Presentaci

1
Advanced Techniques in Power Factor Correction
(PFC) Prof. Dr. Javier Sebastián
Grupo de Electrónica Industrial Universidad de
Oviedo (Spain)
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

3
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

4
Introduction (I)
Focusing the problem

• Input current with a strong harmonic content

• Cheap reliable

5
Introduction (II)
6
Power Factor (PF)
Introduction (III)
Quantifying the problem

• Total Harmonic Distortion (THD)

• Each individual harmonic

7
Introduction (IV)
Conflict of interest

• Electronic equipment manufacturers will
• Low cost
• Reliability

• Power Companies will
• High PF
• No harmonics

8
Introduction (V)
Starting solving the problem (I)

• Using active filters

9
Modifying the electronic load Þ Power Factor
Correctors
Introduction (VI)
Starting solving the problem (II)
10
Introduction (VII)

• However the value of the Power Factor is not
  important.
• According to the European Regulations, only the
  value of each individual harmonic is important.

We should use words such as Low-Frequency
Harmonic Reduction and Low-Frequency Harmonic
Reducer instead of Power Factor Correction and
Power Factor Corrector.
11
Focusing the course
Introduction (VIII)
Line Single-Phase
Line Three-Phase
Conversion AC/DC
Conversion AC/AC
Power High power
Power Low-medium power (230V, lt16A)
Reactive energy Recovery to line
Reactive energy No recovery
Connection External connection
Connection Modifying AC/DC topology
12
Introduction (IX)
What is the right choice in PFC? It strongly
depends on the application. There is not magic
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

13
Introduction (X)
The European Regulation IEC 61000-3-2
Power supplies are either Class A or Class D
14
Introduction (XI)
Harmonic limits for Class A and Class D
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 0.5
11 0.33 0.35
13 0.21 0.296
15 n 39 2.25/n 3.85/n
Very Important!! Limits in Class A are absolute
values A Limits in Class D are relative values
mA/W
15
Introduction (XII)
Example 1 a 100 W (low-power) converter
Harmonic Limits in Class A mA Limits in Class D mA
3 2300 340
5 1140 190
7 770 100
9 400 50
11 330 35
13 210 29.6
15 n 39 2250/n 385/n
Limits in Class A are less strict for low-power
applications
16
Introduction (XIII)
Example 2 a 500 W (medium-power) converter
Harmonic Limits in Class A mA Limits in Class D mA
3 2300 1700
5 1140 950
7 770 500
9 400 250
11 330 175
13 210 148
15 n 39 2250/n 1925/n
Limits in Class A and in Class D become more
similar for medium-power applications
17
Introduction (XIV)
Example 1 a 100 W (low-power) battery charger
(Class A)
PF 0.46 and THD 193.1
This waveform complies with the regulations!!!
Very cheap systems for low-frequency harmonic
attenuation can be used to obtain this type of
waveform
18
Introduction (XV)
Example 1 a 100 W (low-power) TV set (Class D)
It does not comply with the regulations
A slightly more complex system must be used (it
is still very simple)
19
Introduction (XVI)
Example 2 two 500 W (low-power) pieces of
equipment

• Class D

• Class A

The advantages of being Class A vanish at 500 W
20
Introduction (XVII)
Example 3 same Class, different power
The complexity of the systems for low-frequency
harmonic attenuation increases with the power
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 the range

22
Introduction (XIX)
Influence of the input voltage range (II)
Single range (either European or American) and
simple system for low-frequency harmonic
attenuation (PFC) Þ Moderate change in the input
voltage of the DC/DC converter Þ Slight penalty
in efficiency
Simple PFC with single range
23
Introduction (XX)
Influence of the input voltage range (III)
Universal range and simple PFC Þ Large change in
the input voltage of the DC/DC converter
Þ Significant penalty in efficiency Þ Complex
PFCs which guaranty constant input voltage are
interesting
Complex PFC with universal range
24
Introduction (XXI)
Influence of the input voltage range (IV)
Two ranges selected by a switch
Is it compatible with the use of simple PFC?
25
Introduction (XXII)
Influence of the input voltage range (V)
Two ranges selected by a switch and PFC
26
Introduction (XXIII)
Changing the place of the DC/DC converter Þ
Resistor Emulator concept
27
Introduction (XXIV)
Using only a Resistor Emulator (I)
It is not a good solution for low-voltage (lt12 V
DC) applications
28
Introduction (XXV)
Using only a Resistor Emulator (II)
The converter is in charge of cancelling the
output ripple
It is not a good solution when low output-ripple
is needed
29
Introduction (XXVI)
Using only a Resistor Emulator (III)
The converter can get energy from the capacitor
to maintain the output voltage when the output
current changes
It is not a good solution when fast transient
response is needed
30
Introduction (XXVII)
In the case of fast transient response needed
A DC/DC converter (or section) is needed
31
Introduction (XXVIII)
What are the design priorities?

• Cost
• Size
• Weight
• Efficiency
• Only comply with the regulations
• High Power Factor and low Total Harmonic
  Distortion (for marketing reasons)

They also determine the right choice
32
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

33
Using a resistor (I)
Looking for the simplest solution (I)
34
Using a resistor (II)
Looking for the simplest solution (II)
Order Measured A Limits Class D A
1 0.542 -
3 0.527 0.408
5 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 0.012
The compliance is very far
35
Using a resistor (III)
Looking for the simplest solution (III)
What about a Class A piece of equipment?
36
Using a resistor (IV)
Looking for the simplest solution (IV)
Order Measured A Limits Class A A
1 0.542 -
3 0.527 2.3
5 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 0.132
19 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
It does not comply, but it is very near to comply
37
Using a resistor (V)
Looking for the simplest solution (V)

• Let us change the value of the bulk capacitor

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 0.15
17 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 0.078
31 0.067 0.073
33 0.066 0.068
35 0.063 0.064
37 0.058 0.061
39 0.053 0.058
Almost compliance with 100 mF
38
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
39
Using a resistor (VII)
The simplest solution to add a resistor
40
Using a resistor (VIII)
Cbulk 200 mF Pconverter 120 W
Order Measured A with R0 W Measured A with R1 W Measured A with R1.5 W Limits Class 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
41
Using a resistor (IX)
Input-current waveform with a resistor
Cbulk 200 mF Pconverter 120 W
_at_ 230V ac, R 1.5 W iinput peak 4.12
A Presistor 1.85 W
_at_ 230V ac, R 0 W iinput peak 6.37 A
42
Using a resistor (X)
Design procedure
43
Using a resistor (XI)
Value of the resistor needed to comply with the
IEC 61000-3-2 in Class A as a function of the
input power (bulk capacitor in mF per watt as
parameter)
44
Using a resistor (XII)
Absolute power losses at full load and minimum
line voltage (maximum line current)
45
Using a resistor (XIII)
Relative power losses (PR/Poutput) at full load
and minimum line voltage (maximum line current)
46
Using a resistor (XIV)
Design example Poutput150W, C150mF (1mF/W)
47
Using a resistor (XV)
Power losses in the resistor at Poutput150W and
Vline190V
48
Using a resistor (XVI)
Power limits for this solution
Very interesting
Not so interesting
49
Using a resistor (XVII)
Using this solution for Universal line voltage
range
Pconverter 120 W Cbulk 200 mF R1.5 W
Line Quantity _at_ 230V _at_ 110V
iinput peak 4.12 A 5.09A
iinput RMS 1.11 A 1.853 A
Plosses resistor 1.85 W 5.15 W
50
Using a resistor (XVIII)
Adaptation for operation in two ranges (I)
Different operation (AC side DC side)
51
Using a resistor (XIX)
Adaptation for operation in two ranges (II)

• AC side

Both iinput 110V and iinput 230V passing through R
52
Using a resistor (XX)
Adaptation for operation in two ranges (III)

• DC side

iinput 110V passing through R/2 and iinput 230V
passing through R (better)
53
Using a resistor (XXI)
Adaptation for operation in two ranges (IV)
Example Pconverter 120 W Cbulk 2 X 400 mF
(series) R1.5 W
Plosses resistors 3.15 W (total)
Plosses resistor 5.27 W
54
Using a resistor (XXII)
Adaptation for operation in two ranges (V)
Power R C losses _at_ 230V losses _at_ 190V losses _at_ 110V losses _at_ 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
55
Using a resistor (XXIII)
Adaptation for operation in two ranges (VI)
Power R C losses _at_ 230V losses _at_ 190V losses _at_ 110V losses _at_ 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
56
Using a resistor (XXIV)
Experimental results (I)
Pconverter 100 W C 2 X 100 mF (series) R
2x0.82 W
57
Using a resistor (XXV)
Experimental results (II)
Pconverter 200 W C 2 X 200 mF (series) R
2x1.8 W
58
Using a resistor (XXVI)
Conclusions of the use of a resistor to comply
with the IEC 61000-3-2 regulations in Class A

• This is the simplest possible solution
• Low-cost and low-size solution
• Very interesting for low-power (Plt200-300W)
  applications
• High losses with universal line voltage range
  (only valid for Plt150W)
• The DC bus is not regulated
• For the universal line voltage and with a
  voltage-doubler with a mechanical switch, it can
  be used up to 200W
• No perfect sinusoidal, but compliance with IEC
  61000-3-2 is achieved

59
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

60
Using an inductor (I)
Another very simple solution to add an inductor
61
Using an inductor (II)
Cbulk 200 mF Pconverter 120 W
Order Measured A with L0 mH Measured A with L1 mH Measured A with L2 mH Limits Class A A
1 0.542 0.552 0.545 -
3 0.527 0.531 0.515 2.3
5 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
62
Using an inductor (III)
Input-current waveform and harmonic content with
an inductor
Example Cbulk 200 mF Pconverter 120 W L 2
mH
It does not comply
It complies
63
Using an inductor (IV)
Comparing input-current waveform with an inductor
and a resistor for Class A equipment
Cbulk 200 mF Pconverter 120 W
64
Using an inductor (V)
Comparing input-current waveforms with different
bulk capacitor values
L 3.3 mH Pconverter 400 W
Slightly influence of the capacitor value
65
Using an inductor (VI)
Looking for the most restrictive harmonics (I)
Example 100 W, 1.7 mH 47 mF
Harmonics 13th-17th are the most restrictive at
low power
66
Using an inductor (VII)
Looking for the most restrictive harmonics (II)
Example 600 W, 7.8 mH 330 mF
Harmonics 3rd-5th are the most restrictive at
high power
67
Using an inductor (VIII)
Value of the minimum inductor needed to comply
with the IEC 61000-3-2 in Class A as a function
of the input power (bulk capacitor in mF per watt
as parameter)
68
Using an inductor (IX)
Comparing the influence of the bulk capacitor for
the case of the inductor and the resistor
Erratic influence of the value of the bulk
capacitor
Lower inductor values with high bulk capacitor
values
69
Using an inductor (X)
Design procedure for Class A
70
Using an inductor (XI)
Design example Poutput200 W, C100 mF (0.5 mF/W)
71
Using an inductor (XII)
What about the inductor size?

• We must know the maximum peak value of the input
  current (at full load and minimum line voltage) Þ
  determine the gap and number of turns
• We must know the maximum RMS value of the input
  current (at full load and minimum line voltage) Þ
  determine the wire size (diameter) and losses

Input power W L mH Ipeak A IRMS A Equivalent ferrite core size Power losses ()
200 2.7 5.33 _at_ 230V 6.07 _at_ 190V 1.6 _at_ 230V 1.88 _at_ 190V E30/15/7 0.8
72
Using an inductor (XIII)
Inductor size and losses for different power
levels
Input power W L mH Equivalent ferrite core 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
73
Using an inductor (XIV)
Magnetic materials for the inductor (I)
Silicon steel lamination core (instead of
ferrite) Example RG11
High induction levels (1.4 T) are possible
74
Using an inductor (XV)
Magnetic materials for the inductor (II)
75
Using an inductor (XVI)
DC-side or AC-side inductor?
Example Cbulk 200 mF, L 2 mH, Pconverter
120 W
Exactly the same result if the converter is
working in strong DCM
76
Using an inductor (XVII)
What about complying with the IEC 61000-3-2
regulations in Class D?
Example Cbulk 200 mF, L 2 mH, Pconverter
120 W

• Low-frequency harmonics are the most significant
  ones
• A considerable increase in the inductance value
  is needed

77
Using an inductor (XVIII)
Looking for the minimum value of L to comply 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
78
Using an inductor (XIX)
Looking for the minimum value of L to comply with
the regulations in Class D (II)
If we increase the power, the limits will also
increase Þ a similar input-current waveform is
enough to comply with the regulations
Example Cbulk 1200 mF, L 7 mH, Pconverter
600 W
An inductor of 7 mH is needed for 600 W
79
Using an inductor (XX)
Value of the minimum inductor needed to comply
with the IEC 61000-3-2 in Class D as a function
of the input power (bulk capacitor in mF per watt
as parameter)
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)
80
Using an inductor (XXI)
Inductor size and losses for different power
levels
Input power W L mH Equivalent ferrite core 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
81
Using an inductor (XXII)
Comparing the value of the minimum inductor
needed to comply with the IEC 61000-3-2 in Class
A and in Class D
Lower L values at low power
82
Using an inductor (XXIII)
Inductor size and losses for different power
levels
Input power W L mH in Class A Equivalent core size in Class A Power losses in Class A () L mH in Class D Equivalent core size in Class D Power losses 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
83
Using an inductor (XXIV)
Adaptation for operation in two ranges (I)
Different operation (AC side DC side)
84
Using an inductor (XXV)
Adaptation for operation in two ranges (II)

• AC side

Both iinput 110V and iinput 230V passing through L
85
Using an inductor (XXVI)
Adaptation for operation in two ranges (II)

• DC side

iinput 110V passing through L/2 and iinput 230V
passing through L
86
Using an inductor (XXVII)
Experimental results (I)
Class D Pconverter 100 W C 47 mF L 41 mH
87
Using an inductor (XXVIII)
Experimental results (II)
Class A Pconverter 100 W C 47 mF L 1.7 mH
88
Using an inductor (XXVIII)
Conclusions of the use of an inductor to comply
with the IEC 61000-3-2 regulations 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 (Plt200-300W)
  applications in Class A
• Large inductor size for Class D and high-power
  Class A
• The DC bus is not regulated
• For the universal line voltage range, a voltage
  doubler with a mechanical switch can be
  implemented to improve the circuit operation
• No perfect sinusoidal waveform, but compliance
  with the IEC 61000-3-2 regulations

89
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

90
Passive (L or R) versus active systems to reduce
the harmonic content
Using only a RE (I)

• Low-cost
• Either low-losses or low-size
• Non-sinusoidal waveform Þ solutions for low
  power
• Unregulated voltage across the capacitor Þ
  solutions for limited line voltage range (many
  times, voltage doubler needed)

• Sinusoidal waveform Þ solutions for any power
• Regulated voltage across the capacitor Þ
  solutions for universal line voltage range
• A good solution if only the Resistor Emulator
  were enough

91
Is only a Resistor Emulator enough to implement
the overall power supply?
Using only a RE (II)
From the point of view of the capacitor size, it
is not a bad solution for medium and high voltage
applications (gt12 V DC)
92
And, what about the dynamics?
Using only a RE (III)
Example of Resistor Emulator control control
based on an analog multiplier
93
Using only a RE (IV)
The lowpass filter influence (I)
A filter with low cut-off frequency is needed if
a perfect sinusoidal is required
94
Using only a RE (V)
The lowpass filter influence (II)
And, what about the dynamic response?

• Filter with very low cut-off frequency
• Perfect sinusoidal line current
• Very poor dynamic response

• Filter with high cut-off frequency
• Non-perfect sinusoidal line current
• But, can we achieve compliance with the IEC
  61000-3-2 and reasonable dynamic response?

If yes, the use of only a Resistor Emulator as
overall power supply becomes very attractive
95
Line current waveform as a function of the
voltage regulator pole frequency fp
Using only a RE (VI)
fp 1kHz is a practical limit (no significant
phase shift at 100Hz)
96
Line current waveform as a function of the
voltage regulator DC gain AR
Using only a RE (VII)
AR 100 is a practical limit due to the voltage
levels in the controller
97
Using only a RE (VIII)
Looking for the worst case
Theoretical harmonic content Only the third
harmonic is present
98
Why is the third harmonic the only one present in
the line current? (I)
Using only a RE (IX)
For 0 wtp
Viref(wt) VeaoV1sinwt 0.5V1Veacoswt -
0.5V1Veacos3wt Þ
iline DC (wt) (VeaoV1sinwt 0.5V1Veacoswt -
0.5V1Veacos3wt)/Rs
Therefore, for 0 wtp iline AC (wt) iline DC
(wt) (VeaoV1sinwt 0.5V1Veacoswt -
0.5V1Veacos3wt)/Rs
99
Why is the third harmonic the only one present in
the line current? (II)
Using only a RE (X)
Due to the fact that the frequency of iline DC is
2w iline DC (wt) iline DC (wt-p)
For p wt 0 iline AC (wt) -iline DC (wt)
-iline DC (wt-p) -(VeaoV1sin(wt-p)
0.5V1Veacos(wt-p) - 0.5V1Veacos3(wt-p))/Rs
(VeaoV1sinwt 0.5V1Veacoswt - 0.5V1Veacos3wt)/Rs
Therefore, for -p wtp iline AC (wt)
(VeaoV1sinwt 0.5V1Veacoswt - 0.5V1Veacos3wt)/Rs
There are only components of w and 3w
100
Using only a RE (XI)
Looking for the maximum power compatible with
complying with the IEC 61000-3-2 regulations in
Class A (I)
AR Output ripple1 Output ripple2
50 3680 W 3400 W
100 3400 W 1700 W
IEC 61000-3-2 regulations in Class A can be
complied up to very high power levels
101
Using only a RE (XII)
Looking for the maximum power compatible with
complying with the IEC 61000-3-2 regulations in
Class A (II)

• The theoretical and the simulated waveforms are
  slightly different
• The cause is the output voltage ripple.
• Due to this, the actual ripple is not exactly
  sinusoidal

AR Output ripple1 Output ripple2
50 3600 W 2500 W
100 2600 W 1300 W
Compliance up to very high power levels is
achieved
102
Using only a RE (XIII)
Can we get a very fast transient response if we
have a very fast output voltage feedback loop?

• The dynamics depends on the capacitor
• The capacitor is recharged each 10ms (100 Hz) Þ
  the faster response is 10 ms

103
Using only a RE (XIV)
Simulating the dynamic response
fC 10 Hz
fC 1kHz
The output voltage takes 90 ms in recovering the
steady state
The output voltage takes 10 ms in recovering the
steady state
104
Using only a RE (XV)
Resistor Emulator topologies low power
Flyback based
SEPIC based
105
Using only a RE (XVI)
Resistor Emulator topologies medium power
Current-fed Push-Pull based
106
Using only a RE (XVII)
Resistor Emulator topologies high power
Current-fed Full-bridge based
107
Using only a RE (XVIII)
Example of application a power supply for a 300
300 W audio amplifier (I)
Flyback based

• Universal line voltage
• Flyback with 2 Cool-MOS in parallel
• 10 ms dynamic response is good enough for this
  application

108
Using only a RE (XIX)
Example of application a power supply for a 300
300 W audio amplifier (II)
109
Using only a RE (XX)
Experimental results line waveforms
Resistor Emulator based on a 300 W boost converter
110
Using only a RE (XXI)
Experimental results transient response
111
Conclusions of the use of isolated Resistor
Emulators as the only conversion stage for
medium-speed response applications (I)
Using only a RE (XXII)

• Many applications do not need fast dynamic
  response. In these 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

112
Conclusions of the use of isolated Resistor
Emulators as the only conversion stage for
medium-speed response applications (II)
Using only a RE (XXIII)

• The limitations in the transient response are
• The 100-120 Hz output voltage ripple only
  depends on the capacitor value
• This ripple ripple cannot be reduced by
  increasing the corner 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 Hz cycle)

113
Conclusions of the use of isolated Resistor
Emulators as the only conversion stage for
medium-speed response applications (III)
Using only a RE (XXIV)

• 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 Þ Large value of
  the capacitor size
• High current levels passing through the
  capacitor Þ Large capacitor losses due to the ESR

114
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

115
Can we improve the dynamic response of a
Resistor Emulator with a low penalty in the
converter efficiency?
High-efficiency post-regulators (I)
The minimum response time is 10-8.3 ms (one
100-120 Hz cycle)
Another stage can be connected to improve the
transient response
116
Characteristic of the high-efficiency post
regulators
High-efficiency post-regulators (II)

• Common characteristics of all high-efficiency
  post-regulators
• Low additional cost and size
• Only a fraction of the total power undergoes 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

117
High-efficiency post-regulators (III)
Use of the high-efficiency post regulators in
multiple-output applications
Some slow or medium-speed outputs and some fast
response outputs
118
High-efficiency post-regulators (IV)
Operation principle of the high-efficiency post
regulators
How can we implement the voltage source?
119
Implementing the voltage source VS (I)
High-efficiency post-regulators (V)
Where should we connect the input port of this
converter?
120
Implementing the voltage source VS (II)
High-efficiency post-regulators (VI)
Option 1 connect the input port to an
additional Resistor Emulator output
121
Implementing the voltage source VS (III)
High-efficiency post-regulators (VII)
Option 2 connect the input port to the Resistor
Emulator output
122
Implementing the voltage source VS (IV)
High-efficiency post-regulators (VIII)
Option 1 connect the input port to an
additional output of the Resistor Emulator
Option 2 connect the input port to the Resistor
Emulator output
Series-Switching post-Regulator (SSPR)
Two-Input Buck (TIBuck)
123
Why is the efficiency of these post-regulators
very high?
High-efficiency post-regulators (IX)
V1, VO gtgt VS Þ
P1, PO gtgt PS Þ
The Small DC/DC converter is processing only a
small part of the output power Þ Low losses in
the post-regulator Þ High efficiency
post-regulator
124
Why is not possible to implement a over-load or
short-circuit protection in these post-regulators?
High-efficiency post-regulators (X)
If VS 0,
then VO V1 ¹ 0
The over-load or short-circuit protection must be
implemented in the Resistor Emulator
125
High-efficiency post-regulators (XI)
Introducing the Two-Input Buck (TIBuck)
This is a Buck converter with two inputs instead
of one
126
High-efficiency post-regulators (XII)
Single-output Resistor Emulator based on a
Flyback a TIBuck post-regulator
127
High-efficiency post-regulators (XIII)
Multiple-output Resistor Emulator based on a
Flyback a TIBuck post-regulator
128
High-efficiency post-regulators (XIV)
Comparing Buck and TIBuck converters
V1 gt VO VQMAX V1 VDMAX V1 VO V1d (d is the
duty cycle)
V2 gt VO gt V1 VQMAX V2-V1 VDMAX V2-V1 VO V2d
V1(1-d) (from volts-second balance)
129
High-efficiency post-regulators (XV)
DC equivalent circuit for the TIBuck
VO V2d V1(1-d)
(V2-V1)d V1
130
High-efficiency post-regulators (XVI)
Relationship between input and output voltages (I)
ALWAYS V2 gt VO gt V1
131
High-efficiency post-regulators (XVII)
Relationship between input and output voltages
(II)
Case of being used as post-regulator of a
Resistor Emulator
ALWAYS V2 gt VO gt V1, taking into account the
worse case of transient response and ripple
132
High-efficiency post-regulators (XVIII)
Comparing filter inductance for Buck and TIBuck
converters (I)
Lower value in the case of the TIBuck converter
(in practice, 3 times lower)
133
High-efficiency post-regulators (XIX)
Comparing filter inductance for Buck and TIBuck
converters (II)
Boundary between continuous and discontinuous
conduction modes

• CCM 2L/RT gt KCRIT
• DCM 2L/RT lt KCRIT

TIBuck
Lower value in the case of the TIBuck converter
134
High-efficiency post-regulators (XX)
Explaining the high efficiency of the TIBuck
converter (I)
Realistic case for a Buck converter
VOB 50 V IO 1.8 A POB 90 W
VG 100 V IG 1 A PG 100 W
d 0.55 PLosses 10 W
R VOB/IO 27.8 W
? 90 / 100 90
135
High-efficiency post-regulators (XXI)
Explaining the high efficiency of the TIBuck
converter (II)
V1 300 V
IO 1.8 A V1 300 V P1 540 W
IO 1.8 A
P1 540 W
IO 1.8 A Þ R1 V1/IO 166.7 W
We are processing 540 W FREE !!
? (90 540) / (100 540) 98.4
136
High-efficiency post-regulators (XXII)
Explaining the high efficiency of the TIBuck
converter (III)
I2 IG 1 A I1 IO- IG 0.8 A V2 VG
V1 400 V P2 400 W P1 240 W Pi P2 P1
640
IO 1.8 A VO VOB V1 350 V PO POB
P1 630 W
? 630 / 640 98.4
137
High-efficiency post-regulators (XXIII)
Explaining the high efficiency of the TIBuck
converter (IV)
The closer V2 and V1 (and, therefore VO) the
higher the efficiency
138
High-efficiency post-regulators (XXIV)
Explaining the high efficiency of the TIBuck
converter (V)
High efficiency TIbuck with a limited efficiency
in the Buck part
139
High-efficiency post-regulators (XXV)
Small-signal transfer functions of the TIBuck
converter
The quantities with hats are the perturbations
Similar to the case of a Buck converter, but
faster due to the lower values of the output
filter components
140
High-efficiency post-regulators (XXVI)
Implementing the transistor driver

• Requirements
• Galvanic isolation
• Wide duty cycle operation

141
High-efficiency post-regulators (XXVII)
Experimental results of TIBuck-based prototypes
(I)
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
142
High-efficiency post-regulators (XXVIII)
Experimental results of TIBuck-based prototypes
(II)
TIBuck 1 overall efficiency
143
High-efficiency post-regulators (XXIX)
Experimental results of TIBuck-based prototypes
(III)
TIBuck 1 efficiency with V2 V1 variable,
V2-V1 80 V, VO(V1V2)/2
Being V2-V1 a constant, the closer V2 and V1
(and, therefore VO) the higher the efficiency
144
High-efficiency post-regulators (XXX)
Experimental results of TIBuck-based prototypes
(IV)
TIBuck 1 and Buck-part efficiencies
The experimental results fit very well with the
calculated ones
145
High-efficiency post-regulators (XXXI)
Experimental results of TIBuck-based prototypes
(V)
TIBuck 2 overall efficiency and small-signal
modelling
146
High-efficiency post-regulators (XXXII)
Experimental results of TIBuck-based prototypes
(VI)
Resistor Emulator based on a Flyback converter
TIBuck 2
147
High-efficiency post-regulators (XXXIII)
Experimental results of TIBuck-based prototypes
(VII)
Voltage ripple cancellation in the case of the
Resistor Emulator based on a Flyback converter
TIBuck 2
Can we improve the ripple cancellation?
148
High-efficiency post-regulators (XXXIV)
Experimental results of TIBuck-based prototypes
(VIII)
Other TIBuck control methods to improve the
voltage ripple cancellation

• Input voltage feedforward
• Current mode control (average current mode
  control)

149
High-efficiency post-regulators (XXXV)
Experimental results of TIBuck-based prototypes
(IX)
Average current mode control
Voltage ripple attenuation ? 66dB (1900 times).
Also, excellent transient response
150
High-efficiency post-regulators (XXXVI)
Introducing the option 2 Series-Switching
Post-Regulator (SSPR)
Option 2 connect the input port to the Resistor
Emulator output
Series-Switching post-Regulator (SSPR)
151
High-efficiency post-regulators (XXXVII)
Introducing the SSPR based on a Forward converter
The controlled output voltage is VO instead of VS
152
High-efficiency post-regulators (XXXVIII)
Other SSPR implementations
Implementation based on a Flyback

• The implementation based on a Flyback becomes a
  Boost converter if n1n2
• A Boost converter has a very high efficiency if
  the input and output voltages are very close

153
High-efficiency post-regulators (XXXIX)
Single-output Resistor Emulator based on a
Flyback a Forward-type SSPR
154
High-efficiency post-regulators (XL)
Multiple-output Resistor Emulator based on a
Flyback a Forward-type SSPR
155
High-efficiency post-regulators (XLI)
Computing SSPRs efficiency (I)
VO V1 VS
I1 IiDC IO
Being KSVS/V1
156
High-efficiency post-regulators (XLII)
Computing SSPRs efficiency (II)
Example ?C 80 KS VS/V1 0.1
The lower KS, the higher the efficiency
However, VS must reaches VSmax and must be always
positive
157
High-efficiency post-regulators (XLIII)
Experimental results of a Forward-type SSPR (I)
158
Experimental results of a Forward-type SSPR (II)
High-efficiency post-regulators (XLIV)
Average current mode control
(Attenuation ? 50dB)
159
High-efficiency post-regulators (XLV)
Conclusions of the use of High-efficiency
post-regulators to improve the transient response
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 with different transient response
  specifications

160
High-efficiency post-regulators (XLVI)
Conclusions of the use of High-efficiency
post-regulators to improve the transient response
of Resistors Emulators (II)

• V1 and VO are voltages of similar values
• It is not a good solution for low output voltage
  applications because the energy is stored near
  the output voltage
• No short-circuit and/or overload protection can
  be implemented in the post-regulator (it must be
  implemented in the Resistor Emulator)
• However, short-circuit overcurrent from the bulk
  capacitor can be diverted through an additional
  diode (see next slide)

161
High-efficiency post-regulators (XLVII)
Additional diode to divert short-circuit
overcurrent from the bulk capacitor
The overcurrent is diverted by the diode Da

• The drive pulses must be maintained to discharge
  CB2
• CB1is discharged through the additional diode Da

• The drive pulses must be eliminated

162
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

163
SingleStage PFCs (I)
Standard Two-Stage approach (I)
164
SingleStage PFCs (II)
Standard Two-Stage approach (II)

• Compliance with IEC 1000-3-2

• Expensive

• Fast output voltage response

• Low efficiency?
• Not for universal line

• DC bus regulated (interesting for 85-264V ac )

165
SingleStage PFCs (III)
Introducing Single-Stage PFCs (I)
166
SingleStage PFCs (IV)
Introducing Single-Stage PFCs (II)

• Compliance with IEC 1000-3-2

• Fast output voltage response

• DC bus unregulated (not very interesting for
  85-264 V)

• Cheap

• Energy stored at high voltage

167
SingleStage PFCs (V)
Introducing Single-Stage PFCs (III)
ZS
Previous methods to increase the conduction angle
A resistor
Simple passive components
An inductor
168
Introducing Single-Stage PFCs (IV)
SingleStage PFCs (VI)

• Could we find a small-size lossless impedance ZS?
• Lossless Þ Based on inductors
• Small size Þ Working at the switching frequency
• Small size Þ Only diodes (no transistors) Þ It
  is an additional output

169
SingleStage PFCs (VII)
Introducing Single-Stage PFCs (V)
Equivalent circuit for many S2PFC
Magnetic device
HIAN High Impedance Active Network
170
SingleStage PFCs (VIII)
Example of topological transformations (I)
171
SingleStage PFCs (IX)
Example of topological transformations (II)
nS n1-nS
Presented at INTELEC 96 by F. S. Tsai, P.
Markowski E. Whitcomb
172
SingleStage PFCs (X)
Example of topological transformations (III)
Presented at PESC 94 by R. Redl, L. Balog and N.
Sokal
173
SingleStage PFCs (XI)
Examples of HIAN (I)

• Low current and voltage stress
• 2 inductors

• Only 1 inductor
• Either high current or voltage stress (it will
  be explained later)

174
SingleStage PFCs (XII)
Examples of HIAN (II)
175
SingleStage PFCs (XIII)
Generalization
176
Cases to study 1st) only LF and in DCM (DCM1)
SingleStage PFCs (XIV)

• Design parameters
• Ld 0
• LF in DCM
• n1/nS

177
SingleStage PFCs (XV)
Cases to study 2nd) two inductors, LF in CCM

• Design parameters
• Ld
• K LF/Ld
• n1/nS

178
SingleStage PFCs (XVI)
Cases to study 3rd) only Ld (DCM2)

• Design parameters
• LF 0
• Ld
• n1/nS

179
SingleStage PFCs (XVII)
Cases to study Two more HIANs
From
180
Focusing the analysis (I)
SingleStage PFCs (XVIII)

• We need
• To choose the HIAN according the application
  requirements
• To calculate the value of the inductor(s) in
  order to have a line current harmonic content
  below the values specified in the IEC 61000-3-2

How can we establish a relationship between the
HIAN and the line current harmonic
content? Equations
181
Focusing the analysis (II)
SingleStage PFCs (XIX)
Considerations for the study Vc and the
converter duty cycle d considered constant each
line half-cycle
182
Previous design considerations (I)
SingleStage PFCs (XX)

• The variation of Vc should be as low as possible
  Þ
• VHIAN(IHIAN average max) as low as possible Þ
  HIAN with Ld.

The case Ld0 is not desirable (cases a, b and c)
183
Previous design considerations (II)
SingleStage PFCs (XXI)

• The current stress in the DC/DC converter should
  be as low as possible

For this reason, the case Ld0 is not desirable
again (cases a, b and c)

• The total inductor size should be as small as
  possible

184
Voltage-Current Characteristics (calculated from
IHIAN average)
SingleStage PFCs (XXII)
Results after solving the operation equations
185
Input current waveforms (examples) obtained from
the previous Voltage-Current Characteristics
SingleStage PFCs (XXIII)
IHIAN depends on VHIAN , LF , Ld and also on d,
n1/nS and VC
186
Comparing Voltage-Current Characteristics
calculated from IHIAN average and from IHIAN peak
SingleStage PFCs (XXIV)
187
Examples of VCCaverage and VCCpeak for different
HIAN
SingleStage PFCs (XXV)
The values of Vc, d, n1/nS and Ld are the same
for all the examples
188
SingleStage PFCs (XXVI)
Conclusions from the previous examples (I)
189
SingleStage PFCs (XXVII)
Conclusions from the previous examples (II)
190
SingleStage PFCs (XXVIII)
Conclusions from the previous examples (III)
191
SingleStage PFCs (XXIX)
Optimum design of an example

• Flyback as DC/DC converter
• Pout 100 W
• Vout 54 V
• European AC voltage (190-265)
• IEC 61000-3-2, Class D
• Maximum duty 0.35
• 33 W as limit between CCM and DCM
• Switching frequency 100 kHz

192
SingleStage PFCs (XXX)
Total size of magnetic elements for the previous
example
KLF/Ld
K0 K0.1 K0.5 K1 K2 K10
Ld (mH) 70 542 268 268 291 353
LF (mH) 0 54.2 134 268 582 3530
S Ix2Lx (mJ) 943 1488 1003 1338 2179 9693
Ld (mH) 47.8 221 76.5 105.7 87.2 92.7
LF (mH) 0 22.1 38.25 105.7 174.4 927
S Ix2Lx (mJ) 424.5 770.2 440.8 603.7 773.9 2676
Ld (mH) 185.2 167 174.4 178.7 182.5 167.1
LF (mH) 0 16.7 87.2 178.7 365 1671
S Ix2Lx (mJ) 1107 1086 1213 1424 1845 5133
193
SingleStage PFCs (XXXI)
Voltage and current stress for the previous
example
KLF/Ld 0 0.1 0.5 1 2 10
VC_max (V) 423 540 425 413 415 415
IS_peak (A) 2.53 3.14 2.48 2.41 2.39 2.42
VC_max (V) 437 560 420 420 414 416
IS_peak (A) 2.24 2.7 2 2 1.97 1.93
VC_max (V) 420 415 418 419 418 420
IS_peak (A) 2 1.98 1.95 1.94 1.93 1.89
194
SingleStage PFCs (XXXII)
Summary of good designs for the previous
example (I)
Flyback as DC/DC converter Pout 100W Vout
54V European AC voltage (190-265) IEC
61000-3-2, Class D Maximum duty 0.35 33 W as
limit between CCM and DCM Switching frequency
100kHz
KLF/Ld 0.5 1
n1/nS 1.813 1.875
VC_max (V) 425 413
Ld (mH) 268 268
LF (mH) 134 268
S Ix2Lx (mJ) 1003 1338
Interesting for Forward DC/DC converters
195
SingleStage PFCs (XXXIII)
Summary of good designs for the previous
example (II)
Flyback as DC/DC converter Pout 100W Vout
54V European AC voltage (190-265) IEC
61000-3-2, Class D Maximum duty 0.35 33 W as
limit between CCM and DCM Switching frequency
100kHz
KLF/Ld 0.5 1
n1/nS 3.125 2.625
VC_max (V) 420 420
Ld (mH) 76.5 105.7
LF (mH) 38.25 105.7
S Ix2Lx (mJ) 440.8 603.7
Interesting for all DC/DC converters, except
Forward
196
SingleStage PFCs (XXXIV)
Summary of good designs for the previous
example (III)
Flyback as DC/DC converter Pout 100W Vout
54V European AC voltage (190-265) IEC
61000-3-2, Class D Maximum duty 0.35 33 W as
limit between CCM and DCM Switching frequency
100kHz
KLF/Ld 0
n1/nS 2.875
VC_max (V) 420
Ld (mH) 185.2
S Ix2Lx (mJ) 1107
Interesting for all DC/DC converters, except
Forward
197
Analysing the high-frequency harmonics
SingleStage PFCs (XXXV)

• Full-wave HIANs are better than the half-wave
  one
• Comparing full-wave HIANs

The HIAN type e is the most interesting from
this point of view
198
SingleStage PFCs (XXXVI)
The lossless resistor model (I)
Is there any simple model for the HIAN? Yes, if
LF gtgtLd
199
SingleStage PFCs (XXXVII)
The lossless resistor model (II)
If LF gtgtLd (small line current ripple)
VHIAN Vi1(d fStd) Vi1(d
fSLdIHIAN/Vi1) Vi1d fSLdIHIAN
200
SingleStage PFCs (XXXVIII)
The lossless resistor model (III)
After analysing the circuit using this
model Compliance at 220V ?Cgt67.5º Compliance at
230V ?Cgt64.5º (in Class D)
201
SingleStage PFCs (XXXIX)
The lossless resistor model (IV)
VHIAN VS - RLF iHIAN
The same model is valid for the rest of the HIAN
based on two inductors if LFgtgtLd
202
SingleStage PFCs (XL)
Comparing different HIAN based on the lossless
resistor model
203
SingleStage PFCs (XLI)
Set of equations to design with the lossless
resistor model

• Current waveforms
• If vglt (VC-VS) ? ig 0
• If vggt (VC-VS) ? ig
  (vgVS-VC)/RLF

• Conduction angle ?c
  2cos-1((VC-VS)/Vg)

• Power balance Pg
  (?C-sin?C)Vg2/(2?RLF)

• Output voltage VDC VDC f1(VC, d)

• Voltage VS VS f2(VC, d)

• From this set of equations, we obtain
• Voltage across bulk capacitor, VC
• Voltage across semiconductors (from VC)

204
SingleStage PFCs (XLII)
Integrating delaying and filter inductor into
one magnetic core (I)
Can we integrate filter and delaying inductors
into only one magnetic core?
205
SingleStage PFCs (XLIII)
Integrating delaying and filter inductor into
one magnetic core (II)
Process of integration
206
SingleStage PFCs (XLIV)
Integrating delaying and filter inductor into
one magnetic core (III)
Example Two-winding, top-bottom arrangement
(coupling not very tight)
207
SingleStage PFCs (XLV)
Examples of a converter with HIAN (I)
208
SingleStage PFCs (XLVI)
Examples of a converter with HIAN (II)
209
SingleStage PFCs (XLVII)
Examples of a converter with HIAN (III)
210
SingleStage PFCs (XLVIII)
Examples of a converter with HIAN (IV)
211
SingleStage PFCs (XLIX)
Examples of a converter with HIAN (V)
212
SingleStage PFCs (L)
Experimental results with KLF/Ld0.5 (I)
Flyback, 100 W, HIAN case e (4 diodes)

• Ld76.5 ?H (E16)
• LF38 ?H (E12)
• Efficiency 87
• Class D

213
SingleStage PFCs (LI)
Experimental results with KLF/Ld0.5 (II)
Flyback, 100 W, HIAN case e (4 diodes)

• Ld76.5 ?H (E16)
• LF38 ?H (E12)
• Efficiency 87
• Class D

214
SingleStage PFCs (LII)
Experimental results with KLF/Ld1 (I)
Flyback, 100 W, HIAN case e (4 diodes)

• Ld105 ?H (E16)
• LF105 ?H (E16)
• Efficiency 87
• Class D

215
SingleStage PFCs (LIII)
Experimental results with KLF/Ld1 (II)
Flyback, 100 W, HIAN case e (4 diodes)

• Ld105 ?H (E16)
• LF105 ?H (E16)
• Efficiency 87
• Class D

216
SingleStage PFCs (LIV)
Experimental results with KLF/Ldgt1 (I)
Half-bridge prototype
SPP11N60S5 (Cool MOS)
fS 100kHz
217
SingleStage PFCs (LV)
Experimental results with KLF/Ldgt1 (II)
Flyback prototype
IRFPC50
fS 100kHz
218
SingleStage PFCs (LVI)
Experimental results with KLF/Ldgt1 (III)
Implementations of the HIAN
IEC 61000-3-2 Class D, 100W, 190-265V
219
SingleStage PFCs (LVII)
Experimental results with KLF/Ldgt1 (IV)
Half-bridge prototype Input-current waveforms
harmonics
220
SingleStage PFCs (LVIII)
Experimental results with KLF/Ldgt1 (V)
Flyback prototype Input-current waveform
harmonics
221
SingleStage PFCs (LIX)
Experimental results with KLF/Ldgt1 (VI)
With HIAN types 1, 2 3
With HIAN type 1
222
SingleStage PFCs (LX)
Experimental results with KLF/Ldgt1 (VII)
The maximum voltage across the bulk capacitor is
lower than 450V
223
Conclusions of the use of Single-Stage PFC (I)
SingleStage PFCs (LXI)

• Many Single-Stage PFCs can be described as an
  arrangement made up of a line rectifier, a
  conventional DC/DC converter and a High Impedance
  Active Network (HIAN)
• This HIAN is an additional output of the DC/DC
  converter that re-cycles a part of energy
• Using Single-Stage PFC based on the use of HIANs
  we achieve
• Low cost and size (no second stage)
• The energy is stored at high voltage Þ moderate
  bulk capacitor size
• A harmonic content low enough to comply with the
  IEC 61000-3-2 in Class A and Class D

224
Conclusions of the use of Single-Stage PFC (II)
SingleStage PFCs (LXII)

• Only a few of energy is re-cycled to get
  compliance with the regulations Þ High efficiency
  is achieved
• Many different HIAN implementations are
  possible. To comply with the regulations in Class
  D, those based on two inductors are the most
  attractive.
• The size of the additional inductors are very
  small (e.g. two E16 cores for a 100 W converter).
  Moreover, both inductors can be integrated into
  only one magnetic core
• The variation of the voltage across the bulk
  capacitor when the line voltage and the load
  change is reasonable (maximum voltage below 450
  V DC when the line is 265 V AC)

225
Conclusions of the use of Single-Stage PFC (III)
SingleStage PFCs (LXIII)

• Fast output response due to the location where
  the DC/DC converter is placed
• The main limitations are
• The voltage across the bulk capacitor is not
  regulated. This facts deteriorates the DC/DC
  converter efficiency.
• Due to the same fact, the operation with
  universal line is not adequate
• However, for the universal line voltage range, a
  voltage doubler with a mechanical switch can be
  implemented to allow operation in this condition
  (this has not been explained here)

226
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

227
Objective A new low-cost method to control PFC
in CCM
Very simple shaping (I)

• Previous methods
• Control based on an analog multiplier
• Voltage-Follower Control

228
Very simple shaping (II)
Types of control control based on an analog
multiplier

• In CCM
• Perfect PF THD
• Low losses in the transistor
• Current sensor
• Multiplier
• More expensive

229
Very simple shaping (III)
Types of control Voltage-Follower Control

• No current sensor
• No multiplier
• Cheaper
• Lower losses in the diode
• Only high-output-impedance topologies (converters
  in DCM)
• Sometimes THD
• Higher total losses

230
Comparing semiconductor currents for both
control methods (I)
Very simple shaping (IV)
Example battery charger based on a
Flyback Vinput 85-265 Vac VOutput 10-14
V IOutput 3-10 A
231
Comparing semiconductor currents for both
control methods (II)
Very simple shaping (V)
itransistor RMS 2.16 A
itransistor RMS 3.55 A
Losses in the transistor operating in DCM are
3.552 / 2.162 2.7 times as high as in CCM
Operation in CCM is desirable from the point of
view of efficiency
232
Comparing controllers for both control methods
Very simple shaping (VI)
Controller cost UC3843 Þ 0.5 UC3525 Þ 1.1
Controller cost UC3854A Þ 5.3 UC3854B Þ 8.2
Operation in DCM is desirable from the point of
view of the controller cost
233
Can we have some of advantages of both methods
together? Þ Conduction-Angle Control
Very simple shaping (VII)

• In CCM (as MC)
• Low losses (as MC)
• Low cost (as VFC)
• Compliance with regulations
• Current sensor
• No perfect sinusoidal

234
Very simple shaping (VIII)
Principle of operation of Conduction Angle
Control (I)
235
Very simple shaping (IX)
Principle of operation of Conduction Angle
Control (II)
iB1
lt iB2
lt iB3
(The same if it is controlled by light)
236
Very simple shaping (X)
Implementation without galvanic isolation
237
Example Implementation based on a boost
converter
Very simple shaping (XI)
238
Very simple shaping (XII)
Implementation without galvanic isolation
239
Example Implementation based on a flyback
converter
Very simple shaping (XIII)
240
Very simple shaping (XIV)
Design procedure
_at_ Minimum line voltage and maximum output power
fD22.5º
241
Very simple shaping (XV)
Line waveforms at full load
Voltage 85 V AC 110 V AC 130 V AC
Dead angle 0º 37.5º 55.7º
Voltage 85 V AC 110 V AC 230 V AC
Dead angle 0º 37.5º 98.8º
Voltage 190 V AC 230 V AC 26