SKHI26W Datasheet, PDF (6/6 Pages) Semikron International – Double IGBT driver

SKHI 26W, SKHI 26F
when no pulses from the error monitoring are present
and both inputs are zero. The output signal is fed to a
terminal which is to be connected to the control circuit
(open-collector-transistor SKHI 26 W). An external
pull-up-resistor have to be provided on customers
control board.
7. DC/DC-Converter
It is the primary side control of the DC/DC converter for
transmitting the control power to the IGBTs.
8. Power supply monitoring
The supply voltage V_S is monitored for its minimum
value of 13 V. If it falls below this value an error is
monitored and the turn-on pulses for the IGBTs are
blocked.
At initial switch-on the input pulses may only be
relea-sed more than 4 µs after the instant when V_S has
reached its nominal value of 15 V.
The output comprises two drivers with the following
components:
9. Pulse transformer
It transmits the turn-on and turn-off signals for the
IGBT. In the reverse direction the error signal from the
V_CE monitoring is transmitted via the same
transformer.
10. Power supply transformer for the DC/DC converter
11. Rectifier for the auxiliary power supply
12. Flip-flop
The flip-flop is pulse width triggered and is insensitive
to spurious pulses and high dv/dt values.
13. Drivers
The output transistors of the power drivers are
MOSFETs.
14. Reverse drivers for the pulse transformers
They transmit the signals from the VCE monitoring to
the pulse transformers.
15. V_CE monitoring
It monitors the collector-emitter voltage V_CE of the
IGBT during its on-state. V_CE is limited internally to
10 V (see fig. 4).
If the reference voltage V_CEref is exceeded, the output
signal switches to zero. V_CEref is dynamic. Immediately
after turn-on of the IGBT a higher value is effective
than in the steady state. When the IGBT is turned off,
V_CEref is set to this higher value by the signal “reset”.
Thesteady-state value V_CEstat of V_CEref is set for
standard IGBT (1200 V) values and has a typical value
of 5,2 V.
Fig.4 Waveform of the reference voltage V_CEref of the V_CE
monitoring immediately after the turn-on signal for
the IGBT. A possible waveform of V_CE is shown.
VCE is internally clamped to 10 V.
C. Application / Handling
1. The CMOS inputs of the driver are extremely
sensitiveto overvoltage. Voltages higher than (V_S +
0,3 V) orunder - 0,3 V may destroy these inputs.
Therefore the following safety requirements are to be
observed:
- To make sure that the control signals do not
comprise overvoltages exceeding the above values.
- Protection against static discharges during handling.
As long as the driver is not completely assembled the
input terminals must be short circuited. Persons
working with CMOS devices should weara grounded
bracelet. Any floor coverings must notbe statically
chargeable. For transportation the input terminals
must be short circuited using, for example,
conductive rubber. Places of work must be
grounded.
The same safety requirements apply to the IGBTs.
2. The connecting leads between the driver and the
power module must be as short as possible.
For IGBT the leads should be twisted.
3. Any parasitic inductances should be minimized.
Overvoltages may be damped by C or RCD snubber
net-orks between the main terminals of the power
module.
4. When first operating a newly developed circuit, low
collector voltage and load current should be used in
the beginning, and these values should be increasod
gradually, observing the turn-off behaviour of the
freewheeling diodes and the turn-off voltage spikes
across the IGBT by means of the oscilloscope. Further
the case temperature of the power module should be
monitored.
When the circuit works correctly, short circuit tests can
be made, starting again with low collector voltage.
5. lt is important to feed any errors back to the control
circuit and to switch the equipment off immediately in
such events. Repeated turn-on of the IGBT into a short
circuit with a frequency of several kHz may destroy the
device.
© by SEMIKRON 26-01-2005
Driver Electronic – PCB Drivers 1963