Power distribution system

Abstract

A power distribution system that comprises a first and second energy supply systems (11, 12), first and second electric drives (21, 22) associated with first and second input protections units (31, 32), and a power network connecting the first and second energy supply systems (11, 12) with the first and second electric drives (21, 22) The power network comprises a first and second power bus (41, 42) connecting the first and second energy supply systems (11, 21) with the first and second electric drives (21, 22), a first switching unit (51) associated with the first electric drive (21), and a second switching unit (52) associated with the second electric drive (22). The first switching unit (51) comprises a first input (511) from the first power bus (41), a first output (512) to the first power bus (41) or the first electric drive (21), and a second output (513) to the second switching unit (52). The second switching unit (52) comprises a first input (521) from the second power bus (42), a first output (522) to the second power bus (42) or the second electric drive (22), and a second input (524) from the first switching unit (51). The first switching unit (51) is configured to couple its first input (511) with its first output (512) when the input protection unit (31) of first electric drive (21) is switched off and configured to couple its input (511) with its second output (513) when the input protection unit (31) of the first electric drive (21) is switched on. The second switching unit (52) is configured to couple its second input (524) with its first output (522) to receive through its second input (524) power from the first power bus (41) and to couple the received power into the second power bus (42) or the second electric drive (21).

Description

[0001] POWER DISTRIBUTION SYSTEM

[0002] Field of the disclosure

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

[0004] Background

[0005] In aircraft power distribution systems it is known to implement multiple energy supply systems and multiple electric drives. The multiple energy supply systems and multiple electric drives are connected through a power network that may implement a multilane architecture in which different lanes are connected to allow sharing of power from the energy supply systems and / or to provide for redundancy.

[0006] A disadvantage associated with known architectures of a power distribution systems lies in that extensive switching networks which include a plurality of interconnections and associated cables are required to couple the different lanes.

[0007] There is a need to provide a power distribution system that comprises a plurality of energy supply systems and a plurality of electric drives in which the number of interconnections required for a load sharing between different lanes is reduced and in which a single fault does not result in the loss of the network, or at least provides a useful alternative to known power distribution systems.

[0008] Summary of the disclosure

[0009] According to a first aspect, a power distribution system is provided. The power distribution system comprises a first energy supply system and a second energy supply system as well as a first electric drive and a second electric drive, wherein the first electric drive is associated with a first input protection unit and the second electric drive is associated with a second input protection unit. The system further comprises a power network connecting the first and second energy supply systems with the first and second electric drives. The power distribution system provides mechanical power at the output of the electric drives. The power network comprises a first power bus connecting the first energy supply system with the first electric drive, a second power bus connecting the second energy supply system with the second electric drive, a first switching unit associated with the first electric drive, and a second switching unit associated with the second electric drive. The first switching unit comprises a first input from the first power bus, a first output to the first power bus or the first electric drive, and a second output to the second switching unit. The second switching unit comprises a first input from the second power bus, a first output to the second power bus or the second electric drive, and a second input from the first switching unit.

[0010] It is further provided that the first switching unit is configured to couple its first input with its first output when the input protection unit of first electric drive is switched off (i.e., not detecting any fault in the electrical drive) and configured to couple its first input with its second output when the input protection unit of the first electric drive is switched on (i.e., detecting a fault in the electric drive), in order to transfer power from the first power bus to the second switching unit when the second energy supply system is depleted, and when the second electric drive needs to recover the energy from the first energy supply system. Further, the second switching unit is configured to couple its second input with its first output to receive through its second input power from the first power bus and to couple the received power to the second power bus or the second electric drive.

[0011] Aspects of the disclosure are thus based on the idea of directing power of a first power bus from a switching unit of that power bus directly to the switching unit of another, second power bus in case the input protection unit of the first electric drive is detecting a fault and thus switched on. When the input protection unit of the first electric drive is switched on, the first electric drive does not receive power from the first power bus anymore. That power is then provided to the second switching unit and second power bus for load sharing.

[0012] By directing power from the switching unit of one power bus directly to the switching unit of another power bus, the number of interconnections and associated cables and thus the system complexity can be reduced. Further, as the decision to transfer power from the first switching unit to the second switching unit depends on the switching status (ON / OFF) of the input protection unit of the first electric drive, transferring of power to the second switching unit is triggered by the input protection unit and thus an element present anyway, this further reducing the complexity of the system. The functions of protecting an electric drive by an input protection unit and of diverting of energy to another subsystem in case of a failure of the electric drive are combined in aspects of the present disclosure.

[0013] It is pointed out that the second output of the first switching unit which is to the second switching unit may also be a second input from the second switching unit and that the second input of the second switching unit which is from the first switching unit may also be a second output to the first switching unit. Further, the respective second output and second input may be the same physical connection. Such embodiment allows to transfer power from the second energy supply system to the first electric drive when the second electric drive has a fault. Accordingly, the load transfer may work in both directions from the first to the second switching unit, but also from the second to the first switching unit.

[0014] It is pointed out that the power distribution system of the present disclosure can be applied to all voltage levels and to AC and DC. The system applies to any voltage range (low voltage LV to high voltage HV) and thus applies to the LV and HV supplies of electric drives. Usually, HV systems are used to supply the propulsive power of electric drives and LV systems are used for the supply of control electronics of the HV systems.

[0015] An energy supply system may comprise in embodiments a DC battery, a fuel cell, a mixture of DC batteries and fuel cells, a turbo generator with an active rectifier, and / or a DC / DC converter or DC / AC converter. An electric drive may comprise a prime mover such as an electric motor and further components that deliver mechanical power from the prime mover to driven components such as a rotor or propeller.

[0016] According to an embodiment of the present disclosure, the first switching unit is integrated into the first input protection unit. Such embodiment leads to a particular reduction in complexity, as switches of the input protection unit which determine the switching status (ON / OFF) of the input protection unit are part of the first switching unit. Accordingly, the switches of the input protection unit realize two functions, namely, first, shutting off power to the first electric drive in case of a fault in the electric drive by interrupting the connection to the first electric drive and, second, participating in the first switching unit for directing power to the switching unit of another, second power bus in such case.

[0017] However, in other embodiments, the first switching unit is a separate part from the first input protection unit. Such separate part may be a bus sharing unit located upstream of the first electric drive in the first power bus, wherein the first switching unit is configured to receive controls signals indicating if the first input protection unit is switched on or off. Accordingly, also in this embodiment directing power from the first switching unit to the second switching unit is triggered by the status of the first input protection unit and takes place directly between switching units when the first switching unit indicates a fault situation and interrupts of the connection to the first electric drive.

[0018] Similarly, the second switching unit may be integrated into the second input protection unit or be provided by a separate part such as a bus sharing unit located upstream of the second electric drive in the second power bus.

[0019] When the second energy supply system is depleted, the second electric drive needs to recover the energy from the first energy supply system, wherein the second switching unit interrupts the connection to the second energy supply system and switches to the first energy supply system.

[0020] In an embodiment, the first switching unit comprises at least one first switch configured to connect the first input to the first output, and at least one second switch configured to connect the first input to the second output, wherein the first switch is opened (such that current can no longer pass that switch) and the second switch is closed (such that current can pass that switch) when the first input protection unit is detecting a fault condition and switched on. Under normal operation, when the first switch is closed, the output of the first switching unit is provided to the first power bus or directly to the first electric drive. The output of the first switching unit is provided to the first power bus when the switching unit is a separate part from the input protection unit and located in the first power bus and is thus connected by the first power bus (namely, a continuation of the first power bus) to the input protection unit. The output of the first switching unit is provided directly to the first electric drive when the switching unit is integrated into the input protection unit which is integrated into the electric drive such that there is a direct connection between the switching unit and the electric drive.

[0021] However, when the first input protection unit is switched on (meaning that a fault has occurred in the first electric drive), the first switch is opened and the second switch is closed such that power received from the first power bus is directed to the second switching unit and can be coupled by the second switching unit into the second power bus or directly into the second electric drive (this also depending on whether the second switching unit is a separate unit or part of the second electric drive) when the energy of the second energy supply system is depleted and the energy of the first energy supply system is required.

[0022] It is pointed out that the first switch and the second switch of the first switching unit may be combined into a single multiple switch unit such as a rotary switch, wherein the different positions of the rotary switch correspond to different switching situations.

[0023] In a similar manner, it may be provided that the second switching unit comprises at least one third switch configured to connect the second input to the first output of the second switching unit, wherein the third switch is closed when the first input protection unit is switched on. Under normal operation, the second switching unit does not receive any power through its second input from the first switching unit. However, when the first input protection unit is switched on (meaning that a fault has occurred in the first electric drive) such that the second switching unit receives power from the first switching unit through its second input, and when the energy of the first energy supply system is required to supply the second electrical drive, the third switch is closed such that the second switching unit can receive power from the first switching unit and couple the received power into the second power bus or the second electric drive (this depending on whether the second switching unit is a separate unit or part of the second electric drive).

[0024] It is pointed out that the second switching unit may further comprise a first switch configured to connect the first input to the first output to provide power of the second power bus from the first input to the first output under normal operation. If the third switch is switched on, such first switch may be switched off (such that the power from the first energy source from the first power bus replaces the power from the second energy source on the second power bus) or may be kept switched on (such that both power of the first energy source and power of the second energy source are inserted on the second power bus). In this respect, it is to be noted that two electrical energy sources can only be connected when both of them have the same output voltage. Otherwise there is a high current until the voltages are equalized. To avoid an energy flow from the energy supply system with the higher voltage to the energy supply system at the lower voltage such a first switch may be opened to disconnect the second electrical drive from the second energy supply system.

[0025] In a further embodiment, the first switching unit further comprises a second input configured to receive power from another switching unit and to couple the power from the other switching unit into the first power bus or the first electric drive. The second input may be the same physical connection as the second output. According to this embodiment, the option is provided that the first switching unit (besides providing power to the second switching unit) is also able to receive power from another switching unit (which may be the second switching unit). It may be provided that all switching units are implemented in the same manner, wherein each switching unit can both divert power from its power bus to another switching unit and receive power from the power bus of other switching unit for load sharing.

[0026] In an embodiment, to implement such second input (which may be the same physical connection as the second output) of the first switching unit, it may be provided that the first switching unit comprises a first first switch and a second first switch configured to connect the input to the output, the two first switches arranged in series; wherein the at least one second switch that connects the first input to the second output is switched on when the first first switch is switched off (and the power needs to flow to another switching unit); the first switching unit further comprising at least one third switch associated with the second input, wherein the third switch is configured to receive power from another power bus and to couple the power into the first power bus or the first electric drive, wherein the third switch is switched on when the second first switch is switched off.

[0027] Accordingly, in such embodiment, two switches are arranged in series between the first input and the first output of the first switching unit, the two switches being termed first first switch and second first switch. The provision of two switches increases the safety of the input protection unit as the current is interrupted with two switches in case of a problem. Each of the switches can be rated at 14 the supply voltage. Further, the provision of two switches between the input and the output of the first switching unit raises the possibility to use one of the two switches to control output of power to a second switching unit and to use the other of the two switches to control input of power of another (such as the second) switching unit. Accordingly, the at least one second switch is switched on when the first first switch is turned off such that power received from the first power bus is directed to the second switching unit. At the same time, the first switching unit may further comprise at least one third switch, wherein the third switch is configured to receive power from another power bus and switching unit and to couple the power into the first power bus or the first electric drive, wherein the third switch is switched on when the second first switch is switched off. Alternatively, the third switch may be configured to receive power from another power bus even if the second first switch remains switched on. In this respect, it is to be noted that two electrical energy sources can only be connected when both of them have the same output voltage. Otherwise there is a high current until the voltages are equalized. To avoid an energy flow from the energy supply system with the higher voltage to the energy supply system at the lower voltage such a first switch is opened to disconnect the second electrical drive from the second energy supply system.

[0028] According to an embodiment, the first and second power buses are grounded DC systems which each comprise a high voltage rail, wherein the second output of the first switching unit is a high voltage output and the second input of the second switching unit is a high voltage input, wherein the second output of the first switching unit and the second input of the second switching unit are connected through a single power line. Through the same power line the second input of the first switching unit and the second output of the second switching unit may be connected.

[0029] Alternatively, it may be provided that the first and second power buses are ungrounded DC systems which each comprise two high voltage rails, wherein the second output of the first switching unit comprises two high voltage outputs and the second input of the second switching unit comprises two high voltage inputs, wherein the second outputs of the first switching unit and the second inputs of the second switching unit are connected through two power lines for high voltage. In this respect, it is to be noted that all inputs and outputs have to be of the same type (e.g., two high voltage rails or one high voltage rail and ground).

[0030] In a further embodiment, the second output of the first switching unit (both in case of a grounded system and in case of an ungrounded system) may comprise a plurality of outputs, each output associated with a different second switch (there can be several second switches). This allows to direct the power of the first power bus to different other switching units depending on the chosen second switch and corresponding output of the first switching unit.

[0031] The first switching unit and / or the second switching unit may be implemented with an SSPC. SSPCs (Solid State Power Controllers, also referred to a Solid State Protection Controllers) show a fast response time, eliminate arcing during turn-off, and have a high reliability. However, alternatively, the first switching unit and / or the second switching unit may comprise a contactor which provides for an improved galvanic separation. A third alternative can be a contactor in parallel with an SSPC. These hybrid elements can open the contactor first and then the SSPC to avoid sparking / arcing during contact opening.

[0032] Aspects of the present disclosure discussed above regard input protection units of electric drive systems and associated switching units. However, the disclosure may similarly be implemented at the energy supply system side of the system, in particular in the output protection of energy supply systems and associated switching units.

[0033] Accordingly, in a further aspect of the present disclosure, a power distribution system is provided that comprises a first energy supply system and a second energy supply system, wherein the first energy system is associated with a first output protection unit and the second energy system is associated with a second output protection unit. The system further comprises a first electric drive and a second electric drive, and a power network connecting the first and second energy supply systems with the first and second electric drives. The power network comprises a first power bus connecting the first energy supply system with the first electric drive, a second power bus connecting the second energy supply system with the second electric drive, a first switching unit associated with the first energy supply system, and a second switching unit associated with the second energy supply system. The first switching unit comprises a first input from the first energy supply system, a first output to the first power bus, and a second output to the second switching unit. The second switching unit comprises a first input from the second energy supply system, a first output to the second power bus, and a second input from the first switching unit.

[0034] It is further provided that the first switching unit is configured to couple its first input with its first output when the output protection unit of first energy supply system is switched off (i.e. , not detecting any fault within the first energy supply system or in the first power bus or in the first electrical drive) and configured to couple its first input with its second output when the output protection unit of the first energy supply system is switched on (namely, switched to a “downstream fault” condition, i.e., detecting a fault in the first power bus or in the first electrical drive) in order to transfer in such case power from the first energy supply system to the second switching unit. Further, when the second energy supply is depleted or has an internal fault the second electric drive needs to recover energy from the first energy supply system, wherein the second switching unit is configured to couple its second input with its first output to receive through its second input power from the first energy supply system and to couple the received power onto the second power bus.

[0035] Aspects of the disclosure are thus based on the idea of directing power of an energy supply system from a switching unit associated with that energy supply system directly to the switching unit of another, second energy supply system in case the output protection unit of the first energy supply system is detecting a fault situation downstream, i.e., in the first power bus or in the first electrical drive and switched to “downstream fault” condition. When the output protection unit of the first energy supply system is switched to “downstream fault” condition, the first electric energy supply system does not provide power anymore to the first power bus (e.g., because of a short- circuit on the first power bus or in the first electric drive). That power is then provided to the second switching unit for load sharing.

[0036] It is pointed out that the second output of the first switching unit which is to the second switching unit may also be a second input from the second switching unit and that the second input of the second switching unit which is from the first switching unit may also be a second output to the first switching unit. Further, the respective second output and second input may be the same physical connection. Such embodiment allows to transfer power from the second energy supply system to the first supply system. Accordingly, the power transfer may work in both directions from the first to the second switching unit, but also from the second to the first switching unit. In particular, it is provided to couple such second input of the first switching unit with its first output when the output protection unit of the first energy supply system is switched to an “upstream fault” condition (i.e., detecting a fault within the first energy supply system) in order to transfer in such case power from the second energy supply system to the first switching unit. Further, when the first electrical drive needs to receive energy from the second energy supply system, the second switching unit is configured to couple its first input with such second output to provide through its first input power from the second energy supply system and to couple the transmitted power to the first power bus.

[0037] When considering power transfer from the second switching unit to the first switching unit (when there is a fault within the first energy supply system), such embodiment is based on the idea of directing power of a second energy supply system from a (second) switching unit associated with that energy supply system directly to the (first) switching unit of the first energy supply system in case the output protection unit of the first energy supply system is detecting a fault situation in the first energy supply system and switched to an “Upstream fault” condition. When the output protection unit of the first energy supply system is switched to “Upstream fault” condition, the first electric energy supply system does not provide power anymore to the first power bus (e.g., because of a short-circuit on the first energy supply system). That power is then provided by the second switching unit for load sharing.

[0038] By directing power from the switching unit of one energy supply system directly to the switching unit of another energy supply system, the number of interconnections and associated cables and thus the system complexity can be reduced. Further, as the decision to transfer power from the first switching unit to the second switching unit depends on the switching status (’’Upstream fault” / ”Downstream faulf’ / OFF) of the output protection unit of the first energy supply system, transferring of power from or to the second switching unit is triggered by the output protection unit and thus an element present anyway, this further reducing the complexity of the system. The output protection of an energy supply system and the diverting of energy to another subsystem or receiving it from another subsystem (when it is made available by another subsystem) in case the output protection detects a failure are combined.

[0039] According to an embodiment, the first switching unit is integrated into the first output protection unit. Such embodiment leads to a particular reduction in complexity, as switches of the output protection unit which determine the switching status (’’Upstream fault” / ”Downstream fault’VOFF) of the output protection unit are part of the first switching unit. Accordingly, the switches of the output protection unit realize two functions, namely, first, shutting off power to the first power bus in case of a downstream fault (such as a short-circuit) on the first power bus or first electric drive by interrupting the connection to the first power bus or by shutting down the first energy supply system in case of an upstream fault (such as a short-circuit) in the first energy supply system by disconnection of the first energy supply system and, second, participating in the first switching unit for directing power to or from (when the energy is made available by the other switching unit) the switching unit of another, second energy supply system. However, in other embodiments, the first switching unit is a separate part from the first output protection unit. Such separate part may be a bus sharing unit located downstream of the first energy supply system in the first power bus, wherein the first switching unit is configured to receive controls signals indicating if the first output protection unit is switched to “upstream fault”, “downstream fault” or off. Accordingly, also in this embodiment directing power from the first switching unit to the second switching unit or from the second switching unit to the first switching unit (when it is made available by the second switching unit) is triggered by the status of the first output protection unit and takes place directly between switching units when the first switching unit indicates a fault situation and interrupts of the connection to the first power bus.

[0040] In an embodiment, the first switching unit comprises at least one first switch configured to connect the first input to the first output, and at least one second switch configured to connect the first input to the second output, wherein the first switch is opened and the second switch is closed when the first input protection unit is switched to “downstream fault” condition. Under normal operation, when the first switch is closed, the output of the first switching unit is provided to the first power bus. However, when the first output protection unit is switched to “downstream fault” condition (meaning that, e.g., a fault has occurred on the first power bus or the first electric drive), the first switch is opened and the second switch is closed such that power received from the first energy supply system bus is directed to the second switching unit and can be coupled by the second switching unit to the second power bus.

[0041] It is pointed out that the first switch and the second switch of the first switching unit may be combined into a single multiple switch unit such as a rotary switch, wherein the different positions of the rotary switch correspond to different switching situations.

[0042] When the first output protection unit is switched to “upstream fault” condition (meaning that, e.g., a fault has occurred upstream from the first switching unit), the first switch is opened. Further, the first switching unit further comprises at least one third switch (that implements the second input of the first switching unit), wherein the third switch is configured to receive power from another (such as the second) energy source and respective switching unit and to couple the power into the first power bus. Such third switch is closed in case of an “upstream fault” condition such that, when made available, power received from the second energy supply system bus is directed to the second switching unit and, when the energy is required, is made available and can be coupled by the second switching unit to the first power bus.

[0043] In a similar manner, it may be provided that the second switching unit comprises at least one third switch configured to connect the second input to the first output, wherein the third switch is closed when the first output protection unit is switched to “downstream fault” condition. Under normal operation, when the second switch of the second switching unit is opened, the second switching unit does not receive any power through its second input from the first switching unit. However, when the first output protection unit is switched to “downstream fault” condition (meaning that, e.g., a fault has occurred on the first power bus or first electrical drive) such that the second switching unit receives power from the first switching unit through its second input, the third switch is closed such that the second switching unit can receive power from the first switching unit and couple the received power into the second power bus.

[0044] It is pointed out that the second switching unit may further comprise a first switch configured to connect the first input to the first output to provide power of the second energy supply system from the first input to the first output under normal operation. If the third switch is switched on, such first switch may be switched off (such that the power from the first energy source replaces the power from the second energy source) or if the voltages of both energy supply systems are equal may be kept switched on (such that both power of the first energy source and power of the second energy source are inserted on the second power bus).

[0045] In a further embodiment, the first switching unit further comprises a second input configured to receive power from another switching unit and to couple the power from the other switching unit into the first power bus. According to this embodiment, the option is provided that the first switching unit (besides providing power to the second switching unit) is also able to receive power from another switching unit (which may be the second switching unit). It may be provided that all switching units are implemented in the same manner, wherein each switching unit can both divert power to another switching unit and receive power from the energy supply of other switching unit for load sharing.

[0046] In an embodiment, to implement such second input, it may be provided that the first switching unit comprises a first first switch and a second first switch configured to connect the input to the output, the two first switches arranged in series; wherein the at least one second switch that connects the first input to the second output is switched on when the first first switch is switched off; and the first switching unit further comprising at least one third switch, wherein the third switch is configured to receive power from another switching unit and to couple power into the first power bus, wherein the third switch is switched on when the second first switch is switched off.

[0047] Accordingly, in such embodiment, two switches are arranged in series between the input and the output of the first switching unit, the two switches being termed first first switch and second first switch. The provision of two switches increases the safety of the output protection unit as the current is interrupted with two switches in case of a problem. Each of the switches can be rated at 14 the supply voltage. Further, the provision of two switches between the input and the output of the first switching unit raises the possibility to use one of the two switches to control output of power to a second switching unit and use the other of the two switches to control input of power of another (such as the second) switching unit. Accordingly, the at least one second switch is switched on when the first first switch is switched off such that power received from the first energy source is directed to the second switching unit. At the same time, the first switching unit may further comprise at least one third switch, wherein the third switch is configured to receive power from another energy source and respective switching unit and to couple the power into the first power bus, wherein the third switch is switched on when the second first switch is switched off. Alternatively, the third switch may be configured to receive power from another switching unit even if the second first switch remains switched on.

[0048] According to an embodiment, the first and second power buses are grounded DC systems which each comprise a high voltage rail, wherein the second output of the first switching unit is a high voltage output and the second input of the second switching unit is a high voltage input, wherein the second output of the first switching unit and the second input of the second switching unit are connected through a single power line.

[0049] Alternatively, it may be provided that the first and second power buses are ungrounded DC systems which each comprise two high voltage rails, wherein the second output of the first switching unit comprises two high voltage outputs and the second input of the second switching unit comprises two high voltage inputs, wherein the second outputs of the first switching unit and the second inputs of the second switching unit are connected through two power lines for high voltage. In this respect, it is to be noted that all inputs and outputs have to be of the same type (e.g., two high voltage rails or one high voltage rail and ground).

[0050] In a further embodiment, the second output of the first switching unit (both in a grounded system and in an ungrounded system) may comprise a plurality of outputs, each output associated with a different second switch (there can be several second switches). This allows to direct the power of the first energy supply system to different other switching units depending on the chosen second switch and corresponding output of the first switching unit.

[0051] The first switching unit and / or the second switching unit may be implemented with an SSPC. SSPCs (Solid State Power Controllers, also referred to a Solid State Protection Controllers) show a fast response time, eliminate arcing during turn-off, and have a high reliability, however, alternatively, the first switching unit and / or the second switching unit may comprise a contactor which provides for an improved galvanic separation. A third alternative can be a contactor in parallel with an SSPC. These hybrid elements can open the contactor first and then the SSPC to avoid sparking / arcing during contact opening.

[0052] 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.

[0053] 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. Brief description of the drawings

[0054] The invention will be explained in more detail on the basis of exemplary embodiments with reference to the accompanying drawings in which:

[0055] FIG. 1 is an example architecture of an input protection unit for an electric drive in a grounded system, wherein a first integrated switching unit configured to output power to another switching unit is integrated into the input protection unit;

[0056] FIG. 2 is an example architecture of an input protection unit for an electric drive in an isolated ground system, wherein a first integrated switching unit configured to output power to another switching unit is integrated into the input protection unit;

[0057] FIG. 3 is an example architecture of an input protection unit for an electric drive in a grounded system, wherein a second integrated switching unit configured to input power from another switching unit is integrated into the input protection unit;

[0058] FIG. 4 is an example architecture of an input protection unit for an electric drive in an isolated ground system, wherein a second integrated switching unit configured to input power from another switching unit is integrated into the input protection unit;

[0059] FIGS. 5 and 6 are abbreviated depictions of the input protection unit of FIG. 2;

[0060] FIGS. 7 and 8 are abbreviated depictions of an input protection unit similar to that of FIG. 2 but with a reduced amount of outputs to another switching unit;

[0061] FIG. 9 is an abbreviated depiction of an input protection unit similar to that of FIG. 1 with a single output to another switching device;

[0062] FIG. 10 is an example power distribution system comprising several energy supply systems and two electric drives, wherein the electric drives are implemented in accordance with FIGS. 2 and 4 and configured for load sharing;

[0063] FIG. 11 is a further example power distribution system comprising several energy supply systems and several electric drives, wherein the electric drives are implemented in accordance with FIGS.

[0064] 2 and 4 and configured for load sharing;

[0065] FIG. 12 is a further example power distribution system comprising two energy supply systems and two electric drives, wherein the electric drives are implemented in accordance with FIG. 7 and configured for load sharing;

[0066] FIG. 13 is a further example power distribution system comprising several energy supply systems and several electric drives, wherein the electric drives are implemented in accordance with FIG. 7 and configured for load sharing; FIG. 14 is a further example power distribution system comprising two energy supply systems and two electric drives, wherein the electric drives are implemented in accordance with FIG. 9 and configured for load sharing;

[0067] FIG. 15 is a further example power distribution system comprising several energy supply systems and several electric drives, wherein the electric drives are implemented in accordance with FIG. 9 and configured for load sharing;

[0068] FIG. 16 is an example power distribution system comprising several energy supply systems and two electric drives, wherein two switching units configured to output power to another switching unit and associated with the respective drives are implemented in bus sharing units;

[0069] FIG. 17 shows one of the bus sharing units of FIG. 16 with more detail;

[0070] FIG. 18 is an alternative embodiment of the input protection unit of FIG. 1 ;

[0071] FIG. 19 is an alternative embodiment of the input protection unit of FIG. 2;

[0072] FIG. 20 is an example architecture of an output protection unit for an energy supply system in a grounded system, wherein a first integrated switching unit configured to output power to another switching unit is integrated into the output protection unit;

[0073] FIG. 21 is an example architecture of an output protection unit for an energy supply system in an isolated ground system, wherein a first integrated switching unit configured to output power to another switching unit is integrated into the output protection unit;

[0074] FIG. 22 is an example architecture of an output protection unit for an energy supply system in a grounded system, wherein a second integrated switching unit configured to input power from another switching unit is integrated into the output protection unit;

[0075] FIG. 23 is an example architecture of an output protection unit for an energy supply system in an isolated ground system, wherein a second integrated switching unit configured to input power from another switching unit is integrated into the output protection unit;

[0076] FIGS. 24 and 25 are abbreviated depictions of the output protection unit of FIG. 21 ;

[0077] FIGS. 26 and 27 are abbreviated depictions of an output protection unit similar to that of FIG. 21 but with a reduced amount of outputs to another switching unit;

[0078] FIG. 28 is an abbreviated depiction of an output protection unit similar to that of FIG. 20 with a single output to another switching device;

[0079] FIG. 29 is an example power distribution system comprising several energy supply systems and two electric drives, wherein the energy supply systems are implemented in accordance with FIGS. 21 and 23 and configured for load sharing; FIG. 30 is a further example power distribution system comprising several energy supply systems and several electric drives, wherein the energy supply systems are implemented in accordance with FIGS. 21 and 23 and configured for load sharing;

[0080] FIG. 31 is a further example power distribution system comprising two energy supply systems and two electric drives, wherein the energy supply systems are implemented in accordance with FIG. 26 and configured for load sharing;

[0081] FIG. 32 is a further example power distribution system comprising several energy supply systems and several electric drives, wherein the energy supply system are implemented in accordance with FIG. 26 and configured for load sharing;

[0082] FIG. 33 is a further example power distribution system comprising two energy supply systems and two electric drives, wherein the energy supply systems are implemented in accordance with FIG. 28 and configured for load sharing;

[0083] FIG. 34 is a further example power distribution system comprising several energy supply systems and several electric drives, wherein the energy supply system are implemented in accordance with FIG. 28 and configured for load sharing;

[0084] FIG. 35 is an example power distribution system comprising several energy supply systems and two electric drives, wherein two switching units configured to output power to another switching unit and associated with the respective energy supply systems are implemented in bus sharing units;

[0085] FIG. 36 shows one of the bus sharing units of FIG. 35 with more detail;

[0086] FIG. 37 is an alternative embodiment of the output protection unit of FIG. 20;

[0087] FIG. 38 is an alternative embodiment of the output protection unit of FIG. 21 ;

[0088] FIG. 39 is a power distribution system not in accordance with the present disclosure, the power distribution system regarding a grounded system comprising two energy supply systems and two electric drives connected by two interconnected power buses;

[0089] FIG. 40 is a power distribution system not in accordance with the present invention, the power distribution system regarding an isolated ground system comprising two energy supply systems and two electric drives connected by two interconnected power buses;

[0090] FIG. 41 shows an energy supply system with an associated output protection unit in a schematic manner;

[0091] FIG. 42 shows the energy supply system and the associated output protection unit of FIG. 41 with more detail; FIG. 43 shows an electric drive with an associated input protection unit in a schematic manner; and

[0092] FIG. 44 shows the electric drive and associated input protection unit of FIG. 43 with more detail.

[0093] Detailed description

[0094] Aspects and embodiments of the present disclosure will now be discussed with reference to the drawings. Further aspects and embodiments will be apparent to those skilled in the art.

[0095] With increased penetration of electrical systems and the progression towards full electric and hybrid propulsion systems, the use of energy storage system power distribution has gained increased use.

[0096] The background of the present disclosure is initially discussed with respect to FIGS. 39 to 44. FIGS. 39 to 44 do not regard embodiments of the present disclosure but are helpful to understand the background of the present disclosure.

[0097] FIG. 39 shows schematically a power distribution system in which two energy supply systems 11 , 12 and two electric drives 21 , 22 are connected through a power network that comprises a first power bus 41 and a second power bus 42, wherein the first energy supply system 11 is connected to the first electric drive 21 by the first power bus 41 and the second energy supply system 12 is connected to the second electric drive 22 by the second power bus 42. Such system may be used in hybrid propulsion system applications.

[0098] The energy supply systems 11 , 12 can be provided by a plurality of different energy sources. For example, the energy supply systems 11 may comprise a battery, a fuel cell, or a combination thereof, or may be fed from a turbo generator / active rectifier. The energy supply system 11 , 12 may be associated with an energy supply management system such as a battery management system. The energy supply system 11 , 12 may in embodiments also include a DC / DC converter to provide for a constant output voltage or a DC / AC converter in case of an AC power bus.

[0099] The electric drives 21 , 22 may comprise a prime mover such as an electric motor and further components that deliver mechanical power from the prime mover to driven components such as a rotor or propeller. The electric drives 21 , 22 may also include a power converter such as a three- phase inverter providing three-phase AC current to an electric motor. Accordingly, the depiction of the energy supply systems 11 , 12 and of the electric drives 21 , 22 in FIG. 39 and throughout all of the description is of schematic nature and on an abstract level. This applies to the grounded system in FIGS. 38 and 39, but also to the isolated ground system in FIGS. 40 and 41 .

[0100] In the embodiment of FIG. 39, the power distribution system is a grounded system, wherein the first power bus 41 includes a high voltage rail 411 with a positive voltage V1+ and a common ground voltage rail 412 and the second power bus 42 includes a high voltage rail 421 with a positive voltage V2+ and a common ground voltage rail 422.

[0101] Further, in the embodiment of FIG. 39, the first and second power buses 41 , 42 are interconnected by means of a switching network which comprises switches 90. The switching network allows to transfer energy from an energy supply system 11 , 12 to another of the power buses 41 , 42. For example, if the first electric drive 21 fails, the energy of the first energy supply system 1 1 can be transferred to the second power bus 42 and further to the second electric drive 22. The system may be extended by adding further energy supply systems, further electric drives, and / or further power buses and by also extending the switching network. Such switching networks, however, add to the complexity of the power network as they require a plurality of interconnections and associated cables to couple the different lanes.

[0102] FIG. 40 shows the same power distribution system as FIG. 39 except that the system comprises an isolated ground system in which the first power bus 41 includes a high voltage rail 411 with a voltage V1 + and a high voltage rail 413 with a (negative or near zero) voltage V1-, and in which the second power bus 42 includes a high voltage rail 421 with a positive voltage V2+ and a high voltage rail 423 with a (negative or near zero) voltage V2-. Typically, voltages V1 + and V2+ are a positive high voltage of the same value and voltages V1- and V2- are negative high voltages of the same value and equal to V1 + and V2+ but of opposite sign. V1 + and V2+ and V1- and V2- should be of similar value each to permit the switching between networks. However, V1- and V2- may also be at a voltage near 0V even if as part of a high voltage supply. Both supplies are isolated to ground. The switching network comprises switches 60 both for the high voltage rails 411 , 421 and the high voltage rails 413, 423.

[0103] The first energy supply system 11 and the second energy supply system 12 each comprise an associated first output protection unit and second output protection unit. This is illustrated schematically in FIG. 41 , which depicts the first energy supply system 11 and an associated first output protection 61 . The output protection unit 61 is integrated into the first energy supply system 11 . The output of the output protection unit 61 is to the first power bus 41 (which has in the depicted embodiment high voltage rails 411 and 413).

[0104] The output protection unit 61 is further illustrated in FIG. 42. According to FIG. 42, the output protection unit 61 comprises a protection controller 610 which provides control signals S to a first switch SW1v+ and a second switch SW2v+ on the high voltage rail 411 and to a first switch SW1 v- and a second switch SW2v- on the high voltage rail 413. Whenever the protection controller 610 detects a fault condition or receives control signals from another controller that indicate a fault condition, such as a short-circuit on the first power bus, it switches off switches SW1v+, SW2v+, SW1 v- and SW2v-, thereby disconnecting the connection to the first power bus 41 . The protection controller 610 may receive input signals from sensors and / or other controllers. The provision of two switches SW1 v+, SW2v+ in series on the high voltage rail 411 and of two switches SW1v- , SW2v- on the high voltage rail 413 increases the safety of the system and allows to implement higher voltages on the power buses.

[0105] In a similar manner, the second energy supply system 12 comprises a second output protection unit. Also, any further energy supply systems included in the power distribution system comprise an output protection unit.

[0106] Similar as with the output protection, the electric drives 21 , 22 of the power distribution system of FIGS. 39 and 40 comprise an input protection unit. This is illustrated schematically in FIG. 43, which depicts the first electric drive 21 and an associated first input protection 31 . The input protection unit 31 is integrated into the first electric drive 21 . The input of the input protection unit 31 is from the first power bus 41 (which has in the depicted embodiment a high voltage rail 411 and a high voltage rail 413).

[0107] The input protection unit 31 is further illustrated in FIG. 44. According to FIG. 44, the input protection unit 31 comprises a protection controller 310 which provides control signals S to a first switch SW1v+ and a second switch SW2v+ on the high voltage rail 411 and to a first switch SW1 v- and a second switch SW2v- on the high voltage rail 413. Whenever the protection controller 310 detects a fault condition or receives control signals from another controller that indicate a fault condition, such as a failure in the first electric drive, it switches off switches SW1v+, SW2v+, SW1v- and SW2v-, thereby disconnecting the connection between the first power bus 41 and the first electric drive 21 . The protection controller 310 may receive input signals from sensors and / or other controllers.

[0108] The provision of two switches SW1 v+, SW2v+ in series on the high voltage rail 411 and of two switches SW1v-, SW2v- on the high voltage rail 413 increases the safety of the system and allows to implement higher voltages on the power buses.

[0109] In a similar manner, the second electric drive 22 also comprises an input protection unit. Also, any further electric drives included in the power distribution system comprise a corresponding input protection unit.

[0110] In the following, embodiments of power distribution systems in accordance with the present disclosure are described with respect to FIGS. 1 to 38, wherein the function of the input protection unit and / or of the output protection unit of FIGS. 42 and 44 is enhanced by a switching unit which allows to transfer energy to the switching unit of another input / output protection unit. The above discussed implementations regarding the energy supply systems 11 , 12, the electric drives 21 , 22 and the power buses 31 , 32 similarly applies to the embodiments of FIGS. 1 to 38. However, it is pointed out that not necessarily both the energy supply system contains an output protection unit and the electrical drive contains an input protection unit. It is also possible that only the energy supply system or the electrical drive contains a protection and not the other unit. FIG. 1 shows an enhanced input protection unit 31 providing input protection for an electric drive 21 in a power distribution system such as the power distribution system shown in FIG. 39. The enhanced input protection unit 31 comprises a protection controller 310 providing control signals to a first switching unit 51 which comprises a plurality of switches as discussed below. In the depicted embodiment, the first switching unit 51 is integrated into the first input protection unit 31 , for which reason the respective functional block is indicated both by reference numerals 31 and 51 . Alternatively, as will be discussed with respect to FIGS. 16 and 17, the first switching unit 51 may be a separate unit located in the first power bus.

[0111] The system is a grounded system, wherein a power bus 41 at the input of the switching unit 51 includes a high voltage rail 411 with a positive voltage V+ and a common ground voltage rail 412 having a ground potential GND.

[0112] The first switching unit 51 comprises a first input 511 which is from the high voltage rail 411 of the first power bus. The first switching unit 51 also comprises a first output 512 which is the output to the first electric drive 21 . The first switching unit 51 further comprises a second output 513 which is to the switching unit of another input protection unit as will be discussed with respect to FIG. 3. In the depicted embodiment, but not necessarily, the second output 513 comprises two outputs, namely, a first second output 513x and a second second output 513a, as will be explained below.

[0113] The first switching unit 51 comprises a plurality of switches in the high voltage rail 411 as follows. There are provided two switches SW1v, SW2v which are arranged in series and which are configured to couple the first input 511 to the first output 512 under normal operation, i.e. , when there is no fault condition. Switches SW1v and SW2v are in the following also referred to as first first switch SW1v and second first switch SW2v.

[0114] There are further provided two second switches SWIvsa, SWIvsx arranged in parallel to first first switch SW1v and two third switches SW2vsa, SW2vsx arranged in parallel to second first switch SW2v. Second switch SWIvsa is connected to output line 513a and second switch SWIvsx is connected to output line 513x.

[0115] Under normal operation, switches SW1 v and SW2v are closed such that the first input 511 is coupled to the first output 512. In case of a fault condition, when the first input protection unit 31 gets switched on, the protection controller 310 provides control signals S to open switches SW1v, SW2v. At the same time, when the energy of the first electric drive needs to be transferred to a second electric drive (i.e. when the energy source of the second electric drive has been depleted), the protection controller 310 provides control signals S to the effect that one of switches SWIvsa, SWI sx is closed, wherein the first input 511 is coupled to the second output 513, namely, either to output 513a if switch SWIvsa is closed or to output 513x if switch SWIvsx is closed. Accordingly, the voltage V+in present on high voltage line 411 at input 511 is transferred to the output 513a, 513x as voltage Vsx, Vsa. In other embodiments, there may be provided more than two second switches SWIvsa, SWIvsx and corresponding output lines 513a, 513x. The depicted number of two such elements is to be understood as an example only.

[0116] By providing several switches SWIvsa, SWIvsx and corresponding output lines 513a, 513x it is possible to output a voltage on a particular one of the output lines 513a, 513x which may be connected to a particular other switching unit which is configured to provide the voltage to a desired electric drive. Thereby, provision of the energy to several partial drives may be implemented. However, this is to be understood as an example only.

[0117] The voltage on the second output 513a, 513x of switching unit 51 is put on a voltage rail A1a, A1x, and, through that voltage rail, is provided to a second switching unit which is depicted in FIG. 3. FIG. 3 depicts a second input protection unit 32 with an integrated second switching unit 52 for input protection of a second electric drive 22. The second input protection unit 32 with integrated second switching unit 52 is implemented in exactly the same manner as the first input protection unit 31 with integrated first switching unit 51 of FIG. 1 , such that reference to FIG. 1 is made as to the components of the second input protection unit 32. In particular, the second switching unit 52 also comprises two first switches SW1v, SW2v (to couple a first input 521 from a high voltage rail 421 of the second power bus to a first output 522), two second switches SWIvsa, SWIvsx arranged in parallel to first first switch SW1v and two third switches SW2vsa, SW2vsx arranged in parallel to second first switch SW2v.

[0118] However, in the following, a different function of the second input protection unit 32 and second switching unit 52 is considered, namely, the coupling in of power from another switching unit, namely, from the switching unit 51 of FIG. 1 . As long as power is supplied on the first high voltage input rail 421 and as long as there is no fault in the second electric drive 22 there is no need to change the power distribution with the switches as described below. Only when the energy source suppling the first high input rail 421 has been depleted there is an interest to couple the power from first switching unit 51 to the second switching unit 52. More particularly, the second switching unit 52 receives through voltage rail A1a, A1x the voltage V+ present on the first voltage rail 41 of FIG. 1 (as indicated by the arrows). The voltage is received through a second input 524 of second switching unit 52, which connects to the third switches SW2vsa, SW2vsx. The second input 524 is thus connected to the first switching unit 51 of FIG. 1 and receives power from that input.

[0119] Again, in the depicted embodiment, but not necessarily, the second input 524 comprises two inputs, namely, a first second input 524x and a second second input 524a.

[0120] Under normal operation, i.e., when there is no fault condition, the first switches SW1v, SW2v are closed, thereby coupling the first input 521 to the first output 522 such that the voltage of the high voltage rail 421 of the second power bus is coupled to the first output 522. However, if there is a fault condition in the first input protection unit 31 of FIG. 1 and when the energy of the first electric drive 21 needs to be transferred to the second electric drive 22 (i.e. when the energy source of the second electric drive 22 has been depleted), the protection controller 320 provides control signals S to open the first switches SW1v, SW2v. In this respect, it is pointed out that in the context presently considered the relevant question is if there is a fault condition in the first input protection unit 31 , as in that case energy is provided from the first switching unit 51 to the second switching unit 52. Accordingly, the protection controller 320 may receive corresponding control signals from protection controller 310 of the first input protection unit 31 or a supervising controller.

[0121] If there is a fault condition in the first input protection unit 31 of FIG. 1 and when the energy of the first electric drive 21 needs to be transferred to the second electric drive 22 (i.e. when the energy source of the second electric drive 22 has been depleted), protection controller 320 further provides control signals S to the effect that one of switches SW2vsa, SW2vsx is closed, wherein the voltage V+ present on the first voltage rail 411 of FIG. 1 and provided through voltage rail A1 a, A1x and second input 524a, 524x is coupled onto the first output 522 and to the second electric drive 22, wherein second input 524a is coupled in if switch SW2vsa is closed and second input 524x is coupled in if switch SW2vsx is closed.

[0122] Accordingly, in case of a fault condition in the first input protection unit 31 of FIG. 1 which makes it impossible to transmit energy from the first power bus 41 to the first electric drive 21 , the power from the first power bus 41 can be transferred to the second electric drive 22, wherein such transfer is directly from the first switching unit 51 of the first input protection unit 31 of FIG. 1 to the second switching unit 52 of the second input protection unit 52 of FIG. 3.

[0123] As the first switching unit 51 and the second switching unit 52 are identical, each of the switching units 51 , 52 can be used both for coupling energy out and coupling energy in.

[0124] Referring again to FIG. 1 , accordingly, the second output 513 of the first switching unit 51 represents at the same time a second input 514 configured to receive power from another switching unit, such as the switching unit 52 of FIG. 3, for coupling in power from the other switching unit 52 for providing it to the first electric drive 21 . In such case, one of the third switches SW2vsa, SW2vsx is closed similarly as discussed with respect to FIG. 3. The third switch SW2vsa, SW2vsx is closed particularly if the second first switch SW2v is opened.

[0125] FIG. 2 shows the same input protection unit 31 as FIG. 1 except that the input protection unit 31 is for an isolated ground system in which the first power bus 41 includes a high voltage rail 41 1 with a positive voltage V+ and a high voltage rail 413 with a (negative or near zero) voltage V-.

[0126] Accordingly, the input 511 of the first switching unit 51 comprises a high voltage first input 511-1 and a high voltage first input 511-2. Also, there is a high-voltage first output 512-1 and a high voltage first output 512-2. Further, the second output 513 comprises a high-voltage second output 513-1 and a high voltage second output 513-2, wherein the second outputs are also second inputs

[0127] 514-1 , 514-2 as a discussed above.

[0128] Also, in case of an isolated ground system, the switching unit comprises switches for both high voltage rails 411 , 413. Accordingly, first switches SW1v+, SW2v+, second switches SW1vsa+, SW1vsx+, and third switches SW2vsa+, SW2vsx+ are provided for the voltage rail 411 and first switches SW1v-, SW2v-, second switches SWIvsa-, SWIvsx-, and third switches SW2vsa-, SW2vsx- are provided for the voltage rail 413. However, the function is the same as discussed with respect to FIG. 1 for the high voltage rail 41 1 .

[0129] Similarly, FIG. 4 shows the same input protection unit 32 as FIG. 3 except that the input protection unit 32 is for an isolated ground system in which the second power bus includes a high voltage rail 421 with a positive voltage V+ and a high voltage rail 423 with a (negative or near zero) voltage V-. In FIG. 4, the first input 521 of the second switching unit 52 comprises a high voltage first input 521-1 and a high voltage first input 521-2. Also, there is a high-voltage first output 522-1 and a high voltage first output 522-2. Further, the second input 524 comprises a high-voltage second input 524-1 and a high voltage second input 524-2.

[0130] FIG. 18 is a variant of the embodiment of FIG. 1 and FIG. 19 is a variant of the embodiment of FIG. 2, wherein, compared to FIGS. 1 and 2, a rotary switch, namely, rotary switch SW1 in FIG. 18 and rotary switches SW1 + , SW1- in FIG. 19 are implemented to replace switches SW1v, SWIvsa, SWIvsx in FIG. 1 and switches SW1v+, SW1vsa+, SW1vsx+, SW1v-, SWIvsa-, SWIvsx- in FIG. 2. This provides for a simplified switch architecture as less switches are needed. In the same manner, rotary switches may be implemented in the input protection units of FIGS. 3 and 4.

[0131] In the depicted embodiments, the first switching unit and the second switching unit may be implemented as SSPCs, wherein the individual switches are semiconductor switches such as MOSFET, IGBT, JFET, or GaN transistors. Alternatively, some or all of the switches may be implemented with contactors.

[0132] Having discussed embodiments of the main building blocks of a power distribution system with enhanced input protection with reference to FIGS. 1 to 4, 18 and 19, some example configurations of a power distribution system with such input protection systems will be discussed next. As the detailed depiction of the enhanced input protection units in FIGS. 1 to 4, 18 and 19 is inconvenient in a system overview, simplified / abbreviated depictions are introduced. FIGS. 5 and 6 show abbreviated depictions of the input protection unit of FIG. 2, wherein in FIG. 5 only the second outputs 513-1 a, 513-1x, 513-2a, 513-2x of the first input protection and switching unit 31 , 51 are depicted (correctly pointing to the left hand side), and wherein in FIG. 6 only the second outputs 513-1 a, 513-1x, 513-2a, 513-2x are shown as well but pointing to the right hand side, and wherein the first output protection and switching unit is not shown anymore in addition to the first electric drive 21 , in order to further abbreviate the depiction. FIGS. 7 and 8 show similar abbreviated depictions of an input protection unit as FIGS. 5 and 6, but with a reduced amount of second outputs. As can be seen in FIG. 7, there are provided two second outputs 513-1 , 513-2 only for voltages VS+ and VS-. This is the case if a simplified switching unit is provided which differs from the switching unit of FIG. 2 in that only one second switch SW1vs+ on the positive voltage side and one second switch SW1vs- on the negative voltage side and the corresponding second outputs 513-1 , 513-2 are provided. FIG. 8 is a further abbreviated depiction of FIG. 7 which is similar to FIG. 6.

[0133] FIG. 9 is an abbreviated depiction that corresponds to FIG. 8 in case of a grounded system with only a high side voltage Vs, which corresponds to a switching unit as shown in FIG. 1 with a single second switch SW1vs and a single second output 513.

[0134] FIG. 10 shows an embodiment of a power distribution system which comprises two energy supply systems 11-1 , 1 1-2 connected through a first power bus 41 to a first electric drive 21 , and which comprises two further energy supply systems 12-1 , 12-2 connected through a second power bus 42 to a second electric drive 22, wherein the electric drives 21 , 22 are enhanced electric drives as indicated by a depiction that corresponds to that of FIG. 6.

[0135] The first power bus 41 is a shared power bus for the energy supply system 11-1 , 11-2, wherein the respective positive high voltage rails and negative high voltage rails are interconnected. Similarly, the second power bus 42 is a shared power bus for the energy supply system 12-1 , 12-2, wherein the respective positive high voltage rails and negative high voltage rails are interconnected. The power distribution system provides for redundancy in that, if one of the energy supply systems 11-

[0136] 1 , 11 -2 or 12-1 , 12-2 fails, the energy supply for the first and second electric drives 21 , 22 is secured by the respective other energy supply system. Further, by connecting the switching units of the first and second electric drives 21 , 22 as discussed with respect to FIGS. 1 to 4, it is possible to couple the power received at an electric drive 21 , 22 through the respective switching units to the respective other electric drive 22, 21 in case the respective input protection unit is activated (switched on).

[0137] FIG. 11 shows an embodiment of a power distribution system which comprises two energy supply systems 11-1 , 1 1-2 connected through a first shared power bus 41 to two electric drives 21-1 , 21-

[0138] 2, and which comprises two further energy supply systems 12-1 , 12-2 connected through a second shared power bus 42 to two electric drives 22-1 , 22-2, wherein the electric drives 21-1 , 21-2, 22-1 , 22-2 are enhanced electric drives as indicated by a depiction that corresponds to that of FIG. 6. Accordingly, redundancy is provided for at the energy supply system side as, if one of the energy supply system 11-1 , 11-2 or 12-1 , 12-2 fails, the energy supply for the electric drives is secured by the respective other energy supply system. Further, through their respective switching units, the electric drives 12-1 , 12-2, 22-1 , 22-2 are able to couple the received power to another of the electric drives if the respective input protection unit is activated. In this respect, it is pointed out that each electric drive may couple its power to any of the other electric drives. FIG. 12 shows an embodiment of a power distribution system having only two energy supply systems 11 , 12 and two electric drives 21 , 22, wherein the electric drives 21 , 22 are enhanced electric drives as indicated by a depiction that corresponds to that of FIG. 8. While there is no redundancy on the energy supply side, the electric drives 21 , 22 are able to couple the received power to the respective other electric drives 22, 21 if the respective input protection unit is activated.

[0139] FIG. 13 is an embodiment of a power distribution system which is similar to the embodiment of FIG. 11 , except that electric drives with an enhanced input protection in accordance with FIG. 8 are provided for (two second outputs 513-1 , 513-2 for voltages VS+ and VS- only).

[0140] FIG. 14 is an embodiment of a grounded power distribution system which is similar to the embodiment of FIG. 12, except that electric drives with an enhanced input protection in accordance with FIG. 9 are provided for (one output 513 for voltage VS only as the system is grounded).

[0141] FIG. 15 is an embodiment of a grounded power distribution system which is similar to the embodiment of FIG. 13, except that electric drives with an enhanced input protection in accordance with FIG. 9 are provided for (one output 513 for voltage VS only as the system is grounded).

[0142] FIG. 16 shows an embodiment in which the switching unit is not implemented in the input protection unit, but as a separate part. More particularly, the switching unit is separate from the input protection unit and part of a bus sharing unit located upstream of the electric drive. More particularly, in FIG. 16, a first bus sharing unit 81 is located upstream of the first electric drive 21 and a second bus sharing unit 82 is located upstream of the second electric drive 22.

[0143] As shown in FIG. 17, the bus sharing units (wherein FIG. 17 depicts the first bus sharing unit 81) comprise a switching unit which is similar to the switching unit 51 as discussed with respect to FIG. 2 (or, alternatively, which is similar to the switching unit 51 as discussed with respect to FIG. 1 in a grounded system). Accordingly, the switching unit 51 comprises second outputs 513-1 a, 513-1x, 513-2a, 513-2x for the voltages Vsa+, Vsx+, Vsa-, Vsx-. The coupling in / out of power to another switching unit functions in the same manner as a discussed with respect to FIGS. 1 to 4. However, to provide for the appropriate switching, each switching unit in the bus sharing units 81 , 82 needs to receive control signals which indicate if the input protection unit of an electric drive is activated, as such activation triggers the coupling of energy to another electric drive. Such control signals may be provided from the input protection unit of the respective electric drive (which in case of a separate switching unit is a “simple” input protection unit as discussed with respect to FIGS. 43 and 44) or from a system controller or from the output protection (described below) of the respective energy supply system. FIGS. 1 to 19 regard embodiments in which the input protection unit of an electric drive is enhanced to allow coupling of power to another electric drive, wherein the coupling is provided through switching units associated with or integrated into the input protection units. In a similar manner, power can be shared on the energy supply side of a power distribution system, wherein enhanced output protection units associated with the energy supply systems are provided for, as will be discussed with reference to FIGS. 20 to 38.

[0144] FIG. 20 shows an enhanced output protection unit 61 providing output protection for an energy supply system 11 in a power distribution system such as the power distribution system shown in FIG. 40. The enhanced output protection unit 61 comprises a protection controller 610 providing control signals to a first switching unit 71 which comprises a plurality of switches as discussed below. In the depicted embodiment, the first switching unit 71 is integrated into the first output protection unit 61 , for which reason the respective functional block is indicated both by reference numerals 61 and 71 . Alternatively, as will be discussed with respect to FIGS. 35 and 36, the first switching unit 71 may be a separate unit located in the first power bus.

[0145] The system is a grounded system, wherein a power bus 41 at the output of the switching unit 71 includes a high voltage rail 411 with a positive voltage V and a common ground voltage rail 412 having a ground potential GND.

[0146] The first switching unit 71 comprises a first input 711 which is from the first energy supply system 11 . The first switching unit 71 also comprises a first output 712 which is the output to the first power bus 41 . The first switching unit 71 further comprises a second output 713 which is to the switching unit of another output protection unit as will be discussed with respect to FIG. 22. In the depicted embodiment, but not necessarily, the second output 713 comprises two outputs, namely, a first second output 713x and a second second output 713a, as will be explained below.

[0147] The first switching unit 71 comprises a plurality of switches on the high voltage side as follows. There are provided two switches SWI1v, SWI2v which are arranged in series and which are configured to couple the first input 711 to the first output 712 under normal operation, i.e. , when there is no fault condition. Switches SWI1v and SWI2v are in the following also referred to as first first switch SWI1v and second first switch SWI2v.

[0148] There are further provided two second switches SWUvsa, SWUvsx arranged in parallel to first first switch SWI1v and two third switches SWI2vsa, SWI2vsx arranged in parallel to second first switch SWI2v. Second switch SWUvsa is connected to output line 713a and second switch SWUvsx is connected to output line 713x.

[0149] Under normal operation (wherein there is no fault “upstream” in the first energy supply system 11 and no fault “downstream” in the first power bus 41 or in the first electric drive 21), switches SWI1v and SWI2v are closed such that the first input 711 is coupled to the first output 712. In case of a fault condition “downstream” in the first power bus 41 or in the first electric drive 21 (also referred to as “downstream fault” condition), when the first output protection unit 61 gets switched on, the protection controller 610 provides control signals S to open switches SWI1v, SWI2v. At the same time, in case of a downstream fault, the protection controller 610 provides control signals S to the effect that one of switches SWUvsa, SWUvsx is closed, wherein the first input 711 is coupled to the second output 713, namely, either to output 713a if switch SWU vsa closed or to output 713x if switch SWUvsx is closed. Accordingly, the voltage V+ in of energy supply system 11 present at input 711 is transferred to the output 713a, 713x as voltage Vsa, Vsx.

[0150] In other embodiments, there may be provided more than two second switches SWU vsa, SWU vsx and corresponding output lines 713a, 713x. The depicted number of two such elements is to be understood as an example only.

[0151] By providing several switches SWU vsa, SWUvsx and corresponding output lines 713a, 713x it is possible to output a voltage on a particular one of the output lines 713a, 713x which may be connected to a particular other switching unit which is configured to provide the voltage to a desired power bus and electric drive. Thereby, provision of the energy to several electrical drives may be implemented. However, this is to be understood as an example only.

[0152] The voltage on the second output 713a, 713x of switching unit 71 is put on a voltage rail B1 a, B1x, and, through that voltage rail, is provided to a second switching unit which is depicted in FIG. 22. FIG. 22 depicts a second output protection unit 62 with an integrated second switching unit 72 for output protection of a second energy supply system 12. The second output protection unit 62 with integrated second switching unit 72 is implemented in exactly the same manner as the first output protection unit 61 with integrated first switching unit 71 of FIG. 20, such that reference to FIG. 20 is made as to the components of the second output protection unit 62 in FIG. 22. In particular, the second switching unit 72 also comprises two first switches SWI1v, SWI2v (to couple a first input 721 from energy supply system 12 to a first output 722), two second switches SWU vsa, SWUvsx arranged in parallel to first first switch SWI1v and two third switches SWI2vsa, SWI2vsx arranged in parallel to second first switch SWI2v.

[0153] However, in the following, a different function of the second output protection unit 62 and second switching unit 72 is considered, namely, the coupling in of power from another switching unit, namely, from the switching unit 71 of FIG. 20. More particularly, the second switching unit 72 receives through voltage rail B1 a, B1x the voltage V from the first energy supply system 11 of FIG. 20 (as indicated by the arrows). The voltage is received through a second input 724 of second switching unit 72, which connects to the third switches SWI2vsa, SWI2vsx. The second input 724 is thus connected to the first switching unit 71 of FIG. 20 and receives power from that input when the energy of the first energy supply system 11 needs to be transferred to the second electric drive (i.e. when the first output protection unit 61 has detected a downstream fault and when the energy in the second energy supply system 12 has been depleted or when the second energy supply system 12 has an internal fault). Again, in the depicted embodiment, but not necessarily, the second input 724 comprises two inputs, namely, a first second input 724x and a second second input 724a.

[0154] Under normal operation, i.e., when there is no downstream fault condition, the first switches SWI1 v, SWI2v are closed, thereby coupling the first input 721 to the first output 722 such that the voltage of the first energy supply system 12 is coupled to the first output 722 and into the second power bus 421 .

[0155] However, if there is a fault condition (i.e., a downstream fault condition, downstream from energy supply system 11 , or an upstream fault condition within the energy supply system 12), the protection controller 620 provides control signals S to open the first switches SWI1v, SWI2v. In this respect, it is pointed out that in the context presently considered the relevant question is if there is a downstream fault condition in the first output protection unit 61 , as in that case energy is provided from the first switching unit 71 to the second switching unit 72. If there is an upstream fault condition in the first output protection unit 61 , energy is provided from the second switching unit 72 to the first switching unit 71 , as discussed below. Accordingly, the protection controller 620 may receive corresponding control signals from protection controller 610 of the first output protection unit 61 or a supervising controller.

[0156] If there is a fault condition (downstream from energy supply system 11 or upstream from within energy supply system 12), protection controller 620 further provides control signals S to the effect that one of switches SWI2vsa, SWI2vsx is closed, wherein the voltage V of the first energy supply system 11 of FIG. 20 is coupled through the first switching unit 71 , the voltage rail B1 a, B1x and the second input 724a, 724x onto the first output 722 and to the second power bus 41 , wherein second input 724a is coupled in if switch SWI2vsa is closed and second input 724x is coupled in if switch SWI2vsx is closed.

[0157] Accordingly, in case of a downstream fault condition in the first output protection unit 61 of FIG. 20 which makes it impossible to transmit energy to the first power bus 41 , or in case of an upstream fault condition in the second output protection unit 62, the power from the first energy supply system 11 can be transferred to the second power bus 42, wherein such transfer is directly from the first switching unit 71 of the first output protection unit 61 of FIG. 20 to the second switching unit 72 of the second output protection unit 72 of FIG. 22.

[0158] As the first switching unit 71 and the second switching unit 72 are identical, each of the switching units 71 , 72 can be used both for coupling energy out and coupling energy in. Referring again to FIG. 20, Accordingly, the second output 713 of the first switching unit 71 represents at the same time a second input 714 configured to receive power from another switching unit, such as the switching unit 72 of FIG. 22, for coupling in power from the other switching unit 72 for providing it to the first power bus 41 . In such case, one of the third switches SWI2vsa, SWI2vsx is closed similarly as discussed with respect to FIG. 22. The third switch SWI2vsa, SWI2vsx is closed particularly if the second first switch SWI2v is opened.

[0159] Referring again to FIG. 20, if there is an upstream fault within the energy supply system 11 (also referred to as “upstream fault” condition), switches SWI1v and SWI2v of the first switching unit 71 are opened such that the first input 711 is not coupled to the first output 712 anymore. At the same time, the protection controller 610 provides control signals S that the third switches SWI2VSA and SWI2vsx of the first switching unit 71 are closed such that the second input 714 is coupled to the first output 712. Accordingly, if there is an upstream fault condition in the first output protection unit 61 , energy from the second energy supply system 12 is provided through the second switching unit 72 to the first switching unit 71 .

[0160] FIG. 21 shows the same output protection unit 61 as FIG. 20 except that the output protection unit 61 is for an isolated ground system in which the first power bus includes a high voltage rail 411 with a positive voltage V+ and a high voltage rail 413 with a (negative or near zero) voltage V-.

[0161] Accordingly, the input 711 of the first switching unit 71 from energy supply system 11 comprises a high voltage first input 711-1 and a high voltage first input 711-2. Also, there is a high-voltage first output 712-1 and a high voltage first output 712-2. Further, the second output 713 comprises a high-voltage second output 713-1 and a high voltage second output 713-2, wherein the second outputs are also second inputs 714-1 , 714-2 as a discussed above.

[0162] Also, in case of an isolated ground system, the switching unit comprises switches for the positive voltage rail and switches for the negative voltage rail. Accordingly, first switches SWI1v+, SWI2v+, second switches SWI1vsa+, SWI1vsx+, and third switches SWI2vsa+, SWI2vsx+ are provided for the positive voltage rail and first switches SWI1v-, SWI2v-, second switches SWUvsa-, SWHvsx-, and third switches SWI2vsa-, SWI2vsx- are provided for the negative voltage rail. However, the function is the same as discussed with respect to FIG. 20 for the positive voltage rail.

[0163] Similarly, FIG. 23 shows the same output protection unit 62 as FIG. 22 except that the output protection unit 62 is for an isolated ground system in which the second power bus includes a high voltage rail 421 with a positive voltage V+ and a high voltage rail 423 with a (negative or near zero) voltage V-. In FIG. 23, the first input 721 of the second switching unit 72 comprises a high voltage first input 721-1 and a high voltage first input 721-2. Also, there is a high-voltage first output 722-1 and a high voltage first output 722-2. Further, the second input 724 comprises a high- voltage second input 724-1 and a high voltage second input 724-2.

[0164] FIG. 37 is a variant of the embodiment of FIG. 20 and FIG. 38 is a variant of the embodiment of FIG. 21 , wherein, compared to FIGS. 20 and 21 , a rotary switch, namely, rotary switch SWI2 in FIG. 37 and rotary switches SWI2+, SWI2- in FIG. 38 are implemented to replace switches SWI2v, SWI2vsa, SWI2vsx in FIG. 20 and switches SWI2v+, SWI2Vsa+, SWI2vsx+, SWI2v-, SWI2Vsa-, SWI2vsx- in FIG. 21 . This provides for a simplified switch architecture as less switches are needed. In the same manner, rotary switches may be implemented in the output protection units of FIGS. 22 and

[0165] 23.

[0166] In the depicted embodiments, the first switching unit and the second switching unit may be implemented as SSPCs, wherein the individual switches are semiconductor switches such as MOSFET, IGBT, JFET, or GaN transistors. Alternatively, some or all of the switches may be implemented with contactors.

[0167] Having discussed embodiments of the main building blocks of a power distribution system with enhanced output protection with reference to FIGS. 20 to 23, 37 and 38, some example configurations of a power distribution system with such output protection systems will be discussed next. As the detailed depiction of the enhanced output protection units in FIGS. 20 to 23, 37 and 38 is inconvenient in a system overview, simplified / abbreviated depictions are introduced. FIGS. 24 and 25 show abbreviated depictions of the output protection unit of FIG. 21 , wherein in FIG. 24 only the second outputs 713-1a, 713-1x, 713-2a, 713-2x of the first output protection and switching unit 61 , 71 are depicted (correctly pointing to the right hand side), and wherein in FIG. 25 only the second outputs 713-1 a, 713-1 x, 713-2a, 713-2x are shown as well but pointing to the left hand side, and wherein the first output protection and switching unit is not shown anymore in addition to the first energy supply system 11 , in order to further abbreviate the depiction.

[0168] FIGS. 26 and 27 show similar abbreviated depictions of an input protection unit as FIGS. 24 and 25, but with a reduced amount of second outputs. As can be seen in FIG. 26, there are provided two second outputs 713-1 , 713-2 only for voltages VS+ and VS-. This is the case if a simplified switching unit is provided which differs from the switching unit of FIG. 21 in that only one second switch SWI1vs+ on the positive voltage side and one second switch SWHvs- on the negative voltage side and the corresponding second outputs 713-1 , 713-2 are provided. FIG. 27 is a further abbreviated depiction of FIG. 26 which is similar to FIG. 25.

[0169] FIG. 28 is an abbreviated depiction that corresponds to FIG. 27 in case of a grounded system with only a high side voltage Vs, which corresponds to a switching unit as shown in FIG. 20 with a single second switch SWHvs and a single second output 713.

[0170] FIG. 29 shows an embodiment of a power distribution system which comprises two energy supply systems 11-1 , 11-2 connected through a first power bus 41 to a first electric drive 21 , and which comprises two further energy supply systems 12-1 , 12-2 connected through a second power bus 42 to a second electric drive 22, wherein the energy supply systems 11-1 , 11-2, 12-1 , 12-2 are enhanced energy supply systems as indicated by a depiction that corresponds to that of FIG. 25.

[0171] The first power bus 41 is a shared power bus for the energy supply system 11-1 , 11-2, wherein the respective high voltage rails V1+ and high voltage rails V1- are interconnected. Similarly, the second power bus 42 is a shared power bus for the energy supply system 12-1 , 12-2, wherein the respective high voltage rails V2+ and high voltage rails V2- are interconnected. The power distribution system provides for redundancy in that, if one of the energy supply systems 11-1 , 11-2 or 12-1 , 12-2 fails, the energy supply for the first and second electric drives 21 , 22 is secured by the respective other energy supply system. Further, by connecting the switching units of the output protection units of the energy supply systems 11-1 , 11-2, 12-1 , 12-2 as discussed with respect to FIGS. 20 to 23, it is possible to couple the power of an energy supply system to the switching unit of another energy supply system and further to another power bus and associated electric drive 21 , 22 in case the respective output protection unit is activated (switched on). In this respect, it is pointed out that each energy supply system 11-1 , 11-2, 12-1 , 12-2 may couple its power to any of the other energy supply systems 11-1 , 11-2, 12-1 , 12-2.

[0172] FIG. 30 shows an embodiment of a power distribution system which comprises two energy supply systems 11-1 , 11-2 connected through a first shared power bus 41 to two electric drives 21-1 , 21- 2, and which comprises two further energy supply systems 12-1 , 12-2 connected through a second shared power bus 42 to two electric drives 22-1 , 22-2, wherein the energy supply systems 11-1 , 11-2 or 12-1 , 12-2 are enhanced energy supply system as indicated by a depiction that corresponds to that of FIG. 25. Accordingly, redundancy is provided for at the energy supply system side as, if one of the energy supply system 11-1 , 11 -2 or 12-1 , 12-2 fails, the energy supply for the electric drives is secured by the respective other energy supply system. Further, through their respective switching units, the energy supply systems 11-1 , 11-2 or 12-1 , 12-2 are able to couple their power to the switching unit of another energy supply system if the respective output protection unit is activated.

[0173] FIG. 31 shows an embodiment of a power distribution system having only two energy supply systems 11 , 12 and two electric drives 21 , 22, wherein the energy supply systems 11 , 12 are enhanced energy supply systems as indicated by a depiction that corresponds to that of FIG. 27. The energy supply systems 11 , 12 are able to couple their power to the switching unit of the respective other energy supply system 11 , 12 if the respective output protection unit is activated.

[0174] FIG. 32 is an embodiment of a power distribution system which is similar to the embodiment of FIG. 30, except that energy supply systems with an enhanced output protection in accordance with FIG. 27 are provided for (two second outputs 713-1 , 713-2 for voltages VS+ and VS- only).

[0175] FIG. 33 is an embodiment of a power distribution system which is similar to the embodiment of FIG. 31 , except that energy supply systems with an enhanced output protection in accordance with FIG. 28 are provided for (one output 713 for voltage VS only).

[0176] FIG. 34 is an embodiment of a power distribution system which is similar to the embodiment of FIG. 32, except that energy supply systems with an enhanced output protection in accordance with FIG. 28 are provided for (one output 713 for voltage VS only).

[0177] FIG. 35 shows an embodiment in which the switching unit is not implemented in the output protection unit, but as a separate part. More particularly, the switching unit is separate from the output protection unit and part of a bus sharing unit located downstream of the energy supply system. More particularly, in FIG. 35, bus sharing units 83-1 , 83-2, 83-3 and 83-4 are located downstream of the energy supply systems 11-1 , 11-2, 12-1 , 12-2.

[0178] As shown in FIG. 36, the bus sharing units (wherein FIG. 36 depicts bus sharing unit 83-1) comprise a switching unit which is similar to the switching unit 71 as discussed with respect to FIG. 21 (or, alternatively, which is similar to the switching unit 71 as discussed with respect to FIG. 20 in a grounded system). Accordingly, the switching unit 71 comprises second outputs 713-1 a, 713- 1 x, 713-2a, 713-2x for the voltages Vsa+, Vsx+, Vsa-, Vsx-. The coupling in / out of power to another switching unit functions in the same manner as a discussed with respect to FIGS. 20 to 23. However, to provide for the appropriate switching, each switching unit in the bus sharing units 83-1 , 83-2, 83-3 and 83-4 of FIG. 35 needs to receive control signals which indicate if the output protection unit of an energy supply system is activated, as such activation triggers the coupling of energy to the switching unit of another energy supply system. Such control signals may be provided from the output protection unit of the respective energy supply unit (which in case of a separate switching unit is a “simple” output protection unit as discussed with respect to FIGS. 41 and 42) or from a system controller or from an input protection (described above) of the respective electrical drive.

[0179] 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 power distribution system comprising: a first energy supply system (11) and a second energy supply system (12); a first electric drive (21) and a second electric drive (22), the first electric drive (21) associated with a first input protection unit (31) and the second electric drive (22) associated with a second input protection unit (32); a power network connecting the first and second energy supply systems (11 , 12) with the first and second electric drives (21 , 22), the power network comprising: a first power bus (41) connecting the first energy supply system (11) with the first electric drive (21); a second power bus (42) connecting the second energy supply system (12) with the second electric drive (22); a first switching unit (51) associated with the first electric drive (21); and a second switching unit (52) associated with the second electric drive (22); the first switching unit (51) comprising a first input (51 1) from the first power bus (41), a first output (512) to the first power bus (41) or the first electric drive (21), and a second output (513) to the second switching unit (52); and the second switching unit (52) comprising a first input (521) from the second power bus (42), a first output (522) to the second power bus (42) or the second electric drive (22), and a second input (524) from the first switching unit (51); wherein the first switching unit (51) is configured to couple its first input (511) with its first output (512) when the input protection unit (31) of first electric drive (21) is switched off and configured to couple its first input (511) with its second output (513) when the input protection unit (31) of the first electric drive (21) is switched on; and the second switching unit (52) is configured to couple its second input (524) with its first output (522) to receive through its second input (524) power from the first power bus (41) and to couple the received power into the second power bus (42) or the second electric drive (21).

2. The power distribution system of claim 1 , wherein the first switching unit (51) is integrated into the first input protection unit (31).

3. The power distribution system of claim 1 , wherein the first switching unit (51) is separate from the first input protection unit (31) and part of a bus sharing unit (81 , 82) upstream of the firstelectric drive (21), wherein the first switching unit (51) is configured to receive controls signals indicating if the first input protection unit (31) is switched on or off.

4. The power distribution system of any preceding claim, wherein the first switching unit (51) comprises: at least one first switch (SW1v) configured to connect the first input (511) to the first output (512); and at least one second switch (SWIvsa, SWIvsx) configured to connect the first input (511) to the second output (513); wherein the first switch (SW1v) is configured to be opened and the second switch (SWIvsa, SWIvsx) is configured to be closed when the first input protection unit (31) is switched on.

5. The power distribution system of any preceding claim, wherein the second switching unit (52) comprises: at least one third switch (SW2vsa, SW2vsx) configured to connect the second input (524) to the first output (522), wherein the third switch (SW2vsa, SW2vsx) is configured to be closed when the first input protection unit (31) is switched on.

6. The power distribution system of any preceding claim, wherein the first switching unit (51) further comprises a second input (514) configured to receive power from another switching unit and to couple the power from the other switching unit into the first power bus (41) or the first electric drive (21).

7. The power distribution system of claim 6, when dependant on claim 4 or 5, wherein: the first switching unit (51) comprises a first first switch (SW1v) and a second first switch (SW2v) configured to connect the first input (511) to the first output (512), the two first switches (SWi, SW2) arranged in series; wherein the at least one second switch (SWIvsa, SWIvsx) is configured to be closed when the first first switch (SW1v) is opened; and the first switching unit (51) further comprising at least one third switch (SW2vsa, SW2vsx) associated with the second input (514), wherein the third switch (SW2vsa, SW2vsx) is configured to receive power from another switching unit and to couple the power into the first power bus (41) or the first electric drive (21), wherein the third switch (SW2vsa, SW2vsx) is configured to be closed to couple power into the first power bus (41) or the first electric drive (21) when the second first switch (SW2v) is opened.

8. The power distribution system of any preceding claim, wherein the first and second power buses (41 , 42) are grounded systems which each comprise a high voltage rail (411 , 421), wherein the second output (512) of the first switching unit (51) is a high voltage output and the second input (524) of the second switching unit (52) is a high voltage input, wherein the second output (512) of the first switching unit (51) and the second input (524) of the second switching unit (52) are connected through a power line (A1).

9. The power distribution system of any one of claims 1 to 7, wherein the first and second power buses (41 , 42) are ungrounded systems which each comprise a high voltage rail (V+, 411 , 421) and a further high voltage rail (V-, 413, 423), wherein the second output (512) of the first switching unit (51) comprises a high voltage output (V+, 512-1) and a further high voltage output (V-, 512-2) and the second input (524) of the second switching unit (52) comprises a high voltage input (V+, 524-1) and a further high voltage input (V-, 524-2), wherein the second output (512) of the first switching unit (51) and the second input (524) of the second switching unit (52) are connected through two power lines (A1 , A2) for the high voltages (V+, V-).

10. The power distribution system of any preceding claim, wherein the first switching unit (51) and / or the second switching unit (52) is implemented with an SSPC.11 . The power distribution system of any preceding claim, wherein the first switching unit (51) and / or the second switching unit (52) comprises a contactor.

12. A power distribution system comprising: a first energy supply system (11) and a second energy supply system (12), the first energy system associated with (11) a first output protection unit (61) and the second energy system (12) associated with a second output protection unit (62); a first electric drive (21) and a second electric drive (22); and a power network connecting the first and second energy supply systems (11 , 12) with the first and second electric drives (21 , 22), the power network comprising: a first power bus (41) connecting the first energy supply system (11) with the first electric drive (21); a second power bus (42) connecting the second energy supply system (12) with the second electric drive (22); a first switching unit (71) associated with the first energy supply system (11); and a second switching unit (72) associated with the second energy supply system (12); the first switching unit (71) comprising a first input (71 1) from the first energy supply system (11), a first output (712) to the first power bus (41), and a second output (713) to the second switching unit (72); and the second switching (72) unit comprising a first input (721) from the second energy supply system (12), a first output (722) to the second power bus (42), and a second input (724) from the first switching unit (71);wherein the first switching unit (71) is configured to couple its first input (711) with its first output (712) when the output protection unit (61) of first energy supply system (11) is switched off, and configured to couple its first input (711) with its second output (713) when the output protection unit (61) of the first energy supply system (11) is switched to downstream fault condition; and the second switching unit (72) is configured to couple its second input (724) with its first output (722) to receive through its second input (724) power from the first energy supply system (11) and to couple the received power into the second power bus (42).

13. The power distribution system of claim 12, wherein the first switching (71) unit is integrated into the first output protection unit (61).

14. The power distribution system of claim 12, wherein the first switching unit (71) is separate from the first output protection unit and part of a bus sharing unit (83) downstream of the first energy supply system (11), wherein the first switching unit (71) is configured to receive controls signals indicating if the first output protection unit (61) is switched to downstream fault condition, upstream fault condition, or off.

15. The power distribution system of any one of claims 12 to 14, wherein the first switching unit (71) comprises: at least one first switch (SWI1v) configured to connect the first input (711) to the first output (712), and at least one second switch (SWUvsa, SWUvsx) configured to connect the first input (711) to the second output (713), wherein the first switch (SWI1v) is configured to be opened and the second switch (SWUvsa, SWUvsx) is configured to be closed when the first input protection unit (61) is switched to downstream fault condition.

16. The power distribution system of any one of claims 12 to 15, wherein the second switching unit (72) comprises: at least one third switch (SWI2vsa, SWI2vsx) configured to connect the second input (724) to the first output (722), wherein the third switch (SWI2vsa, SWI2vsx) is configured to be closed when the first input protection unit (61) is switched to downstream fault condition and when power of the first energy supply system (11) shall be coupled into the second power bus (42).

17. The power distribution system of any one of claims 12 to 16, wherein the first switching unit (71) further comprises a second input (714) configured to receive power from another switching unit (72) and to couple the power from the other switching unit (72) into the first power bus (41).

18. The power distribution system of claim 17, wherein the first switching unit (71) is further configured to couple its second input (714) with its first output (712) when the output protection unit (61) of first energy supply system (11) determines an upstream fault in the first energy supply system (11) and is switched to upstream fault condition.

19. The power distribution system of claim 17 or 18, when dependent on claim 15 or 16, wherein: the first switching unit (71) comprises a first first switch (SWI1v) and a second first switch (SWI2v) configured to connect the first input (711) to the first output (712), the two first switches (SWI1v, SWI2v) arranged in series; the at least one second switch (SWUvsa, SWMvsx) is configured to be closed when the first first switch (SWI1v) is opened; and the first switching unit (71) further comprising at least one third switch (SWI2vsa, SWI2vsx), wherein the third switch (SWI2vsa, SWI2vsx) is configured to receive power from another switching unit (12) and to couple the power into the first power bus (41), wherein the third switch (SWI2vsa, SWI2vsx) is configured to be closed when the second first switch (SWI2v) is opened.

20. The power distribution system of claim 19, when dependent on claim 18, wherein the first switching unit (71), if the output protection unit (61) of first energy supply system (11) determines an upstream fault in the first energy supply system (11) and is switched to upstream fault condition, is further configured to open the first switch (SWI1v), and to close the third switch (SWI2vsa, SWI2vsx) to couple the second input (714) with the first output (712).

21. The power distribution system of any one of claims 12 to 20, wherein the first and second power buses (41 , 42) are grounded systems which each comprise a high voltage rail (411 , 421), wherein the second output (713) of the first switching unit (71) is a high voltage output and the second input (724) of the second switching unit (72) is a high voltage input, wherein the second output (713) of the first switching unit (71) and the second input (724) of the second switching unit (72) are connected through a power line (B1).

22. The power distribution system of any one of claims 12 to 20, wherein the first and second power buses (41 , 42) are ungrounded systems which each a high voltage rail (V+, 411 , 421) and a further high voltage rail (V-, 421 , 423), wherein the second output (712) of the first switching unit (71) comprises a high voltage output (V+, 712-1) and a further high voltage output (V-, 712-2) and the second input (724) of the second switching unit (72) comprises a high voltage input (724-1) and a further high voltage output (724-2), wherein the second output (712) of the first switching unit (71) and the second input (724) of the second switching unit (72) are connected through two power lines (B1 , B2) for the high voltages (V+, V-).

23. The power distribution system of any preceding claim, wherein a plurality of energy supply systems (11 , 11-1 , 11-2) and a plurality of electric drives (21 , 21-1 , 21-2) are connected by the first power bus (41) and / or a plurality of energy supply systems (12, 12-1 , 12-2) and a plurality of electric drives (22, 22-1 , 22-2) is connected by the second power bus (42).

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