DC power distribution and protection system

Abstract

A DC power distribution and protection system comprising: a first DC power source (21), a first load (R1), a first power bus (31, 41) connecting the first power source (21) and the first load (R01), the first power bus (31, 41) comprising a high side voltage rail (31) and a low side voltage rail (41), a first solid state power controller (SSPC_A) arranged in the high side voltage rail (31) or low side voltage rail (41) at a DC power source side (61) of the voltage rail, and a second solid state power controller (SSPC_B) arranged in the same voltage rail (31, 41) as the first solid state power controller (SSPC_A) at a load side (62) of that voltage rail (31, 41) A first bypass line (51) is provided that connects the first DC power source (21) with the first load (R1) under bypassing of the first and second solid state power controllers (SSPC_A, SSPC_B), wherein the first bypass line (51) comprises a third solid state power controller (SSPC_R), and wherein the third solid state power controller (SSPC_R) is configured to be switched on only if the first and second solid state power controllers (SSPC_A, SSPC_B) are switched off.

Description

[0001] DC POWER DISTRIBUTION AND PROTECTION SYSTEM

[0002] Field of the disclosure

[0003] The present disclosure relates a DC power distribution and protection system, in particular for aerospace and marine power systems.

[0004] Background

[0005] DC power distribution is a critical technology required in both aerospace and marine industries. DC power distribution and protection systems serves to connect at least one DC power source with at least one load and provide protection against fault conditions such as a short-circuit condition. To break a current, SSPCs (Solid State Power Controllers, also referred to a Solid State Protection Controllers) are preferred over electro-mechanical switches as they show a fast response time, eliminate arcing during turn-off, and have a higher reliability.

[0006] SSPC units may be implemented in the positive rail and / or the negative rail of a DC power distribution and protection systems. One limitation of using such architecture lies in that in case of a short circuit fault at the DC common bus, all basic SSPC units will trip such that critical loads will lose all power supply from the DC power source. However, this may not be acceptable for critical loads. For example, critical loads may suffer from losing power supply in case of a DC common bus short circuit fault. One solution is to provide a separate backup DC power source. Such solution, however, increases weight and costs.

[0007] There is a need to provide for a DC power distribution and protection system which allows to maintain power supply to a load even in case of a short-circuit condition, thereby avoiding the need for a separate backup DC power source, or at least provides a useful alternative to known DC power distribution and protection systems.

[0008] Summary of the disclosure

[0009] According to an aspect of the invention, a DC power distribution and protection system is provided for, the system comprising a first DC power source having a positive terminal and a negative terminal, a first load, and a first power bus connecting the first power source and the first load, the first power bus comprising a high side voltage rail connected to the positive terminal and a low side voltage rail connected to the negative terminal. The system further comprises a first solid state power controller (SSPC) arranged in the high side voltage rail or low side voltage rail at a DC power source side of the voltage rail, the first solid state power controller allowing control of the current flow between the first DC power source and the first load, and a second solid state power controller arranged in the same voltage rail as the first solid state power controller at a load side of that voltage rail, the second solid state power controller also allowing control of the current flow between the first DC power source and the first load.

[0010] A first bypass line is provided that connects the first DC power source with the first load under bypassing of the first and second solid state power controllers, wherein the first bypass line comprises a third solid state power controller, and wherein the third solid state power controller is configured to be switched on only if the first and second solid state power controllers are switched off.

[0011] Aspects of the present invention are thus based on the idea to provide for a redundant leg in the form of a bypass line to protect and maintain the power supply to a critical load in case of a common bus failure in the DC power distribution and protection system. The bypass line bypasses the first and second SSPCs and thus those elements which trip in case of a short-circuit and provides an additional, redundant connection path between a DC power source and a load. The bypass line is not operational during normal operating mode but only activated during fault conditions.

[0012] The bypass line and the SSPC located in the bypass line represent a redundant DC circuit with a reduced number of SSPCs to supply the first load. By providing a bypass line in case of a short-circuit condition or other fault condition, it is possible to maintain power supply to a critical load in a simple manner, without the requirement of a separate backup DC power source.

[0013] Aspects of the present invention are further based on the idea to maintain power supply at a critical load with a reduced number of SSPCs which are arranged in the bypass line: while the first and the second SSPCs are arranged in the normal operation DC network connection line between the DC power source and the Lord, only one (the third) SSPC is arranged in the bypass line, thereby relying on a reduced complexity in case the bypass line is activated.

[0014] The present invention is based on a DC power distribution and protection system in which an SSPC architecture is implemented that allows control of the current flow between connected source and load and which also supports power transfer and protection capability to various fault conditions. SSPCs are implemented in the positive rail and / or the negative rail and in the bypass line. The SSPC architecture may be a bidirectional SSPC architecture that allows bidirectional control of the current flow between connected source and load. In such case, bidirectional SSPCs are implemented in the positive rail and / or the negative rail and in the bypass line. It is pointed out that the SSPC may provide for further functions in the DC power distribution and protection system as known to the skilled person, such as supressing inrush currents and voltages during pre-charging.

[0015] In some embodiments, each of the solid state power controllers comprises two switching devices with antiparallel diodes connected in common source / emitter configuration. Such a configuration is an example bidirectional topology for an SSPC, wherein other topologies may be implemented as well. The switching devices may be MOSFET, IGBT, JFET, and GaN transistors. The SSPC may further comprise at least one inductance which is configured to limit the rate of rise of current in case of a short-circuit fault.

[0016] In some embodiments, the power protection system of any of the present invention further comprises a controller which controls the operation of the solid state power controllers, in particular, the state of the switching devices is controlled by the controller controlling the gate voltage of the switching devices of the SSPCs.

[0017] In some embodiments, the controller is configured to: switch the first and second solid state power controllers on in case of a normal operation mode of the power protection system; switch the first and second solid state power controllers off in case of a short- circuit condition or other fault condition at the first power bus; and subsequently switch on the third solid state power controller to activate the first bypass line.

[0018] Accordingly, under the control of the controller, the SSPC in the bypass line is only activated after the SSPCs in the line used under normal operation mode are deactivated.

[0019] In a refinement of such control, the first solid state power controller comprises an upstream first switching device and a downstream second switching device, the second solid state power controller comprises an upstream third switching device and a downstream fourth switching device, and the third solid state power controller comprises an upstream fifth switching device and a downstream sixth switching device, wherein the controller is configured to: switch the first, second, third and fourth switching devices on in case of a normal operation mode of the power protection system; switch the first, second, third and fourth switching devices off in case of a short-circuit condition or other fault condition at the first power bus; check if the first load is a critical load that needs to be powered up; and if so, subsequently switch on the fifth and sixth switching devices of the third solid state power controller.

[0020] Accordingly, there may be a check if the first load is a critical load (meaning that the load is under a critical condition) and only in such case the fifth and sixth switching devices of the bypass line are activated. If the load is under a critical condition may be sensed by sensors providing their information to the controller. In some embodiments, the power protection system further comprises: a second DC power source having a positive terminal and a negative terminal; a second power bus connecting the second power source and the first load, the second power bus comprising a high side voltage rail connected to the positive terminal and a low side voltage rail connected to the negative terminal, wherein the high side voltage rail of the first power bus and the high side voltage rail of the second power bus are connected and wherein the low side voltage rail of the first power bus and the low side voltage rail of the second power bus are connected; and a fourth solid state power controller arranged in the high side voltage rail or low side voltage rail of the second power bus at a DC power source side of the voltage rail.

[0021] Accordingly, in such embodiments, a further (the second) DC power source is connected to the first load, wherein the high side voltage rails and the low side voltage rails of first and second power bus are interconnected, such that the first load is also powered by the second DC power source. The first DC power source and the second DC power source can be considered to be arranged in parallel. An SSPC (the fourth SSPC) is arranged at the DC power source side, this SSPC protecting the second DC power source in case of a short-circuit.

[0022] In such an arrangement, a second bypass line connecting the second DC power source with the first load under bypassing of the fourth and second solid state power controllers may be provided, wherein the second bypass line comprises a fifth solid state power controller, and wherein the fifth solid state power controller is configured to be switched on only if the fourth and second solid state power controllers are switched off. This aspect of the invention provides for a further backup and bypass line which is able to supply a critical load with power from the second DC power source (in addition to supply power from the first DC power source through the first bypass line). The first bypass line and the second bypass line and the SSPCs located in the bypass lines represent a redundant DC circuit with a reduced number of SSPCs to supply the first load. By providing first and second bypass lines, redundancy is increased and the safeguarding that sufficient power is maintained at the critical load in case of a DC common bus short-circuit fault is improved.

[0023] There may be provided further DC power sources and further bypass lines to the first (critical) load.

[0024] In some embodiments, the power protection system comprises additional DC power sources and additional loads connected through an additional DC power bus, the additional DC power bus having a high side voltage rail and a low side voltage rail, wherein the high side voltage rails of the first power bus and of the additional power bus and / or the low side voltage rails of the first power bus and of the additional power bus are connected through an additional solid state power controller, and wherein the additional solid state power controller is configured to be switched off in case of a short-circuit condition or other fault condition at the first power bus.

[0025] In such embodiments, a two DC power bus system is provided, wherein the two DC power buses are linked through an SSPC (the additional SSPC). Under normal operation, when the additional SSPC is switched on, the two DC power buses are interconnected and the power sources of the two DC power buses jointly provide power to the loads connected to the two power buses. However, in case of a short-circuit fault in the first DC power bus (when the SSPCs in the first DC power bus trip), the additional SSPC is switched off such that the second DC power bus is disconnected from the first DC power bus and not affected by the short circuit fault in the first DC power bus. The additional SSPC thus allows to separate the two DC power buses in case of a short-circuit in one of the DC power buses.

[0026] In some embodiments, the additional solid state power controller comprises a first additional switching device and a second additional switching device with antiparallel diodes and connected in common source / emitter configuration, and the controller is configured to: switch the first, second, third, fourth, first additional and second additional switching devices on in case of a normal operation mode of the power protection system; switch the first, second, third, fourth, first additional and second additional switching devices off in case of a short-circuit condition or other fault condition at the first power bus (thereby disconnecting the link to the second power bus); check if the first load is a critical load that needs to be powered up; and if so, subsequently switch on the fifth and sixth switching devices of the third solid state power controller (thereby opening the bypass line to the first load).

[0027] In some embodiments, the additional DC power sources and the additional loads connected through the additional DC power bus include: a third DC power source having a positive terminal and a negative terminal; a third load; a third power bus connecting the third power source and the third load, the third power bus comprising a high side voltage rail connected to the positive terminal and a low side voltage rail connected to the negative terminal; a sixth solid state power controller arranged in the high side voltage rail or low side voltage rail at a DC power source of the third power bus side of the voltage rail, the sixth solid state power controller allowing control of the current flow between the third DC power source and the third load; a seventh solid state power controller arranged in the same voltage rail as the sixth solid state power controller at a load side of that voltage rail, the seventh solid state power controller also allowing control of the current flow between the third DC power source and the third load; and a third bypass line connecting the third DC power source with the third load under bypassing of the sixth and seventh solid state power controllers, wherein the third bypass line comprises an eights solid state power controller, and wherein the eights solid state power controller is configured to be switched on only if the sixth and seventh solid state power controllers are switched off.

[0028] In such embodiments, an additional, third DC power source is connected to an additional, third load through an additional, third power bus (that is connected to the first power bus through the additional SSPC), wherein similar as with the first power bus a bypass line is provided that includes another SSPC. The function is the same as discussed with respect to the first bypass line branching off the first power bus. There is thus provided a two-bus system with two redundant bypass lines in such embodiments.

[0029] In a further refinement of such embodiments, the power protection system may further comprise at least one additional DC power source and / or at least one additional load. The present invention is not limited to any particular number of DC power sources and loads.

[0030] In some embodiments, the DC power sources and the loads may be connected such that each of the DC power sources powers at least two of the loads and in that each of the loads is powered by at least two of the DC power sources. Accordingly, a DC network is provided for with the ability to share energy between different lanes (power buses) and / or to provide for redundancy in case of a failure.

[0031] The first load may be or comprise a power converter circuitry, such as a three phase inverter circuitry used to drive electric motors.

[0032] The skilled person will appreciate that except where mutually exclusive, a feature or parameter described in relation to any one of the above aspects may be applied to any other aspect. Furthermore, except where mutually exclusive, any feature or parameter described herein may be applied to any aspect and / or combined with any other feature or parameter described herein.

[0033] Brief description of the disclosure

[0034] The invention will be explained in more detail on the basis of exemplary embodiments with reference to the accompanying drawings in which:

[0035] FIG. 1 is a first embodiment of a DC power distribution and protection system, the DC power distribution and protection system comprising a bypass line bypassing two SSPCs arranged in a high side voltage rail of the DC power distribution and protection system, wherein the bypass line connects a DC power source and a critical load with a reduced number of switches; FIG. 2 is a flowchart of a method used in the DC power distribution and protection system of FIG. 1 , the method controlling use of the bypass line;

[0036] FIG. 3 is a second embodiment of a DC power distribution and protection system, the second DC power distribution and protection system comprising several bypath lines, each bypass line connecting a DC power source and a critical load with a reduced number of switches;

[0037] FIG. 4 is a third embodiment of a DC power distribution and protection system, the third DC power distribution and protection system comprising a first power bus at a second power bus each connecting DC power sources and loads, wherein the two power buses are interconnected through an SSPC, and wherein a bypass line is provided in a high side voltage rail of the first power bus;

[0038] FIG. 5 is a flowchart of a method used in the DC power distribution and protection system of FIG. 4, the method controlling use of the bypass line;

[0039] FIG. 6 is a fourth embodiment of a DC power distribution and protection system, the third DC power distribution and protection system comprising a first power bus and a second power bus each connecting DC power sources and loads, wherein the two power buses are interconnected through an SSPC, and wherein a bypass line is provided that bypasses the high side voltage rail of the first power bus and a bypass line is provided that bypasses the high side voltage rail of the second power bus;

[0040] FIG. 7 is an example architecture of a bidirectional SSPC; and

[0041] FIG. 8 is an example of a DC power distribution and protection system not in accordance with the present invention:

[0042] Detailed description

[0043] Before discussing embodiments of the present invention with respect to FIG.s 1 to 6, the background of the invention is discussed with respect to FIGs. 7 and 8 to provide for a better understanding of the present invention.

[0044] FIG. 8 shows an example DC power distribution and protection system which comprises three DC power sources 21 , 22, 23 and two loads R1 , R2 which are connected through a DC distribution network. Such system may be used in hybrid propulsion system or marine applications. More particularly, the system of FIG. 8 comprises a first power source 21 and a first load R1 connected through a first power bus 31, 41. The first power source 21 has a positive terminal 211 and a negative terminal 212. Between these terminals 211, 212 a constant DC voltage such as a battery voltage is present. A high side voltage rail 31 is connected to the DC positive terminal 211 and a low side voltage rail 41 is connected to the DC negative terminal 212. The high side voltage rail 31 and the low side voltage rail 41 form the first power bus.

[0045] In a similar manner, the system further comprises a second power source 22 and a second load R2 connected through a second power bus 32, 42. The second power source 22 has a positive terminal 221 and a negative terminal 222. Between these terminals 221, 222 a constant DC voltage such as a battery voltage is present. A high side voltage rail 32 is connected to the DC positive terminal 221 and a low side voltage rail 42 is connected to the DC negative terminal 222. The high side voltage rail 32 and the low side voltage rail 42 form the second power bus.

[0046] The system further comprises a third power source 23 having an additive terminal 231 and a negative terminal 232 to which a high side voltage rail 33 and a low side voltage rail 43 are connected, which form a third power bus.

[0047] Further, the first, second and third power buses are interconnected, thereby forming a first common bus. To this end, the high side voltage rail 31 of the first power bus, the high side voltage rail 32 of the second power bus, and the high side voltage rail 33 of the third power bus are connected. Further, the low side voltage rail 41 of the first power bus, the low side voltage rail 42 of the second power bus, and the low side voltage rail 43 of the third power bus are connected. Accordingly, the same voltage VB+ is present at the high side voltage rails 31, 32, 33 and the same voltage VB- is present at the low side voltage rails 41, 42, 43. As the voltage rails 31, 32, 33 and 41 , 42, 43 share a common voltage, they may be referred to as a common bus.

[0048] In case one of the loads R1 , R2 fails, all three power sources 21, 22, 23 can be used to power the remaining load. Further, in case one of the power sources 21, 22, 23 fails, the remaining power sources can power both loads R1, R2. The loads R1 , R2, in principle, can be any load. In some embodiments, each load R1, R2 comprises an inverter circuitry and an associated electric motor. Each such inverter circuitry may comprise six semiconductor power switches which provide for a three-phase current as is well known to the person skilled in the art.

[0049] There may be provided further power sources and loads connected to the system in the same manner. In aerospace applications, the power sources 21 , 22, 23 may be battery energy storage systems or fuel cells or be fed from a turbo generator / active rectifier.

[0050] The system of FIG. 1 further comprises a plurality of SSPCs, wherein two SSPCs are located in the high side voltage rail 31 of the first power bus, two SSPCs are located in the high side voltage rail 32 of the second power bus and one SSPC is located in the high side voltage rail 33 of the third power bus.

[0051] More particularly, SSPC_A is located at the power source side 61 of the first power bus, SSPC_B is located at the load side 62 of the first power bus, SSPC_C is located at the power source side 61 of the second power bus, SSPC_D is located at the load side 62 of the second power bus, and SSPC_E is located at the power source side 61 of the third power bus.

[0052] All SSPCs are a bidirectional, i.e. , they provide bidirectional protection, e.g., because the loads R1 , R2 may backfeed. They provide a protection function for the respective individual lanes 31, 32, 33 both at the power source side 61 (SSPC_A, SSPC_C, SSPC_E) and at the load side 62 (SSPC_B, SSPC_D). FIG. 8 also depicts an example architecture of the SSPCs, which is shown in more detail in FIG. 7.

[0053] According to FIG. 7, each bidirectional SSPC comprises two semiconductor switches S1, S2 with antiparallel diodes D connected in common source / emitter configuration, wherein semiconductor switch S1 is an upstream switching device and semiconductor switch S2 is a downstream switching device of the SSPC. The antiparallel diodes D give current that flows in the opposite direction a path to flow. Without the diodes D, inductive currents would cease instantly, generating high voltage peaks. The switches S1 , S2 may be MOSFET, GaN (Gallium Nitride), SiC (Silicon Carbide), JFET (Junction Gate Field-Effect Transistor) or IGBT (Insulated Gate Bipolar Transistor) switches. They are controlled by the respective gate voltage, which is controlled by a controller 6. Each SSPC may comprise its own controller 6 or, alternatively, one controller 6 may provide control signals to all SSPCs.

[0054] The SSPC of FIG. 7 further comprises two inductances L1 , L2, one before switch S1 and one behind switch S2, wherein the inductances L1, L2 are configured to limit the rate of rise of current in case of a short-circuit fault. In addition, the system of FIG. 8 may comprise inductances L for the same reason. It is pointed out that the system of FIG. 8 may comprise further elements such as capacitive loads not depicted as not relevant in the present context.

[0055] The bidirectional SSPCs in the system of FIG. 8 (SSPC_A to SSPC_E) allow bidirectional control of the current flow between connected source 21, 22, 23 and loads R1 , R2. However, one limitation in the system of FIG. 8 lies in that in case of the short-circuit fault directly at the DC common bus, SSPC_A1, SSPC_A2, SSPC_B1 , SSPC_B2, SSPC_C1, SSPC_C2, SSPC_D1 , SSPC_D2, SSPC_E1 and SSPC_E2 will trip simultaneously to avoid excessive faulty current in the DC system.

[0056] In such case, critical loads will lose all power supply from the DC sources, which may cause safety issues, e.g., for inflight aerospace power system. Similar demanding requirements may be present in More Electric Engine applications where generators are fed into a single common bus and critical loads such as oil pumps and fuel pumps which are electrically driven are also connected into the same distribution feeder, wherein a short circuit within the common bus will result in complete loss of power to those critical loads. Accordingly, critical DC loads may suffer from losing power supply in case of DC common bus short circuit fault.

[0057] To address this problem, a back-up DC circuit is provided that comprises a bypass line and a reduced number of SSPCs and corresponding switches to supply a critical load in case of DC common bus short circuit fault, as will be discussed in several embodiments with respect to FIGs. 1 to 5. In this respect, in the following, it is assumed that load R1 is a critical load, e.g., a load which may be damaged, cause safety issues, etc., if its power supply is interrupted, while this is to be understood as an example only.

[0058] The system of FIG. 1 is similar to the system of FIG. 8 except that an additional bypass line 51 is provided for as backup. The bypass line 51 connects the DC power source 21 with the critical load R1 under bypassing of the bidirectional SSPCs SSPC_A and SSPC_B present on the high side voltage rail 31 of the first power bus. At the same time, the bypass line 51 comprises a further bidirectional solid state power controller SSPC_R, wherein the further bidirectional solid state power controller SSPC_R is configured to be switched on only if the bidirectional SSPCs SSPC_A, SSPC_B which are bypassed are switched off. The further SSPC_R also comprises two switching devices SSPC_R1, SSPC_R2 with antiparallel diodes and connected in common source / emitter configuration (similar as SSPCs SSPC_A and SSPC_B). However, the total number of switching devices is reduced to two (namely, switching devices SSPC_R1 , SSPC_R2) compared to the total four switching devices of the SSPCs SSPC_A and SSPC_B.

[0059] In case of short circuit fault on the DC common bus of the system of FIG. 1 , SSPC_A1 , SSPC_A2, SSPC_B1, SSPC_B2, SSPC_C1, SSPC_C2, SSPC_D1, SSPC_D2, SSPC_E1 , SSPC_E2 will trip simultaneously due to excessive current. Therefore, the back-up circuit which consists of bypass line 51 and SSPC_R is provided. Line 51 and SSPC_R provide a power flow path for the critical load R1 in case of DC common bus short circuit when the switching devices the high side voltage rail 31 trip. The SSPCs are controlled through a controller 6 which is also schematically depicted in FIG. 1. Controller 6 comprises a plurality of control lines 61 , each control line 61 controlling the gate voltage and thus the switching state of one of the switching devices SSPC_A1, SSPC_A2, SSPC_B1, SSPC_B2, SSPC_C1, SSPC_C2, SSPC_D1, SSPC_D2, SSPC_E1, SSPC_E2, SSPC_R1 , SSPC_R2. The controller 6 may receive input signals 62 from sensors and / or another controller.

[0060] The logic flowchart for controlling SSPC_R is illustrated in FIG. 2. After start 201, all switching devices SSPC_A1 , SSPC_A2, SSPC_B1 , SSPC_B2, SSPC_C1, SSPC_C2, SSPC_D1, SSPC_D2, SSPC_E1 , SSPC_E2 are turned on, step 202, providing the normal operation mode. Accordingly, load R1 is supplied with power through power sources 21, 22, 23. In case of a DC common bus short circuit or other fault condition, decision 203, the switching devices are turned off, step 204, such that the power supply to load R1 is interrupted. At this point, it may be checked if the first load R1 is a critical load that needs to be powered up, decision 205. If so, subsequently, switching devices SSPC_R1 and SSPC_R2 of SSPC_R are turned on to open the bypass line 51 from the DC power source 21 to the critical load R1, thereby providing power to the critical load R1. The process ends at 207.

[0061] FIG. 3 shows a further embodiment of a DC power distribution and protection system. The system of FIG. 3 is similar to the system of FIG. 1 except that additional bypass lines are provided for. More particularly, a second bypass line 52 is provided connecting DC power source 22 and critical load R1. Further, a third a bypass line 53 is provided connecting DC power source 23 and critical load R1. Each of the bypass lines 51, 52, 53 comprises an SSPC (SSPC_R in bypass line 51, SSPC_Y in bypass line 52 and SSPC_X in bypass line 53). The SSPCs in the bypass lines 51 , 52, 53 may have the same architecture as SSPC_R in FIG. 1 (and as all other SSPCs in the system).

[0062] By providing further bypass lines 52, 53, additional redundancy is provided for in case a short circuit or other fault condition leads to the tripping of SSPCs SSPC_A1 , SSPC_A2, SSPC_B1, SSPC_B2, SSPC_C1, SSPC_C2, SSPC_D1, SSPCJD2, SSPC_E1 , SSPC_E2, SSPC_R1 and SSPC_R2, wherein further of the DC voltage sources 22, 23 are connected to the critical load R1 through a bypass line 52, 53. Accordingly, in case of short circuit fault on the DC common bus, bypass lines 51 , 52, 53 with SSPCs SSPC_R1 , SSPC_Y, and SSPC_X are provided which allow to feed the critical load R1 with power from multiple DC power sources 21 , 22, 23.

[0063] The system may be expanded in that multiple critical loads such as both load R1 and load R2 are provided power through the back-up network, such that several critical loads are fed with power from the multiple DC power sources 21, 22, 23. To this end, bypass lines may also be provided to such further critical loads in the same manner as with bypass lines 51, 52, 53.

[0064] A still further embodiment of a DC power distribution and protection system is shown in FIG. 4. The system of FIG. 4 comprises a two DC common buses power network. More particularly, the system comprises a first DC power source 21, a second DC power source 22, a first load R1 and a second load R2 connected through a first power bus 31 , 41 and a second power bus 32, 42 which are interconnected in the manner discussed with respect to FIG. 8 and which form a first common power bus. In a similar manner, a third DC power source 24, a fourth DC power source 25, a third load R3 and a fourth load R4 are connected through a third power bus 34, 44 and a fifth power bus 35, 45 which are interconnected in the same manner as power buses 31, 41 and 32, 42, thereby forming a second common power bus.

[0065] The high side voltage rails 31, 32, 34, 35 comprise SSPCs SSPC_A, SSPC_B, SSPC_C, SSPC_D, SSPC_F, SSPC_G, SSPC_H, SSPC_J in the manner discussed before.

[0066] Further, the high side voltage rails 31, 32, 34, 35 of the two common power buses are connected through an SSPC SSPC_M which has the same architecture as the other SSPCs previously discussed and, accordingly, comprises two switching devices SSPC_M1 , SSPC_M2 with antiparallel diodes connected in common source / emitter configuration. SSPC_M is configured to be switched off in case of a short-circuit condition or other fault condition at the first power bus. Switching off and on of the switching devices of SSPC_M is provided through a controller such as a controller similar to controller 6 of FIG. 1.

[0067] In case of short circuit fault on the first DC common bus, SSPC_A1 , SSPC_A2, SSPC_B1, SSPC_B2, SSPC_C1, SSPC_C2, SSPC_D1, SSPCJD2, SSPC_M1 , SSPC_M2 will trip simultaneously due to excessive current. To supply power to the critical load R1 in case of first DC common bus short circuit, a back-up switch circuit which consists of bypass line 51 and SSPC_R is provided for. Due to the turning of SSPC_M1 and SSPC_M2, the second DC common bus 34, 35, 44, 45 is not affected by the short circuit fault in first DC common bus. The two common buses are completely isolated. However, the critical load R1 in the first DC common may still suffer from losing power due to a short circuit fault, which is addressed by bypass line 51 and SSPC_R, wherein bypass line 51 and SSPC_R provide a power flow path from DC power source 21 to the critical load R1 in the first DC common bus.

[0068] The logic flowchart for controlling SSPC_R in the system of FIG. 4 is illustrated in FIG. 5. After start 501, all switching devices SSPC_A1 , SSPC_A2, SSPC_B1, SSPC_B2, SSPC-C1, SSPC_C2, SSPC-D1, SSPCJD2, SSPC_F1, SSPC_F2, SSPC_G1 , SSPC_G2, SSPC_H1, SSPC_H2, SSPC_J1, SSPC_J2, SSPC_M1, SSPC_M2 are turned on, step 502, providing the normal operation mode of the two bus system. Accordingly, load R1 (and loads R2-R4) is supplied with power through power sources 21 , 22, 24, 25. In case of the first DC common bus short circuit or other fault condition, decision 503, the switching devices SSPC_A1, SSPC_A2, SSPC_B1 , SSPC_B2, SSPC_C1, SSPC_C2, SSPC_D1, SSPC_D2 in the first DC common bus and the two buses interconnection switching devices SSPC_M1, SSPC_M2 are turned off, step 504, such that the power supply to load R1 is interrupted. At this point, it may be checked if the first load R1 is a critical load that needs to be powered up, decision 505. If so, subsequently, switching devices SSPC_R1 and SSPC_R2 of SSPC_R are turned on to open the bypass line 51 from the DC power source 21 to the critical load R1 , thereby providing power to the critical load R1. The process ends at 507.

[0069] Another still further embodiment of a DC power distribution and protection system in accordance with the principles of the present invention is illustrated in FIG. 6. The system is similar to the system of FIG. 4 except that additionally a further bypass line 54 with an SSPC_S is provided for that bypasses SSPC_F and SSPC_G in the high side voltage rail 34, thereby providing the power of DC power source 24 through the bypass line 54 to load R3 which may be a further critical load.

[0070] The system functions in the same manner as the system of FIG. 4, except that redundancy is provided for both in the first DC common bus 31, 32, 41, 42 and in the second DC common bus 34, 35, 44, 45 by providing two redundant bypass lines 51, 54. The interconnection switching devices SSPC_M1, SSPC_M2 are turned off both in case of a short-circuit in the first DC common bus and in case of a short-circuit in the second DC common bus, thereby isolating the respective other common buses.

[0071] It is pointed out that in the above embodiments SSPCs are located in the high side voltage rails of the power buses only. In further embodiments, SSPCs (such as bidirectional SSPCs) are located in the low side voltage rails the power buses as well, thereby allowing to isolate the high side voltage rail and the low side voltage rail independently in case of a short-circuit or ground fault. However, a bypass line is provided for one of the voltage rails only, such as the high side voltage rail as depicted in the drawings.

[0072] It should be understood that the above description is intended for illustrative purposes only, and is not intended to limit the scope of the present disclosure in any way. Also, those skilled in the art will appreciate that other aspects of the disclosure can be obtained from a study of the drawings, the disclosure and the appended claims. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. Various features of the various embodiments disclosed herein can be combined in different combinations to create new embodiments within the scope of the present disclosure. In particular, the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein. Any ranges given herein include any and all specific values within the range and any and all sub-ranges within the given range.

Claims

CLAIMS1. A DC power distribution and protection system comprising: a first DC power source (21) having a positive terminal (211) and a negative terminal (212) a first load (R1) a first power bus (31, 41) connecting the first power source (21) and the first load (R01), the first power bus (31, 41) comprising a high side voltage rail (31) connected to the positive terminal (211) and a low side voltage rail (41) connected to the negative terminal (212) a first solid state power controller (SSPC_A) arranged in the high side voltage rail (31) or low side voltage rail (41) at a DC power source side (61) of the voltage rail, the first solid state power (SSPC_A) controller allowing control of the current flow between the first DC power source (21) and the first load (R1); and a second solid state power controller (SSPC_B) arranged in the same voltage rail (31, 41) as the first solid state power controller (SSPC_A) at a load side (62) of that voltage rail (31, 41), the second solid state power controller (SSPC_B) also allowing control of the current flow between the first DC power source (21) and the first load (R1); wherein a first bypass line (51) connecting the first DC power source (21) with the first load (R1) under bypassing of the first and second solid state power controllers (SSPC_A, SSPC_B), wherein the first bypass line (51) comprises a third solid state power controller (SSPC_R), and wherein the third solid state power controller (SSPC_R) is configured to be switched on only if the first and second solid state power controllers (SSPC_A, SSPC_B) are switched off.

2. The system of claim 1 , wherein each of the solid state power controllers (SSPC_A, SSPC_B, SSPC_R) comprises two switching devices (S1, S2; SSPC_A1, SSPC_A2, SSPC_B1, SSPC_B2, SSPC_R1 , SSPC_R2) with antiparallel diodes (D) connected in common source / emitter configuration.

3. The system of claim 2, wherein the switching devices (S1 , S2; SSPC_A1 , SSPC_A2, SSPC_B1, SSPC_B2, SSPC_R1, SSPC_R2) are MOSFET, IGBT, JFET, or GaN transistors.

4. The system of claim 2 or 3, wherein the solid state power controllers (SSPC_A, SSPC_B, SSPC_R) additionally comprise at least one inductance (L1 , L2) which is configured to limit the rate of rise of current in case of a short-circuit fault.

5. The system of any preceding claim, wherein a controller (6) controlling the operation of the solid state power controllers (SSPC_A, SSPC_B, SSPC_R), wherein the controller (6) is configured to: switch the first and second solid state power controllers (SSPC_A, SSPC_B) on in case of a normal operation mode of the system; switch the first and second solid state power controllers (SSPC_A, SSPC_B) off in case of a short-circuit condition or other fault condition at the first power bus; and subsequently switch on the third solid state power controller (SSPC_R) to activate the first bypass line (51).

6. The system of any preceding claim, when dependent on claim 2 or 5, wherein the first solid state power controller (SSPC_A) comprises an upstream first switching device (SSPC_A1) and a downstream second switching device (SSPC_A2), the second solid state power controller comprises (SSPC_B) an upstream third switching device (SSPC_B1) and a downstream fourth switching device (SSPC_B2), and the third solid state power controller (SSPC_R) comprises an upstream fifth switching device (SSPC_R1) and a downstream sixth switching device ((SSPC_R2); wherein the controller (6) is configured to: switch (202) the first, second, third and fourth switching devices (SSPC_A1, SSPC_A2, SSPC_B1, SSPC_B2) on in case of a normal operation mode of the system; switch (204) the first, second, third and fourth switching devices (SSPC_A1, SSPC_A2, SSPC_B1, SSPC_B2) off in case of a short-circuit condition or other fault condition at the first power bus (31, 41); check (205) if the first load (R1) is a critical load that needs to be powered up; and if so, subsequently switch on (206) the fifth and sixth switching devices (SSPC_R1, SSPC_R2) of the third solid state power controller (SSPC_R).

7. The system of any preceding claim, wherein the power protection system further comprises: a second DC power source (22, 23) having a positive terminal (221 , 231) and a negative terminal (222, 232); a second power bus (32, 42; 33, 43) connecting the second power source (22, 23) and the first load (R01), the second power bus (32, 42; 33, 43) comprising a high side voltage rail (32, 33) connected to the positive terminal (221, 231) and a low sidevoltage rail (42, 43) connected to the negative terminal (222, 232), wherein the high side voltage rail (31) of the first power bus and the high side voltage rail (32, 33) of the second power bus are connected and wherein the low side voltage rail (41) of the first power bus and the low side voltage rail (42, 43) of the second power bus are connected; and a fourth solid state power controller (SSPC_C, SSPC_E) arranged in the high side voltage rail (32, 33) or low side voltage rail (42, 43) of the second power bus at a DC power source side (61) of the voltage rail.

8. The system of claim 7, wherein a second bypass line (52, 53) connecting the second DC power source (22, 23) with the first load (R1) under bypassing of the fourth and second solid state power controllers (SSPC_C, SSPC_B; SSPC_E, SSPC_B), wherein the second bypass line (52, 53) comprises a fifth solid state power controller (SSPC_Y, SSPC_X), and wherein the fifth solid state power controller (SSPC_Y, SSPC_X) is configured to be switched on only if the fourth and second solid state power controllers (SSPC_C, SSPC_B; SSPC_E, SSPC_B) are switched off.

9. The system of any preceding claim, wherein the power protection system comprises additional DC power sources (24, 25) and additional loads (R3, R4) connected through an additional DC power bus (34, 44; 35, 45), the additional DC power bus having a high side voltage rail (34, 35) and a low side voltage rail (44, 45), wherein the high side voltage rails of the first power bus (31) and of the additional power bus (34, 35) and / or the low side voltage rails of the first power bus (41) and of the additional power bus (44, 45) are connected through an additional solid state power controller (SSPC_M), and wherein the additional solid state power controller (SSPC_M) is configured to be switched off in case of a short-circuit condition or other fault condition at the first power bus (31, 41).

10. The system of claim 9, when dependent on claim 6, wherein the additional solid state power controller (SSPC_M) comprises a first additional switching device (SSPC_M1) and a second additional switching device (SSPC_M2) with antiparallel diodes and connected in common source / emitter configuration, and in that the controller (6) is further configured to: switch (502) the first, second, third, fourth, first additional and second additional switching devices (SSPC_A1, SSPC_A2, SSPC_B1 , SSPC_B2, SSPC_M1, SSPC_M2) on in case of a normal operation mode of the power protection system; switch (504) the first, second, third, fourth, first additional and second additional switching devices (SSPC_A1, SSPC_A2, SSPC_B1 , SSPC_B2, SSPC_M1,SSPC_M2) off in case of a short-circuit condition or other fault condition at the first power bus (31 , 41); check (505) if the first load (R1) is a critical load that needs to be powered up; and if so, subsequently switch on (506) the fifth and sixth switching devices (SSPC_R1 , SSPC_R2) of the third solid state power controller (SSPC_R).

11. The system of claim 9 or 10, wherein the additional DC power sources and the additional loads connected through the additional DC power bus include: a third DC power source (24) having a positive terminal and a negative terminal; a third load (R3); a third power bus (34, 44) connecting the third power source (24) and the third load (R1), the third power bus (34, 44) comprising a high side voltage rail (34) connected to the positive terminal and a low side voltage rail (44) connected to the negative terminal; a sixth solid state power controller (SSPC_F) arranged in the high side voltage rail (34) or low side voltage rail (44) of the third power bus at a DC power source side (61) of the voltage rail, the sixth solid state power (SSPC_F) controller allowing control of the current flow between the third DC power source (24) and the third load (R3); a seventh solid state power controller (SSPC_G) arranged in the same voltage rail (34, 44) as the sixth solid state power controller (SSPC_F) at a load side (62) of that voltage rail, the seventh solid state power controller (SSPC_G) also allowing control of the current flow between the third DC power source (24) and the third load (R3); and a third bypass line (54) connecting the third DC power source (24) with the third load (R3) under bypassing of the sixth and seventh solid state power controllers (SSPC_F, SSPC_G), wherein the third bypass line (54) comprises an eights solid state power controller (SSPC_S), and wherein the eights solid state power controller (SSPC_S) is configured to be switched on only if the sixth and seventh solid state power controllers (SSPC_F, SSPC_G) are switched off.

12. The system of any one of claims 7 to 11 , wherein the DC power sources (21-24) and the loads (R1-R4) are connected such that each of the DC power sources (21-24) powers at least two of the loads (R1-R4) and in that each of the loads (R1-R4) is powered by at least two of the DC power sources (21-24).

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