Application Note AN-1077
PFC Converter Design with IR1150
One Cycle Control IC
R. Brown, M. Soldano, International Rectifier
This Application Note describes the design methodology of a Continuous Conduction Mode Power
Factor Correction circuit utilizing a boost converter and featuring the IR1150S PFC IC. The IR1150
is based on International Rectifier’s proprietary “One Cycle Control” technique for PFC converter
control. This application note presents a complete, step-by-step, design procedure including con-
verter specifications and necessary design tradeoffs.
Topics Covered
• Power Factor Correction
• One Cycle Control operation
• IR1150 Detailed Description
• Design procedure and example
• Design Tips
¾ For additional data, please visit our website at:
http://www.irf.com/product-info/smps/
http://www.irf.com/e/ir1150ppdus.html/
Keywords: PFC, Power Factor Correction, THD, One
Cycle Control, OCC
Introduction
Power factor is defined as the ratio of real power
to apparent power, where real power is the time inte-
gral of the instantaneous power measured over a full
period and the apparent power is simply the product
of the rms voltage and rms current measured over the
entire period.
For a sinusoidal voltage this can be written as:
PF = Vrms ⋅ Irms1 ⋅ cos( φ ) = Irms1 cos( φ ) (4)
Vrms ⋅ I rms
I rms
Vrms is the line voltage RMS value
I rms is the line current RMS value
I rms1 is the line current fundamental harmonic
φ is the displacement angle between voltage and current
In this case power factor can be split into distortion
factor and displacement factor:
kD
=
I rms1
I rms
; kφ
= cos(φ
)
(5)
Phase shift between the voltage and current
waveforms is introduced by the reactive nature of the
input, either inductive or capacitive.
In a purely resistive load, the voltage and current
will be sine waves, in phase, true power will equal
apparent power and PF = 1.
∫ Real
Power
=
1
T
T
0
VIN
IIN dt
(1)
Apparent Power = VinRMS ⋅ IinRMS
(2)
PF = PREAL
(3)
PAPPARENT
∞
∑ Irms =
I2
rmsn
(6)
n=1
THD =
I2
rms
−
I2
rms1
I2
rms1
(7)
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