Method and system of operating a bi-directional double-base bipolar junction transistor (B-TRAN)

1. A method of operating a power module having bi-directional double-base bipolar junction transistor, the method comprising:

conducting a first load current from an upper terminal of the power module to an upper collector-emitter of the transistor, through the transistor, and from a lower collector-emitter to a lower terminal of the power module; and then responsive assertion of a first interrupt signal

interrupting the first load current from the lower collector-emitter to the lower terminal by opening a lower-main FET and thereby commutating a first shutoff current through a lower base of the transistor to the lower terminal; and

blocking current from the upper terminal to the lower terminal by the transistor.

2. The method of claim 1 :

wherein interrupting the first load current further comprises interrupting the first load current with the lower-main FET having a breakdown voltage of 100 Volts or less; and

wherein blocking current further comprises blocking at an applied voltage across the upper terminal and the lower terminal of 600 Volts or greater.

3. The method of claim 1 further comprising, after blocking current from the upper terminal to the lower terminal:

conducting a second load current from the lower terminal of the power module to the lower collector-emitter, through the transistor, and from the upper collector-emitter to the upper terminal; and then responsive to assertion of a second interrupt signal

interrupting the second load current from the upper collector-emitter to the upper terminal by opening an upper-main FET and thereby commutating a second shutoff current through an upper base to the upper terminal; and

blocking current from the lower terminal to the upper terminal by the transistor.

4. The method of claim 3 :

wherein interrupting the second load current further comprises interrupting the second load current with the upper-main FET having a breakdown voltage of 100 Volts or less; and

wherein blocking current from the lower terminal to the upper terminal further comprises blocking at an applied voltage across the lower terminal and the upper terminal of 600 Volts or greater.

5. A switch assembly comprising:

an upper terminal, a lower terminal, and an upper-control input;

a transistor defining an upper base, an upper collector-emitter, a lower base, and a lower collector-emitter;

an upper-main FET defining a first lead coupled to the upper terminal, a second lead coupled to the upper collector-emitter, and a gate;

a lower-main FET defining a first lead coupled to the lower collector-emitter, a second lead coupled to the lower terminal, and a gate;

a controller coupled to the upper-control input, the gate of the upper-main FET and the gate of the lower-main FET, and for a first applied voltage across the upper terminal and lower terminal, the controller configured to:

assert the gate of the upper-main FET to make the upper-main FET conductive, arrange the transistor for conduction from the upper collector-emitter to the lower collector-emitter, and assert the gate of the lower-main FET to make the lower-main FET conductive such that a first load current flows from the upper terminal to the lower terminal;

sense de-assertion of the upper-control input; and responsive to de-assertion of the upper-control input

de-assert the gate of the lower-main FET to interrupt the first load current and thereby commutate a first shutoff current through the lower base to the lower terminal; and

arrange the transistor to block current flow from the upper terminal to the lower terminal.

6. The switch assembly of claim 5 wherein the breakdown voltage of the transistor is 600 Volts or greater, and the breakdown voltage of the lower-main FET is 100 Volts or less.

7. The switch assembly of claim 5 wherein the breakdown voltage of the transistor is about 1200 Volts, and the breakdown voltage of the lower-main FET is 80 Volts or less.

8. The switch assembly of claim 5 further comprising:

an upper-base FET having a first lead coupled to the upper base, a second lead coupled to the upper terminal, and a gate, and during periods when the first load current flows from the upper terminal to the lower terminal, the upper-base FET is conductive; and

wherein when the controller arranges the transistor to block current flow from the upper terminal to the lower terminal, the controller is further configured to de-assert the gate of the upper-base FET to electrically float the upper base.

9. The switch assembly of claim 5 further comprising:

a lower-control input coupled to the controller; and

wherein for a second applied voltage across the upper terminal and lower terminal, the second applied voltage having a polarity opposite the first applied voltage, the controller is further configured to:

assert the gate of the lower-main FET to make the lower-main FET conductive, arrange the transistor for conduction from the lower collector-emitter to the upper collector-emitter, and assert the gate of the upper-main FET to make the upper-main FET conductive such that a second load current flows from the lower terminal to the upper terminal;

sense de-assertion of the lower-control input; and responsive to de-assertion of the lower-control input

de-assert the gate of the upper-main FET to interrupt the second load current and thereby commutate a second shutoff current through the upper base to the upper terminal; and

arrange the transistor to block current flow from the lower terminal to the upper terminal.

10. The switch assembly of claim 9 further comprising:

a lower-base FET having a first lead coupled to the lower base, a second lead coupled to the lower terminal, and a gate, and during periods when the second load current flows from the upper terminal to the lower terminal, the lower-base FET is conductive; and

wherein when the controller arranges the transistor to block current flow from the lower collector-emitter to the upper collector-emitter, the controller is further configured to de-assert the gate of the lower-base FET to electrically float the lower base.

11. The switch assembly of claim 9 wherein the breakdown voltage of the transistor is 600 Volts or greater, and the breakdown voltage of the lower-main FET is 100 Volts or less.

12. A method of operating a bi-directional double-base bipolar junction transistor, the method comprising:

making the transistor conductive from an upper collector-emitter to a lower collector-emitter by supplying current to an upper base of the transistor and electrically floating a lower base of the transistor; and then

making the transistor non-conductive by electrically floating the upper base, electrically floating the lower collector-emitter, and conducting a shutoff current through the lower base of the transistor.

13. The method of claim 12 wherein electrically floating the lower collector-emitter further comprises making non-conductive a lower-main electrically-controlled switch having a first lead coupled to the lower collector-emitter.

14. The method of claim 12 wherein making the transistor conductive further comprises:

closing an upper-main electrically-controlled switch coupled between an upper terminal and the upper collector-emitter; and

closing a lower-main electrically-controlled switch coupled between a lower conductor terminal and the lower collector-emitter.

15. The method of claim 14 wherein making the transistor non-conductive further comprises:

opening the upper-main electrically-controlled switch;

conducting the shutoff current to the upper collector-emitter through a diode associated with the upper-main electrically-controlled switch; and

commutating the shutoff current from the lower collector-emitter to the lower base by opening the lower-main electrically-controlled switch.

16. The method of claim 12 wherein conducting the shutoff current through the lower base further comprises conducting current through a diode associated with an electrically-controlled switch having a first lead coupled to the lower base.

17. The method of claim 12 wherein supplying current to the upper base further comprises at least one selected from a group comprising: supplying current at a base voltage about the same as a collector voltage applied to the upper collector-emitter; and supplying current to the upper base at the base voltage higher than the collector voltage.