Dual mode power transfer switches

1 . A transfer switch configured to operate in different transfer modes, the transfer switch comprising:

first and second inputs configured to couple with first and second power sources, respectively;

first and second contactors configured to selectively couple with the first and second inputs, respectively, wherein the first and second contactors comprise electro-mechanical devices configured to provide galvanic isolation via an air gap when opened;

an output configured to couple with a load;

first and second solid-state power stages configured to conduct electrical power when active, and to block the electrical power when inactive, wherein the first solid-state power stage is configured to selectively couple the first contactor with the output, and wherein the second solid-state power stage is configured to selectively couple the second contactor with the output;

a controller communicatively coupled with the first and second solid-state power stages and the first and second contactors, wherein the controller is configured to:

determine whether the first solid-state power stage is electrically shorted in a state of electrical conduction and incapable of being deactivated while the first solid-state power stage is active, the first power source is powering the load, and the second solid-state power stage is inactive; and

in response to determining that the first solid-state power stage is electrically shorted in the state of electrical conduction and incapable of being deactivated, the controller is further configured to:

open the first contactor; and

activate the second solid-state power stage to transfer the load from the first power source to the second power source.

2 . The transfer switch of claim 1 , wherein the controller is further configured to open the first contactor and activate the second solid-state power stage in response to determining that the first solid-state power stage is electrically shorted in the state of electrical conduction and incapable of being deactivated and that a power quality of the first power source is outside of a pre-defined range.

3 . The transfer switch of claim 2 , wherein the power quality comprises at least one of a voltage, a frequency, and a harmonic distortion of the first power source.

4 . The transfer switch of claim 1 , wherein the first and second solid-state power stages comprise one or more silicon carbide metal-oxide-semiconductor field-effect transistors (SiC MOSFETs) and thyristors.

5 . The transfer switch of claim 1 , wherein the controller is further configured to:

determine whether the first solid-state power stage is no longer electrically shorted in the state of electrical conduction and is capable of being deactivated while powering the load from the second power source; and

in response to determining that the first solid-state power stage is no longer electrically shorted in the state of electrical conduction and is capable of being deactivated, the controller is further configured to:

close the first contactor;

activate the first solid-state power stage; and

deactivate the second solid-state power stage to transfer the load from the second power source to the first power source.

6 . A method operable by a controller of a transfer switch of operating the transfer switch in different transfer modes, wherein:

the transfer switch comprises:

first and second inputs coupled with first and second power sources, respectively;

first and second contactors selectively coupling with the first and second inputs, respectively, wherein the first and second contactors comprise electro-mechanical devices configured to provide galvanic isolation via an air gap when opened;

an output coupled with a load;

first and second solid-state power stages that conduct electrical power when active, and block the electrical power when inactive, wherein the first solid-state power stage selectively couples the first contactor with the output, and wherein the second solid-state power stage selectively couples the second contactor with the output, and

the method comprises:

determining whether the first solid-state power stage is electrically shorted in a state of electrical conduction and incapable of being deactivated while the first solid-state power stage is active, the first power source is powering the load, and the second solid-state power stage is inactive; and

in response to determining that the first solid-state power stage is electrically shorted in the state of electrical conduction and incapable of being deactivated, the method further comprises:

opening the first contactor; and

activating the second solid-state power stage to transfer the load from the first power source to the second power source.

7 . The method of claim 6 , wherein the method further comprises:

opening the first contactor and activating the second solid-state power stage to transfer the load from the first power source to the second power source in response to determining that the first solid-state power stage is electrically shorted in the state of electrical conduction and incapable of being deactivated and that a power quality of the first power source is outside of a pre-defined range.

8 . The method of claim 7 wherein:

the power quality comprises at least one of a voltage, a frequency, and a harmonic distortion of the first power source.

9 . The method of claim 6 , wherein:

the first and second solid-state power stages comprise one or more silicon carbide metal-oxide-semiconductor field-effect transistors (SiC MOSFETs) and thyristors.

10 . The method of claim 6 , further comprising:

determining whether the first solid-state power stage is no longer electrically shorted in the state of electrical conduction and is capable of being deactivated while powering the load from the second power source; and

in response to determining that the first solid-state power stage is no longer electrically shorted in the state of electrical conduction and is capable of being deactivated, the method further comprises:

closing the first contactor;

activating the first solid-state power stage; and

deactivating the second solid-state power stage to transfer the load from the second power source to the first power source.

11 . A transfer switch configured to alternate between automatic transfer switch (ATS) mode and static transfer switch (STS) mode, the transfer switch comprising:

first and second inputs configured to couple with first and second power sources, respectively;

first and second contactors configured to selectively couple with the first and second inputs, respectively, wherein the first and second contactors comprise electro-mechanical devices configured to provide galvanic isolation via an air gap when opened;

an output configured to couple with a load;

first and second solid-state power stages configured to conduct electrical power when active, and to block the electrical power when inactive, wherein the first solid-state power stage is configured to selectively couple the first contactor with the output, and wherein the second solid-state power stage is configured to selectively couple the second contactor with the output;

a controller communicatively coupled with the first and second solid-state power stages and the first and second contactors, wherein the controller is configured to:

operate the transfer switch in the ATS mode by opening one of the first and second contactors and one of the first and second solid-state power stages to transfer the load between the first and second power sources in response to determining that one of the first and second solid-state power stages is electrically shorted in a state of electrical conduction and incapable of being deactivated; and

operate the transfer switch in the STS mode using the first and second solid-state power stages to transfer the load between the first and second power sources while the first and second contactors remain closed.

12 . The transfer switch of claim 11 , wherein the controller is further configured, while the first solid-state power stage is active, to:

operate the transfer switch in the ATS mode to transfer the load from the first power source to the second power source in response to determining that the first solid-state power stage is electrically shorted in a state of electrical conduction and incapable of being deactivated.

13 . The transfer switch of claim 12 , wherein the controller is further configured, to operate the transfer switch in the ATS mode to transfer the load from the first power source to the second power source, to:

open the first contactor; and

activate the second solid-state power stage.

14 . The transfer switch of claim 12 , wherein the controller is further configured, while the load is powered from the second power source, to:

determine whether the first solid-state power stage is no longer electrically shorted in the state of electrical conduction and is capable of being deactivated; and

operate the transfer switch in the STS mode to transfer the load from the second power source to the first power source in response to determining that the first solid-state power stage is no longer electrically shorted in the state of electrical conduction and is capable of being deactivated.

15 . The transfer switch of claim 14 , wherein the controller is further configured, to operate the transfer switch in the STS mode to transfer the load from the second power source to the first power source, to:

close the first contactor;

activate the first solid-state power stage; and

deactivate the second solid-state power stage.

16 . The transfer switch of claim 11 , wherein the first and second solid-state power stages comprise one or more silicon carbide metal-oxide-semiconductor field-effect transistors (SiC MOSFETs) and thyristors.