Disconnector unit

Abstract

A circuit breaker unit (3) comprising a circuit breaker for connecting at least two electrical networks (1, 2) comprising a first electrical network (1) and a second electrical network (2), and a control unit (4) configured to monitor voltages (U1, U2) of the networks (1, 2) and / or at least one current (I1, I2) through the circuit breaker and, upon the occurrence of one of the fault cases of overvoltage or undervoltage in one of the networks (1, 2) or overcurrent via the circuit breaker, to separate the two networks (1, 2) from one another, wherein the circuit breaker comprises at least one controllable first resistor (R1), one controllable second resistor (R2), and one controllable third resistor (R3), wherein all three resistors (R1 to R3) are each connected directly or indirectly to a common node (K),wherein the first resistor (R1) is further connected directly or indirectly to the first network (1) and the second resistor (R2) is connected directly or indirectly to the second network (2), wherein the third resistor (R3) is connected to a reference potential (G), wherein the control unit (4) is configured, in the event of a fault in one of the networks (1, 2), to adapt the values ​​of the resistors (R1, R2, R3) such that the networks (1, 2) are separated from one another and that the voltage (U1, U2) in the fault-free network (1, 2) remains within predetermined limits, wherein the control unit (4) is designed, when adapting the values ​​of the resistors (R1, R2, R3) so that the networks (1, 2) are separated from one another and that the voltage (U1, U2) in the fault-free network (1, 2) remains within predetermined limits, to temporarily adjust at least one of the resistors (R1, R2, R3) depending on values ​​detected in predetermined time steps or provided values ​​for the voltage (U1,U2) of the fault-free network and / or for the voltage (U1, U2) of the faulty network and / or for the at least one current (I1, I2) in such a way that the at least one resistor (R1, R2, R3) functions as a continuous linear regulator.

Description

The invention relates to a circuit breaker unit having a circuit breaker for connecting at least two electrical networks. The invention further relates to a method and a corresponding control device for operating the circuit breaker.Circuit breakers are known which are used either directly on an electrical source or between two interconnected supply grids (for example in on-board electrical systems with 12V and 48V for motor vehicles). These circuit breakers react to the three fault modes: overcurrent, overvoltage and undervoltage (with the special case short circuit). These fault modes are triggered by reaching threshold values in the current and voltage measurement.Depending on a measuring speed and on the thresholds for overcurrent, overvoltage and undervoltage detection, known circuit breakers trigger a disconnection of the source or of two supply networks connected to one another by the circuit breaker. In this case, the voltages in both electrical supply grids can reach values which are critical for connected consumers. The isolating switches are partially limited in their ability to limit the voltage, for example by means of suppressor diodes. In addition, known circuit breakers react very lately to high currents, which requires a large number of power components because of the high energies which build up in the networks. This results in high costs for both the circuit breaker and protection elements and memories in control devices to handle over-voltages and under-voltages.DE 100 201 41 A1 discloses an on-board electrical system comprising at least one on-board vehicle electrical system and at least one onboard electrical subsystem in which safety-relevant loads are arranged, wherein the on-board vehicle electrical system and the onboard electrical subsystem with the safety-relevant loads operate at the same voltage level, wherein a DC / DC converter is arranged between the on-board vehicle electrical system and the onboard electrical subsystem, wherein a power diode having a first switching element arranged downstream is arranged parallel to the DC / DC converter and at least one second switching element is arranged in series to the parallel connection.DE 10 2018 201 863 A1 discloses a method for operating an on-board power supply system which has a first on-board power supply system channel and a second on-board power supply system channel, wherein the two on-board power supply system channels are connected to one another via a coupling element, wherein the coupling element has a first switch and a second switch, and wherein a center tap is carried out on the coupling element by measuring an electrical variable between the first switch and the second switch of the coupling element in order to carry out monitoring of the on-board power supply system.DE 10 2019, 212 473 A1 discloses a battery system for a motor vehicle, comprising a battery module which has an internal voltage source, a positive pole and a negative pole, and a switching unit for electrically connecting the battery module to an on-board power supply system of the motor vehicle.DE 10 2018 206 269 A1 discloses open DC-DC converters comprising: a primary-side current connection for connecting the DC-DC converter to a first voltage; a secondary-side current connection for connecting the DC-DC converter to a second voltage; a ground current connection for connecting the DC-DC converter to an electrical ground.DE 10 2016 220 466 A1 discloses a vehicle electrical system which comprises three on-board electrical system branches. DE 10 2019,205 801 A1 discloses a circuit breaker which is designed to enable bidirectional clamping, having a first current path and a second current path. DE 10 2018 202 987 A1 discloses a battery connection which realizes an electronically controlled on-board power supply system coupling-isolating functionality with an electronically controlled power distribution.The object of the invention is to specify an improved circuit breaker unit.The object is achieved according to the invention by the respective subject matter of the independent claims.Advantageous embodiments of the invention are the subject matter of the dependent claims.According to a first aspect, the invention is distinguished by a disconnection switch unit. The circuit breaker unit according to the invention has a circuit breaker and a control device. The circuit breaker serves for connecting at least two electrical networks comprising a first electrical network and a second electrical network. The control device is configured to monitor voltages of the networks and / or at least one current through the circuit breaker and to disconnect the two networks from one another in the event of one of the fault cases overvoltage or undervoltage in one of the networks or overcurrent via the circuit breaker. According to the invention, the circuit breaker comprises at least one controllable first resistor, one controllable second resistor and one controllable third resistor, wherein all three resistors are each connected to a common node, wherein the first resistor is furthermore connected to the first grid and the second resistor is connected to the second grid, wherein the third resistor is connected to a reference potential, in particular ground, wherein the control device is configured to adapt the values of the resistors in the event of a fault in one of the grids such that the grids are disconnected from one another and that the voltage in the fault-free grid remains within predefined limits.When adjusting the values of the resistors, so that the networks are separated from one another and that the voltage in the fault-free network remains within predefined limits, the control unit is designed to actuate at least temporarily at least one of the resistors depending on values for the voltage of the fault-free network detected or provided in predefined time steps and / or for the voltage of the fault-free network and / or for the at least one current, in such a way that the at least one resistor functions as a continuous linear regulator.This ensures that at least one of the at least two networks remains in the position for full supply or sufficient, restricted supply of the connected loads.In the circuit breaker according to the invention, the three resistors can each be connected directly or indirectly to the node and / or can be connected directly or indirectly to the respective electrical grid. For example, a shunt for current measurement or a diode or an inductance can be provided between the node and one of the resistors or between one of the resistors and one of the electrical networks, which shunt thus represents an indirect connection.It is also possible for a part of the components of the circuit breaker unit to be arranged in one housing and another part of the components to be arranged in another housing, and for the components to be connected to one another via one or more lines.The two electrical networks can be related to a reference potential, in particular ground.A disconnection of the two networks in the sense of the present invention is also to be understood in particular as a high-resistance connection (for example several megaohms) of the two networks via the appropriately set resistors. In contrast, in the case of a low-impedance connection, the two networks are understood to be connected to one another via the appropriately set resistors.It is conceivable that a higher, external logic disables the complete control of the circuit breaker unit. For example, it can be provided that a starter current flows via the isolating switch when the vehicle is stationary. This would actually be an overcurrent event, but since it is to be expected and the switch is not to trip, the function of the circuit breaker could be deactivated in this case.In an embodiment according to the first aspect, an inductance is arranged in series with the first resistor and / or an inductance is arranged in series with the second resistor.In one embodiment according to the first aspect, the control device is configured to set and / or maintain the first resistor and the second resistor with a low impedance and the third resistor with a high impedance in the fault-free case.For the separation of both networks and for the stabilization of the error-free network in quasi-real time, a measurement speed of the parameters voltage and / or current can be provided which is many times higher than an underlying control speed. Furthermore, a sufficiently accurate measurement with respect to the threshold values should preferably take place in a sufficiently short time, for example 0.1 μs to 20 μs, and after these threshold values have been reached or exceeded, a direct reaction of the circuit breaker should preferably take place.In one embodiment according to the first aspect, the control device is configured to set the first or second resistor connected to the fault-free grid with a high impedance in the event of the fault event under voltage in one of the grids and to set the third resistor with a low impedance shortly thereafter. This means that if the fault undervoltage occurs in the second grid, the first resistor is set to have a high impedance, and if the fault undervoltage occurs in the first grid, the second resistor is set to have a high impedance. In particular, the control device is configured to set the third resistor to be low-ohmic immediately after the first or the second resistor has reached a predefined high-ohmic value.In one embodiment according to the first aspect, the control device is configured to increase the first or second resistor connected to the fault-free network and to set the third resistor to be low-ohmic in the event of the fault case occurring in one of the networks. This means that if the fault case overcurrent occurs in the second grid, the first resistance is increased, and if the fault case overcurrent occurs in the first grid, the second resistance is increased. The increase of the first or the second resistor takes place in such a way that the voltage in the fault-free grid remains within the predefined limits for the grid voltages. The increase of the first or the second resistance takes place in particular depending on values for the voltage of the fault-free network and / or for the voltage of the fault-free network and / or for the at least one current that are detected or provided in predetermined time steps.The following procedure can be adopted for undervoltage and overcurrent:The first and second resistors, which are in particular configured as transistors, are each connected with a terminal drain in the direction of one of the connected networks and with a terminal source directly or indirectly connected to the node. The first and second resistors are driven from conductive to non-conductive via their respective gate, i.e. are switched off. The turn-off speed of both transistors should be so high that a current that builds up does not reach such a level that would result in one of the two transistors being outside its specified values when this current is turned off. The transistors must not be damaged by disconnection and must repeatedly sustain this turn-off pulse. The term "switch-off speed" is to be understood further here. For correct regulation, the total time results in particular from the times: time for the voltage measurement and / or current measurement, transit time of the digital filter, drive time of the transistor and the total pulse duration of the switch-off pulse.It is preferably ensured that when the networks are reconnected, the transistors withstand the full pulse again without damage at all times. Thermal aspects can be taken into account for this purpose in the regulation of the circuit breaker.Owing to the current, inductive energy occurs in a circuit breaker lead inductance of the fault-free network, which leads to an increase in the voltage when the first resistor, which is designed as a transistor, is switched off. If this current is sufficiently large, the voltage would go beyond a defined overvoltage limit, for example 16V. The gate of the resistor designed as a transistor, which is connected to the fault-free network, is now driven (switched on) again in such a way that the voltage is regulated to the defined overvoltage limit, for example 16 V, by the renewed opening or by the reduction of the linear resistance. This takes place until the current ideally reaches the value zero and thus the entire energy in the circuit breaker feed inductance has been dissipated. The fault-free network thus remains at least approximately within the specified voltage limits.In order that no interaction of the two circuit breaker lead inductances occurs (the values of which lie between 0.3 μH and 8 μH and can also be unequal), the third resistor, which is designed, for example, as a transistor or from two transistors connected antiseriesly or from two parallel transistors or from four antiserial and parallel transistors, is intended to become conductive. Due to the unknown energies and induction values of the circuit breaker lead inductances, a non-regulable state would be established without the low-resistance connection of the first and second resistors to the reference potential, in particular to ground. In addition, the energies in the transistors would potentially lead to destruction.In one embodiment according to the first aspect, the control device is configured to regulate the resistor connected to the faulty network in such a way that an undervoltage on the part of the faulty network caused by a line inductance in the faulty network does not fall below the predefined limits in the case of the fault-free network, wherein the third resistor remains or is set to have a high impedance and the resistor connected to the fault-free network is likewise set to have a high impedance after a current in the line inductance has been reduced. The resistor connected to the faulty network is thus controlled on the part of the faulty network as a function of an undervoltage on the part of the faulty network caused by a line inductance in the faulty network in such a way that it functions as a continuously linear regulator. The resistor, which is embodied as a transistor, retains its diode function for the case when the fault-free network is connected very highly inductively. The current to be dissipated can then freewheel in the third resistor.For example, when an overvoltage occurs, the first and second resistors, which may be configured as transistors, for example, are switched to a high impedance (switched off). Directly after the switching off, the gate of that transistor which points with its drain terminal to the faulty network is driven in such a way that the voltage in the fault-free network falls only up to a defined lower threshold value. Due to inductive discharge of the circuit breaker lead inductance in the fault-free network, the voltage would otherwise become lower than this lower threshold, potentially even negative. Therefore, the third resistor, which is configured as a transistor, is also not activated in order not to let the voltage at the node drop.In one embodiment according to the first aspect, the resistors are formed as semiconductor components, in particular transistors, for example MOSFETs, bipolar transistors, IGBTs, GaN-HEMTs and / or SIC semiconductors.In an embodiment according to the first aspect, the disconnection switch unit may be configured to be supplied with energy redundantly from the at least two connected networks. Furthermore, a separate power supply independent of the connected networks is also conceivable, which only has the same reference potential reference, in particular ground reference, on the output side. A separate storage-type supply within the control unit is also conceivable.In one embodiment according to the first aspect, at least one of the resistors is designed to be redundant. For example, a plurality of variants with anti-parallel or anti-serial paths and combinations thereof are conceivable, all of which are connected directly or indirectly to the node.According to a second and third aspect, the invention is distinguished by a method and a corresponding control device for operating a circuit breaker. The circuit breaker is designed for connecting a group of electrical networks. The group of electrical grids comprises at least a first electrical grid and a second electrical grid. The circuit breaker comprises at least one controllable first resistor, one controllable second resistor and one controllable third resistor, wherein all three resistors are each connected directly or indirectly to a common node, wherein the first resistor is furthermore connected directly or indirectly to the first grid and the second resistor is connected directly or indirectly to the second grid, wherein the third resistor is connected to a reference potential, in particular ground. In the method, the voltages of the networks and / or of at least one current through the circuit breaker are monitored. Furthermore, when one of the fault cases overvoltage or undervoltage in one of the networks or overcurrent occurs via the circuit breaker, the values of the resistors are adapted in such a way that the networks are disconnected from one another and that the voltage in the fault-free network remains within predefined limits.In an advantageous embodiment according to the second and third aspect, the adaptation of the values of the resistors so that the networks are separated from one another and that the voltage in the fault-free network remains within predefined limits comprises at least temporarily driving at least one of the resistors depending on values for the voltage of the fault-free network detected or provided in predefined time steps and / or for the voltage of the fault-free network and / or for the at least one current such that the at least one resistor acts as a continuous linear regulator.Advantageous embodiments according to the first aspect, which relate to the control device, also apply to the second and third aspects.The solution according to the invention can stabilize a redundantly constructed voltage supply, for example for 12 V, in the event of a fault. This leads to an improvement in the reliability. Furthermore, costs are reduced compared to the solutions known from the prior art.Due to the quasi-real-time response of the circuit breaker, it is possible to keep the voltage values of the non-defective branch in a predefined corridor without providing additional components, for example for voltage limiting, which must also be switchable in order to allow special cases such as permitted jump start. This corridor ensures that all the components in this branch maintain their function completely or to a limited extent allowed. An uncontrolled restart of a component is thus prevented. This condition leads to a significant increase in the reliability.The circuit breaker unit can be used in a battery monitoring system and in all devices in which, for example, electrical short circuits are to be intercepted and disconnected in real time. In particular, the circuit breaker unit can be used for connecting or disconnecting a plurality of electrical networks in a motor vehicle on a case-by-case basis.Exemplary embodiments of the invention are explained in more detail below with reference to drawings.The following are shown: FIG. 1 shows a schematic view of a circuit breaker unit with a circuit breaker arranged between a first electrical grid and a second electrical grid, FIG. 2 shows a schematic view of the circuit breaker unit with the circuit breaker when an undervoltage, for example a short circuit, occurs in the second grid, FIG. 3 shows a schematic view of the circuit breaker unit with the circuit breaker when an overcurrent occurs in the second grid, FIG. 4 shows a schematic view of the circuit breaker unit with the circuit breaker when an overvoltage occurs in the first grid, FIG. 5 shows a schematic view of an embodiment of the disconnection switch unit, FIGS. 6 a) to d) show various exemplary embodiments of redundantly designed circuit breakers, and FIGS. 7 a) to e) show different exemplary embodiments for an embodiment of a third resistor of the circuit breaker.Corresponding parts are provided with the same reference numerals in all figures.It is an object of the present invention to separate two networks coupled with low impedance to one another in the event of a fault in one of the networks in such a way that the respective other network remains fully or to a limited extent operable. If both networks have an electrical source which is dimensioned such that it can carry the electrical load of this network, the possibility arises of constructing a redundant network with extremely high reliability. The low-ohmic connection results in an electrical dependency. This requires a disconnection when a fault occurs, which stabilizes the non-faulted network within voltage limits to be specified. This ensures that at least one of the two networks remains fully functional. The following defect images can occur:1) Undervoltage2) Overcurrent Over-current3) OvervoltageThe actual cause of a failure (for example, breakdown of a source, short circuit in a consumer) is basically irrelevant, since such a failure is always expressed in one of the three fault patterns mentioned.FIG. 1 is a schematic view of an electronic circuit for solving all three fault patterns in the form of a circuit breaker unit 3 with a circuit breaker arranged between a first electrical grid 1 and a second electrical grid 2.The circuit breaker comprises at least one controllable first resistor R 1, one controllable second resistor R 2 and one controllable third resistor R 3, wherein all three resistors R 1 to R 3 are each connected directly or indirectly to a common node K. The first resistor R 1 is further connected directly or indirectly to the first network 1 and the second resistor R 2 is connected directly or indirectly to the second network 2. The third resistor R 3 is connected to a reference potential G, in particular ground.The first grid 1 is represented by a voltage source U q1 and one or more consumers, which are in the present case represented as parallel-connected complex resistors Z 11, Z 12, Z 1n (for example applications with pin capacitances and inductive components). A lead between the voltage source U q1 and the loads has a source lead inductance L 1. A lead between the first grid 1 and the circuit breaker has a circuit breaker lead inductance L' 1.The second grid 2 is represented by a voltage source U q2 and one or more consumers, which in the present case are represented as parallel-connected complex resistors Z 21, Z 22, Z 2n (for example applications with pin capacitances and inductive components). A lead between the voltage source U q2 and the loads has a source lead inductance L 2. A lead between the second grid 2 and the circuit breaker has a circuit breaker lead inductance L' 2.The voltage sources U q1, U q2 may have any voltage which is however the same for both voltage sources U q1, U q2 unless one of the voltage sources U q1, U q2 is also a memory (for example a lead battery). In this case, different voltage values can be set during a charging process. A larger number of voltage sources can be provided in at least one of the networks 1, 2. Furthermore, it is conceivable that more than two networks are coupled to one another via the circuit breaker and are correspondingly regulated by the circuit breaker.A value of the source lead inductances L 1, L 2 from the voltage sources U q1, U q2 to the loads is not known at the time of the circuit breaker design.Depending on the dimensioning of the circuit of the circuit breaker, a necessary minimum inductance, for example 0.5 μH, is obtained for the circuit breaker lead inductances L' 1, L' 2 in order to maintain the required voltage limit on the non-defective side in the event of a voltage dip on the fault side. If this minimum inductance is not present at the required level in the respective feed line, a corresponding inductance in the circuit breaker can be provided in series with the respective circuit breaker feed line inductance L' 1, L' 2. While the circuit breaker lead inductances L' 1, L' 2 are voltage stabilizing on the functional side, they can increase stored energies that must be dissipated in the resistor R 1, R 2.In the event of a fault in one of the networks 1, 2, the values of the resistors R 1, R 2, R 3 are adapted such that both networks 1, 2 can be separated from one another and that the voltage values on the non-defective side move within desired limits.In a normal state, the first and second resistors R 1 and R 2 have as low a resistance as possible, for example less than 100 milliohms or less than 30 milliohms, in particular less than 1 milliohm, and the third resistor R 3 has as high a resistance as possible, for example greater than 1 kiloohm, in particular several megaohms.FIG. 2 is a schematic view of the circuit breaker unit 3 with the circuit breaker disposed between the first electric grid 1 and the second electric grid 2 upon occurrence of an under voltage in the second grid 2.In the event of the occurrence of undervoltage in one of the networks 1, 2, for example in the event of a short circuit in the second network 2, a rapidly increasing short-circuit current I k which reduces a voltage U 2 at a connection of the circuit breaker to the second network 2, that is to say at the second resistor R 2, results. As a result, because of the low-impedance connection, a voltage U 1 at a connection of the circuit breaker to the first network 1, that is to say at the first resistor R 1. also decreases.A rate of change of the two voltages U 1, U 2 is decisively limited by the source lead inductances L 1, L 2 and the pin capacitances at the measurement points of the voltages U 1 and U 2.When predetermined threshold values of the voltages U 1, U 2 are undershot, the resistors R 1, R 2 and R 3 are changed such that: a) the two networks 1, The voltage U 1 cannot rise above a desired threshold value of the voltage in the first grid 1 during the inductive discharge of the source lead inductance L 1 and L 2 or after the discharge of the source lead inductance L and L are only still connected to one another with very high resistance. c) the inductive discharge of the source lead inductance L 2 can take place via the low-resistance third resistor R 3.Here, a time point at which a first current I 1 through the first resistor R 1 is zero and at which a second current I 2 through the second resistor R 2 is equal to a third current I 3 through the third resistor R 3 is not known. However, the third resistor R 3 should become low-ohmic after a short waiting time, for example shortly after the first resistor R 1 becomes high-ohmic. The waiting time can be, for example, a few μs, in particular less than 10 μs.In general, therefore, first the resistor R 1 or R 2 of the circuit breaker connected to the faulty network 1 or 2 should become high-ohmic and shortly thereafter the third resistor R 3 of the circuit breaker going to the reference potential G, in particular to ground, should become low-ohmic. If the resistors R 1, R 2, R 3 are formed as transistors, for example MOSFETs, bipolar transistors, IGBTs, GaN-HEMTs and / or SIC semiconductors (silicon carbide), the resistor R 1 or R 2 connected to the faulty network 1, 2 can also be switched off after the waiting time. The inductive pulse due to the inductance in the faulty network 1, 2 can freewheel via a body diode of the resistor R 1 or R 2 designed as a transistor.The fault itself is not corrected by the isolating switch unit 3. The two networks 1, 2 can be reconnected to one another as soon as the fault is eliminated and the values in both networks 1, 2 are within predefined threshold values. For example, the third resistor R 3 can first be set to have a high impedance and then, for example after a short waiting time, the resistor R 1, R 2 connected to the previously faulty network can be set to have a low impedance. In this case, the reconnection can have a thermal dependence by the transistors. For example, the circuit breaker and the nets 1, 2 are recovered. Due to a massive temperature increase in the resistors R 1 and / or R 2, such a pulse may not be instantaneously absorbed.FIG. 3 is a schematic view of the circuit breaker unit including the circuit breaker disposed between the first electric grid 1 and the second electric grid 2 when an overcurrent occurs in the second grid 2.If too high a current arises via the first resistor R 1 and the second resistor R 2 for example as a result of too high a load current I v through the loads in the second grid 2, although the predefined values for the voltages U 1 and U 2 are complied with, a disconnection of the two grids 1, 2 can likewise be triggered. In order to stabilize the first grid 1, the following conditions must be fulfilled: a) The first resistor R 1 should rise so quickly or so slowly that, during the inductive discharge of the source lead inductance L 1 the voltage U 1 does not exceed a desired voltage value. If the first resistor R 1 is designed as a transistor, its gate is regulated in such a way that the voltage U 1 does not exceed a desired voltage value. b) The inductive discharge of the circuit breaker lead inductances L' 1 and L' 2 takes place again with the aid of the third resistor R 3 by setting it to be low-ohmic, for example after a waiting time of 5 μs to 10 μs after the rise of the first resistor R 1. Depending on whether the first current I 1 or the second current I 2 is first zero, the free-wheeling path, i.e. the body diode, with a low-ohmic third resistor R 3 takes over the current of the respective other path.In general, therefore, first the resistor R 1 or R 2 of the circuit breaker connected to the fault-free network 1 or 2 should rise and then the third resistor R 3 of the circuit breaker, which goes to the reference potential G, in particular to ground, should become low-ohmic.For the cases of undervoltage and overcurrent, a measuring speed of the parameters voltage (U 1 or U 2) and / or current (I 1 or I 2) can be provided for the separation of both networks 1, 2 and for the stabilization of the fault-free network in quasi-real time, which measuring speed is many times higher than an underlying regulating speed. Furthermore, a sufficiently accurate measurement with respect to the threshold values should take place in a sufficiently short time, for example 0.1 μs to 20 μs, and after these threshold values have been reached or exceeded, a direct reaction of the circuit breaker unit 3 or of the circuit breaker should take place.The procedure can be as follows:The resistors R 1 and R 2, which are designed as transistors, are connected with the terminal drain respectively to the points U 1 and U 2 shown in FIG. 2 and are connected with the terminal source directly or indirectly to the node K, are driven from conducting to non-conducting via their respective gate, i.e. are switched off. The turn-off speed of both transistors should be so high that a current which builds up does not reach such a level that would lead to one of the two transistors being outside its specified values when this current is turned off. The transistors must not be damaged by disconnection and must repeatedly sustain this turn-off pulse.Owing to the first current I 1 inductive energy occurs in the circuit breaker lead inductance L' 1 of the fault-free network 1, which leads to an increase in the voltage U 1 when the first resistor R 1 designed as a transistor is switched off. If the first current I 1 is sufficiently large, the voltage U 1 would go beyond a defined overvoltage limit, for example 16V. The gate of the first resistor R 1 designed as a transistor is now driven (switched on) again in such a way that the voltage U 1 is regulated to the defined overvoltage limit, for example 16 V, by the renewed opening or by the reduction of the linear resistance. This takes place until the first current I 1 ideally reaches the value zero and thus the entire energy in the circuit breaker feed inductance L' 1 is reduced. The first grid 1 thus remains at least approximately within the specified voltage limits.In order that there is no interaction between the two of the circuit breaker lead inductances L' 1 and L' 2( whose values are between 0.3 μH and 8 μH and can also be unequal), the third resistor R, which is designed as a transistor or as two transistors connected in antiseries, should become conductive in a 3 manner. Due to the unknown energies and induction values of the circuit breaker lead inductances L' 1 and L' 2 a non-regulable state would be established without the low-ohmic connection of the two resistors R 1 and R 2 with respect to the reference potential G, in particular ground. In addition, the energies in the transistors would potentially lead to destruction.FIG. 4 is a schematic view of the circuit breaker unit 3 with the circuit breaker disposed between the first electric grid 1 and the second electric grid 2 upon occurrence of overvoltage in the first grid 1.Caused by a defective voltage source, for example U q1, a strong increase of a current I q1 flowing from the voltage source U q1 can occur and the predetermined threshold value can be exceeded by the voltage U 1. The network to be stabilized is in this case the second network 2. therefore at least one of the resistors R 1 to R 3, for example the first resistor R 1, should be changed such that: a) the inductive discharge of the source lead inductance L 2 does not lead to a dropping below the predetermined value of the voltage U 2 b) the first resistor R 1 is or becomes high-ohmic in order to reduce the first current I 1 c) the third resistor R 3 is regulated such that the voltage U 2 is not low-ohmic with the reference potential G, The second current I2 is not equal to zero and the second resistor R is 2 high-ohmic.In this case, the first resistor R 1 should be sufficiently voltage-proof that no damage is caused to the circuit breaker.In general, the resistor R 1, R 2 connected to the faulty network 1, 2 is thus regulated in such a way that an undervoltage on the part of the faulty network 1, 2 caused by a line inductance in the faulty network 1, 2 does not fall below the predefined limits, wherein the third resistor R 3 remains or is set to have a high impedance and the resistor R 1, R 2 connected to the faulty network 1, 2 is likewise set to have a high impedance after a current in the line inductance has been dissipated.In the case of overvoltage, a measurement speed of the parameters voltage (U 1 or U 2) and / or current (I 1 or I 2) can be provided for the separation of both networks 1, 2 and for the stabilization of the error-free network in quasi-real time, which measurement speed is many times higher than an underlying control speed. Furthermore, a sufficiently accurate measurement with respect to the threshold values should take place in a sufficiently short time, for example 0.1 μs to 20 μs, and after these threshold values have been reached or exceeded, a direct reaction of the circuit breaker unit 3 or of the circuit breaker should take place.When an overvoltage occurs, both resistors R 1, R 2, which can be designed as transistors, for example, are switched to high impedance (switched off). Directly after the switching off, the gate of that transistor which points with its drain terminal to the faulty network 1 is driven in such a way that the voltage U 2 falls only up to a defined lower threshold value. Due to inductive discharge of the circuit breaker lead inductance L' 2 the voltage U 2 would otherwise become lower than this lower threshold, potentially even negative. Therefore, the third resistor R 3 formed as a transistor is not activated either in order not to let the voltage at the node K drop.FIG. 5 is a schematic view of an embodiment of the circuit breaker unit 3 with an exemplary embodiment of the circuit breaker, which may be installed, for example, in a 12V supply network of a vehicle, for example a car. In general, numerous varying embodiments of isolating switches 3 are possible.The controllable resistors R 1 to R 3 can be designed as semiconductor components, for example transistors. Depending on the drive, these semiconductor components can have values of less than 1 milliohm to several megaohms. In an exemplary embodiment, the transistors may be implemented as N-channel MOSFETs. In the circuit breaker unit 3, for example, a very fast measurement of the voltages U 1, U 2 and of the current I1 and / or I2 and also a control of the resistors R 1, R 2, R 3 takes place with a high measurement frequency, for example up to several MHz, by means of a measurement unit. The measuring unit is arranged in a housing, for example, with the isolating switch. Alternatively, the control device can comprise the measuring unit.The circuit breaker, the control device and the measuring unit are arranged, for example, in a housing. Alternatively, it is possible for the circuit breaker or, in the case of a redundant, i.e. multiple, embodiment of the circuit breaker, the circuit breakers, the control device and the measuring unit to be arranged in at least two separate housings which are arranged offset from one another in a vehicle.In FIG. 5, the resistors R 1 and R 2 are formed by the transistors T 1, T 2 respectively. The resistor R 3 is formed by two transistors T 3, T4 connected in series.Permanent monitoring of the voltages U 1 and U 2 can take place, which are decisive as controlled variables. For this purpose, the voltages U 1 and U 2 can be detected in predefined time steps. The measurement of the current I1and / or I2as a triggering criterion can likewise take place permanently. Solutions are likewise conceivable in which the monitoring and / or measurement does not take place permanently, for example by switching off the monitoring and / or measurement.If the desired voltage or current values are exceeded or undershot, the transistors T 1 to T 4 are to be controlled in such a way that the non-defective grid 1 or 2 remains within specific limits. This means that the driving of the gates of the transistors takes place at exactly the speed at which the inductive discharges of the source lead inductances L 1 and L 2 do not lead to exceeding or falling below the predefined values of the voltages U 1 and / or U 2.Preferably, a separate power supply is provided for the control unit 4, since the circuit breaker, just like any other component, relies on at least one stable supply. This means that the power supply of its own is likewise carried out twice from both networks in an OR arrangement. Alternatively or additionally, external energy supplies are conceivable. When a stable voltage U 1 and / or U 2 is ensured, the supply of the circuit breaker unit 3 is also ensured.The transistor T4 in FIG. 5 serves merely as polarity reversal protection and is not absolutely required.The current measurement can be made at any point along the horizontal line via the resistors R 1 and R 2 respectively. For example, instead of current I 1, current I 2 may be measured. Measurement of current I3is not provided in the embodiment of Figure 5. However, in alternative embodiments, a measurement of current I3may be additionally provided.Instead of MOSFETs, other semiconductor components, for example bipolar transistors, IGBTs, GaN HEMTs and / or SIC semiconductors, can also be used.In one embodiment, the paths via T 1, T 2 and / or T 3 can be constructed redundantly, for example by means of a series, anti-serial or parallel transistor to T 1 and / or T 2, also in order to enable a cyclical testing during operation and in order to ensure full reliability in the event of damage. FIG. 6 shows various exemplary embodiments of redundantly designed circuit breakers, in particular for the respective paths between the mains voltage nodes at which the voltages of the mains U 1, U 2 are present in each case, and the common node K. FIG. 7 shows various exemplary embodiments for an embodiment of the third resistor of the circuit breaker.Excessively rapid or uncontrolled opening of the connection, that is to say via the semiconductor components, in particular the transistors T 1, T 2 and / or T 3, can lead to under- or over-voltages on one terminal or both terminals of the semiconductor component. This can be avoided by linearly controlling at least a part of the semiconductor components used, in particular by driving the semiconductor component, so that these behave like controllable linear resistors.List of reference characters1 first grid 2 second grid 3 circuit breaker unit 4 control device G reference potential I 1 first current I 2 second current I 3 third current I k short-circuit current I v load current I q1 current K node L 1 source lead inductance L 2 source lead inductance L' 1 circuit breaker lead inductance L' 2 circuit breaker lead inductance R1 first resistor R2z further resistor R3 third resistor t 1 to T 4 transistors U 1 voltage U 2 voltage U q1 voltage source U q2 voltage source Z 11, Z 12, Z 1n complex resistors Z 21, Z22, Z2ncomplex resistors

Claims

Circuit breaker unit (3) having a circuit breaker for connecting at least two electrical networks (1, 2) comprising a first electrical network (1) and a second electrical network (2), and a control device (4) which is configured to monitor voltages (U 1, U 2) of the networks (1, 2) and / or at least one current (I1, I2) through the circuit breaker and, if one of the fault cases overvoltage or undervoltage in one of the networks (1, 2) or overcurrent occurs via the circuit breaker, to disconnect the two networks (1, 2) from one another, wherein the circuit breaker comprises at least one controllable first resistor (R 1), one controllable second resistor (R 2) and one controllable third resistor (R 3), wherein all three resistors (R 1 to R 3) are each connected directly or indirectly to a common node (K), wherein the first resistor (R 1) is furthermore connected directly or indirectly to the first grid (1) and the second resistor (R 2) is connected directly or indirectly to the second grid (2), wherein the third resistor (R 3) is connected to a reference potential (G), wherein the control device (4) is configured to adapt the values of the resistors (R 1, R 2, R 3) in a fault case in one of the grids (1, 2) such that the grids (1, The voltage across the grid of electrodes of the voltage source may be separated from one another in a manner such that the voltage (U 1, U 2) in the fault-free grid (1, 2) remains within predefined limits, wherein the control unit (4) is designed, when the values of the resistors (R 1, R 2, R 3), are adjusted, such that the grids (1, 2) are separated from one another and that the voltage (U 1, U 2) in the fault-free grid (1, 2) remains within predefined limits, to temporarily at least one of the resistors (R1, R2, R3) depending on values for the voltage (U 1, which are detected or provided in predefined time steps, U 2) of the fault-free network and / or for the voltage (U 1, U 2) of the fault-free network and / or for the at least one current (I1, I2) to be controlled in such a way that the at least one resistor (R1, R2, R3) functions as a continuous linear regulator.The circuit breaker unit (3) according to claim 1, wherein an inductance is arranged in series with the first resistor (R 1) of the circuit breaker and / or that an inductance is arranged in series with the second resistor (R 2) of the circuit breaker.Circuit breaker unit (3) according to one of the preceding claims, wherein the control device (4) is configured to set the first resistor (R 1) and the second resistor (R 2) to have a low impedance and the third resistor (R 3) to have a high impedance in the fault-free case.Circuit breaker unit (3) according to one of the preceding claims, wherein the control device (4) is configured to set the first or second resistor (R 1, R 2) connected to the fault-free network (1, 2) to have a high impedance in the event of the fault event under-voltage in one of the networks (1, 2) and to set the third resistor (R 3) to have a low impedance shortly thereafter.Circuit breaker unit (3) according to one of the preceding claims, wherein the control device (4) is configured to increase the first or second resistor (R 1, R 2) connected to the fault-free network (1, 2) and to set the third resistor (R 3) to be low-ohmic in the event of the fault situation in one of the networks (1, 2).Circuit breaker unit (3) according to one of the preceding claims, wherein the control device (4) is configured to, in the event of the fault situation, regulate the overvoltage in one of the networks (1, 2) with the resistor (R 1, R 2) connected to the fault network (1, 2) in such a way that an undervoltage on the part of the fault-free network (1, 2) caused by a line inductance does not fall below the predefined limits for the voltage (U 1, U 2) wherein the third resistor (R 3) remains or is set with high impedance and the resistor (R 1, connected to the fault-free network (1, 2), R 2) is likewise set to a high impedance after a current in the line inductance has been reduced.Circuit breaker unit (3) according to one of the preceding claims, wherein the resistors (R 1, R 2, R 3) are designed as semiconductor components.The circuit breaker unit (3) according to claim 7, wherein the transistors are formed as MOSFETs, bipolar transistors, IGBTs, GaN HEMTs and / or SIC semiconductors.The circuit breaker unit (3) according to any of the preceding claims, wherein the circuit breaker unit (3) is configured to be supplied with energy redundantly from the at least two connected networks (1, 2).Circuit breaker unit (3) according to one of the preceding claims, wherein at least one of the resistors (R 1, R 2, R 3) is designed to be redundant.Method for operating a circuit breaker, wherein - the circuit breaker is designed for connecting a group of electrical grids and the group of electrical grids has at least a first electrical grid and a second electrical grid, - the circuit breaker comprises at least one controllable first resistor (R 1), one controllable second resistor (R 2) and one controllable third resistor (R 3) wherein all three resistors (R 1 to R 3) are each connected directly or indirectly to a common node (K), wherein the first resistor (R 1) is further connected directly or indirectly to the first grid (1) and the second resistor (R 2) is connected directly or indirectly to the second grid (2), wherein the third resistor (R 3) is connected to a reference potential (G), and the method comprises the following steps: - monitoring voltages (U 1, U 2) of the grids (1, 2) and / or at least one current (I1, I2) through the circuit breaker and - if one of the fault cases occurs, overvoltage or undervoltage in one of the grids (1, 2) or overcurrent via the circuit breaker adapt the values of the resistors (R 1, R 2, R 3), so that the networks (1, 2) are disconnected from each other and that the voltage (U 1, U 2) in the fault-free network (1, 2) remains within predetermined limits, wherein adjusting the values of the resistors (R 1, R 2, R 3), so that the networks (1, 2) are disconnected from each other and that the voltage (U 1, U 2) in the fault-free network (1, 2) remains within predetermined limits comprises that second at least one of the resistors (R 1, R2, R 3) is controlled as a function of values for the voltage of the fault-free network and / or for the voltage of the fault-free network and / or for the at least one current that are detected or provided in predetermined time steps, such that the at least one resistor (R 1, R 2, R 3) functions as a continuous linear regulator.Control device for operating a circuit breaker, wherein - the circuit breaker is designed for connecting a group of electrical networks and the group of electrical networks has at least a first electrical network and a second electrical network, - the circuit breaker comprises at least one controllable first resistor (R 1), one controllable second resistor (R 2) and one controllable third resistor (R 3) wherein all three resistors (R 1 to R 3) are each connected directly or indirectly to a common node (K), wherein the first resistor (R 1) is further connected directly or indirectly to the first grid (1) and the second resistor (R 2) is connected directly or indirectly to the second grid (2), wherein the third resistor (R 3) is connected to a reference potential (G), and - the control device is configured to carry out the method according to claim 11.

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