plug + play
protection
easy interface
integrated
DC-DC converter
4kV isolation
IGBT and MOSFET
SKHI - Drivers
Integrated Components
and Integrated Solutions
SEMIKRON - IGBT/MOSFET Drivers SKHI
SEMIKRON - Driver ASICs SKIC
SKHI-DRIVER
Protection
Easy User Interface
Integrated
DC-DC Converter
4kV Isolation
IGBT Power Stage
SKHI-Driver Family
PCB
Driver
Protection
• TOP BOTTOM
Interlock
• Short Pulse
Suppression
• V
CEsat
Monitoring
• Undervoltage
Monitoring
• Optional TTL-
compatible Input
• Very high EMI
Immunity
• "Plug and Play"
• Very high dv/dt-
Resistance
• High Isolation
Features
PCB mountable
Driver
Primary side
ASIC
Easy User
Interface
Integrated
DC-DC
converter
Profile of SKHI-advantages
Needs only one non-isolated +15V power supply
(even when using 3 drivers in 3-phase systems)
Very high dv/dt capability by using magnetic transformers, up
to 75 kV/µs
Isolation between control/lGBT up to 4kV
Output peak current capability up to 30A
Interlock top/bottom avoids two IGBTs of same leg being
switched-on at same time
Dead-time, V
CE
-supervision, R
GON/OFF
seperately adjustable to
optimize for user’s specific application
Fault memory informs the control system via an error signal
Supply undervoltage protection
SKHI details that make a difference
SKHI-drivers output stage
Technical advantages
MOSFET output transistor pair,
with reduced ohmic contact
Integrated voltage source
Regulated supply voltage
Customer advantages
Improves speed of turn-on
and turn-off with reduced
power losses
Increased reliability
Provides full power output
pulses without V
GE
degrada-
tion
+15 V
Under static operating condi-
tions the IGBT needs no gate
drive current because it is volt-
age controlled, but since the
gate input has a large capaci-
tance, a gate drive current of
short duration pulses at turn
on/off has to be generated.
In
fig.1
basic circuit drive of an
IGBT is shown.
For a 75A/1200V device (e.g.
SKM75GB123D)
fig.2
details
the behaviour of V
GE
and I
G
.
The peak gate current reaches
approx 1.3A during the turn-
on time (e.g. 200ns) and still
has to charge the input ca-
pacitance without reducing
V
GE
, a feature which can only
be achieved with a special out-
Rin
Rgon
Ig
V
GE
GND
Rgoff
GND
-8V
(or -15 V)
fig.1- Output stage of an IGBT driver
I
G
V
GE
V=5V/div H=2µs/div
V=0,5A/div
fig.2 SKM75GB123D
Output voltage V
GE
and output current I
G
put buffer rather than an opto-
coupler.
Another important point is how
fast the IGBT can be switched.
With gate charge Q
on
, (Q
off
re-
spectively), the total power P
G
needed to drive the IGBT may
be calculated with the follow-
ing simple equation:
P
G
= V
GE
x f x Q
on
+ |-V
GE
| x f x Q
off
From this equation the maxi-
mum possible switching fre-
quency f can be calculated.
The voltage of the driver out-
put stage has to be kept stable
all the time to achieve the low-
est possible V
CEsat
related
losses.
Furthermore gate resistor R
G
is
important. It limits the ampli-
tude of the gate current pulses
during turn-on and turn-off. By
varying R
G
it is possible to con-
trol the switching losses. (De-
tailed informations are given in
application)
SKHI short-circuit detection
Technical advantages
V
CE
trip level fixed to the IGBT
in use (factory adjusted)
Adjustable delay time for the
V
CE
signal
Error fault memory
Error signal output
Customer advantages
Easier engineering and
handling
Avoids false short circuit sig-
nal to the V
CE
monitor
Avoids repetitive high current
peaks
Informs the main control board
When using an IGBT in an in-
verter circuit, short circuit
breakdown of a device be-
comes an important protec-
tion parameter.
Over-currents are mainly
caused by the following condi-
tions:
• Short-circuited output
• Simultaneous switch-on of a
pair of transistors from same
leg
• Earth fault in the load circuit
The detection of the over-cur-
rent as well as the processing
of the response signal in the
electronic monitoring stage
requires a certain time. To pre-
vent electrical components
from undesired stress and to
achieve a high degree of reli-
ability, it is always an advan-
tage to terminate the over-cur-
rent as quick as possible. To
perform this, the turn-off sig-
nal should be applied to the
driver stage of the IGBT with
the shortest possible delay
(<10µs). The detection of the
overcurrent is made with V
CE
-
monitoring.
For the efficient detection of a
short-circuit current the col-
lector-emitter voltage (V
CE
) of
an IGBT can be utilized be-
cause it rapidly increases as a
result of desaturation.
During short circuit the V
CE
de-
tection circuit always monitors
the input “on-signal” and the
collector-emitter voltage; when
the input signal is high after 3
... 5µs V
CE
is higher than the
normal value range the output
signal turns off (fig.3).
Error
Error
Fault
Fault
memory
memory
On delay
On delay
VCE
VCE
detection
detection
fig.3 - Short-circuit detection
Output
Output
gate
buffer
gate
buffer
SKHI potential isolation
Technical advantages
Using coated toroid ferrite
transformers.
High dv/dt capability by using
isolated transformers instead
of opto-couplers.
Customer advantages
Provides high isolation be-
tween input and output (up to
4kV, drives IGBTs up to 1700V)
High dv/dt immunity between
primary and secondary side
(up to 75kV/µs).
The elements of the control
system (IC,
µP,
etc.) operate
always at a low voltage level of
between 5V to 15V and, there-
fore, noise voltages may influ-
ence their function. For this
reason it is an advantage to
place the interface for poten-
tial separation in the control
section between the electron-
ics and driver stage.
In the case of two-pulse or six-
pulse inverter bridge circuits
the relatively fast turn on and
turn off of the IGBTs cause
steep voltage steps (high dv/
dt values).
Therefore it has to be taken
京公网安备 11010802033920号
EEWORLD
