Gate drive circuit with a voltage stabilizer and a method
View Patent ↗A gate drive circuit creates a bipolar voltage to a gate of an IGB power transistor, and compensates for Miller currents of the IGB power transistor. The compensating is performed by a switching element connected in series with a capacitor between the gate (X 4 ) and a supply voltage.
1. A gate drive circuit with an active gate voltage stabilizer, comprising:
means for creating a bipolar voltage to a gate of an IGB power transistor; and
means for compensating for Miller currents of the IGB power transistor, the means for compensating being formed by a switching element connected in series with a capacitor between the gate and a supply voltage input;
wherein a switching voltage of the switching element is controlled by two resistances; and
wherein one of the two resistances is connected between a source and gate of the switching element, and is an NTC-resistor.
2. The gate drive circuit according to claim 1 , wherein the means for compensating comprises:
a ceramic capacitor as the capacitor, and a power MOSFET as the switching element connected in series.
3. The gate drive circuit according to claim 1 , wherein the means for compensating is connected between a positive supply voltage and the gate of the IGB transistor.
4. The gate drive circuit according to claim 1 , wherein the switching element is a varistor or transient suppressor.
5. A method for controlling an IGB power transistor with a gate drive circuit, which method comprises:
creating a bipolar voltage to a gate of the IGB power transistor;
compensating for Miller currents of the IGB power transistor with a switching element connected in series with a capacitor between the gate and supply voltage input; and
controlling a switching voltage of the switching element by two resistances;
wherein one of the two resistances is a resistor connected between a source and gate of the switching element, and is an NTC-resistor.
6. The method according to claim 5 , whereby the compensating is performed by a ceramic capacitor as the capacitor, and a power MOSFET as the switching element connected in series.
7. The method according to claim 6 , wherein the switching element and capacitor are connected between a positive supply voltage of the supply voltage input and the gate of the IGB transistor.
8. The method according to claim 5 , wherein the switching element is a varistor or transient suppressor.
9. The method according to claim 5 , wherein the compensating is performed after an actual switching event, when a temperature load of a chip housing the IGB power transistor has started to decrease and the chip is recovering from the switching event.
10. The method according to claim 9 , wherein a decreasing edge of a temperature load curve is adjusted such that a decreasing edge of at least a heated portion of the chip decreases faster than a corresponding edge of an unheated cold module.
11. The method according to claim 9 , comprising:
compensating thermal cycling by changing voltage losses in a conducting state of the IGBT power transistor even though control occurs during a state change of the IGBT power transistor.
12. The gate drive circuit according to claim 2 , wherein the means for compensating is connected between a positive supply voltage and the gate of the IGB transistor.
13. The gate drive circuit according to claim 12 , wherein the switching element is a varistor or transient suppressor.
14. The method according to claim 5 , wherein the compensating is performed after an actual switching event, when a temperature load of a chip housing the IGB power transistor has started to decrease and the chip is recovering from the switching event.
15. The method according to claim 10 , comprising:
compensating thermal cycling by changing voltage losses in a conducting state of the IGBT power transistor even though control occurs during a state change of the IGBT power transistor.
16. The method according to claim 5 , wherein the switching element and capacitor are connected between a positive supply voltage of the supply voltage input and the gate of the IGB transistor.
17. The method according to claim 6 , wherein the switching element is a varistor or transient suppressor.
18. The method according to claim 6 , wherein the compensating is performed after an actual switching event, when a temperature load of a chip housing the IGB power transistor has started to decrease and the chip is recovering from the switching event.
19. The method according to claim 18 , wherein a decreasing edge of a temperature load curve is adjusted such that a decreasing edge of at least a heated portion of the chip decreases faster than a corresponding edge of an unheated cold module.
20. The method according to claim 19 , comprising:
compensating thermal cycling by changing voltage losses in a conducting state of the IGBT power transistor even though control occurs during a state change of the IGBT power transistor.