Power Factor Controller Circuit - NEC MultiSync FP1370 Service Manual

8-11. Power Factor Controller Circuit

This circuit is composed of Low pass filter block and Power feedback block. AC input is rectified by D601,
then it charge C6Y2, C610 and C609.
C610 is not charged during period α and period γ from input voltage directly, because the voltage of
C6Y2 is smaller than the voltage of C610. Then, C610 is charged during period α and periodγby Power
feedback block. When TR1 (internal IC621) turn on, the N1 winding of T6Y1 is charged with energy. When
TR1(internal IC621) turn off, the N2 winding of T6Y1 discharge energy. So, the voltage of point A is the
part of slant line(Fig.8-12 : VC610-VC6Y2).And C610 is charged with feedback energy during period α
and period γ, because the voltage of point A is bigger than the voltage of C610.
C610 is charged during period β(Fig.8-12) from input voltage directly.(Power supply which doesn't have
"Power Factor Controller Circuit" is only charged during this period.)
Finally, the voltage of C610 and input current become Wave of Fig.8-12.The harmonic current is decrease,
and Power Factor is improved. Because C610 is charged not only period βbut also many parts of 1 cycle.
LOW PASS FILTER BLOCK
AC
AC
(Fig.8-11) POWER FOCTER CONTROLLER CIRCUIT
VOLTAGE
V
C6Y2min
INPUT CURRENT
GND
Period α
POINT A
L6Y1
D601
C6Y1
V
C610
V
C6Y2
I
N2
γ
β
(Fig.8-12) VOLTAGE・INPUT CURRENT
C6Y2
D6Y3
IC621
V >V
C6Y2 C610
V <V
C6Y2 C610
GND
V <V
C6Y2 C610
I
N2
+
8-50
POWER FEEDBACK BLOCK
T6Y1
D6Y1
+
+
D6Y2
-
-
C609
C610
3
B
TR1
C
1
B C
E
2
GND
V >V
C6Y2 C610
+I
D6Y2
N2
T601
N1
C611
R605
D603
L601