ELECTRICAL POWER SUPPLY PROTECTION AND SHUT-OFF CIRCUIT

Abstract

The present invention relates to a protection and switching circuit (CPC1) for the supply of electrical power in a network comprising a DC voltage source (SE1). The protection and switching circuit (CPC1) is connected between the voltage source and the network. The protection and switching circuit consists of four switches, each with a diode (SO11, SO12, SO13, SO14), and a control device (100). When the current delivered or received by the voltage source is less than a predetermined threshold, the control device causes two switches (SO11, SO14) to close and the other two switches (SO12, SO13) to open. When the current delivered or received by the voltage source is greater than or equal to the predetermined threshold, the control device causes two switches (SO11, SO14) to open and each diode in the other two switches (SO12, SO13) to conduct. Fig. 1

Description

Title of the invention: Electrical Power Supply Protection and Shutdown Circuit technical field

[0001] The present invention relates to a circuit for protecting and cutting off the supply of electrical power to an electrical power supply network. It applies in particular, but not exclusively, to direct current voltage networks on board aircraft, used especially to supply electrical power to non-propulsive loads (computers for example) and / or propulsive loads (electric actuators for example). STATE OF PRIOR ART

[0002] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies both to new types of aircraft and to those already in operation, requiring the implementation of technological solutions to bring existing aircraft into compliance with current regulations. Civil aviation has been actively working for several years now to contribute to the fight against climate change.

[0003] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order to obtain aeronautical components and products that are less energy-intensive, more environmentally friendly, and whose integration and use in civil aviation have moderate environmental impacts, with the aim of improving the energy efficiency of aircraft.

[0004] Consequently, the Applicant is constantly working to reduce its climate impact by using methods and operating virtuous development and manufacturing processes that minimize greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint related to its activity.

[0005] This sustained research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, in particular through the materials used and lighter on-board equipment, the development of the use of electrical technologies to provide propulsion, and, as essential complements to technological progress, aviation biofuels.

[0006] To this end, the invention is the result of technological research aimed at significantly improve aircraft performance and, in this sense, contribute to reducing the environmental impact of aircraft.

[0007] For this purpose, the invention relates to a protection and disconnection circuit for the supply of electrical energy in a high-voltage electrical energy supply network, which is less constrained in terms of the voltage rating of the components and which reduces the losses related to the protection and disconnection circuit.

[0008] A high voltage electrical power supply network is generally understood as a network that supplies a voltage greater than 1kVolts and less than 10kVolts.

[0009] The voltage rating corresponds to the theoretical maximum voltage that a component can withstand. This is also referred to as the breakdown voltage. To say that a semiconductor component is less constrained in terms of voltage rating means that it does not have to exhibit a breakdown voltage much higher, for example 1.5 to 2 times higher than the mains voltage.

[0010] Conventionally, the circuit topologies for protecting and interrupting the electrical power supply of an electrical power supply network depend heavily on the characteristics of the power semiconductor switches used and the requirements in terms of speed and the power output of the electrical power supply network. The characteristics of the protection circuits are their power losses, cost, size, fault current attenuation time, and control circuitry.

[0011] Various protection circuit topologies can be found in the technical literature on the subject. These protection circuits are based on power semiconductor components of the type insulated-gate bipolar transistor (IGBT Si, ​​from the English Insulated-Gate Bipolar Transistor Silicon) or insulated-gate field-effect transistors more commonly called MOSFET SiC (English acronym for Metal-Oxide-Semiconductor Field-Effect Transistor Silicon Carbide), in association with transient-voltage-suppression (TVS) systems or metal-oxide varistors (MOV, English acronym for Metal Oxide Varistor).

[0012] Certain power semiconductor-based protection circuits require the use of at least one power semiconductor component with a voltage rating (breakdown voltage), i.e., rated to withstand a voltage at least 1.5 to 2 times the DC voltage supplied by the electrical power grid. Thus, for a 3 kV DC power grid, 4.5 kV to 6.5 kV semiconductor components are selected.

[0013] To avoid such semiconductor components exhibiting such a high breakdown voltage, other protection circuits are composed of several power semiconductor components in series to maintain the required high voltage level, but they require a more complex control and command circuit.

[0014] Furthermore, these switches are sometimes associated with overvoltage protection systems such as metal oxide varistors (MOVs). Metal oxide varistors (MOVs) have a limited lifespan due to their degradation during the energy absorption process, thus limiting the number of times the electrical power supply can be interrupted.

[0015] The present invention makes it possible to reduce the voltage withstand constraints of power semiconductor components and to reduce losses related to the protection circuit, as well as to not need the transient voltage suppression system and fault energy absorption of the line. Description of the invention

[0016] To this end, according to a first aspect, an embodiment proposes a circuit for protecting and cutting off the supply of electrical energy in an electrical energy supply network, the electrical energy supply network comprising at least one voltage source supplying a direct current voltage, characterized in that the circuit for protecting and cutting off the supply of electrical energy is connected between the two terminals of the voltage source and the two terminals of the electrical energy supply network, the circuit for protecting and cutting off the supply of electrical energy consists of four switches configured in an H-bridge configuration and a control device, each switch comprising a diode, the opening and closing of the switches being triggered by the control device, and in that when the current delivered or received by the voltage source is less than a predetermined threshold,The control device causes two switches to close and two other switches to open, and when the current delivered or received by the voltage source is greater than or equal to the predetermined threshold, the control device causes two switches to open and each diode of the other two switches to conduct.

[0017] Thus, the present invention makes it possible to avoid using power semiconductor components with a voltage rating higher than the network voltage and reduces losses related to the protection and switching circuit.

[0018] According to one embodiment, the protection and switching circuit further comprises a capacitor connected to the terminals of the voltage source.

[0019] According to one embodiment, the switches are controlled switching switches, each switch comprising a transistor and the diode of each in- A terrupteur is an antiparallel diode.

[0020] Thus, the protection and switching circuit is adapted to an operation in which the current flows from the source to the load (power supply mode to the load) or in which the current flows from the load to the source (current injection mode to the source).

[0021] According to one embodiment, among the four switches, two are controlled switching switches, each comprising a transistor and diode; the two controlled switching switches are antiparallel diodes and the other two switches are diodes.

[0022] Thus, the protection and switching circuit is then adapted for a current flowing from the source to the load (power supply mode to the load).

[0023] According to one embodiment, the capacitor connected to the terminals of the voltage source is sized to absorb the current flowing in the protection and switching circuit when both switches are open and each diode of the other two switches is conducting.

[0024] Thus, the protection and switching circuit is then adapted for a current which flows from the source to the load (energy supply mode to the load).

[0025] According to one embodiment, the controlled switching switches are of the IGBT type.

[0026] According to one embodiment, the controlled switching switches are of the SiC MOSFET type.

[0027] According to one embodiment, the electrical power supply system comprises a plurality of voltage sources and for each voltage source, a protection circuit according to the present invention.

[0028] According to one embodiment, when the current delivered or received by each voltage source is less than a predetermined threshold, the device causes two switches of each protection and breaking circuit to close and two other switches to open, and causes, when the current delivered by a voltage source is greater than or equal to the predetermined threshold, the opening of the two switches and the conduction of each diode of the two other switches of the protection and breaking circuit connected between the two terminals of the voltage source which delivers the current greater than or equal to the predetermined threshold.

[0029] The invention also relates to an aircraft which includes a circuit for protecting and cutting off electrical energy in an electrical energy supply network according to the present invention. Brief description of the drawings

[0030] The features of the invention mentioned above, as well as others, appear will become clearer upon reading the following description of an example implementation, said description being made in relation to the attached drawings, among which:

[0031] [Fig.1] schematically illustrates an example of an electrical power supply network in which a circuit for protecting and cutting off the electrical power supply according to the present invention is implemented;

[0032] [Fig.2a] schematically illustrates an example of a simplified diagram of the electrical power supply network of the [Fig.1] comprising a bidirectional protection and switching circuit according to a first embodiment of the invention and in which the energy sources are capable of delivering or receiving a current;

[0033] [Fig.2b] schematically illustrates an example of a simplified diagram of the electrical power supply network of [Fig.l] comprising a unidirectional protection and switching circuit according to a second embodiment of the invention and in which the energy sources are only capable of delivering a current;

[0034] [Fig.3a] and

[0035] [Fig.3b] schematically illustrate, according to a first example, corresponding to a case of use of voltage sources delivering current, the operating state of the components of the protection and switching circuit of the [Fig.2a], respectively of an operating mode in which no short circuit appears in the electrical power supply network ([Fig.3a]) and in an operating mode in which a short circuit appears in the electrical power supply network ([Fig.3b]);

[0036] [Fig.4] schematically illustrates, according to the first example, the variations in voltage and current when the protection and switching circuit changes from an operating mode in which no interruption of the supply of electrical energy is carried out to an operating mode in which an interruption of the supply of electrical energy is carried out;

[0037] [Fig.5a] schematically illustrates, according to a second example, in the same case of use of source(s) delivering current, the state of operation of the components of the protection and switching circuit of the [Fig.2a] in an operating mode in which no short circuit appears in the electrical power supply network;

[0038] [Fig.5b] schematically illustrates, according to the second example, the operating state of the components of the protection and switching circuit of the [Fig.2a] at the end of a first period of time of an operating mode in which a short circuit appears in the electrical power supply network;

[0039] [Fig. 5c] schematically illustrates, according to the second example, the operating state of the components of the protection and switching circuit of [Fig. 2a] at the end of a second time period of an operating mode in which a short circuit appears in the electricity supply network;

[0040] [Fig.5d] schematically illustrates, according to the second example, the operating state of the components of the protection and switching circuit of the [Fig.2a] at the end of a third period of time of an operating mode in which a short circuit appears in the electrical power supply network;

[0041] [Fig.6] schematically illustrates, according to the second example, the variations in voltage and current when the circuit for protecting and cutting off the supply of electrical energy changes from a mode of operation in which no interruption of the supply of electrical energy is carried out to a mode of operation in which an interruption of the supply of electrical energy is carried out.

[0042] DETAILED DESCRIPTION OF EMBODIMENT METHODS

[0043] Fig. 1 schematically illustrates an example of an electrical power supply network in which a circuit for protecting and cutting off the electrical power supply according to the present invention is implemented.

[0044] In the example of [Fig.1], the electrical power supply network comprises a plurality of electrical power supply sources denoted SEi, SE2,..., to SEN, a plurality of protection circuits CPCi, CPC2, ....CPCN and a plurality of loads denoted Zn, Zi2, Z2i, Z22,..., Zmi to Zm2.

[0045] The charge Zn is the charge located at the end of a first sub-branch of a first branch of the electrical power supply network, and the charge Z[2 is the charge located at the end of a second sub-branch of the first branch of the electrical power supply network.

[0046] Load Z2i is the load located at the end of a first sub-branch of a second branch of the electrical power supply network and load Z22 is the load located at the end of a second sub-branch of the second branch of the electrical power supply network.

[0047] Load ZMi is the load located at the end of a first sub-branch of an Mth branch of the electrical power supply network and load ZM2 is the load located at the end of a second sub-branch of the Mth branch of the electrical power supply network.

[0048] A first termination of each charge Zn, Zn, Z2b Z22,..., ZMi and ZM2 is connected to a ground denoted 0VCh-

[0049] For example, a second termination of each charge Zn, Zn, Z2b Z22, to ZMi to ZM2 is connected respectively to a first termination of a charge opening system denoted respectively Su, Si2, S2i, S22,..., SMi to SM2.

[0050] The second terminations of the charge opening systems Su, Si2, S2i, S22,..., S mi to Sm2 are connected to a point marked A in the [Fig.1].

[0051] The inductance LCn represents the line inductance of the first sub-branch of the first branch of the electrical power supply network and the inductance LC^ represents the line inductance of the second sub-branch of the first branch of the electrical power supply network.

[0052] The inductance LC2i represents the line inductance of the first sub-branch of the second branch of the electrical power supply network and the inductance LC22 represents the line inductance of the second sub-branch of the second branch of the electrical power supply network.

[0053] The inductance LCMi represents the line inductance of the first sub-branch of the M-th branch of the electrical power supply network and the inductance LCM2 represents the line inductance of the second sub-branch of the M-th branch of the electrical power supply network.

[0054] The inductance LDi represents another line inductance of the first branch of the electrical power supply network, the inductance LD2 represents another line inductance of the second branch of the electrical power supply network and the inductance LDM represents another line inductance of the Mth branch of the electrical power supply network.

[0055] The inductance LSEi represents the line inductance between the first voltage source SEi and point A, the inductance LSE2 represents the line inductance between the second voltage source SE2 and point A, and the inductance LSEN represents the line inductance between the Nth voltage source SEN and point A.

[0056] The outputs of each voltage source denoted SE; (i=1 to N) are connected to a capacitor C; and a protection and cut-off circuit CPC; composed of switches denoted SOü, SOi2, SOi3 and SOi4 which form an H-bridge.

[0057] In this document, the term switch refers to both: - a transistor, which is a controlled switching switch, is controlled by a control electrode (a gate) driven by a control device, to switch it to the open or closed state. In this document, the transistors may include MOSFETs, preferably SiC MOSFETs, or IGBTs. Combined with a diode whose anode and cathode are respectively connected to the source (or emitter) and drain (or collector) electrodes of the MOSFET (or IGBT) transistor, such a switch is bidirectional for current. - a diode, which is a spontaneously switching, unidirectional switch for current.

[0058] The CPC protection and switching circuits have a similar structure. The following describes in more detail the CPC circuit associated with the SE1 source. This description will apply similarly to the other CPC2, ...CPCN circuits respectively associated with the SE2, ...SEN sources.

[0059] The CPCi circuit comprises four switches SOn, SOi2, SOn and SOi4.

[0060] In a first embodiment illustrated in [Fig. 2a], the switches SO1, SO12, SO13, and SO14 are controlled-switching switches, for example, of the IGBT or MOSFET type, preferably SiC MOSFETs, and each includes an antiparallel diode (intrinsic and / or external depending on the technology as mentioned above), and the assembly forms a bidirectional switch. The direction of the current, source to load or load to source, is determined by the control method of the switches controlled by the control device 100. This embodiment with four controlled-switches is particularly well-suited to energy sources that, by nature (battery, for example) or by construction (busbar), are capable of delivering or receiving current. In this case, the sources are, for example, busbars of an electrical network, such as an avionics network known as HVDC (High Voltage Direct Current), or even batteries.

[0061] A “busbar” is equivalent to the term “bus bar” or “omnibus bar” and designates, according to the definition given by the International Electronic Commission, a low impedance conductor to which several electrical circuits can be connected at separate points.

[0062] When, by nature or design, the power supply sources are intended solely to deliver current, it is possible to reduce the cost (size, price) of the CPCi circuit by replacing two controlled switching switches with two self-switching switches, i.e., by a diode that replaces / implements the antiparallel diode. This is the variant schematically illustrated in [Fig. 2b]. The two controlled switching switches SOi2, SOn are replaced (implemented by) self-switching switches; in other words, the switches SO12, SOn are implemented by diodes. The two other switches SOn, SOi4 remain controlled switching switches, controlled by the control device 100.

[0063] Of course, the embodiment as described with reference to [Fig.2a] is also applicable when the sources of the electrical network are designed solely to deliver a current.

[0064] As previously stated, each controlled switching switch of the protection and breaking circuit, SOn, SOi2, SOn and SO[4 in the embodiment of [Fig.2a], or SOnet SO[4 in the embodiment of [Fig.2b], comprises a transistor and an antiparallel diode, also called a freewheeling diode as shown in [Fig.1].

[0065] In the case of an IGBT type controlled switching switch, the antiparallel diode is an external diode whose anode and cathode are respectively connected to the emitter and collector of the IGBT switch.

[0066] In the case of a MOSFET-controlled switching switch (silicon or silicon carbide SiC), the anode and cathode of the antiparallel diode are connected to the source and drain of the switch, respectively. The antiparallel diode can be implemented here by the diode natively present in the MOSFET transistor and known in the literature as the "diode body." Alternatively, an additional external diode can be used to enhance the electrical properties of the transistor's intrinsic diode body.

[0067] The term "antiparallel diode" used in this application encompasses all these variants of controlled switching switch embodiments, including an intrinsic diode and / or an external diode of the transistor considered connected between the emitters / collectors or sources / drains as indicated above.

[0068] In the remainder of this document, reference is generally made to IGBT switches. Those skilled in the art will transpose this to the case of MOSFET or SiC MOSFET type switches by replacing the terms emitter and collector with the terms source and drain, respectively.

[0069] Finally, the terms "diode" ([Fig.2b]) and "antiparallel diode" ([Fig.2a]) referring to the same switch references used (SOi2, SOb, SO2i, SO23) in this description are equivalent in the electrical functional plan.

[0070] Thus, and with regard to the CPCi circuit in both the embodiment of [Fig.2a] and that of [Fig.2b]: the diode of switch SO[2 has its anode connected to the emitter of switch SOi4, and its cathode connected to the emitter; the diode of switch SOi3 has its anode connected to the collector of switch SOi4, and its cathode connected to the collector of switch SOn.

[0071] In both embodiments of Figs. 2a and 2b, the controlled switching switches of the protection and breaking circuit, i.e. the switches SOn, SO12, SO13 and SO14 of the CPCide la circuit [Fig.2a] and the switches SOn and SO14 of the CPCide la circuit [Fig.2b], are controlled by a control device denoted 100.

[0072] The collector of the switch SOn is connected to a positive terminal of the electrical power supply source SEi, to a first termination of the capacitor Ci and in the preferred embodiment of [Fig.2a], to the collector of the switch SO[3 or, according to the variant of [Fig.2b], to the cathode of the switch SO[2.

[0073] The emitter ([Fig.2a]) or the anode ([Fig.2b]) of the switch SO[2 is connected to a negative terminal of the electrical power supply source SEi, to a second termination of the capacitor Ci and to the emitter of the switch SO[4.

[0074] The emitter of the switch SOn is connected to the collector ([Fig.2a]) or to the cathode ([Fig.2b]) of the switch SO[2 and to point A via the inductance LSEi and a current sensor denoted Cui.

[0075] The emitter ([Fig.2a]) or the anode ([Fig.2b]) of switch SOn is connected to the collector of switch SOi4 and to ground 0VCh*

[0076] The description of the embodiments with reference to Figs. 2a and 2b, taking as an example the source SEi and the associated protection and switching circuit CPCi, applies generally to each of the sources SE; and to the associated protection and switching circuit CPC;, with i=1 to N, of [Fig. 1]. In particular, and with reference to [Fig. 1], the outputs of the voltage source denoted SE2 (respectively SEN) are connected to a capacitor C2 (respectively CN) and to a protection and switching circuit CPC2 (respectively CPCN) composed of switches denoted SO2[, SO22, SO23 and SO24 (respectively SONi, SON2, SON3 and SON4) which form an H-bridge.

[0077] Figs. 2a and 2b schematically illustrate a simplified diagram of the electrical power supply network of [Fig.1], [Fig.2a] in the case of energy sources which by nature or construction are capable of delivering or receiving current, and [Fig.2b] in the case where these sources can only deliver current.

[0078] To facilitate understanding, in Figs. 2a and 2b, only the voltage sources SEi and SE2 are shown with their respective protection and switching circuits CPCi and CPC2; the loads Zn, Z2, Z2b, Z22, to ZM to ZM2 shown in [Fig. 1] are represented by a single load labeled RCh, and the line inductances LDi, LD2, LDM, Len, LCi2, LC2i, LC2i, Lcmi, LCm2 are represented by a single line inductance LD CH*

[0079] As explained previously:

[0080] - in [Fig. 2a], the four switches of each of the circuits CPC1 and CPC2, i.e. SO1, SO2, SO1 SO4, SO2, SO22, SO23 and SO24 are controlled switching switches, and they include an antiparallel diode (intrinsic and / or external), compatible with voltage sources that can deliver or receive current; and

[0081] - in [Fig.2b], two controlled switching switches (and anti-dimming diode) intrinsic and / or external parallel) are replaced by spontaneously switching switches, in other words, diodes. More precisely, the switches SOn, SO[4, SO2[ and SO24 are IGBT or SiC MOSFET type switches each containing an antiparallel diode (intrinsic and / or external), and the switches SO[2, SO13, SO22 and SO23 are diodes, connected in the same way as the antiparallel diodes of the switches SO[2, SOn, SO22 and SO23 in their realization of [Fig.2a].

[0082] In the following, and with reference to [Fig. 3a] and subsequent figures, we consider the case of voltage sources used in mode as power suppliers, which is compatible with both embodiments of Figs. 2a and 2b. Current flows to the loads and the operating states of the components described are valid for both embodiments of Figs. 2a and 2b.

[0083] The different operating states of the components of the protection circuits and The switching states CPC1 and CPC2 are shown as follows: in the conducting state, the component is shown with solid lines; in the blocking state, the component is shown with dashed lines. These operating states (open and closed) of the switches are controlled or triggered by the control signals delivered by the control device 100: controlled in the case of transistor switches; or triggered in the case of diode switches.

[0084] Figs 3a, 3b and 4 illustrate a first situation. In this first situation, the line inductances LSEi and LSE2 are identical and the voltage sources SEi and SE2 are identical and are equal to the same positive voltage, the voltage VLSi across the terminals of the inductance LSEi is equal to the voltage VLS2 across the terminals of the inductance LSE2 and the current ILSi flowing in the inductance LSEi is equal to the current ILS2 flowing in the inductance LSE2.

[0085] Fig. 3a schematically illustrates the operating state of the components of the protection and switching circuit of Fig. 2a and of the electrical signals, in an operating mode in which no short circuit appears (is detected) in the electrical power supply network; Fig. 3b, the operating state of the components of the protection and switching circuit when a short circuit appears (is detected) in the electrical power supply network; and Fig. 4, the voltage and current variations before and after a short circuit is detected by the detection device 100.

[0086] Fig. 3a schematically illustrates the operating state of the protection and switching circuit components when no short circuit occurs (is detected) in the electrical power supply network; Fig. 3b, the operating state of the protection and switching circuit components when a short circuit occurs (is detected) in the electrical power supply network; and Fig. 4, the voltage and current variations before and after a short circuit is detected by the detection device 100.

[0087] In [Fig. 3a], no short circuit occurs in the electrical power supply network; switches SOn, SOi4, SO2[ and SO24 conduct, and switches SO[2, SOi3, SO22 and SO23 are blocked. The antiparallel diodes of each switch do not conduct.

[0088] When a short circuit occurs at the RCH resistance, the ISEi current delivered by the SEi voltage source increases, as does the ISE2 current delivered by the SE2 voltage source.

[0089] In [Fig.4], the time period denoted PO is a time period in which no short circuit appears at the level of the resistance RCh, the time period denoted PI is a time period in which a short circuit appears at the level of the resistance Rch.

[0090] During the time period PI, the currents ISE1 and ISE2 are compared by the control device 100 to a predetermined threshold, for example between 2 and 4 times the nominal value of the current delivered by the electrical power supply network.

[0091] When the currents ISE1 and ISE2 are above the predetermined threshold, the control device 100 commands the opening of the switches SOn, SOi4, SO2[ and SO24 thus causing the conduction of the antiparallel diodes of the switches SO[2, SOn, SO22 and SO23 as shown in [Fig.3b].

[0092] The currents ISEi and ISE2 and the voltages VLSi and VLS2 change polarity. The currents ISE1 and ISE2 decrease as shown in time period P2 of [Fig.4].

[0093] Thus, the operation of the protection and switching circuit components reverses the voltage supplied to the electrical power grid during the time period P2, through the antiparallel diodes. The advantage is that the energy stored in the line during the short circuit is fed back into the source. Another important advantage is that this structure allows the use of power semiconductors with lower voltage withstand requirements than those of power semiconductors in prior art protection and switching circuits, since the current slope reversal at the short-circuit output is achieved by turning on the antiparallel diodes.

[0094] As soon as the currents ILSi and ILS2 cancel each other out, the antiparallel diodes of the switches SO[2 and SO22 block.

[0095] Thus, the energy stored in the line inductors during the short circuit is not dissipated in the switches but is fed back into the voltage sources. Another important advantage is that this structure allows the use of low-voltage transistors since the reversal of the current slope at the short-circuit output is achieved by turning on the antiparallel diodes of the switches. In other words, it is not necessary to have a voltage rise across a semiconductor in order to reverse the line voltage.

[0096] The voltage and current variations before and after a short circuit detection by the detection device 100 have been described in the example of [Fig.2a].

[0097] The signals in [Fig.4] are also valid for [Fig.2b]. In the case of [Fig.2b], the capacitors Ci and C2 across the voltage sources SEi and SE2 are sized to absorb the currents during the time period P2 in place of the voltage sources SEi and SE2, whereas in [Fig.2a], since the energy is reinjected into the voltage sources SEi and SE2, the capacitors Ci and C2 across the voltage sources SEi and SE2 can be sized to absorb part of the currents during the time period P2.

[0098] It will be understood that the electrical power supply system can be mixed, that is to say, include one or more voltage sources capable of delivering or receiving a current and one or more voltage sources only capable of delivering a current.

[0099] In one example, the voltage source SEi is capable of delivering or receiving current, such as for example a battery, and the capacitor Ci can be sized to absorb part of the current during the time period P2; and the voltage source SE2 is only capable of delivering current, for example a current generator, and the capacitor C2 is sized to absorb the current during the time period P2 instead of the voltage source SE2.

[0100] Also, in this example, a bidirectional type protection and switching circuit can be associated with each of the two voltage sources ([Fig.2a]); alternatively, and for the voltage source SE2 only capable of delivering a current, the protection and switching circuit can be unidirectional as illustrated in [Fig.2b].

[0101] Figs. 5a to 5d and 6 illustrate a second situation in which the line inductance L'sei is different from and smaller than the line inductance L'Se2, the voltage sources SEi and SE2 are identical and the voltages VSEi and VSe2 that they deliver are equal to the same positive voltage (VSei = VSe2)-

[0102] Figure 5a schematically illustrates the operating state of the components of the protection and switching circuits CPCi and CPC2 when no short circuit occurs in the electrical power supply network: switches SOn, SOi4, SO2i, and SO24 conduct, and switches SO2, SOi3, SO22, and SO23 are blocked. In both circuits CPCi and CPC2, the diodes of each switch do not conduct.

[0103] When a short circuit occurs at the level of the resistance RCH, the voltages across the two inductances L'SEi and L'SE2 are identical.

[0104] Since the inductance L'SEi is smaller than the inductance L'SE2, the current through the inductance L'SEi increases with a steeper slope than the current through the inductance L'SE2-

[0105] Fig. 6 then schematically illustrates the voltage and current variations before and after a short circuit is detected by the detection circuit 100, i.e. when the circuit for protecting and cutting off the supply of electrical energy changes from the operating mode shown in Fig. 5a in which no interruption of the supply of electrical energy is carried out to an operating mode in which an interruption of the supply of electrical energy is carried out.

[0106] In [Fig.6], the time period denoted P'0 is a time period in which no short circuit appears at the level of the resistance RCh, the time period denoted P'1 is a time period in which a short circuit appears at the level of the resistance Rch.

[0107] During the time period P' 1, the currents ISEi and ISE2 are compared by the control device 100 to a predetermined threshold, for example between 2 and 4 times the nominal value of the current delivered by the electrical power supply network.

[0108] The current ISEide becomes greater than or equal to the predetermined threshold before the current I sE2ne is greater than or equal to the predetermined threshold. The control device 100 controls the opening of switches SOn, SOi4 (thus blocking them) thereby causing the conduction of the antiparallel diodes of switches SOi2 and SOn while the transistors of switches SO2i and SO24 are still conducting as seen in [Fig. 5b] which schematically shows the operating state of the components of the protection and switching circuits CPCi and CPC2 at the end of the time period P' 1.

[0109] During the time period P'2, the current ISE1 decreases while the current ISE2 increases.

[0110] The control device 100 compares the ISE2 current to the predetermined threshold.

[0111] When the current IsE2 is greater than or equal to the predetermined threshold, the control device 100 controls the opening of the SO2i, SO24 switches, thus causing the conduction of the antiparallel diodes of the SO22 and SO23 switches as seen in [Fig.5c].

[0112] Fig. 5c schematically illustrates the operating state of the components of the protection and switching circuits CPCi and CPC2 at the end of the time period P'2.

[0113] During the time period P'3, the currents ISEi and ISE2 decrease.

[0114] As soon as the current flowing in the inductance LSEi becomes zero, the antiparallel diodes of the switches S0[2 and SOi3 no longer conduct.

[0115] Fig. 5d schematically illustrates the operating state of the components of the electrical power supply protection and cut-off circuit at the end of the time period P'3.

[0116] During the time period P'4, as long as the current flowing through the inductor LSE2 is positive, the diodes of switches SO22 and SO23 remain conducting. This phase ends when the current flowing through the inductor LSE2 becomes zero.

[0117] Thus, the energy stored in the line inductances during the short circuit is not dissipated in the switches but is fed back into the voltage sources. Another important advantage is that this structure allows the use of low-voltage transistors since the reversal of the current slope at the short-circuit output is achieved by turning on the antiparallel diodes of the switches. In other words, it is not necessary to have a voltage rise across a semiconductor in order to reverse the line voltage.

[0118] Since energy is reinjected into the voltage sources, the capacitors Ci, C2, .. .CN across the voltage sources SEi, SE2, .. .Sen are sized to take into account such operation.

[0119] It should be noted here that, alternatively, as soon as one of the currents IseiOu ISE2 becomes greater than or equal to the predetermined threshold, the control device 100 commands the opening of each switch SOn, SOi4 SO2i, SO24.

[0120] The voltage and current variations before and after a short circuit detection by the detection device 100 have been described in the example of [Fig.2a].

[0121] The signals of [Fig.6] are also valid for [Fig.2b]. In the case of [Fig.2b], the capacitors Ci and C2 across the voltage sources SEi and SE2 are sized to absorb the currents during the time periods P'2, P'3 and P'4 instead of the voltage sources SEi and SE2, whereas in [Fig.2a], since the energy is reinjected into the voltage sources SEi and SE2, the capacitors Ci and C2 across the voltage sources SEi and SE2 can be sized only to absorb part of the currents during the time periods P'2, P'3 and P'4.

[0122] As mentioned in relation to [Fig.4], it will be understood that the electrical power supply system can be mixed, that is to say, include one or more voltage sources capable of delivering or receiving current and one or more voltage sources only capable of delivering current.

[0123] In one example, the voltage source SEi is capable of delivering or receiving current, such as for example a battery, and the capacitor Ci can be sized to absorb part of the current during the time periods P'2 P'3 and P'4; and the voltage source SE2 is only capable of delivering current, for example a current generator, and the capacitor C2 is sized to absorb the current during the time periods P'2 P'3 and P'4 instead of the voltage source SE2.

[0124] Also, in this example, a bidirectional type protection and switching circuit can be associated with each of the two voltage sources ([Fig.2a]); alternatively, and for the voltage SE2 only capable of delivering a current, the protection and switching circuit can be unidirectional as illustrated in [Fig.2b].

[0125] In the embodiment of [Fig.2a], the operation has been described in a mode in which the current is delivered by the voltage sources SEi and SE2.

[0126] When current is injected into or received by voltage sources SEi and SE2, the components of the protection and switching circuits CPCi and CPC2 are all controlled-switch switches comprising a transistor and an antiparallel diode (internal and / or external). Compared to previous operating states, the switches are controlled by the control circuit 100 in the reverse manner described previously. For example, when (as long as) no short circuit occurs in the electrical power supply network, the control device 100 controls switches SOi2, SOb, SO22, and SO23 to conduct and controls switches SOn, SOi4, SO2i, and SO24 so that they do not conduct. The antiparallel diodes of each switch do not conduct.

[0127] When a short circuit occurs, the switches SOi2, SOi3, SO22 and SO23 are blocked and the antiparallel diodes of each switch SOn, SOi4, SO2[ and SO24 conduct.

[0128] Current is injected into the voltage sources SEi and SE2 by a current generator such as, for example, a battery or a busbar.

[0129] In the case where the electrical power supply system is mixed, that is to say includes one or more voltage sources capable of delivering or receiving current and one or more voltage sources only capable of delivering current, only the switches of each protection and switching circuit connected between the two terminals of a voltage source capable of delivering or receiving current are controlled by the control circuit 100 in the opposite way to that described previously.

Claims

Claims

1. A circuit for protecting and cutting off (CPCi) the supply of electrical energy in an electrical energy supply network, the electrical energy supply network comprising at least one voltage source (SEi) supplying a direct voltage, characterized in that the circuit for protecting and cutting off (CPCi) the supply of electrical energy is connected between the two terminals of the voltage source and the two terminals of the electrical energy supply network, the circuit for protecting and cutting off the supply of electrical energy consists of four switches (SOn, SOi2, SOn, SOi4) configured in an H-bridge configuration and a control device (100), each switch comprising a diode, the opening and closing of the switches being caused by the control device, and in that when the current delivered or received by the voltage source is less than a predetermined threshold,the control device causes the closing of two switches (SOn, SOi4) and the opening of the other two switches (SOi2, SOn) and, when the current delivered or received by the voltage source is greater than or equal to the predetermined threshold, the control device causes the opening of the two switches (SOn, SOM) and the conduction of each diode of the other two switches (SO[2, SOn).,

2. The protection and cut-off circuit according to claim 1, characterized in that the protection and cut-off circuit further comprises a capacitor (Ci) connected to the terminals of the voltage source (SEÛ.

3. The protection and cut-off circuit according to claim 1, characterized in that the switches are controlled switching switches each comprising a transistor and the diode of each switch is an antiparallel diode.

4. The protection and cut-off circuit according to claim 1, characterized in that two switches are controlled switching switches each comprising a transistor and the diodes of said two switches are antiparallel diodes and the other two switches are diodes.

5. The protection and cut-off circuit according to claim 1, characterized in that the capacitor (Ci) connected to the terminals of the voltage source (SEi) is sized to absorb the current circulating in the protection and cut-off circuit when both switches are open and each diode of the other two switches conducts.

6. The protection and cut-off circuit according to claim 3 or 4, characterized in that the controlled switching switches are of the IGBT type.

7. The protection and cut-off circuit according to claim 3 or 4, characterized in that the controlled switching switches are of the SiC MOSFET type.

8. An electrical power supply system, characterized in that the electrical power supply system comprises a plurality of voltage sources and for each voltage source, a protection and cut-off circuit according to any one of claims 1 to 7

9. / . The system according to claim 8, characterized in that when the current delivered or received by each voltage source is less than a predetermined threshold, the device causes the closing of two switches of each protection and cut-off circuit and the opening of two other switches, and causes, when the current delivered by a voltage source is greater than or equal to the predetermined threshold, the opening of the two switches and the conduction of each diode of the two other switches of the protection and cut-off circuit connected between the two terminals of the voltage source which delivers the current greater than or equal to the predetermined threshold.

10. An aircraft characterized in that it comprises a circuit for protecting and cutting off electrical energy in an electrical energy supply network according to any one of claims 1 to 7.

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