PROTECTION IN A DIRECT CURRENT HIGH VOLTAGE ELECTRIC SYSTEM

An electrical arrangement for protection in a direct current high voltage electric system comprises an input connection with an input terminal, an output connection with a output terminal, a main disconnection component between the input terminal and the output terminal and at least one clamping circuit between the input terminal and the output terminal. The clamping circuit has a first connecting path and a second connecting path, arranged in parallel to each other. The first connection path comprises a storage coupling for temporarily buffering an overvoltage present between the input terminal and the output terminal. The first connection path also comprises an activatable switch for selectably connecting the storage coupling with the output terminal. The second connection path comprises a supply coupling for operating the activatable switch in dependency of the overvoltage.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of European Patent Application Number 23170425.5 filed on Apr. 27, 2023, the entire disclosure of which is incorporated herein by way of reference.

FIELD OF THE INVENTION

The present invention relates to an electrical arrangement for protection in a direct current high voltage electric system, to an electric system with a direct current network, to an aircraft and to a method for protected switching in a direct current high voltage electric system.

BACKGROUND OF THE INVENTION

In electrical systems, switching components can be provided, such as for de-activating the system to avoid unwanted conditions. An example are switches or fuses that provide a temporal disconnection. For switching in a direct current high voltage electric system, additional measures, like clamping circuits, need to be provided to avoid a temporal overload situation due to the switching-off. However, it has been shown that clamping devices like varistors and Zener diodes require a complex matching procedure and may result in rather bulky arrangements.

SUMMARY OF THE INVENTION

There may thus be a need for improved measures for supporting disconnections in a high voltage network.

The object of the present invention may be solved by the subject-matter of one or more embodiments described herein. It should be noted that the following described aspects of the invention apply also for the electrical arrangement for protection in a direct current high voltage electric system, for the electric system with a direct current network and for the method for protected switching in a direct current high voltage electric system.

According to the present invention, an electrical arrangement for protection in a direct current high voltage electric system is provided. The arrangement comprises an input connection with an input terminal, an output connection with an output terminal, a main disconnection component between the input terminal and the output terminal and at least one clamping circuit between the input terminal and the output terminal. The clamping circuit has a first connecting path and a second connecting path, arranged in parallel to each other. The first connection path comprises a storage coupling for temporarily buffering an overvoltage present between the input terminal and the output terminal and an activatable switch for selectably connecting the storage coupling with the output terminal. The second connection path comprises a supply coupling for operating the activatable switch in dependency of the overvoltage.

As an effect, in case of a disconnection of the main circuit, energy still present can be temporarily stored within the clamping circuit. The main switching element can thus be provided in a more efficient and targeted manner. In the event the main switch opening, the energy stored on the lines, e.g. due to inductance, can be absorbed by the clamping circuit.

In an example, the clamping circuit is arranged in parallel to a main switch or fuse.

According to an example, the main disconnection component is a safety element configured to open an electrical circuit in the direct current high voltage electric system in order to protect at least a part of the electrical circuit.

According to an example, the storage coupling comprises a capacitor and a first resistor in a parallel connection.

As an option, the storage coupling also comprises a second resistor in series with the parallel connection of the capacitor and the first resistor.

According to an example, the activatable switch comprises a semiconductor switch that is blocked in a first state and that provides a connection to the output terminal in a second state.

According to an example, the activatable switch comprises an enhancement type field-effect-transistor, which is connected to the storage coupling with its drain connector, to the output terminal with its source connector and to the supply coupling with its gate as control coupling.

According to an example, the supply coupling comprises a first coupling resistor and a second coupling resistor connected in series between the input terminal and the output terminal. A trigger element is provided that comprises an input voltage terminal connected to a connection point between the first coupling resistor and the second coupling resistor with its positive connector and to a reference voltage connection with its negative connector. The trigger element also comprises a supply voltage terminal connected to a supply source with its positive connector and to output terminal with its negative connector. When the voltage present at the connection point between the first coupling resistor and the second coupling resistor exceeds a predetermined threshold, the trigger element is configured to provide a switch supply voltage to the gate of the activatable switch in order to close the activatable switch for activating the storage coupling.

According to another example, the supply coupling comprises a first transorber, a second transorber and a third transorber connected in series. A supply resistor is connected to a connection point of the second transorber and the third transorber, and a supply diode connected between the supply resistor and the activatable switch. The diode is connected to the supply resistor with its anode end. Further, a supply filter capacitor is connected between a connection point of the supply resistor and the supply diode.

According to an example, a pull down resistor is connected between the gate and the output terminal. An overvoltage protection diode is connected between the gate and the output terminal.

According to an example, the electrical arrangement is provided as a bi-directional electrical arrangement. The input connection comprises a first input terminal and a second input terminal. The main disconnection component comprises a first main disconnection element between the first input terminal and the output terminal, and a second main disconnection element between the second input terminal and the output terminal. The clamping circuit is provided as a first clamping circuit between the first input terminal and a midpoint terminal, and a second clamping circuit is provided between the second input terminal and the midpoint terminal. The first clamping circuit has the first connecting path and the second connecting path; and the second clamping circuit has a third connecting path and a fourth connecting path, arranged in parallel to each other. The third connection path comprises a second storage coupling for temporarily buffering an overvoltage present between the second input terminal and the midpoint terminal, and a second activatable switch for selectably connecting the second storage coupling with the output terminal. The fourth connection path comprises a second supply coupling for operating the second activatable switch in dependency of the overvoltage. The second connection path and the fourth connection path are provided at least partly as a shared connection path.

According to the present invention, also an electric system with a direct current network is provide. The system comprises at least one source, at least one load and an electrical arrangement according to one of the preceding examples. The source is selected from the group of: batteries, super capacitors, fuel cells, solar cells, power network and combinations thereof. The at least one load comprises at least one of the group of: electrical engines, electric drives and motors, electric actuators. The source is connected to the at least one load via an electric connection. The electrical arrangement is provided within the electric connection such that the main disconnection component can temporarily disconnect the least one load from the source.

According to an example, the direct current network is provided on board of a vehicle comprising at least one of the group of an aircraft and an automotive.

According to an example, the electrical arrangement is configured to handle voltages larger than 800 V and currents larger than 1000 A.

According to the present invention, also an aircraft is provided. The aircraft comprises a fuselage structure comprising a use portion, a lift and propulsion structure connected to the fuselage structure and an electric system with a direct current network according to one of the preceding examples. The electric system is configured to be at least temporarily used for an operation of the aircraft.

According to the present invention, also a method for protected switching in a direct current high voltage electric system is provided. The method comprises the steps of: providing an electrical arrangement for protection according to one of the preceding examples in the direct current high voltage electric system; and activating the main disconnection component. The clamping circuit is temporarily absorbing at least a part of an excess energy present as an overcurrent in the direct current high voltage electric system at the time of activating the main disconnection component.

According to an aspect, a component for disconnection in a high voltage circuit is supplemented with a topology that provides a buffer for temporarily storing energy that is still present when the disconnection of the circuit takes place by the component for disconnection. The topology also provides the possibility for draining the buffer automatically.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Certain embodiments will now be described in greater details with reference to the accompanying drawings. In the following description, like drawing reference numerals are used for like elements, even in different drawings. The matters defined in the description, such as detailed construction and elements, are provided to assist in a comprehensive understanding of the exemplary embodiments. Also, well-known functions or constructions are not described in detail since they would obscure the embodiments with unnecessary detail. Moreover, expressions such as “at least one of”, when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

Exemplary embodiments of the invention will be described in the following with reference to the following drawings:

FIG.1schematically shows an example of an electrical arrangement10for protection in a direct current high voltage electric system. The arrangement10comprises an input connection12with an input terminal14. The arrangement10also comprises an output connection16with an output terminal18. The arrangement10further comprises a main disconnection component20between the input terminal and the output terminal and at least one clamping circuit22between the input terminal14and the output terminal18. The clamping circuit22has a first connecting path24and a second connecting path26, arranged in parallel to each other. The first connection path24comprises a storage coupling28for temporarily buffering an overvoltage present between the input terminal14and the output terminal18. The first connection path24also comprises an activatable switch30for selectably connecting the storage coupling28with the output terminal. The second connection path26comprises a supply coupling32for operating the activatable switch in dependency of the overvoltage.

The at least one clamping circuit22between the input terminal14and the output terminal18is connected in parallel to the main disconnection component.

The main disconnection component20provides a conducting state as a normal state. Only if a predetermined maximum current level is exceeded, the main disconnection component turns into a high-resistance state.

The main disconnection component20can also be referred to as main disconnector, main switch, main switchable component or main switching component.

In an example, the main disconnection component20acts like an electronic fuse.

In an example, the input terminal14is a positive input terminal and the output terminal18is a negative output terminal.

The clamping circuit22provides a controlled clamping circuit. The clamping circuit22provides the effect of absorbing an energy stored within the network or circuit when interrupting an electric current in the circuit.

As an example, the conductors provide an inductivity that results in urging to continue a current when suddenly interrupted.

The clamping circuit22provides a limitation or clamping of voltage when opening the circuit.

In a first option, the main disconnection component20is provided as a safety element configured to open an electrical circuit in the direct current high voltage electric system in order to protect at least a part of the electrical circuit.

In a second option, the main disconnection component20is provided as a fuse that opens the connection when exceeding a predetermined threshold current.

In an example, the main disconnection component20is a fuse within a positive conductor of a system circuit. As an example, the system circuit relates to an avionic system of an aircraft.

The storage coupling28is used to charge the capacitor when an overvoltage between the input terminal14and the output terminal18is detected.

In an example, the activatable switch30for selectably connecting the storage coupling with the output terminal is configured to activate the clamping circuit in case of an overcurrent.

FIG.2shows an example of an electric system100with a direct current network. The electric system100comprises at least one source102and at least one load104. The electric system100further comprises an example of the electrical arrangement10according to one of the examples above and below. The source102is selected from the group of: batteries, super capacitors, fuel cells, solar cells, power network and combinations thereof. The at least one load104comprises at least one of the group of: electrical engines, electric drives and motors, electric actuators. The source102is connected to the at least one load104via an electric connection106. The electrical arrangement10is provided within the electric connection106such that the main disconnection component can temporarily disconnect the least one load104from the source102.

In an example, the electric system100comprises multiple sources102.

In an option, the direct current network is provided on board of a vehicle, such as an aircraft or an automotive.

In a further option, the electrical arrangement is configured to handle voltages larger than 800 V and currents larger than 1000 A.

FIG.3shows an example of an aircraft150. The aircraft150comprises a fuselage structure152comprising a use portion. The aircraft150further comprises a lift and propulsion structure154connected to the fuselage structure152. The aircraft150also comprises an example of the electric system100with a direct current network according to one of the examples above and below. The electric system100is configured to be at least temporarily used for an operation of the aircraft150. For example, the electric system100is used for the propulsion or for adjusting flight components. As an example, the use portion is a cabin area156or a cargo area within the fuselage. The lift and propulsion structure154may comprise, among others, a pair of wings158and engines160mounted to the wings.

FIG.4shows basic steps of an example of a method200for protected switching in a direct current high voltage electric system. The method200comprises the following steps: In a first step202, an electrical arrangement for protection according to one of the examples above and below are provided in the direct current high voltage electric system. In a second step204, the main disconnection component is activated, and the clamping circuit is temporarily absorbing at least a part of an excess energy present as an overcurrent in the direct current high voltage electric system at the time of activating the main disconnection component.

FIG.5shows an example of a configuration of the electrical arrangement10ofFIG.1. As an option, the storage coupling28of the first connecting path24comprises a capacitor34and a first resistor36in a parallel connection. As an additional or alternative option (see e.g.FIG.6), the storage coupling28also comprises a second resistor38in series with the parallel connection of the capacitor34and the first resistor36.

The capacitor34is constantly discharged via the first resistor36.

The capacitor34is connected to the input terminal14on the one side and to the activatable switch30on the other side.

The first resistor36can also be referred to as discharge resistor.

The second resistor38is provided as an additional option in combination with the first resistor36and the capacitor34. The second resistor38is coupled between the parallel connection and the activatable switch30.

The second resistor38restricts the current flow and also absorbs energy.

In an example, the capacitor34is provided in a non-charged state.

In an option, the main disconnection component20is provided as a semiconductor switch that provides a connection in a first state and that is blocked in a second state when exceeding a predetermined threshold current.

In an option, the semiconductor switch is bridged by a diode element connected to the input terminal with its cathode.

In another option, the activatable switch30comprises a semiconductor switch that is blocked in a first state and that provides a connection to the output terminal in a second state.

In a further option, the activatable switch30comprises an enhancement type field-effect-transistor, which is connected to the storage coupling28with its drain connector, to the output terminal18with its source connector and to the supply coupling32with its gate.

In a normal state, the switch is open, and the capacitor does not get loaded or charged.

As another option, a pull down resistor37is connected between the gate and the output terminal18. As an additional option (seeFIG.6), an overvoltage protection diode39is connected between the gate and the output terminal18. The overvoltage protection diode39can also be referred to as transorber, with the same reference numeral39. The resistor37is a pull-down resistor to keep the activatable switch30closed. The pull-down resistor37pulls the gate to zero, such that the transistor is turned off, in case that there is no supply, which avoids unwanted charge of the gate capacitance. The transorber39is provided as a gate protection. The transorber39is also referred to as transient voltage suppression diode. The transorber39is provided as additional option to the pull down resistor37.

In an option, shown inFIG.5, the first resistor36with the capacitor34in parallel connection are provided connected to the activatable switch30. The first and second coupling resistors40,42are provided together with the trigger element44as well as the pull down resistor37.

FIG.6shows another example of a configuration of the electrical arrangement10ofFIG.1. As an option, the supply coupling32comprises a first coupling resistor40and a second coupling resistor42connected in series between the input terminal14and the output terminal18. Further, a trigger element44is provided that comprises an input voltage terminal46connected to a connection point between the first coupling resistor40and the second coupling resistor42with its positive connector, and to a reference voltage connection48with its negative connector49. The reference voltage connection48is also referred to as Vref. Further, the trigger element44comprises a supply voltage terminal50connected to a supply source52with its positive connector and to the output terminal18with its negative connector. The supply source52is also referred to as Vsupply. When the voltage present at the connection point between the first coupling resistor40and the second coupling resistor42exceeds a predetermined threshold, the trigger element44is configured to provide a switch supply voltage to the gate of the activatable switch30in order to close the activatable switch30for activating the storage coupling28.

The first and second coupling resistor40,42provide a dividing of the voltage in half design, to fit the needs of the control circuit to switch at the desired voltage.

In an option, shown inFIG.6, the first resistor36with the capacitor34in parallel connection are provided together with the second resistor38in series connection connected to the activatable switch30. The first and second coupling resistors40,42are provided together with the trigger element44as well as the transorber and the pull down resistor.

FIG.7shows a further example of a configuration of the electrical arrangement10ofFIG.1. As an option, the supply coupling32comprises a first transorber54, a second transorber56and a third transorber58connected in series. A supply resistor60is connected to a connection point of the second transorber56and the third transorber58, and a supply diode62is connected between the supply resistor60and the activatable switch30. The supply diode62is connected to the supply resistor60with its anode end. Further, a supply filter capacitor64is connected between a connection point of the supply resistor60and the supply diode62.

In an example, the supply filter capacitor64acts as a low pass filter together with the supply resistor60.

The supply resistor60, the supply diode62and the supply filter capacitor64are referencing to the transorber setup.

As an advantage, an external supply voltage is not needed for activating, i.e. operating the activatable switch.

The first, second and third transorbers54,56,58provide a voltage dependent series connection. The first and second transorbers54,56may be provided as higher-voltage transorbers. The third transorber58is configured for a lower gate voltage for the activatable switch30.

In an example (seeFIG.6), the pull down resistor37and the transorber39are provided in combination with the first coupling resistor40and the second coupling resistor42connected in series and the trigger element44.

In another example (seeFIG.7), the pull down resistor37and the transorber39are provided in combination with the first transorber54, the second transorber56and the third transorber58connected in series, as well as the supply resistor60and the supply diode62and the supply filter capacitor64.

In an option, shown inFIG.7, the first resistor36with the capacitor34in parallel connection are provided together with the second resistor38in series connection connected to the activatable switch30. The first transorber54, the second transorber56and the third transorber58are provided together with the supply resistor60, the supply diode62and the supply filter capacitor64as well as the transorber39and the pull down resistor37.

In an example, the electrical arrangement is provided as a uni-directional electrical arrangement comprising the main disconnection component.

The electrical arrangement is provided for a use in the field of power electronics to solve problems during switching, such as opening of a fuse or a safety switch, in high power DC networks. The electrical arrangement provides high performance overvoltage clamping and ensures a proper operation of such networks in case of a failure where the safety element, e.g., fuse, is triggered.

The electrical arrangement provides a controlled electronic solution to overcome existing problems.

The version shown inFIG.7also comes with a redundancy feature and does not require an auxiliary voltage supply. Also the energy distribution and switch protection during switching or fuse blow is considered.

According to an aspect, a solution is provided for clamping overvoltages generated when a DC network is opened, e.g., a fuse, in case of failure. The active current, or even worse, failure current, comes with a high amount of stored energy in the unavoidable parasitic inductances of the cables/network. When the safety element triggers and opens the circuit, this energy is absorbed to avoid very high overvoltage. To preclude this and protect the residual network from overvoltage, protection is provided. The electrical arrangement provides improved flexibility and enhanced performance. Further, redundancy concepts can be combined with reasonable weight compared to actual solutions. The electrical arrangement benefits from a combination of a fast and controllable energy storage and clamping method based on a fast semiconductor switch with fast analog control circuit. This solution enables increased functionalities compared to the actual solutions.

This solution is intended to be used for network and energy storage reconfiguration, switching and protection.

The topology of active controlled hybrid clamping circuit with energy distribution and redundancy shown inFIG.7provides the benefits that main energy is stored in the capacitor, and that the capacitor max. voltage has not to respect the overall operating voltage but the considered energy to clamp. A further benefit is that the rest of the energy is distributed, and that the switch current is limited by the resistor, since the resistor also takes some energy. A still further benefit is that no power supply is needed, and that some redundancy is implemented e.g., in case of failure at the controlled switch. The transorbers are still active; and the capacitor is discharged by the resistor.

The topology of active controlled hybrid clamping circuit with energy distribution and high accuracy shown inFIG.6, provides the benefits that the main clamping energy is stored in the capacitor, and that the capacitor max. voltage has not to respect the overall operating voltage but the considered energy to clamp switch current is limited by the resistor and the resistor also takes some energy and a simplified circuit with high clamping accuracy is provided with the capacitor discharged by the resistor.

The topology of active controlled hybrid clamping circuit with high accuracy shown inFIG.5provides the benefits that the clamping energy is stored mainly in the capacitor which results in no heating of further components. The capacitor max. voltage has to respect the overall operating voltage but the considered energy to clamp. In the very simple circuit, only the essential components are considered but high clamping accuracy is still given. And the capacitor is discharged by the resistor.

FIG.8shows an example of a bi-directional electrical arrangement for protection in a direct current high voltage electric system. The input connection comprises a first input terminal70and a second input terminal72. The main disconnection component20comprises a first main disconnection element74between the first input terminal70and the output terminal18, and a second main disconnection element76between the second input terminal72and the output terminal18. The clamping circuit22is provided as a first clamping circuit78between the first input terminal70and a midpoint terminal80. Further, a second clamping circuit82is provided between the second input terminal72and the midpoint terminal80. The first clamping circuit78has the first connecting path24and the second connecting path26. The second clamping circuit82has a third connecting path84and a fourth connecting path86, arranged in parallel to each other. The third connection path84comprises a second storage coupling88with a second capacitor87for temporarily buffering an overvoltage present between the second input terminal and the midpoint terminal. The third connection path84also comprises a second activatable switch90for selectably connecting the second storage coupling with the output terminal18. The fourth connection path comprises a second supply coupling92for operating the second activatable switch in dependency of the overvoltage. The second connection path26and the fourth connection path86are provided at least partly as a shared connection path. As an example, the second supply coupling92is provided as the (first) supply coupling32. In other words, a common supply coupling is provided shared by the two connecting paths24,84.

The second connecting path26is provided with a first diode91controlling a first current flow direction for the first clamping circuit78. The fourth connecting path86is provided with a second diode89controlling a second current flow direction for the second clamping circuit82.

The midpoint terminal80is provided as a common source.

In an example, the shared connection path comprises a first coupling resistor94and a second coupling resistor96connected in series between an input connection terminal and the output terminal. A common trigger element98is provided that comprises an input voltage terminal connected to a connection point between the first coupling resistor and the second coupling resistor with its positive connector and to a reference voltage connection with its negative connector; and a supply voltage terminal connected to a supply source with its positive connector and to an output terminal with its negative connector. When the voltage present at the connection point between the first coupling resistor and the second coupling resistor exceeds a predetermined threshold, the trigger element is configured to provide a switch supply voltage to the gate of the first activatable switch and the second activatable switch in order to close the first activatable switch and the second activatable switch.

Further, a common pull down resistor99is provided. A connection97connects the common supply coupling to the second activatable switch90.

In an example, the main disconnection component20comprises a first semiconductor switch that provides a connection in a first state and that is blocked in a second state, and a second semiconductor switch that provides a connection in a first state and that is blocked in a second state. Each of the semiconductor switches is bridged by a diode element95,93connected to the respective input terminal with its cathode.

The systems and devices described herein may include a controller or a computing device comprising a processing and a memory which has stored therein computer-executable instructions for implementing the processes described herein. The processing unit may comprise any suitable devices configured to cause a series of steps to be performed so as to implement the method such that instructions, when executed by the computing device or other programmable apparatus, may cause the functions/acts/steps specified in the methods described herein to be executed. The processing unit may comprise, for example, any type of general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, a central processing unit (CPU), an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitably programmed or programmable logic circuits, or any combination thereof.

The methods and systems described herein may be implemented in a high-level procedural or object-oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of the controller or computing device. Alternatively, the methods and systems described herein may be implemented in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing the methods and systems described herein may be stored on the storage media or the device, for example a ROM, a magnetic disk, an optical disc, a flash drive, or any other suitable storage media or device. The program code may be readable by a general or special-purpose programmable computer for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein.

Computer-executable instructions may be in many forms, including modules, executed by one or more computers or other devices. Generally, modules include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types. Typically, the functionality of the modules may be combined or distributed as desired in various embodiments.

It will be appreciated that the systems and devices and components thereof may utilize communication through any of various network protocols such as TCP/IP, Ethernet, FTP, HTTP and the like, and/or through various wireless communication technologies such as GSM, CDMA, Wi-Fi, and WiMAX, is and the various computing devices described herein may be configured to communicate using any of these network protocols or technologies.