Intelligent gate driver for IGBT
View Patent ↗A reverse-conducting insulated gate bipolar transistor, particularly a bi-mode insulated gate transistor, is controlled by responding to an ON command by applying high-level gate voltage for a first period, during which a current is fed into a connection point, from which it flows either through the RC-IGBT or along a different path. Based hereon, it is determined whether the RC-IGBT conducts in its forward/IGBT or reverse/diode mode, and the RC-IGBT is either driven at high or low gate voltage. Subsequent conduction mode changes may be monitored in the same way, and the gate voltage may be adjusted accordingly. A special turn-off procedure may be applied in response to an OFF command in cases where the RC-IGBT conducts in the reverse mode, wherein a high-level pulse is applied for a second period before the gate voltage goes down to turn-off level.
1. A method of controlling a reverse-conducting insulated gate bipolar transistor, RC-IGBT, the method comprising,
upon receiving an ON command:
always applying high-level gate voltage during a first time period, and feeding a current during the first time period into a connection point connected, via a unidirectional conducting element, to a collector terminal of the RC-IGBT and, via a series resistor, to an emitter terminal of the RC-IGBT;
monitoring the connection point potential during the first time period; and
applying low-level gate voltage whenever it is determined that said connection point potential is below a threshold potential at the end of the first time period.
2. The method of claim 1 , wherein, in said step of applying, the current fed into the connection point is supplied by a gate unit.
3. The method of claim 2 , wherein, in said step of applying, a regulated constant current is fed into the connection point.
4. The method of claim 2 , further comprising:
continuing to monitor the connection point potential while maintaining low-level gate voltage; and
when the connection point potential exceeds the threshold potential, applying high-level gate voltage.
5. The method of claim 2 , further comprising:
continuing to monitor the connection point potential while maintaining low-level gate voltage; and
when an OFF command is received, applying high-level gate voltage for a second time period.
6. The method of claim 1 , wherein, in said step of applying, a regulated constant current is fed into the connection point.
7. The method of claim 6 , further comprising:
continuing to monitor the connection point potential while maintaining low-level gate voltage; and
when the connection point potential exceeds the threshold potential, applying high-level gate voltage.
8. The method of claim 6 , further comprising:
continuing to monitor the connection point potential while maintaining low-level gate voltage; and
when an OFF command is received, applying high-level gate voltage for a second time period.
9. The method of claim 1 , further comprising:
continuing to monitor the connection point potential while maintaining low-level gate voltage; and
when the connection point potential exceeds the threshold potential, applying high-level gate voltage.
10. The method of claim 1 , further comprising:
continuing to monitor the connection point potential while maintaining low-level gate voltage; and
when an OFF command is received, applying high-level gate voltage for a second time period.
11. The method of claim 10 , wherein the RC-IGBT is connected to a further RC-IGBT via its collector or emitter terminal, wherein the second time period is less than a blanking time of said further RC-IGBT.
12. The method of claim 1 , wherein the low-level gate voltage is in the range from 10 to 50% of the gate threshold voltage of the RC-IGBT.
13. The method of claim 1 , wherein the first time period is between 1 and 10 microseconds.
14. The method of claim 1 , wherein the RC-IGBT is a bi-mode insulated gate transistor, BIGT.
15. A non-transitory computer readable medium comprising computer-readable instructions for performing the method of claim 1 .
16. The method of claim 1 , wherein the threshold potential is a voltage between two terminals of the unidirectional conducting element.
17. A controller comprising:
a drive circuit accepting ON and OFF commands and being electrically connected at its output side to a gate terminal of a reverse-conducting insulated gate bipolar transistor, RC-IGBT, which is operable to admit a collector-emitter current; and
a detection circuit comprising a connection point connected, via a unidirectional conducting element, to a collector terminal of the RC-IGBT and, via a series resistor, to an emitter terminal of the RC-IGBT, said detection circuit being adapted to feed a current into said connection point and providing a detected value of the connection point potential to the drive circuit during a first time period,
wherein the drive circuit is configured to respond to an ON command by always applying a high-level gate voltage during the first time period and, whenever the detected value of said potential is below a threshold potential at the end of the first time period, by subsequently applying low-level gate voltage.
18. The controller of claim 17 , wherein the drive circuit is a gate unit.
19. A voltage source converter for converting between AC and DC current, comprising:
at least one RC-IGBT; and
a controller according to claim 18 , the drive circuit of which is electrically connected to the gate terminal of the RC-IGBT.
20. The controller of claim 17 , further comprising
a constant-current source arranged to feed a regulated constant current into the connection point.
21. The controller of claim 17 , wherein the drive circuit is configured to apply low-level gate voltage which is in the range from 10 to 50% of the gate threshold voltage of the RC-IGBT.
22. The controller of claim 17 , wherein the threshold potential is a voltage between two terminals of the unidirectional conducting element.