Power system based on current source

1. A power branching unit, comprising:

an input at which a regulated current is received;

an output at which the regulated current is output; and

a plurality of parallel-redundant converter groups connected in series with each other within a current path for the regulated current between the input and the output, each parallel-redundant converter group configured to selectively receive the regulated current and each parallel-redundant converter group comprising:

two or more direct current (DC)/DC converters connected in parallel with each other within the current path, each of the DC/DC converters configured to selectively receive at least a portion of the regulated current and each of the DC/DC converters connected in series with a protection device within the current path, wherein each protection device is configured to selectively disconnect a respective series-connected one of the DC/DC converters from the current path when the respective series-connected DC/DC converter fails in a condition presenting a short circuit or an open circuit to the current path, and wherein the parallel-redundant converter group is configured to cause one of the DC/DC converters to receive more of the regulated current when another one of the DC/DC converters fails in the condition presenting the short circuit or the open circuit to the current path; and

an active clamp connected in parallel with all of the DC/DC converters within the current path, the active clamp configured:

to temporarily sink a portion of the regulated current when the another one of the DC/DC converters fails in the condition presenting the short circuit or the open circuit to the current path, and

to selectively shunt the regulated current around all of the DC/DC converters when all of the DC/DC converters fail in the condition presenting the short circuit or the open circuit to the current path.

2. The power branching unit according to claim 1 , wherein the plurality of parallel-redundant converter groups includes two bias parallel-redundant converter groups and two load parallel-redundant converter groups.

3. The power branching unit according to claim 1 , further comprising:

an emergency clamp connected in parallel within the current path with all of the parallel-redundant converter groups; and

a power branching unit controller communicatively coupled to the plurality of parallel-redundant converter groups and configured to selectively activate the emergency clamp to shunt the regulated current around the parallel-redundant converter groups.

4. The power branching unit according to claim 3 , further comprising:

an emergency power source connected in series within the current path with all of the parallel-redundant converter groups, wherein the emergency power source is configured to produce a voltage drop within the current path when the emergency clamp shunts the regulated current around the parallel-redundant converter groups.

5. The power branching unit according to claim 1 , wherein, for each parallel-redundant converter group:

each protection device includes a current sensor configured to sense current through the respective series-connected DC/DC converter,

each DC/DC converter includes a converter controller configured to selectively adapt operation of the respective DC/DC converter, and

the active clamp includes a clamp controller configured to: receive signals indicating a voltage across the parallel-redundant converter group and a current sensed by one of the protection devices through the respective series-connected DC/DC converter, and transmit signals to the converter controllers to cause the one of the DC/DC converters to receive more of the regulated current when the another one of the DC/DC converters within the parallel-redundant converter group fails in the condition presenting the short circuit or the open circuit to the current path.

6. The power branching unit according to claim 5 , further comprising:

a power branching unit controller communicatively coupled to the plurality of parallel-redundant converter groups and configured to cause the DC/DC converters within one of the parallel-redundant converter groups to increase a voltage across those DC/DC converters when all DC/DC converters within another one of the parallel-redundant converter groups fail in the condition presenting the short circuit or the open circuit to the current path.

7. An apparatus comprising a plurality of the power branching units of claim 1 , the apparatus further comprising:

a power source; and

an alternating current (AC)/DC converter connected to the power source and to a cable, the AC/DC converter configured to generate the regulated current,

wherein the power branching units are connected in series with each other within a current path for the regulated current, the respective input of each power branching unit and the respective output of each power branching unit both connected to a power bus within the cable.

8. A method, comprising:

receiving a regulated current at an input of a power branching unit;

outputting the regulated current from an output of the power branching unit;

passing the regulated current through a plurality of parallel-redundant converter groups connected in series with each other within a current path for the regulated current between the input and the output, each parallel-redundant converter group configured to selectively receive the regulated current and each parallel-redundant converter group comprising:

two or more direct current (DC)/DC converters connected in parallel with each other within the current path, each of the DC/DC converters configured to selectively receive at least a portion of the regulated current and each of the DC/DC converters connected in series with a protection device within the current path; and

an active clamp connected in parallel with all of the DC/DC converters within the current path;

within one of the parallel-redundant converter groups, causing one of the DC/DC converters within the one parallel-redundant converter group to receive more of the regulated current when another one of the DC/DC converters within the one parallel-redundant converter group fails in a condition presenting a short circuit or an open circuit to the current path and using one of the protection devices to selectively disconnect the another one of the DC/DC converters series-connected to the one protection device from the current path when the another one of the DC/DC converters fails in the condition presenting the short circuit or the open circuit to the current path;

using the active clamp of the one parallel-redundant converter group, temporarily sinking a portion of the regulated current when the another one of the DC/DC converters fails in the condition presenting the short circuit or the open circuit to the current path; and

using the active clamp of the one parallel-redundant converter group, selectively shunting the regulated current around all of the DC/DC converters within the one parallel-redundant converter group when all of the DC/DC converters within the one parallel-redundant converter group fail in the condition presenting the short circuit or the open circuit to the current path.

9. The method according to claim 8 , wherein the plurality of parallel-redundant converter groups includes two bias parallel-redundant converter groups and two load parallel-redundant converter groups.

10. The method according to claim 8 , wherein the power branching unit further comprises:

an emergency clamp connected in parallel within the current path with all of the parallel-redundant converter groups; and

a power branching unit controller communicatively coupled to the plurality of parallel-redundant converter groups and configured to selectively activate the emergency clamp to shunt the regulated current around the parallel-redundant converter groups.

11. The method according to claim 10 , wherein the power branching unit further comprises an emergency power source connected in series within the current path with all of the parallel-redundant converter groups, the method further comprising:

using the emergency power source, producing a voltage drop within the current path when the emergency clamp shunts the regulated current around the parallel-redundant converter groups.

12. The method according to claim 8 , wherein, for each parallel-redundant converter group:

each protection device includes a current sensor configured to sense current through the respective series-connected DC/DC converter,

each DC/DC converter includes a converter controller configured to selectively adapt operation of the respective DC/DC converter, and

the active clamp includes a clamp controller configured to: receive signals indicating a voltage across the parallel-redundant converter group and a current sensed by one of the protection devices through the respective series-connected DC/DC converter, and transmit signals to the converter controllers to cause the one of the DC/DC converters to receive more of the regulated current when the another one of the DC/DC converters within the parallel-redundant converter group fails in the condition presenting the short circuit or the open circuit to the current path.

13. The method according to claim 12 , wherein the power branching unit further comprises a power branching unit controller communicatively coupled to the plurality of parallel-redundant converter groups, the method further comprising:

using the power branching unit controller, causing the DC/DC converters within one of the parallel-redundant converter groups to operate with increased voltage across those DC/DC converters when all DC/DC converters within another one of the parallel-redundant converter groups fail in the condition presenting the short circuit or the open circuit to the current path.

14. The method according to claim 8 , wherein the power branching unit is one of a plurality of the power branching units connected by a cable to an alternating current (AC)/DC converter connected to a power source and configured to generate the regulated current, wherein the power branching units are connected in series with each other within a current path for the regulated current, the respective input of each power branching unit and the respective output of each power branching unit both connected to a power bus within the cable.

15. A power branching unit, comprising:

an input at which a regulated current is received;

an output at which the regulated current is output;

a first parallel-redundant converter group connected to the input and configured to selectively receive the regulated current, the first parallel-redundant converter group including:

first and second parallel-connected direct current (DC)/DC converters each configured to selectively receive at least a portion of the regulated current from, respectively, first and second protection devices connected in series with the first and second DC/DC converters, wherein the first and second protection devices are each configured to selectively disconnect the first or second DC/DC converter from receiving any of the regulated current upon failure of the first or second DC/DC converter in a short circuit or open circuit condition, such that one of the first and second DC/DC converters receives more of the regulated current when another of the first and second DC/DC converters fails, and

a first active clamp connected in parallel with the first and second DC/DC converters, the first active clamp configured to temporarily sink a portion of the regulated current when the one of the first and second DC/DC converters fails and to selectively shunt the regulated current around both of the first and second DC/DC converters; and

a second parallel-redundant converter group connected in series with the first parallel converter group and configured to selectively receive the regulated current, the second parallel-redundant converter group including:

third and fourth parallel-connected DC/DC converters each configured to selectively receive at least a portion of the regulated current from, respectively, third and fourth protection devices connected in series with the third and fourth DC/DC converters, wherein the third and fourth protection devices are each configured to selectively disconnect the third or fourth DC/DC converter from receiving any of the regulated current upon failure of the third or fourth DC/DC converter in the short circuit or open circuit condition, such that one of the third and fourth DC/DC converters receives more of the regulated current when another of the third and fourth DC/DC converters fails, and

a second active clamp connected in parallel with the third and fourth DC/DC converters, the second active clamp configured to selectively shunt the regulated current around one of the third and fourth DC/DC converters and to temporarily sink a portion of the regulated current when the one of the third and fourth DC/DC converters fails.

16. The power branching unit according to claim 15 , wherein the first and second parallel-redundant converter groups are each connected to a controller.

17. The power branching unit according to claim 15 , wherein the first and second parallel-redundant converter groups are each connected to one or more loads.

18. The power branching unit according to claim 15 , further comprising:

an emergency clamp connected in parallel with the first and second parallel-redundant converter groups; and

a power branching unit controller communicatively coupled to the first and second parallel-redundant converter groups and configured to selectively activate the emergency clamp to shunt the regulated current around the first and second parallel-redundant converter groups.

19. The power branching unit according to claim 18 , further comprising:

an emergency power source connected in series with the first and second parallel-redundant converter groups, wherein the emergency power source is configured to produce a voltage drop based upon the regulated current when the emergency clamp shunts the regulated current around the first and second parallel-redundant converter groups.

20. The power branching unit according to claim 15 , further comprising:

a power branching unit controller communicatively coupled to the first and second parallel-redundant converter groups and configured to cause one of the first and second DC/DC converters within the first parallel-redundant converter group or one of the third and fourth DC/DC converters within the second parallel-redundant converter group to increase a voltage across the respective DC/DC converter when all DC/DC converters within one of the first and second parallel-redundant converter groups fail.