Avago Technologies ACPL-224-500E - Manual (Page 50)

AV02-4387EN 47 Avago Technologies
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
VIN+
VIN–
V
CC1
GND1
RESET
FAULT
VLED1+
VLED1–
VE
VLED2+
DESAT
V CC2
VC
VOUT
V EE
V EE
HIGH GATE-DRIVE
(LOW GATE-DRIVE CIRCUIT IS
IDENTICAL TO HIGH
GATE-DRIVE CIRCUIT)
HCPL-316J
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
VIN+
VIN–
V
CC1
GND1
RESET
FAULT
VLED1+
VLED1–
VE
VLED2+
DESAT
V CC2
VC
VOUT
V EE
V EE
LOW GATE-DRIVE
HCPL-316J
N/C
R TONH
10
R BIASDH
20K
V CC2 (H)
V DESAT (H)
V C (H)
V O (H)
V E (H)
V EE (H)
D ZLH
18 V
C 2H
1.2 µF
(20%)
C 3H
0.1 µF
1 k
R DESATH
R GH
12.5
D Z2H
12 V
C 4H
250 nF
D 2H
A14P
1,000 V
R 1L
47K
R 2L
20
15nF
C 1L
1K
R DESATL
D DSL
HV DIODE
R GL
12.5
D FBLO
(DSE130-12A,
IXYS)
HV–
AC
MOTOR
D FBHI
(DSE130-12A,
IXYS)
D DSH
A14P
1,000 V
HV+
DUAL IGBT
R 2H
20
15 nF
C 1H
HV+
HV+
R 1H
47K
D 1H
A14P
1,000 V
M1
M2
Figure 4. Bootstrap Circuit for Power Control System
Motor Control Applications
Figure 4 shows a bootstrapped out-
put power supply circuit that has
the following benefits:
• eliminates the need for an iso-
lated power supply or a dc-to-dc
converter,
• lower cost solution compared to
transformer based power supply,
• less printed circuit board space.
This circuit includes a bootstrap
circuit for providing output power
to the HCPL-316J gate drive opto-
couplers, thereby eliminating the
need for isolated power supplies or
dc-to-dc converters. It can be modi-
fied to suit other Avago gate drive
optocouplers and current/voltage
sensing isolation amplifiers.
Component values were chosen for
a 350 V rail =
HV+ - HV - (240 V x 1.414).
When the lower IGBT is turned on,
V
C1H
charges up (through
D
1H
) to a voltage of:
V
C1H
= HV+ - [HV- + V
SATM2
+ V
CC2H
+
V
F
(D
1H
)]
= 350 V - 3 V - 18 V - 1 V
= 328 V
where V
SATM2
is the saturation or
“on” voltage across the collector-
emitter of IGBT M2; V
F (D1H)
is the
voltage across diode D
D1H
; and
HV+, HV- are the rail voltages.
Bootstrap Power Supply Circuit for Power Control Systems
When M2 (low IGBT) switches off
and M1 (upper IGBT) switches on,
V
E(H)
pulls up to HV+ -V
SATM1
. This
causes C
4H
to become charged
through D
2H
. Charge sharing be-
tween C
1H
and C
4H
results in the voltage across C
4H
which (in the absence of clamping
diode D
Z2H
) can be approximated
by:
C
4H
× ∆V
C4H
= C
1H
× 328 V
-> ∆V
C4H
= 19.6 V
where ∆V
C4H
= the voltage drop
across C
4H
. The negative gate bias
then is held at 12 V by clamping
Zener D
Z2H
.