of L tocomply with the regulations in Class D (I)

Example: Cbulk

= 200 mF, L = 41 mH, Pconverter

= 100 W

An inductor of 41 mH is needed for 100 W

Looking for the minimum value of L tocomply with the regulations in Class D (II)

Using an inductor (XIX)


78/268


Factor Correction

78

comply with the regulations in Class D (II)


An inductor of 7 mH is needed for 600 W

If we increase the power, the limits will also increase a similarinput-current waveform is enough to comply with the regulations

-10

0

108.12 A

0 10 ms 20 ms

Input current [A]

Time3 5 7 9 11 13 15 17 19

1

1.5

2

2.5

3

Harmonic Order

0.5

@ 230V, 600W, 7mH & 1200mF

Input current [A]

Limits inClass D

@ 600W

Simulated

0

Using an inductor (XX)Value of the minimum inductor needed to comply


79/268


Factor Correction

79

with the IEC 61000-3-2 in Class D as a functionof the input power (bulk capacitor inmF per wattas parameter)

0.5 F/W

2 F/W

L [mH]

Output power [W]

100 200 300 400 500 600

10

20

30

40

50

The value of the inductors

inductance decreases

when the power increases,

but the size increases

(because it depends on the

square value of the peak

current)

Using an inductor (XXI)Inductor size and losses for different


80/268


Factor Correction

80

power levels

Input power[W]

L [mH]Equivalent

ferritecore size

Power losses(%)

100 41 E42/21/15 1

200 21 E42/21/15 2

300 14 E42/21/20 1.1

400 10 E42/21/20 1.25

500 8.7 E42/21/20 1.8

600 6.9 E42/21/20 2.18

Using an inductor (XXII)Comparing the value of the minimum inductor

d d l i h h IEC 61000 3 2 i


81/268


Factor Correction

81

needed to comply with the IEC 61000-3-2 inClass A and in Class D

0.5 F/W

2 F/W

L [mH]

Output power [W]

100 200 300 400 500 600

10

20

30

40

50Minimum inductor tocomply in Class D

100 200 300 400 500 600

2

4

6

8L [mH]

Output power [W]

0.5 F/W

2 F/W

Minimum inductor tocomply in Class A

Lower L values at low power Similar L values at high power

Using an inductor (XXIII) Inductor size and losses for different power levels


82/268


Factor Correction

82

Similar L sizes at high powerLower L sizes at low

power in Class A

Input power[W]

L [mH] inClass A

Equivalentcore size in

Class A

Powerlosses in

Class A (%)

L [mH] inClass D

Equivalentcore size in

Class D

Powerlosses in

Class D (%)

100 2 E20/10/5 0.53 41 E42/21/15 1

200 2.7 E30/15/7 0.8 21 E42/21/15 2

300 3.4 E42/21/15 0.3 14 E42/21/20 1.1

400 4.4 E42/21/15 0.66 10 E42/21/20 1.25

500 6.8 E42/21/20 0.57 8.7 E42/21/20 1.8

600 7.8 E42/21/20 1.66 6.9 E42/21/20 2.18

Using an inductor (XXIV)Adaptation for operation in two ranges (I)


83/268


Factor Correction

83

Different operation (AC side & DC side)

AC sideElectronic

circuitry

Class A

DC/DC

converter

Power supply

Line230V

110V

L

DC/DCconverter

Electronic

circuitry

Class A

Line

Power supply

L/2

L/2

DC side

230V

110V

Adaptation for operation in two ranges (II)Using an inductor (XXV)


84/268


Factor Correction

84

AC side

Both iinput 110V and iinput 230V passing through L

Electronic

circuitry

Class A

DC/DC

converter

Power supply

Line

230V

110V

L

Electronic

circuitry

Class A

DC/DC

converter

Power supply

Line

230V

110V

Liinput 110V

iinput 230V

Adaptation for operation in two ranges (II)Using an inductor (XXVI)


85/268


Factor Correction

85

DC side

L/2

L/2

DC/DC

converter

Electronic

circuitry

Class ALine

Power supply

230V

110V

iinput 110V passing through L/2and iinput 230V passing through L

DC/DC

converter

Electronic

circuitryClass ALine

Power supply

L/2

230V

110V

L/2iinput 110V

iinput 230V

Experimental results (I)Using an inductor (XXVII)


86/268


Factor Correction

86

Line

L

C

0.5 A/div

@ 230V, 100W

Class D

Pconverter = 100 W

C = 47 F

L = 41 mH

5 9 13 21 25 29 33

0.1

0.2

0.3

3717

@ 230V, 100W,41 mH

Harmonic order

Input current [A]

Limits inClass D

Measured

Experimental results (II)Using an inductor (XXVIII)


87/268


Factor Correction

87

Line

L

C

1 A/div

@ 230V, 100W

Class A

Pconverter = 100 W

C = 47 F

L = 1.7 mH

@ 230V, 100W,1.7 mH

Harmonic order

Input current [A]

Limits inClass A

Measured

3 15 19 23 27 31 35

1

2

119

Conclusions of the use of an inductorto comply with the IEC 61000 3 2

Using an inductor (XXVIII)


88/268


Factor Correction

88

to comply with the IEC 61000-3-2regulations in Class A and Class D

This is a very simple solution Low-cost and high-efficiency (low-losses) solution Very interesting for low-power (P


89/268


Factor Correction

89

Outline

Introduction



Class D

Exploring the use of isolated Resistor Emulators as the onlyconversion stage for medium-speed response applications





Using only a RE (I) Passive (L or R) versus active systems toreduce the harmonic content


90/268


Factor Correction

90

Line

Power supply

DC/DC

converter Outpu

t

R or L

Current

Line

Power supply

DC/DCconverter

as

ResistorEmulator O

utput

Current

Low-cost

Either low-losses or low-size Non-sinusoidal waveform solutions for low power

Unregulated voltage across thecapacitor solutions for limited linevoltage range (many times, voltage

doubler needed)

Sinusoidal waveform solutions for anypower

Regulated voltage across the capacitorsolutions for universal line voltage range

A good solution if only the

Resistor Emulator were enough

Using only a RE (II) Is only a Resistor Emulator enough toimplement the overall power supply?


91/268


Factor Correction

91

p p pp y

Power supply

DC/DC

converteras

ResistorEmulator

Output

Energy stored at the output

voltage the size depends onthe voltage

From the point of view of the capacitor size, it is not a bad

solution for medium and high voltage applications (>12 V DC)

Power supply

DC/DC

converter Output

R or L

Energy stored at high voltage

(325 V DC) small size

Using only a RE (III) And, what about the dynamics?


92/268


Factor Correction

92

DC/DCconverter

Example of Resistor Emulator control:control based on an analog multiplier

Lowpassfilter

Why a lowpass filter

here?

Using only a RE (IV)The lowpass filter influence (I)


93/268


Factor Correction

93

DC/DCconverter

LowpassfilterVeaVea

Input voltage

Current Reference=VeaSinus

Vea

Input voltage

Current Reference=VeaSinus

Filter with very-

low cut-offfrequency

Filter with

high cut-offfrequency

A filter with low cut-off frequencyis needed if a perfect sinusoidal

is required

Using only a RE (V)The lowpass filter influence (II)


94/268


Factor Correction

94

DC/DCconverter

LowpassfilterVea

Filter with very low cut-off frequency:

Perfect sinusoidal line current

Very poor dynamic response

If yes, the use of only a Resistor

Emulator as overall power

supply becomes very attractive

And, what about the

dynamic response?

Filter with high cut-off frequency:

Non-perfect sinusoidal line currentBut, can we achieve compliance withthe IEC 61000-3-2 and reasonable

dynamic response?

Using only a RE (VI) Line current waveform as a function ofthe voltage regulator pole frequency fp


95/268


Factor Correction

95

p

fp: 10 Hz

fp: 100 Hzfp: 1000 Hz

fp: 500 Hz

Voltage

regulator

fp

timef [Hz]

-135

-90

-45

0

45

1 10 100 1000 10000

AR []

AR [dB]

-40

-20

020

40

60

fp fp fpfp = 1kHz is a practical limit (no

significant phase shift at 100Hz)

Using only a RE (VII) Line current waveform as a function ofthe voltage regulator DC gain AR


96/268


Factor Correction

96

AR = 100AR = 50

fp: 10 Hz

fp: 100 Hz

fp: 1000 Hz

fp: 500 Hz AR = 100

is a practical limitdue to the voltage

levels in the

controller

Using only a RE (VIII)Looking for the worst case


97/268


Factor Correction

97

AR 100fp1000 Hz

Line current

3 11 21 31 390

1

2

3

2.3 A

Harmonic Order

Input current [A]

Limits inClass D@ 100W

Simulated

Theoretical harmonic content: Onlythe third harmonic is present

Using only a RE (IX) Why is the third harmonic the only onepresent in the line current? (I)

V i tFor 0 wt


98/268


Factor Correction

98

DC/DC

converter

LowpassfilterVea

Viref

V1sinwt

Rs

Viref

= V1

sinwt (Veao

+ Vea

sin2wt)

Veao+ Veasin2wt

V1sinwt

Viref( t) = VeaoV1sinwt +0.5V1Veacoswt - 0.5V1Veacos3wt

For 0 wtiline DC

iline DC ( t) = (VeaoV1sinwt +0.5V1Veacoswt - 0.5V1Veacos3wt)/Rs

Therefore, for 0 wtiline AC ( t) = iline DC ( t) = (VeaoV1sinwt +0.5V1Veacoswt - 0.5V1Veacos3wt)/Rs


99/268

Using only a RE (XI)Looking for the maximum power compatiblewith complying with the IEC 61000 3 2


100/268


Factor Correction

100

IEC 61000-3-2 regulations in Class A can be

complied up to very high power levels

with complying with the IEC 61000-3-2regulations in Class A (I)

AR 50-100fp1000 Hz

Line current

AR Output ripple=1 % Output ripple=2 %

50 3680 W 3400 W

100 3400 W 1700 W

Using only a RE (XII) Looking for the maximum powercompatible with complying with the IEC


101/268


Factor Correction

101

compatible with complying with the IEC61000-3-2 regulations in Class A (II)

Theoretical

Theoretical

Line current obtainedby simulation

AR = 100,fC: 1 kHz

0

1

2

3

AR = 100,fC: 500 Hz

0

1

2

3

Simulated

Simulated

The theoretical and the simulatedwaveforms are slightly different

The cause is the output voltageripple.

Due to this, the actual ripple is

not exactly sinusoidal

AR Output ripple=1 % Output ripple=2 %

50 3600 W 2500 W

100 2600 W 1300 W

Compliance up to very high

power levels is achieved

Using only a RE (XIII) Can we get a very fast transientresponse if we have a very fast


102/268


Factor Correction

102

response if we have a very fastoutput voltage feedback loop?

The dynamics depends on

the capacitor

The capacitor is recharged

each 10ms (100 Hz) the

faster response is 10 ms

Line

Power supply

DC/DCconverter

asResistorEmulator

Out

put

No devices to storeenergy at 100 Hz

PowerVoltage

Little (or no) power processed at

specific moments no energyavailable to maintain the output

voltage when the output current

changes, except the energystored in the capacitor

Current

Energystored here

Using only a RE (XIV)Simulating the dynamic response


103/268


Factor Correction

103

The output voltage takes 90 ms in

recovering the steady state

fC = 10 HzOutput voltage

20 40 60 80 100 120 140 160

360

380

400

420

40 ms

90 ms

Time (ms)

4300 W 1700 W

fC = 1kHz

20 40 60 80 100 120

Time (ms)

360

370

380

390

400

410

2600 W 400 W

10 ms

Output voltage

The output voltage takes 10 ms in

recovering the steady state

Using only a RE (XV) Resistor Emulator topologies: low power

Voltage


104/268


Factor Correction

104

Line Power supply Load(Electronic

circuitry)

Voltage

Current

Voltage

Current

Line Power supplyLoad(Electronic

circuitry)

Flyback

based

SEPICbased

Using only a RE (XVI) Resistor Emulator topologies: medium power

Current-fed Push-Pull based


105/268


Factor Correction

105

Line

Power supply

Load(Electronic

circuitry)

Voltage

Current

Line

Power supply

Load(Electronic

circuitry)

Voltage

Current

Cu e t ed us u based

Using only a RE (XVII) Resistor Emulator topologies: high power

Current fed Full bridge based


106/268


Factor Correction

106

Line

Power supply

Load(Electronic

circuitry)

Voltage

Current

Current-fed Full-bridge based

Line

Power supply

Voltage

Current

Load(Electronic

circuitry)

Using only a RE (XVIII) Example of application: a power supplyfor a 300 + 300 W audio amplifier (I)


107/268


Factor Correction

107

p ( )

Flyback based

Universal line voltage

Flyback with 2 Cool-MOS in parallel

10 ms dynamic response is good enough for this application

Line

Power supply

300 W audioamplifier

(Channel Right)

300 W audioamplifier

(Channel Left)

+70 V

-70 V

GND85-250 V

Using only a RE (XIX) Example of application: a power supplyfor a 300 + 300 W audio amplifier (II)


108/268


Factor Correction

108

p ( )

300 + 300 W

audio amplifier

Power supply

For Behringer

Developed at the

University of Oviedo

(GEI group)

Using only a RE (XX) Experimental results: line waveforms

R i t E l t b d 300 W b t t


109/268


Factor Correction

109

0.5 A/div 5ms/div

AR = 10

fC = 1 kHz

AR = 25 fC = 1 kHz

0.5 A/div 5ms/div

AR = 40 fC = 1 kHz

0.5 A/div 5ms/div

0.5 A/div 5ms/div

AR = 10

fC = 10 Hz

Simulated ResultSimulated Result

Simulated Result Simulated Result

Resistor Emulator based on a 300 W boost converter

Using only a RE (XXI) Experimental results: transient response


110/268


Factor Correction

110

1/3 Full load Full load

60 ms

fC = 10 Hz

10 ms

fC = 1kHz

1/3 Full load Full load

Using only a RE (XXII) Conclusions of the use of isolated ResistorEmulators as the only conversion stage formedium-speed response applications (I)


111/268


Factor Correction

111

medium speed response applications (I)

Many applications do not need fast dynamic response. Inthese cases conventional Resistor Emulators (like flyback)

can be used directly as power supply with no second stage

and with several advantages:

Low cost and size (no second stage)

Very low harmonic content

Can be used in high and low power applications.

Can be used with universal line voltage

Using only a RE (XXIII) Conclusions of the use of isolated ResistorEmulators as the only conversion stage formedium-speed response applications (II)


112/268


Factor Correction

112

medium speed response applications (II)

The limitations in the transient response are:

The 100-120 Hz output voltage ripple only depends on thecapacitor value

This ripple ripple cannot be reduced by increasing thecorner frequency of the output-voltage feedback loop

The maximum effective corner frequency is about 1kHz(10 times the ripple frequency)

The minimum response time is 10-8.3 ms (one 100-120 Hzcycle)

Using only a RE (XXIV) Conclusions of the use of isolated ResistorEmulators as the only conversion stage formedium-speed response applications (III)


113/268


Factor Correction

113

ed u speed espo se app cat o s ( )

This solution should not be used if the output voltage is

relatively low (lower than 12 V) due to the fact that the bulk

capacitor is placed just at the output, which means:

Energy stored at low voltage Large value of thecapacitor size

High current levels passing through the capacitorLarge capacitor losses due to the ESR

Outline


114/268


Factor Correction

114

Introduction



Class D







High-efficiency post-regulators (I)

fp: 1000 Hz

Can we improve the dynamic responseof a Resistor Emulator with a lowpenalty in the converter efficiency?

Line curent


115/268


Factor Correction

115

DC/DCconverter

Lowpassfilter

p 000

fp: 10 Hz

90 ms

10 ms

AR

Output voltage

20 40 60 80 100 120

Time (ms)

f [Hz]

-135

-90

-45

0

45

1 10 100 1000 10000

-40

-20

0

20

40

60

AR [dB]

AR []

Time (ms) 10

fp fp

The minimum response time is

10-8.3 ms (one 100-120 Hz cycle)

Another stage can be connected to

improve the transient response

High-efficiency post-regulators (II) Characteristic of the high-efficiencypost regulators


116/268


Factor Correction

116

DC/DCconverter

Lowpassfilter

Line

+

-

V1+

-

VO

Output

High-efficiency

post-regulators

Common characteristics of all high-

efficiency post-regulators:

Low additional cost and size

Only a fraction of the total powerundergoes a power switching processing

Very high efficiency: 96-98%

No short-circuit protection in the post-regulator

V1 and VO are voltages of similar values

High-efficiency post-regulators (III) Use of the high-efficiency post regulatorsin multiple-output applications


117/268


Factor Correction

117

Lowpassfilter

Line +

-

V1+

-

VO Output

High-efficiency

post-regulators

10 ms

fp: 1000 Hz

90 ms

fp: 10 Hz

Some slow or medium-speed outputs andsome fast response outputs

fp: 10 Hz

fp: 1000 Hz

High-efficiency post-regulators (IV) Operation principle of the high-efficiency post regulators


118/268


Factor Correction

118

DC/DCconverter

Lowpassfilter

Line

+

-

V1+

-

VO Output

How can we implement thevoltage source?

+-VS

Time

v1

vO

vS

High-efficiency

post-regulators

High-efficiency post-regulators (V) Implementing thevoltage source VS(I)


119/268


Factor Correction

119

?DC/DC

converter

Lowpassfilter

Line

+

-

V1+

-

VO Output+- VS

High-efficiency

post-regulators

Small

DC/DC

converter

Where should weconnect the input port

of this converter?

High-efficiency post-regulators (VI) Implementing thevoltage source VS(II)


120/268


Factor Correction

120

DC/DC

converter

Lowpassfilter

Line

+

-

V1

Option #1: connect the input port to anadditional Resistor Emulator output

+

-

VO Output

High-efficiencypost-regulators

+- VS

Small

DC/DC

converter

One additionaloutput

High-efficiency post-regulators (VII) Implementing the voltagesource VS(III)


121/268


Factor Correction

121

DC/DC

converter

Lowpassfilter

Line

+

-

V1

Option #2: connect the input port to theResistor Emulator output

+

-

VO Output


+- VS

SmallDC/DC

converter

High-efficiency post-regulators (VIII) Implementing the voltagesource VS(IV)


122/268


Factor Correction

122

+

-

V1

+

-

VO

High-efficiency post-regulators

+- VS

Small

DC/DC

converter

+

-

V1

+

-

VO


+- VS

Small

DC/DCconverterV2

Option #1: connect the input

port to an additional output of

the Resistor Emulator


port to the Resistor

Emulator output

Two-Input Buck (TIBuck) Series-Switching post-Regulator (SSPR)

High-efficiency post-regulators (IX) Why is the efficiency of these post-regulators very high?


123/268


Factor Correction

123

Time

v1 vO

vS

V1, VO >> VS

P1, PO >> PS

+

-

VO

DC/DCconverter

Lowpass

filter

+

-

V1


+- VS

Small

DC/DCconverterIO

The Small DC/DC converter is processing

only a small part of the output powerLow losses in the post-regulator

High efficiencypost-regulator

High-efficiency post-regulators (X) Why is not possible to implement aover-load or short-circuit protectionin these post-regulators?


124/268


Factor Correction

124

then VO=V1 0

+

-VO

DC/DCconverter

Lowpassfilter

+

-V1


+- VS

SmallDC/DC

converterIO

The over-load or short-circuitprotection must be implemented

in the Resistor Emulator

0

A over-load occurs

If VS = 0,

High-efficiency post-regulators (XI) Introducing the Two-Input Buck(TIBuck)


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Factor Correction

125

This is a Buck converter withtwo inputs instead of one

+

-

V1

+

-

VO


+- VS

Small

DC/DC

converterV2

+-

V1

V2

+

-

VO

DC/DC converter


VS+

-

High-efficiency post-regulators (XII) Single-output Resistor Emulatorbased on a Flyback + a TIBuckpost-regulator


126/268


Factor Correction

126

+

-VO+

-

V1

V2

Standard

controller

ResistorEmulatorcontroller

p g

TIBuckpost-regulators

High-efficiency post-regulators (XIII) Multiple-output Resistor Emulatorbased on a Flyback + a TIBuckpost-regulator


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Factor Correction

127

p g

+

-VO+

- V1

V2

Standard

controller


+

-V3

-

+V

4

TIBuckpost-regulators

V V+ V -

High-efficiency post-regulators (XIV) Comparing Buck and TIBuckconverters


128/268


Factor Correction

128

V1 > VO

VQMAX = V1

VDMAX = V1

VO = V1d(d is the duty cycle)

V2 > VO > V1

VQMAX= V2-V1

VDMAX= V2-V1

VO= V2d + V1(1-d)

(from volts-second balance)

Buck

V1

VO

+ VQ -

+VD

-

TIBuck

V2

V1

VO

+ VQ -

+VD

-

High-efficiency post-regulators (XV) DC equivalent circuitfor the TIBuck


129/268


Factor Correction

129

VO= V2d + V1(1-d) =

Poorlyregulated

Controlled

(V2-V1)d + V1

(V2-V1)d

V1

VO

+PWM -

Regulated

High-efficiency post-regulators (XVI) Relationship between inputand output voltages (I)


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Factor Correction

130

V2 range

Voltages

Time

VO

V2

V1

+VD

-

VO

+ VQ -

PWM +-

V1 range

ALWAYS

V2 > VO > V1

High-efficiency post-regulators (XVII) Relationship between inputand output voltages (II)


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Factor Correction

131

+

-VO+

-V1

V2

VO

Voltages

Time

v2

v1

Transient responseSteady state

ALWAYS V2 > VO > V1, taking into account theworse case of transient response and ripple

Case of being used as post-regulator of a Resistor Emulator

High-efficiency post-regulators (XVIII) Comparing filter inductance forBuck and TIBuck converters (I)

LB


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Factor Correction

132

Buck

V1

VO+VFilter

-

LB

TIBuck

V2

V1

VO

LTB

VFilter

-

+

Time

VFilter

VOV2

V1

VFilter

Time

VOV1

Lower value in the case ofthe TIBuck converter (inpractice, 3 times lower)

High-efficiency post-regulators (XIX) Comparing filter inductance forBuck and TIBuck converters (II)

Boundary between continuous and discontinuous conduction modes


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Factor Correction

133

CCM: 2L/RT > KCRIT

DCM: 2L/RT < KCRIT

Boundary between continuous and discontinuous conduction modes

TIBuckV2 /V1=4

KCRIT

d(duty cycle)

Buck

1

00 1

1.25

2

3

)d1(CRITKBuck:

1)11V/2V(d

)11V/2V)(d1(d

CRITKTIBuck:

Lower value in the caseof the TIBuck converter

High-efficiency post-regulators (XX) Explaining the high efficiency ofthe TIBuck converter (I)

Realistic case for a Buck converter:


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Factor Correction

134

d = 0.55PLosses = 10 W

= 90 / 100 = 90%

VOB = 50 VIO = 1.8 APOB = 90 W

Realistic case for a Buck converter:

VG = 100 VIG = 1 APG = 100 W

R= VOB/IO = 27.8

VG

VOB

Buck

R

d = 0 55

High-efficiency post-regulators (XXI) Explaining the high efficiency ofthe TIBuck converter (II)


135/268


Factor Correction

135

VG

VOB

Buck

VOB = 50 VIO = 1.8 APOB = 90 W

VG = 100 VIG = 1 APG = 100 W

d = 0.55PLosses = 10 W

IO = 1.8 A

IO = 1.8 A

V1 = 300 VP1 = 540 W

We are processing 540 W FREE !!

= (90 + 540) / (100 + 540) = 98.4 %

IO = 1.8 A R1 = V1/IO = 166.7

V1 = 300 V

P1 = 540 W

V1 IOIO

R1

High-efficiency post-regulators (XXII) Explaining the high efficiency ofthe TIBuck converter (III)


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Factor Correction

136

VOB = 50 VIO = 1.8 A

POB = 90 W

IO = 1.8 AV1 = 300 VP1 = 540 W

IO = 1.8 AV1 = 300 VP1 = 540 W

VG = 100 VIG = 1 A

PG = 100 W 27.8

166.7

d = 0.5

I2

I1

d = 0.5

V1

V2

194.5IO = 1.8 AVO = VOB+ V1= 350 VP

O= P

OB+ P

1= 630 W

= 630 / 640 = 98.4%

I2 = IG = 1 AI1 = IO- IG = 0.8 AV2 = VG+ V1= 400 VP2 = 400 W

P1 = 240 WPi = P2 + P1 =640

High-efficiency post-regulators (XXIII) Explaining the high efficiency ofthe TIBuck converter (IV)


137/268


Factor Correction

137

The closer V2 and V1 (and,therefore VO) the higherthe efficiency

V2

V1

VO

V1

V2 V1

VO-V1

V1

V1

V2 V1

VO-V1

V1

V1

V2 V1

VO-V1

V1

High-efficiency post-regulators (XXIV) Explaining the high efficiency ofthe TIBuck converter (V)


138/268


Factor Correction

138

TBis the TIBuck efficiency

V1

V2 V1

VO-V

1

V1TB=1

B =50%

75%

90%

85%

0.4 0.6 0.8 1

100

80

60

TIbuck efficiency

V1/VO

O

1B

BTB

V

V)(1-1-

Bis the Buck-part efficiency

High efficiency TIbuckwith a limited efficiency

in the Buck part

TB=96.6%

High-efficiency post-regulators (XXV) Small-signal transfer functions ofthe TIBuck converter


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Factor Correction

139

Similar to the case of a Buck converter, but faster dueto the lower values of the output filter components

V2

V1

VO

RCTB

LTB

Output filter

1sR

LsLC TB2TBTB

1OvD

V2-V1

1-D

++

+

2v

1v

d

The quantities with hats

are the perturbations

High-efficiency post-regulators (XXVI) Implementing the transistor driver


140/268


Factor Correction

140

Requirements:

Galvanic isolation

Wide duty cycle operation

High-efficiency post-regulators (XXVII) Experimental results ofTIBuck-based prototypes (I)


141/268


Factor Correction

141

TIBuck DC/DC post-regulators

V2 V1 VO IO LTB CTB fS

TIBuck 1 440-400 V 360-320 V 380 V 1-0.1 A 1 mH 250 nF 100 kHz

TIBuck 2 67-57 V 52-42 V 54.5 V 4-0.4 A 51.4 mH 4.7 mF 100 kHz

High-efficiency post-regulators (XXVIII) Experimental results ofTIBuck-based prototypes (II)

TIBuck 1: overall efficiency


142/268


Factor Correction

142

V2=400V

V1=320V

V2=440VV1=360V

V2=420VV1=340V

100 200 300Output power [W]

100

99

98

Efficiency [%]

High-efficiency post-regulators (XXIX) Experimental results ofTIBuck-based prototypes (III)


143/268


Factor Correction

143

100

95

90

85

Efficiency [%]

0 500 1000Output current [mA]

V2 = 80 VV1 = 0 VVO = 40 V

V2 = 180 VV1 = 100 V

VO = 140 V

280,200240

380,300,340

V1

V2VO

TIBuck 1 efficiency with V2 & V1 variable, V2-V1 =80 V, VO=(V1+V2)/2

Being V2-V1 a constant, the

closer V2 and V1 (and, thereforeVO) the higher the efficiency

High-efficiency post-regulators (XXX) Experimental results ofTIBuck-based prototypes (IV)

TIBuck 1 and Buck-part efficiencies


144/268


Factor Correction

144

The experimental results fit very well with the calculated ones

TIBuck(calculated)

TIBuck(measured)

Output current [mA)]

Efficiency [%]100

90

80

70200 400 600

Buck-part(measured)

TBis the TIBuck efficiencyV1

V2 V1

VO-V1

V1

=1

Bis the Buck-part efficiency

O1B

BTB

V

V)(1-1-

High-efficiency post-regulators (XXXI) Experimental results ofTIBuck-based prototypes (V)

TIBuck 2: overall efficiency and small-signal modelling


145/268


Factor Correction

145

100 1,000 10,000

0

-20

20

40

Gain [dB] , phase

Frequency [Hz]

-180

-90

0

Measured

0 100 200

100

96

92

Output power [W]

Efficiency [%]

y g g

Theoretical

Theoretical

51 4 H25CPF40

High-efficiency post-regulators (XXXII) Experimental results ofTIBuck-based prototypes (VI)

Resistor Emulator based on a

Flyback converter + TIBuck 2


146/268


Factor Correction

146

1.5mF

1.5mF

51.4 H

4.7 F

IRF7403

10T045 54V4A85-264V

IRFPC50

25CPF40

24 t

9 t

3 t

UC3854

UC3825

80 120 160 200Output power [W]

Overall efficiency [%]

84

86

88220V

110V0.01A/ s

2.1A 3.23A

IOV2 5V/div

VO 1V/div

Transient response

200 ms/div

High-efficiency post-regulators (XXXIII) Experimental results ofTIBuck-based prototypes (VII)

Voltage ripple cancellation in the case of the Resistor


147/268


Factor Correction

147

g pp

Emulator based on a Flyback converter + TIBuck 2

+

-

VOV1

V251.4 H

4.7 F

IRF7403

10T045

UC3825

V2 2V/div.

VO 0.5V/div.

V1 2V/div.

Voltage ripples

Can we improve theripple cancellation?

Voltage-Mode control

High-efficiency post-regulators (XXXIV) Experimental results ofTIBuck-based prototypes (VIII)

Other TIBuck control methods to improve the voltage ripple cancellation


148/268


Factor Correction

148

+

-

VOV1

V2 51.4 H

4.7 F

IRF7403

10T045

UC3825

Input voltage feedforward

Other TIBuck control methods to improve the voltage ripple cancellation

Feedforward

Input voltage feedforward

Current mode control (average current mode control)

+ V2+ V1

R2

R1 CextRext

+ Vdc

vC UC3825Feedforward

implementation

High-efficiency post-regulators (XXXV) Experimental results ofTIBuck-based prototypes (IX)

Average current mode control Voltage ripples


149/268


Factor Correction

149

Average current mode control

+

-

VOV1

V2 51.4 H

4.7 F

IRF7403

10T045

UC3825TL082

VO 2mV/div.

V2 2V/div.

V1 2V/div.

Voltage ripple attenuation 66dB (1900 times). Also,

excellent transient response

V2 (5 V/div)

VO (20 mV/div)

100 ms/div

Transient response

0.01A/ s

2.1A 3.23A

IO

High-efficiency post-regulators (XXXVI) Introducing the option #2: Series-Switching Post-Regulator (SSPR)


150/268


Factor Correction

150

+

-

V1

+

-

VO

High-efficiency post-regulators

+- VS

Small

DC/DC

converter


port to the Resistor

Emulator output

Series-Switching post-Regulator (SSPR)

+

-

V1

+

-

VO

+- VS

Small DC/DCconverter

+

-

V1 +

-

VOSmall DC/DC

converter

+

-V

S

Re-drawing

High-efficiency post-regulators (XXXVII) Introducing the SSPR basedon a Forward converter


151/268


Factor Correction

151

+

-

V1 +

-

VOSmall DC/DC

converter

+

-VS

Re-placing

the capacitor

+

-

V1+

-VO

Small DC/DC

converter

+

-

V1 +

-

VOSmall DC/DC

converter

+

-VS

Controller

The controlled outputvoltage is VO instead of VS

High-efficiency post-regulators (XXXVIII) Other SSPR implementations

Implementation based on a Flyback


152/268


Factor Correction

152

+

-V1 +

-

VOSmall DC/DC

converter

Controller

The implementation based on a Flyback

becomes a Boost converter if n1=n2

A Boost converter has a very high

efficiency if the input and output voltages

are very close

+

-

V1

+

-

VO

+- VS


+

-

V1 +

-

VO

Controller

n1 n2

If n1=n2

High-efficiency post-regulators (XXXIX) Single-output ResistorEmulator based on a Flyback+ a Forward-type SSPR


153/268


Factor Correction

153

+

-V

O

+

-

V1

Standardcontroller


Forward-type SSPR

High-efficiency post-regulators (XL) Multiple-output ResistorEmulator based on a Flyback+ a Forward-type SSPR


154/268


Factor Correction

154

+

-VO

+

-

V1

Standardcontroller


+

-V2

-

+V3

Forward-type SSPR

High-efficiency post-regulators (XLI) Computing SSPRs efficiency (I)

VS +-I1 IOIO


155/268


Factor Correction

155

VO+

-

V1+

-

SSPRss

VO = V1 + VS

I1

= IiDC

+ IO

C=VSIO

V1IiDC

Being KS=VS/V1


C

PWM +-

IiDC

SS=

VOIO

V1I1 =

1+KS

1+KS

C

High-efficiency post-regulators (XLII) Computing SSPRs efficiency (II)

Example:100

SS [%]


156/268


Factor Correction

156

C = 80%

KS = VS/V1 = 0.1 ss = 97.7%

The lower KS, the higher the efficiency

However, VS must reaches VSmaxand must be always positive

Voltages vO

Time

Steadystate

Transient

response

vSmax

v1

vS

KS=0.3

0.10.2

60 70 80 90 10080

85

90

95

KS=VS/V1

c [%]

11DQ10

High-efficiency post-regulators (XLIII) Experimental results of aForward-type SSPR (I)


157/268


Factor Correction

157

11DQ10E20

12CTQ045

47 H, E20

47 FSMP20N20

6,800 F28 : 28 : 15

fS = 100 kHz

V1 = 47V

+

-

VO= 54.5 VIO = 4 A

+

-

VS = 7.5V+

-

0 50 100 150 200 25095

96

97

98

Output power [W]

Efficiency [%]

High-efficiency post-regulators (XLIV) Experimental results of aForward-type SSPR (II)

Average current mode control

V (1V/di )

Voltage ripples


158/268


Factor Correction

158

V1

+

-VO+

-

UC3825TL082

V1 (1V/div)

VO (10mV/div)

10 ms/div

V1 (5V/div)

VO (20mV/div)

200 ms/div

Transient response

0.01A/ s1.83A

3.67A

IO

(Attenuation 50dB)

Conclusions of the use of High-efficiency post-regulators toimprove the transient responseof Resistors Emulators (I)

High-efficiency post-regulators (XLV)


159/268


Factor Correction

159

of Resistors Emulators (I)

Low additional cost and size

Low output voltage ripple and fast dynamic response

Very high post-regulator efficiency (96-98%)

Very low harmonic content

Can be used in high and low power applications

Can be used with universal line voltage

Very interesting for multiple-output applications withdifferent transient response specifications

Conclusions of the use of High-efficiency post-regulators toimprove the transient responseof Resistors Emulators (II)

High-efficiency post-regulators (XLVI)


160/268


Factor Correction

160

of Resistors Emulators (II)

V1 and VO are voltages of similar values

It is not a good solution for low output voltage applicationsbecause the energy is stored near the output voltage

No short-circuit and/or overload protection can beimplemented in the post-regulator (it must be implemented in

the Resistor Emulator)

However, short-circuit overcurrent from the bulk capacitorcan be diverted through an additional diode (see next slide)

High-efficiency post-regulators (XLVII) Additional diode to divert short-circuit overcurrent from the bulkcapacitor

Small

DC/DC


161/268


Factor Correction

161

+

-

VO+

-V1

V2

CB1

CB2

V1

+

-VO+

-

+

-

V1

+

-

VO


+- VS

DC/DC

converter

overcurrent

The overcurrent i

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