
28-6 Power Electronics and Motor Drives
(c)
AC mains
voltage
Fluorescent
lamp
Rectifier
Power factor
correction circuit
DC/AC
converter
Resonant
tank circuit
(Figure 28.4d
through g)
S
PFC
Q
1
Q
2
C
PFC
L
PFC
D
PFC
(a) (b)
v
ac
Full power
Dimmed power
i
ac
0
0
π
π
2π
2π
AC mains
High-
frequency
DC/AC
converter
Resonant
tank
circuit
Discharge
lamp
DC
link
i
ac
v
ac
Ballast controller
Control
Signal
Active or
passive
power
factor
correction
circuit
L
ν
o
ν
o
ν
i
heating circuit
(d) (e)
(f) (g)
External
heating circuit
C
L
ν
i
heating circuit
External
heating circuit
C
L
ν
o
ν
i
External
heating circuit
External
heating circuit
C
p
C
s
L
1
L
2
C
s
FIGURE 28.4 Electronic ballasts for discharge lamps. (a) Gener