Active Power in 1~AC mains Apparent / Reactive / Active Power ~ L W 0 P ~ C cos I U P W 0 P ~ R pure resistor R : phase shift = 0° active power 1 pure reactance L : phase shift = 90° no active power pure capacitance C : phase shift = 90° no active power
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Active Power in 1~AC mains Apparent / Reactive / Active Power ~ L ~ C ~ R pure resistor R : phase shift = 0° active power 1 pure reactance L : phase shift.
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Active Power in 1~AC mainsApparent / Reactive / Active Power
~ L
W0P
~ C
cosIUPW0P
~ R
pure resistor R : phase shift = 0°
active power
1
pure reactance L : phase shift = 90°
no active power
pure capacitance C : phase shift = 90°
no active power
Apparent / Reactive / Active Power
applicable for distorted voltage and current (harmonics)
wave-form must not be continuous
Power Factor
distorted voltage contains harmonics
By means of
Fourier transformation
a distorted wave form can be synthesized by a infinite number of sine-waves of ascending order
Power Factor
Current Power Factor 0,53
distorted AC current caused by rectifier
Power Factor 1~AC mains current without PFC
mains current harmonics / Fourier transformation
current harmonics in mains supply
Inetz [mA]
0
100
200
300
400
500
600
700
50 150 250 350 450 550 650 750 850 950
w/o PFC
Power Factor current harmonics 1~AC fan without PFC
Limits acc. DIN EN61000-3-2
harmonic number permitted maximum valuen A rms
3 2,305 1,147 0,779 0,4011 0,3313 0,21
15<=n<=39 0,15 x 15/n
2 1,084 0,436 0,30
8<=n<=40 0,23 x 8/n
odd harmonics
even harmonics
Limits for class A-devices Power factor (PF)
Power FactorDIN EN61000-3-2
DC-linkcapacitorUac
rectifier
Power Factor Correction PFC1~AC mains input – circuit without PFC
Choke
DC-Link capacitorUac
rectifier
Power Factor Correction PFC 1~AC mains input – circuit with 1~choke (passive PFC)
choke boost-diode
DC-linkcapacitor
shunt
MOS-FET
capacitorUac
rectifier
Power Factor Correction1~AC-mains input – circuit with active PFC
reduced harmonics by PFC
w/o PFCPower Factor = 0,53
current IRMS = 958 mA
with active PFCPower Factor = 0,99
current IRMS = 628 mA
Power Factor Correction
Current harmonics with and without aktive PFC compared in the same duty point
@ 230V50Hz
Imains [mA]
0
100
200
300
400
500
600
700
1 3 5 7 9 11 13 15 17 19
without PFC
with PFC
Power Factor1~AC with active PFC / without
distorted AC current caused by rectifier
cables, switches and fuses are dimensioned according to current !