Download Power Factor Correction

Ali Fawaz
Senior Application
Engineer
POWER FACTOR
CORRECTION
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IMS Research,
July 2009
10.11.2010
For internal use only
Semicast,
May 2008
Frost & Sullivan,
October 2009
Copyright © Infineon Technologies 2009. All rights reserved.
Strategy Analytics,
July 2009
Page 2
Agenda Overview
Power Factor basics
Definition of Power factor
PF for various loads
Total Harmonic Distortion
PF correction methods
ICL8001G: High PFC Dimmable LED Driver
For internal use only
Copyright © Infineon Technologies 2009. All rights reserved.
Page 3
Agenda Overview
Power Factor basics
Definition of Power factor
PF for various loads
Total Harmonic Distortion
PF correction methods
ICL8001G: High PFC Dimmable LED Driver
For internal use only
Copyright © Infineon Technologies 2009. All rights reserved.
Page 4
What is Power Factor? Why is it important for
lighting?
Power Factor is a measure of how effectively the load takes
power from the line (power plant)
¬ Alternate definition: PF provides a measure of how close your load
is to a incandescent light bulb (which has a PF of 1)

Systems with Low PF require additional power to be
generated by utilities

Lighting consumes ~20% of all generated power.

Much of this power is consumed by traditional bulbs
with PF of 1

Transition to low PF LED bulbs negates some of these
savings.
 High power factor solutions are required for LED bulbs
and fixtures
10.11.2010
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Page 5
Power Factor Requirements -- Regulatory
 DOE energy star requires PF >0.7 for energy star rating of
LED light sources
 Europe EN61000-3-2 requires power factor to meet
harmonic requirements for light sources above 25W
These standards provide a baseline requirements!
 Market requirements for LED bulbs and fixtures are
driving PF >0.9 for powers as low as 5W.
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Page 6
Detailed of Low Power factor effects
 A Power Factor less than 1 could result in the
problems below

Power is recycled from the LED Bulb/ Fixture to the power
source?

Harmonics from LED bulb/ fixture are degrating the line and
affecting the performance of other equipment on the line

The load is generating additional losses

The load is requiring that the power grid provide more power
than used.
10.11.2010
For internal use only
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Page 7
Agenda Overview
Power Factor basics
Definition of Power factor
PF for various loads
Total Harmonic Distortion
PF correction methods
ICL8001G: High PFC Dimmable LED Driver
For internal use only
Copyright © Infineon Technologies 2009. All rights reserved.
Page 8
Definition of Power Factor
 Power Factor is defined as
AVERAGE POWER
P F
APPARENT POWER
 Derivation of Average Power
P avg
1 

T 
T
1 

T 
p ( t ) dt
0
T
v ( t )  i( t ) dt
0
A periodic voltage v(t) can be expressed in Fourier Series as:

v ( t)

V dc 
k
10.11.2010
For internal use only
 V k  sin  wt
 
k

 1
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Page 9
Average Power
For Pure AC voltages Vdc=0

 V sinkwt   
v( t )
k
k
V1 sin wt  1  V2 sin 2wt  2  V3 sin 3wt  3  .....
k 1
Similarly a current i(t) that is periodic can be represented as:


Ir sin rwt   r
I1 sin  wt   1  I2 sin  2wt   2  I3 sin  3wt   3  ....
r 1
Pavg
1 

T 
T
0
10.11.2010
For internal use only
p ( t ) dt
1 

T 
T
v ( t )  i( t ) dt
0
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Average Power
T
1 
  V1 sin wt  1   I1 sin wt   1   V2 sin 2wt  2   I2 sin 2wt   2   V3 sin 3wt  3   I3 sin 3wt   3   ....dt
T
Pavg
0
+
1 

T 
T
V1 sin  wt  1  I2 sin  2wt   2  V1 sin  wt  1  I3 sin  3wt   3  V1 sin  wt  1  I4 sin  4wt   4  ...... dt
0
Unlike Terms (different frequencies) r ≠ k;
deliver zero Average Power. Therefore,
P avg
10.11.2010

1 

T


T


 Vk  Ik  sin  kwt
  k   sin  kwt   k   dt
k 1
0
For internal use only
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Average Power

Pavg

k 1

Pavg

 Vk Ik

 cos  k   k 

 2

In terms of Peak Voltage
and Peak Current
Vrmsk Irmsk cos k   k
In terms of RMS voltage
and RMS current
k 1
■ P.F Formulas


PF
10.11.2010
 Vrms k  Irms k  cos   k
 
k

k  1
For internal use only
P.F Mother Equation
Vrms  Irms
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Page 12
Power Factor Formulas
 Assuming V(t) is an ideal sinusoidal voltage Source:
Vrms1 Irms1
P F
Vrms Irms
Irms1
P F
Irms
Irms
Kdisp
Kdisp Kdist
Distortion Factor
cos  1   1
1   1
10.11.2010
 cos  1   1
Irms1
Kdist
 cos  1   1
Displacement Factor
Displacement angle between V(t) and i(t)
at Fundamental frequency.
For internal use only
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Page 13
Agenda Overview
Power Factor basics
Definition of Power factor
PF for various loads
Total Harmonic Distortion
PF correction methods
ICL8001G: High PFC Dimmable LED Driver
For internal use only
Copyright © Infineon Technologies 2009. All rights reserved.
Page 14
AC Power at PF =1
Resistive Load
(Incandescent Light Bulb)
1 voltage
There is no phase
shift between
Voltage and
Current.
All power taken
from the source is
used by load
8.00
200
4.00
100
2 current
3 power
400
1
3
200
0
Power
0
Voltage
AC Power
Current
2
0
-4.00
-100
-200
-8.00
-200
-400
2.00m
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6.00m
10.0m
time in seconds
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14.0m
18.0m
Page 15
Sinusoidal v(t) & Sinusoidal i(t) with PF < 1
Reactive power
Oscillates
between
Source and
reactive part
of load
(cap or inductor)
Current
Phase Shift
Cap (0<Φ <90)
Ind (-90<Φ<0)
8.00
200
Irms1
P F
Irms
product in watts
0
1
Irms-8.00
3 product
Red- Reactive Power
1
400
3
2
0
Kdisp Kdist
1
-200
P.F = Kdisp
10.11.2010
2 i(l1)
800
-4.00  
-100  -400
 cos
 1
1
Irms
K dist
0
100
v(1) in volts
Plot1
i(l1) in amperes
4.00
1 v(1)
For internal use only
-800
102m
106m
110m
time in seconds
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114m
118m
Page 16
Non-Linear Load and Power Factor
 The input current in a system with diode rectifier followed by a capacitor is
nonsinusoidal: This is observed in Lighting Solutions
Iin
Vout
Resistive Load
Voltages
Current
Vin
t
• Problems:
- a large harmonic component in the distorted input current leads to an
increasing pollution of the mains voltages
- the amount of reactive power is dramatically increased
(a 100W TV set consumes 90W reactive power => The input power is only partly
transferred to the output)
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Page 17
Harmonic Content
200
100
0
-100
-200
input_current in amperes
Input Voltage and Current
input_voltage in volts
1 input_voltage
2 input_current
3 harmonic_content
20.0
10.0
0
2
1
-10.0
-20.0
110m
130m
150m
time in seconds
170m
190m
60.0
180
300
frequency in hertz
420
540
Current Harmonics
(amperes)
4.50
3.50
2.50
1.50
500m
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3
Page 18
1st Harminic Power
1 v1
2 i(v1)
3 v1*i(v1)
4 result
1
2.00
1rd Harmonic
Power
Is actual
Power Transfer
between
Source
and
Load
-6.00
4.00
2
600
6.00
1 st harminc energy (J)
-300
-2.00
1st harmonic current
Energy transfer
Input voltage
-100
800
8.00
1st harmonic Power
100
400
4
3
-500
-10.0
2.00
200
-700
-14.0
0
0
2.00m
6.00m
10.0m
time in seconds
14.0m
18.0m
Total energy transfer is positive all the time.
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Page 19
3rd Harmonic Power
3rd Harmonic
Power
Oscillates
between
Source
and
Load
Apparent power
only!!!
600m
-500
200m
0
400
Power in VA
-300
400m
energy in joules
Enrgy transfer
Input Voltage
-100
600
200
0
3rd Harmonic current
100
1 v1
3 i(v1)
0
4 v1*i(v1)
5 energy
1
1
2.00
3
-2.00
-6.00
5
-10.0
4
-700
-200m
-200
-14.0
2.00m
6.00m
10.0m
time in seconds
14.0m
18.0m
Total energy transfer after each half period is equal zero “0”
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Power Factor Formula for Non-Linear Loads:
 Power Factor Formula:
Irms
PF
1
Irms
 cos
 1
 
1

K disp  K dist
 V(t) and i(t) fundamental components are in phase;
cos (θ - Φ ) = K
1
 P.F=
10.11.2010
Kdist
Irms1
Irms
For internal use only
1
=1
disp
<1
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Page 21
AC-DC conversion with and without PFC
Output voltage
Input current
Input voltage
Without Power
Factor Correction
Power factor: 0.43
Output voltage
Input current
Input voltage
With Power
Factor Correction
Power factor: >0.90 !
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Page 22
Agenda Overview
Power Factor basics
Definition of Power factor
PF for various loads
Total Harmonic Distortion
PF correction methods
ICL8001G: High PFC Dimmable LED Driver
For internal use only
Copyright © Infineon Technologies 2009. All rights reserved.
Page 23
Total Harmonic Distortion
 A frequently-used measure of harmonic levels is total harmonic distortion (or
distortion factor), which is the ratio of the rms value of the harmonics (above
fundamental) to the rms value of the fundamental, times 100%, or:
THD
I rms ( Distorted
I
I rms1
)
 100
Irms(Distorted) is the sum of all the harmonics other than the fundamental.
2
2
Irms  Irms1
Irms(Distorted)
2
THD
I
 Irms 

  1  100
 Irms1 
1
PF
1 
10.11.2010
THD
I
100
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Total Harmonic Distortion
 Incorporating these two assumptions
(Pavg ≈ P1avg and Vrms ≈ V1rms)
the following approximate form for Power Factor:
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Page 25
Agenda Overview
Power Factor basics
Definition of Power factor
PF for various loads
Total Harmonic Distortion
PF correction methods
ICL8001G: High PFC Dimmable LED Driver
For internal use only
Copyright © Infineon Technologies 2009. All rights reserved.
Page 26
Methods of Power Factor Correction
Passive Solution
by iron core choke
Characteristics:
Pros:
rugged, supports EMI, cheap
Contras: heavy, big, tends to humming
output voltage dependent on load
Active Solution
by ferrite/powder core choke, diode,
MOSFET, control IC
Characteristics:
Pros:
light, effective, output voltage stable
allows wide input voltage range
Contras: additional components but costs partially
compensated in remaining system
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Active Power Factor Correction Concept
 Emulate Load after bridge rectifier as a lossless resistor.
 Output ripple is twice the line frequency.
Vdc
 Conversion ratio=
Vin  sinwt
 Control is needed for Rin =V2in /Pin to provide
required output power.
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Page 28
Active Power Factor Correction Concept
 Slow control loop. Cross-over frequency should be about 20Hz
at high line input voltage.
 Input Voltage Feed-forward is required to provide constant
output Regulation. The input voltage feed-forward must be
constant during each half cycle.
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Active Power Factor: Two Stage Method
 Two Stage Method

Tight Output Voltage Regulation at load is provided by second
stage.

Boost most commonly used. CRM for Po<250watts; CCM
Average current mode control for Po>250watts
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Page 30
Active Power Factor Correction: Single Stage
Method
 Single Stage Method

Output Voltage Regulation at load is not tight.

High output ripple (second harmonic) at load. Used in
applications such as LED lighting in which high output ripple
voltage is inconsequential.

CRM Flyback (Buck-Boost) most commonly used.

Coupled inductor provides galvanic Isolation for safety is
provided.
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Page 32
Control Methods for Boost-Converter
V, I
Critical Conduction Mode
CRM Variable frequency
fixed Ton.
Continuous Current Mode CCM
usually constant frequency
V, I
VOUT
OUT
VIN
IN
IL
IIN
IL
IIN
t
10.11.2010
Characteristics:
Characteristics:
Pro
no reverse recovery losses of diode
simple control method
Contra
difficult smoothing of peak currents
at light load
Pro
easy smoothing of peak currents
stable operation at light load
Contra
reverse recovery losses of diode
complex control method
For internal use only
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Page 33
Active Power Factor Correction: PFC Flyback Converter
features
Advanatges
Disadvantages
- Is inherently a Power Factor Corrector when
operated in DCM. Simple hysteretic fixed ton
control.
- High Voltage Stress on MOSFET and diode.
- Coupled Inductor provides galvanic isolation for
safety.
- Filtering for EMI due to switching input current.
However, this problem is reduced by QR operation.
- Inherent Current limiting.
- Low Cost: Few Components, single stage . Can
Buck & Boost.
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Page 34
Flyback with QR operation
 Flyback can be implemented with FF or QR. QR offers the
following advantages:
 High efficiency due to zero
voltage switching.
 Reduced EMI noise.
11/10/2010
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Page 35
Agenda Overview
Power Factor basics
Definition of Power factor
PF for various loads
Total Harmonic Distortion
PF correction methods
ICL8001G: High PFC Dimmable LED Driver
For internal use only
Copyright © Infineon Technologies 2009. All rights reserved.
Page 36
LEDs AND POWER FACTOR CORRECTION.
 Requirements for LED solutions:

Appears to the source as a resistive load

Meets regulatory, market and safety requirements

Control to provide required output power.

LOW COST (Let us not Forget):
¬ Solution: Single Stage Flyback.
– Very few components --primary side control results in as few as
20 components.
–
Has inherent current limiting. No added circuitry for protection.
– Simple low cost hysteretic control can be used.
– Inherent very high PF.
– Full galvanic isolation
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Page 37
ICL8001G: Single Stage LED Driver
ICL 8001G Performance
- vs standard PFC controller -
•Precise PWM generation
•Propagation delay correction
•Fold back correction
•Start Up Cell
•Programmable Protection
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ICL8001G: Single Stage LED Driver
Supports
worldwide line
voltages with
power output
up to 30W
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Page 39
PFC performance
Vin
Iin
Vcs
For internal use only
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Phase Cut Dimming – Leading Edge
Maximum
DimmingLevel
• PFC function as ideal
precondition for stable
leading edge dimmer
operation
• Oscillations caused by
interaction of EMI filter with
leading edge dimmer are
depending on EMI filter
design applied
Vin
Vout
Medium
DimmingLevel
Iout
Minimum
DimmingLevel
Reference Dimmer : Ehmann Lumeo Domus 1060 60-300W
For internal use only
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Phase Cut Dimming – Trailing Edge
Maximum
DimmingLevel
Vin
Vout
Medium
DimmingLevel
Iout
Minimum
DimmingLevel
Reference Dimmer : Ehmann Lumeo Domus 4660 20-315W
For internal use only
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Page 42
LED Bulb Driver with ICL8001G
Feature Summary
 Best in class BOM cost with 30% material cost reduction
 Isolated Driver output for efficient thermal management
 High quasiresonant ( QR ) flyback driver efficiency up to 90%
 High power factor PF > 98% adjustable
 Phase cut controlled continuous LED current dimming
 Primary side output power control
 Small formfactor fits E27 bulb
 Cycle by cycle current limitation
 Output short circuit and output over voltage protection
 Over temperature detection
For internal use only
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Backup material
 Additional PFC corrected LED solutions from Infineon.
10.11.2010
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Page 44
Single Stage PFC with Fly-back combined
with linear drivers on secondary side
Module 1
as reference
Module 2 .. 7
VCC
Current-controlled
reference
MASTER string
determines output voltage
90 ...
270 VAC
Several number of SLAVE strings with
linear driver operating at optimal
voltage range 
Very high DC/DC efficiency
TDA4863
Single Stage PFC + Flyback
converter allows for good power factor
and efficiency at optimized system BOM
Optocoupler
TLE4305
EVALLED-TDA4863-40W
BCR450
BCR450
BCR450
REFGND
GND
PWMDimming
Optimized System Solution:
Combination of single-stage PFC + Flyback AC/DC converter, constant
current control and linear drivers allows
• high power factor,
• high efficiency and
• no EMI on secondary side
For internal use only
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Page 45
Off-Line LED Driver Solution
40W Single Stage Evaluation Board
Order Code EVAL-LED-TDA4863G-40W




TDA4863 Flyback controller & PFC in a single stage
topology
TLE4305 CV CC Feedback
Optimised for low cost multi LED string system
with BCR450 linear current regulators
Scalable and low cost BOM
For internal use only






40W Output: Input 190-270V AC
20W Output: Universal Input
Variable, Stable Output (15V-25V)
High Efficiency ~88% (AC to LED)
High Power Factor >0.9
Order Code EVAL-LED-TDA4863G-40W
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Page 46
High Power Lighting Power Supply Architecture
PFC+LLC [+DC-DC]
PFC Converter
EMI Filter / Rectifier
DCM PFC
TDA 4863-2
ICE2PDS01
LLC
ICE1HS01G
ICE2HS01G
CCM PFC
ICE2PCS0x
ICE3PCS0x
For internal use only
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Page 47