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SKHI 10/12
Absolute Maximum Ratings Symbol Conditions Values Units
SEMIDRIVERTM High Power IGBT Driver
SKHI 10/12 Characteristics Symbol Conditions
min.
typ.
max.
Units
Features
Typical Applications
This technical information specifies semiconductor devices but promises no characteristics. No warranty or guarantee expressed or implied is made regarding delivery, performance or suitability.
1)
2)
3)
4)
1
22-08-2003 MHW
(c) by SEMIKRON
Block diagram SKHI10
ISOLATION
1
2 Vin
2
INPUT BUFFER
VCE MONITORING
INPUT LEVEL SELECTOR
15V 5V
9 5
RCE
VCE 5
CCE
4 3
RESET
J1 J3
3
ERROR MEMORY
8
SOFT TURN-OFF Vs DC/DC CONVERTER
+15V Rgoff SC
ERROR
Vs
8,9 10,11 1 1 +15V 0V 0
4
Vs MONITOR
7
OUTPUT BUFFER IRgoff
Rgon
J2
Gon Goff 3 2 1
Vs
- 8V
Rgoff
E
6 primary side
10
secondary side
Fig.1 The numbers refer to the description on page 4, section B.
124
CCE
RCE Output Connector
14 13
Input Connector
Rgon Rgoff Rgoff-SC IRgoff J2
5
0 2 1 4x3.5 ERROR logic J3 Input Level J1
3 2 66 1
4.5
4.5
Input connector = 14 pin flat cable according to DIN 41651 Output connector = MOLEX 41791 Series (mates with 41695 crimp terminal housing and crimp terminals 7258)
Fig.2 Dimensions (in mm) and connections of the SKHI 10
(c) by SEMIKRON 22-08-2003
Driver Electronic - PCB Drivers
1939
SEMIDRIVERTM SKHI 10
SEMIDRIVERTM SKHI 10/17
High Power Single IGBT Driver General The intelligent single IGBT driver, SKHI10 respectively SKHI 10/17 is a standard driver for all power IGBTs on the market. The high power output capability was designed to switch high current modules or several paralleled IGBTs even for high frequency applications. The output buffer has been improved to make it possible to switch up to 400A IGBT modules at frequencies up to 20kHz. A new function has been added to the short circuit protection circuitry (Soft Turn Off), this automatically increases the IGBT turn off time and hence reduces the DC voltage overvoltage spikes, enabling the use of higher DC-bus voltages. This means an increase in the final output power. An integrated DC/DC converter with high galvanic isolation (4 kV) ensures that the user is protected from the high voltage (secondary side). The power supplies for the driver may be the same as used in the control board (0/+15V) without the requirement of isolation. All information that is transmitted between input and output uses ferrite transformers, resulting in high dv/dt immunity (75kV/s). The driver input stage is connected directly to the control board output and due to different control board operating voltages the SKHI10's input circuit includes a user voltage level selector (+15V or +5V). In the following only the designation SKHI 10 is used. This is valid for both driver versions. If something is to be explained special to SKHI 10/17 it will be descriped by marking SKHI 10/17. A. Features and Configuration of the Driver A short description is given below. For detailed information, please refer to section B. a) The SKHI10 has an INPUT LEVEL SELECTOR circuit which is adusted by J1 for two different levels. It is present for CMOS (15V) level, but can be changed by the user to HCMOS (5V) level by solder bridging the pads marked J1 together. For long input cables, we do not recommend the 5V level due to possible disturbances emitted by the power side. b) The ERROR MEMORY blocks the transmission of all turn-on signals to the IGBT if either a short circuit or malfunction of VS is detected, and sends a signal to the external control board through an open collector transistor. c) With a FERRITE TRANSFORMER the information between primary and secondary may flow in both directions and high levels of dv/dt and isolation are obtained. d) A high frequency DC/DC CONVERTER avoids the requirement of external isolated power supplies to obtain the necessary gate voltage. An isolated ferrite transformer in half-bridge configuration supplies the necessary power to the gate of the IGBT. With this 1940 Driver Electronic - PCB Drivers
feature, we can use the same power supply used in the external control circuit, even if we are using more than one SKHI10, e.g. in H-bridge configurations. e) Short circuit protection is provided by measuring the collector-emitter voltage with a VCE MONITORING circuit. An additional circuit detects the short circuit after a delay (determined by RCE,CCE) and decreases the turn off speed (adjusted by Rgoff-SC) of the IGBT. SOFT TURN-OFF under fault conditions is necessary as it reduces the voltage overshoot and allows for a faster turn off during normal operation. f) The OUTPUT BUFFER is responsible for providing the correct current to the gate of the IGBT. If these signals do not have sufficient power, the IGBT will not switch properly, and additional losses or even the destruction of the IGBT may occur. According to the application (switching frequency and gate charge of the IGBT) the equivalent value of Rgon and the Rgoff must be matched to the optimum value. This can be done by putting additional parallel resistors Rgon, Rgoff with those already on the board. If only one IGBT is to be used, (instead of parallel connection) only one cable could be connected between driver and gate by soldering the two J2 areas together. Fig.1 shows a simplified block diagram of the SKHI10 driver. Some preliminary remarks will help the understanding: * Regulated +15V must be present between pins 8,9 (Vs) and 10,11 (); an input signal (ON or OFF command to the IGBTs) from the control system is supplied to pin 2 (Vin) where HIGH=ON and LOW=OFF. * Pin 5 (VCE) at secondary side is normally connected to the collector of the IGBT to monitor VCE, but for initial tests without connecting the IGBT it must be connected to pin 1 (E) to avoid ERROR signal and enable the output signals to be measured. * The RESET input must be connected to 0V to enable the Vin signal. If it is left opened, the driver will be blocked. * To monitor the error signal, a pull-up resistor must be provided between pin 3 (ERROR) and VS. B. Description of the Circuit Block Diagram (Fig. 1) The circuit in Fig. 1 shows the input on the left and output on the right (primary/secondary). 1. Input level circuit This circuit was designed to accept two different logic voltage levels. The standard level is +15V (factory adjusted) intended for noisy environments or when long connections (l > 50 cm) between the external control circuit and SKHI10 are used, where noise immunity must be considerate. For lower power, and short connections between control and driver, the TTL-HCMOS level (+5V) 22-08-2003 (c) by SEMIKRON
can be selected by carefully soldering the small areas of J1 together, specially useful for signals coming from P based controllers.
VIT- (Low) 15 V 5V
min 3,6 V 0,50 V
typ 4,2 V 0,65 V
max 4,8 V 0,80 V
3. Error memory and reset signal Fig.3 Selecting J1 for 5V level (TTL) When connecting the SKHI10 to a control board using short connections no special attention needs to be taken (Fig. 4a). The ERROR memory is triggered only by following events: * short circuit of IGBTs * VS-undervoltage In case of short circuit, the VCE monitor sends a trigger signal (fault signal) through the impulse transformer to a FLIP-FLOP on the primary side giving the information to an open-collector transistor (pin 3), which may be connected to the external control circuit as ERROR message in HIGH logic (or LOW if J3 is short-circuited). If VS power supply falls below 13V for more than 0,5ms, the same FLIP-FLOP is set and pin 3 is activated. For HIGH logic (default), an external RC must be connected preferentiatty in the control main board. In this way the connection between main board and driver is also checked. If low-logic version is used (J3 short-circuited), an internal pull-up resistor (internally connected to VS) is provided, and the signal from more SKHI10s can be connected together to perform an wired-or-circuit.
Fig.4a Connecting the SKHI10 with short cable
Fig.4b Conneeting the SKHI10 with long cable Otherwise, if the length is 50cm or more (we suggest to limit the cable length to about 1 meter), some care must be taken. The TTL level should be avoided and CMOS/ 15V is to be used instead; flat cable must have the pairs of conductors twisted or be shielded to reduce EMI/RFI susceptibility (Fig. 4b). If a shielded cable is used, it can be connected to pin 1. It is coupled to 0V through a resistor (0 ). As the input impedance of the INPUT LEVEL SELECTOR circuit is very high, an internal pull-down resistor keeps the IGBT in OFF state in case the Vin connection is interrupted or left non connected. 2. Input buffer This circuit enables and amplifies the input signal Vin to be transferred to the pulse transformer when RESET (pin 4) is LOW and also prevents spurious signals being transmitted to the secondary side. The following overview is showing the input treshold voltages
VIT+ (High) 15 V 5V min 9,5 V 1,8 V typ 11,0 V 2,0 V max 12,5 V 2,4 V
1)
Fig.5 Driver status information ERROR, and RESET The ERROR signal may be disabled either by RESET=HIGH (pin4) or by switching the power supply (VS) off. The width of the RESET pulse must be more than 5s, and in case of interrupted connection an internal pull-up resistor will act.
FAULT no no yes yes RESET 0 1 0 1 ERROR1) 0 0 1 0 Vin enable disable disable disable
default logic (HIGH); for LOW logic the signals are complementary
Table 1 ERROR signal truth table The open-collector transistor (pin 3) may be connected through a pull-up resistor to an extemal (intemal VS for the ``low-logixc`` version) vorltage supply +5V...+24V, limiting the current to lsink 6mA. Driver Electronic - PCB Drivers 1941
(c) by SEMIKRON 22-08-2003
4. Power supply (Vs) monitor The supply voltage VS is monitored. If it falls below 13V an ERROR signal is generated and the turn-on pulses for the IGB's gate are blocked. 5. Pulse transformer It transmits the turn-on and turn-off signals to the IGBT. In the reverse direction the ERROR signal from the VCE monitoring is transmitted via the same transformer. The isolation is 4 kV. 6. DC/DC converter In the primary side of the converter, a half-bridge inverter transfers the necessary energy from VS to the secondary of a ferrite transformer. In the secondary side, a full bridge and filters convert the high frequency signal coming from the primary to DC levels (+15V/- 8V) that are stabilised by a voltage regulator circuit. 7. Output buffer The output buffer is supplied by the +15V/- 8V from the DC/DC converter. If the operation proceeds normally (no fault), the on- and off-signal is transmitted to the gate of an IGBT through Rgon and Rgoff. The output stage has a MOSFET pair that is able to source/sink up to 8A peak current to/from the gate improving the turn-on/off time of the IGBT. Additionally, we can select IRgoff (see Fig. 2) either to discharge the gate capacitance with a voltage source (standard) or with a current source, specially design for the 1700V IGBT series (it speeds up the turn-off time of the IGBT). The present factory setting is voltage source (IRgoff = 0). Using the current source IRgoff, Rgoff must be 0 .
Volt 18 IGBT turn-on 14 RCE=100K CCE=1nF RCE=18K CCE=330pF 3
turn-off time" can be reduced by connecting a parallel resistor Rgoff-SC (see Fig. 2) with those already on the printed circuit board. 9. VCE monitoring This circuit is responsible for short-circuit sensing. Due to the direct measurement of VCEstat on the IGBT's collector, it blocks the output buffer (through the soft turn-off circuit) in case of short-circuit and sends a signal to the ERROR memory on the primary side. The recognition of which VCE level must be considered as a short circuit event, is adjusted by RCE and CCE (see Fig. 2), and it depends of the IGBT used. Typical values RCE =18k and CCE =330 pF for SKHI 10 are delivered from factory (Fig. 6, curve 2). Using SKHI 10/17 the driver will be delivered with RCE = 36 k and CCE = 470 pF from factory. The VCEref is not static but a dynamic reference which has an exponential shape starting at about 15V and decreases to VCEstat (5V VCEstat 10V determinated by RCE), with a time constant (0,5 s 1ms controlled by CCE). The VCEstat must be adjusted to remain above VCEsat in normal operation (the IGBT is already in full saturation). To avoid a false failure indication when the IGBT just starts to conduct (VCEsat value is still too high) some decay time must be provided for the VCEref. As the VCE signal is internally limited at 10V, the decay time of VCEref must reach this level after VCE or a failure indication will occur (see Fig.6, curve 1). A tmin is defined as function of VCEstat and to find out the best choice for RCE and VCE (see Fig.6, curve 2). The time the IGBT come to the 10V (represented by a " in Fig. 6) depends on the IGBT itself and Rgon used. The RCE and CCE values can be found from Fig. 7 by taking the VCEstat and tmin as input values with following remarks: * RCE > 10K * CCE < 2,7nF
VCE
VCEref = f(RCE,CCE)
10
tmin1
tmin2
RCE=10K CCE=10pF 2 VCEstat2 VCEstat1 VCEsat
6
1
Attention!: If this function is not used, for example during the experimental phase, the VCE MONITORING must be connected with the EMITTER output to avoid possible fault indication and consequent gate signal blokking. 10. Rgon, Rgoff These two resistors are responsible for the switching speed of each IGBT. As an IGBT has input capacitance (varying during the switching time) which must be charged and discharged, both resistors will dictate what time must be taken to do this. The final value of resistance is difficult to predict, because it depends on many parameters, as follows: * DC-link voltage * stray inductance of the circuit * switching frequency * type of IGBT 22-08-2003 (c) by SEMIKRON
2 1 3 5 7 9 sec
Fig.6 VCEref waveform with parameters RCE, CCE 8. Soft turn-off In case of short-circuit, a further circuit (SOFT TURN-OFF) increases the resistance in series with Rgoff and turns-off the IGBT at a lower speed. This produces a smaller voltage spike (due LSTRAY x di/dt) above the DC link by reducing the di/dt value. Because in short-circuit conditions the Homogeneous IGBT's peak current increases up to 8 times the nominal current (up to 10 times with Epitaxial IGBT structures), and some stray inductance is ever present in power circuits, it must fall to zero in a longer time than at normal operation. This "soft 1942 Driver Electronic - PCB Drivers
100 sec
10 volts
CCE 10 1nF 470pF 330pF 220pF 100pF
1
t min 0.1 0 20 40 60 80 RCE 100 k
VSTAT
1 0 20 40 60 80 RCE 100 k
Fig.7a
tmin as function of RCE and CCE
Fig.7b VCEstat as function of RCE
CONTROL BOARD
+15V
C. Operating Procedure 1. One IGBT connection
INPUT CONNECTOR
OUTPUT CONNECTOR
l < 50cm
2
CCE
RCE
5
To realize the correct switching and short-circuit monitoring of one IGBT some additional external components must be used (Fig.8). The driver is delivered with four Rg resistors (43). This value can be reduced to use the driver with bigger modules or higher frequencies/lower voltages, by putting additional resistors in parallel to the existing ones. The outputs Gon and Goff were previewed to connect the driver with more than one IGBT (paralleling). In that case we need both signals ON/OFF separately to connect additional external resistors Rgon and Rgoff for each IGBT. If only one IGBT is to be used, we suggest to connect both points together through J2 (see Fig. 1 and 2). This can be done by soldering the two small pads together, which saves one external connection. Typical component values: *)
SK-IGBT-Module SKM 75GAL123D SKM 100GAL(R)123D SKM 150GAL(R)123D SKM 200GA(L/R)123D SKM 300GA(L/R)123D SKM 400GA123D SKM 500GA123D RGon 22 15 12 10 8,2 6,8 5,6 RGoff 22 15 12 10 8,2 6,8 5,6 CCE pF 330 330 330 330 330 330 330 RCE kW 18 18 18 18 18 18 18 IRgoff 0 0 0 0 0 0 0
4
2K7
Rgon Rgoff Rgoff-SC IRgoff
J2
3 1
3 10,11 control GND
SKHI10
as short as possible
Fig. 8 Preferred standard circuit
SK-IGBT-Module SKM 200GAL173D SKM 300GA173D SKM 400GA173
RGon 8,2 6,8 5,6
RGoff 8,2 6,8 5,6
CCE pF 470 470 470
RCE kW 36 36 36
IRgoff 0 0 0
Table 2b 1700V IGBT@ DC-link< 1000V *) Only starting values, for final optimization. The adjustment of RgoffSC (factory adjusted RgoffSC = 22 ) should be done observing the overvoltages at the module in case of short circuit. When having a low inductive DC-link the module can be switched off faster. The values shown should be considered as standard values for a mechanical/electrical assembly, with acceptable stray inductance level, using only one IGBT per SKHI10 driver. The final optimized value can be found only by measuring. 2. Paralleling IGBTs The parallel connection is recommended only by using IGBTs with homogeneous structure (IGHT), that have a positive temperature coefficient resulting in a perfect Driver Electronic - PCB Drivers 1943
Table 2a 1200V IGBT@ DC-link< 700V (c) by SEMIKRON 22-08-2003
Fig. 9 Preferred circuit for paralleled IGBT's current sharing without any external auxiliary element. After all some care must be considered to reach an optimized circuit and to obtain the total performance of the IGBT (Fig. 9). The IGBTs must have independent values of Rgon and Rgoff. An auxiliary emitter resistor Re as well as an auxiliary collector resistor Rc must also be used. The external resistors Rgonx, Rgoffx, Rex and Rcx should be mounted on an additional circuit board near the paralleled modules, and the Rgon/Rgoff on the driver should be changed to zero ohms. The Rex assumes a value of 0,5 and its function is to compensate the wiring resistance in the auxiliary emitters what could make the emitter voltage against ground unbalanced. The Rcx assumes a value of 47 and its function is to create an average value of VCEsat in case of short circuit for VCE monitoring. The Mechanical assembly of the power circuit must be symmetrical and low inductive. The maximum recommended gate charge is 9,6 C. See als Fig.14.
Fig. 11 Output voltage (VGE) and output current (IG)
Fig. 10 Input and output voltage propagation time 1944 Driver Electronic - PCB Drivers
Fig. 12 Short-circuit and ERROR propagation time worst-case (Vin with SC already present) 22-08-2003 (c) by SEMIKRON
D. Signal Waveforms The following signal waveforms were measured under the conditions below: * * * * * * * VS = 15 V Tamb = 25 C load = SKM150GAL161D RCE = 18 k CCE = 330 pF UDC = 1200 V IC = 100 A
If small IGBT modules are used, the frequency could theoretically reach 100kHz. For bigger modules or even paralleled modules, the maximum frequency must be determinate (Fig. 14). QG is the total equivalent gate charge connected to the output of the driver. The maximum allowed value is limited (9,6C), and depends on the output internal capacitance connected to the power supply (energy storage capacitance). E. Application / Handling 1. The CMOS inputs of the driver are extremely sensitive to overvoltage. Voltages higher than (VS + 0,3 V) or under - 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 hybrid driver is not completely assembled the input terminals must be short circuited. Persons working with CMOS devices should wear a grounded bracelet. Any floor coverings must not be chargeable. For transportation the input terminals must be short circuited using, for example, conductive rubber. Places of work must be grounded. The same foam requirements apply to the IGBTs. 2. The connecting leads between the driver and the power module must be as short as possible, and should be twisted. 3. Any parasitic inductance should be minimized. Overvoltages may be damped by C or RCD snubber networks between the main terminals [3] = C1 (+) and [2] = E2 (-) of the power module. 4. When first operating a newly developed circuit, low collector voltage and load current should be used in the beginning. These values should be increased gradually, observing the turn-off behavior of the free-wheeling diodes and the turn-off voltage spikes across the IGBT by means of an oscilloscope. Also 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. It is important to feed any ERROR back to the control circuit 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.
All results are typical values if not otherwise specified. The limit frequency of SKHI10 depends on the gate charge connected in this output pins.
VCE =1200V
Vpeak=1360V Vpeak=1280V
Isc=860A
100ohm 22ohm V=200V/div H=1s/div V=250A/div
Fig.13 Effect of Rgoff-SC in short - circuit
100 kHz 80
not allowed area
60
f max
40 9,6C 20
0 0 2 4
QG
6
8
C
10
For further details ask SEMIKRON Nr.11224040
Fig.14 Maximum operating frequency x gate charge
(c) by SEMIKRON 22-08-2003
Driver Electronic - PCB Drivers
1945

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