Control circuit of a hybrid switch

Abstract

The invention relates to a control circuit (22) of a hybrid switch (2) comprising a main current path (10), which has a disconnecting element (24), and an auxiliary current path (12), which is connected in parallel with the main current path (10) and has a semiconductor switch (16). The control circuit (22) has a first terminal (30) for the disconnecting element (24) and a second terminal (20) for the semiconductor switch (16) and is provided and configured to carry out a method (50) in which a request (54) for interrupting a current flow via the hybrid switch (2) is recognized. A temporal sequence of an electrical voltage applied to each of the two terminals (20, 30) is chosen depending on the disconnecting element (24) connected to the first terminal (30) and the semiconductor switch (16) connected to the second terminal (20). Furthermore, the invention relates to a hybrid switch (2).

Description

[0001] Description

[0002] Control circuit of a hybrid switch

[0003] The invention relates to a control circuit for a hybrid switch and a hybrid switch. The hybrid switch has a main current path with an isolating element and a secondary current path connected in parallel to the main current path with a semiconductor switch.

[0004] From WO 2010 / 108565 A1 a hybrid switch (hybrid isolating switch) with a mechanical switch or isolating element and semiconductor electronics connected in parallel thereto is known, which comprises a semiconductor switch, preferably an IGBT. The semiconductor electronics has no additional energy source and, when the mechanical switch is closed, is current-blocking, i.e. there is practically no current or voltage. To interrupt the current via the hybrid switch, the mechanical switch is opened, which can create an arc. The energy of the arc created when the mechanical switch opens is used by the semiconductor electronics, wherein the semiconductor electronics are connected to the mechanical switch in such a way that when the mechanical switch opens, the arc voltage across it (as a result of the arc) causes the semiconductor switch to conduct current.

[0005] As soon as the semiconductor switch is switched on, the electrical current begins to commutate from the mechanical switch to the semiconductor switch. The corresponding arc voltage or arc current also charges an energy storage device in the form of a capacitor, which provides the control voltage for the semiconductor electronics. As soon as the electrical current has commutated to the semiconductor switch, the arc is extinguished and the charging process of the energy storage device is completed. An ionized gas, created by the arc, is located between the switching contacts of the mechanical switch and dissipates over time. Following the charging process, a timer starts, during which the energy storage device keeps the semiconductor switch conducting. After the timer period has elapsed, the semiconductor switch is switched to blocking current again.Instead of using the timer, for example, the time duration is specified based on the charge level of the energy storage device.

[0006] If the time period is chosen too short, it is possible that the ionized gas still present between the switching contacts of the mechanical switch and the applied electrical voltage will cause an arc to ignite again, causing an electrical current to flow through the mechanical switches again. Therefore, the time period is usually chosen to be relatively long, assuming that the ionized gas has sufficiently dissipated after this time and / or that the distance between the switching contacts of the mechanical switch is large enough to prevent the arc from igniting again.

[0007] Such a hybrid switch is also known from EP 1 881 511 A1. However, in this case, the semiconductor switch is closed essentially simultaneously with the mechanical switch opening, so that when the contacts of the mechanical switch mechanically separate, a current already flows through the semiconductor switch. This prevents the formation of an arc. However, an external voltage source is required to actuate the semiconductor switch.

[0008] Since in the embodiment according to EP 1 881 511 A1 a comparatively large electrical current is carried by the semiconductor switch, it is necessary to design it to be comparatively robust. In other words, it is not possible to operate the hybrid switch shown in WO 2010 / 108565 A1, in which only a comparatively small electrical current is carried by the semiconductor switch, according to the method known from EP 1 881 511 A1, even if an external voltage source were available. Therefore, the interconnection of the individual components is adapted to the respective hybrid switch, and it is not possible to use identical parts during production. Therefore, the manufacturing costs of each hybrid switch are comparatively high.

[0009] The invention is based on the object of specifying a particularly suitable control circuit of a hybrid switch and a particularly suitable hybrid switch, wherein manufacturing costs are expediently reduced.

[0010] With regard to the control circuit, this object is achieved according to the invention by the features of claim 1 and with regard to the hybrid switch by the features of claim 7. Advantageous embodiments and further developments are the subject of the dependent claims.

[0011] In the assembled state, the control circuit is a component of a hybrid switch. In other words, the control circuit is provided and configured to form a component of the hybrid switch. Consequently, the control circuit is provided and configured to be mounted on other components of the hybrid switch. In the assembled state, the hybrid switch or other components of the hybrid switch are controlled by means of the control circuit, and the control circuit is provided and configured to operate the hybrid switch or at least other components of the hybrid switch.

[0012] The hybrid switch is a disconnecting device, i.e., a switch unit / switching unit. The hybrid switch has a main current path, which is formed in particular between two terminals of the hybrid switch or at least connected between them. The two terminals serve in particular to make contact with other components of an electrical circuit, such as cables or busbars, and are formed, for example, by means of terminals or plugs. The main current path has an actuatable disconnecting element. It is possible to close this disconnecting element, in which, in particular, the main current path has a low resistance, so that, in particular, a current flow is possible between the two ends of the main current path, expediently between the two terminals.In the open state, however, the isolating element is designed with high resistance, so that current flow through the main current path is essentially impossible, or at least an increased ohmic resistance prevails. In summary, the isolating element is electrically conductive in the closed state and electrically non-conductive in the open state.

[0013] The isolating element is expediently a galvanically isolating component when open. The isolating element is expediently a mechanical switch, such as a relay, a contactor, or a plug, or comprises at least one of these. Alternatively, the isolating element is designed in the manner of a surge protector. The surge protector in particular has a spark gap, which is also referred to as a gas discharge tube (GDT) or at least comprises one. The isolating element is particularly suitable, preferably provided and configured, for galvanically isolating the main current path upon opening, i.e., upon being placed in the open / open state.

[0014] The hybrid switch further comprises a secondary current path comprising a semiconductor switch. In particular, the semiconductor switch is connected in parallel to the isolating element, such that the isolating element is bridged by the semiconductor switch. Alternatively, for example, further components of the main current path are bridged by the semiconductor switch. The semiconductor switch is expediently a power semiconductor switch and preferably a field-effect transistor, such as a MOSFET, an IGBT, or a GTO. In particular, during normal operation, i.e. when a current is to flow through the hybrid switch, the semiconductor switch blocks current. Thus, electrical losses of the hybrid switch during operation are comparatively low. When the semiconductor switch is open, it has a high-impedance design, so that a current flow through it is essentially impossible.In other words, in the open state, the semiconductor switch is electrically non-conductive. In a closed state of the semiconductor switch, the semiconductor switch has low resistance and is therefore electrically conductive. The control circuit is suitable, in particular provided and configured, to be electrically contacted with the isolating element and the semiconductor switch. In particular, during operation, the isolating element and the semiconductor switch are controlled by means of the control circuit, and this is suitable, provided and configured for this purpose. In particular, the isolating element and the semiconductor switch are also suitable, provided and configured to be actuated by means of the control circuit and are therefore each electrically actuable.

[0015] The control circuit has a first connection for the isolating element and a second connection for the semiconductor switch. In the assembled state, the isolating element is connected to the first connection and the semiconductor switch is connected to the second connection. To actuate the semiconductor switch / isolating element, a corresponding electrical voltage is applied to the respectively assigned connection, such that a state of the semiconductor switch or of the isolating element is changed, and this is in particular electrically conductive or electrically non-conductive. The control circuit is suitable, in particular provided and configured, to apply a different electrical voltage to the respective connections, and the application of the respective electrical voltage to the connections is in particular possible independently of one another.To open and close the isolating element / semiconductor switch, the corresponding electrical voltage is applied to the respective terminal. The applied electrical voltage is always different from 0 V, for example. Preferably, at least one of the applied electrical voltages is equal to 0 V. In particular, the applied electrical voltage is adapted to the respective semiconductor switch / isolating element used.

[0016] The control circuit is provided and configured to carry out a method. In other words, the method is carried out during operation by means of the control circuit. According to the method, a request to interrupt a current flow via the hybrid switch is detected. For example, the request is provided externally and received by the control circuit. In particular, the control circuit has a corresponding interface for this. Alternatively or in combination with this, the request is generated by means of the control circuit or at least the hybrid switch itself, for example upon manual actuation of an input device such as a switch or due to a malfunction, for example in the event of a fault current, an overcurrent and / or an overvoltage. In this case, the hybrid switch is, for example, a component of a circuit breaker or forms a circuit breaker.

[0017] The method thus serves, in particular, to interrupt current via the hybrid switch, expediently interrupting direct current. In other words, the method involves interrupting an electrical current flow between a direct current source and an electrical device that are electrically connected via the hybrid switch. In particular, the method is thus only initiated when an electrical current is being conducted via the hybrid switch. The hybrid switch is designed, for example, to be unidirectional or bidirectional. For example, the electrical voltages that can be switched via the hybrid switch, preferably the respective nominal voltage, are between 200 V and 3 kV and in particular 220 V, 400 V, 650 V, 1000 V, or 1500 V.

[0018] In particular, the control circuit has one or more sensor terminals via which current data regarding the electrical current flowing through the hybrid switch and / or the electrical voltage applied thereto can be received. In particular, a corresponding sensor of the hybrid switch, for example a current sensor and / or an electrical voltage sensor, is connected to the sensor terminal(s) in the assembled state. Based on the measurement data, it is checked, in particular, whether a malfunction exists, and if so, the request is generated.

[0019] According to the method, a temporal sequence of an electrical voltage applied to the two connections is further selected as a function of the isolating element connected to the first connection and as a function of the semiconductor switch connected to the second connection. In other words, the temporal sequence is changed if different isolating elements and / or semiconductor switches are connected, i.e. in particular different types or types of isolating elements / semiconductor switches which in particular have different electrical performance data and / or properties. For example, after the request to interrupt is recognized, it is first checked which type of isolating element is connected to the first connection and which type of semiconductor switch is connected to the second connection. Alternatively, this is stored, for example, in the control circuit, for example in a memory, and is read out accordingly.Alternatively, one or more switches, such as coding switches or jumper plugs, are set depending on the isolating element / semiconductor switch used, and the setting is read out.

[0020] In this case, it is possible, for example, that an electrical voltage is first applied to the second terminal so that the semiconductor switch is closed. Subsequently, for example, the isolating element is opened, for which a corresponding electrical voltage is applied to the first terminal. The semiconductor switch is then opened again, for which the electrical voltage applied to the second terminal is adjusted. The electrical current carried by the hybrid switch thus initially commutates to the secondary current path so that no arc is created when the isolating element is opened. The current flow is then safely interrupted by the subsequent opening of the semiconductor switch. In this variant, no arc occurs, which is why the isolating element is essentially not loaded during such a switching operation of the hybrid switch.

[0021] Alternatively, for example, the semiconductor switch is closed essentially at the same time as the isolating element opens, so that the commutation of the electrical current also takes place essentially immediately upon opening of the isolating element. To open and close the isolating element / semiconductor switch, the corresponding electrical voltage is applied to the respective connection. With this variant, it is possible that an arc may occur briefly, but this arc will extinguish essentially immediately due to the commutation of the electrical current to the secondary current path. Subsequently, in particular, the semiconductor switch is opened, so that the flow of electrical current is interrupted. Due to this process, the time until the hybrid switch is in the electrically non-conductive state is shortened. However, the load on the isolating element is increased.

[0022] With another semiconductor switch and / or isolating element, for example, the isolating element is first opened, with the semiconductor switch also being open. This allows an arc to form due to the now applied electrical voltage, so that an electrical current continues to flow through the isolating element. Only subsequently is the semiconductor switch closed, so that the electrical current commutates to the secondary current path and the arc is extinguished. The semiconductor switch is then opened, safely preventing the flow of electrical current. In this case, the load on the semiconductor switch is reduced.

[0023] In particular, not only the temporal sequence of application of the respective electrical voltage, i.e. its opening and closing, is specified based on the isolating element / semiconductor switch used, but also, for example, the time interval at which the respective opening / closing of the semiconductor switch / isolating element takes place, for which the corresponding electrical voltage is applied. For example, the time for switching on the semiconductor switch is selected depending on the presence of an arcing chamber in the isolating element. If this is present, the semiconductor switch is expediently closed when the arc has reached the arcing chamber. The period of time in which the semiconductor switch remains in the open state after the isolating element has opened is shortened compared to when using an isolating element that does not have an arcing chamber.The arcing chamber increases the electrical voltage required to maintain the arc. This prevents the arc from re-igniting when the semiconductor switch is subsequently opened after the electrical current has commutated to the secondary current path. In a further development, alternatively or in combination, the respective (electrical) voltage is adjusted such that the electrical current flow is limited. In other words, for example, the voltage applied to the second terminal does not completely close the semiconductor switch, and the switch is not fully switched on. Thus, the semiconductor switch continues to exhibit an electrical resistance.

[0024] Since the timing for applying the respective electrical voltage depends on the semiconductor switch / isolating element used, it is possible to use the control circuit with a wide variety of hybrid switches and combine it with a wide variety of semiconductor switches / isolating elements. These can be adapted to the specific application, increasing flexibility. The timing of the actuation of the semiconductor switch and the isolating element is also adjusted accordingly after the request to interrupt the current flow has been issued. No modification or adaptation of the control circuit is required. Consequently, the control circuit can be produced in comparatively large quantities, thus reducing manufacturing costs.The method also relates in particular to the method for operating the control circuit or the hybrid switch, in which the above-mentioned work steps are carried out.

[0025] The method is expediently carried out by interconnecting the individual components of the control circuit, for example discrete components such as electrical components, for example resistors, capacitors, diodes or inductors. The control circuit preferably comprises an application-specific integrated circuit (ASIC) and is formed, for example, by means of this. Alternatively or in combination with this, the control circuit has a computer that is suitably designed to be programmable. The computer is, for example, a programmable microprocessor or comprises one. Expediently, the control circuit has a storage medium on which a computer program product, also referred to as a computer program, is stored, wherein upon execution of this computer program product, i.e. the program, the computer is caused to carry out the method.In summary, the control circuit is expediently constructed in such a way, and the individual components / parts of the control circuit are preferably interconnected in such a way that the method is carried out during operation. For example, the interconnection is provided by a common printed circuit board, or the control circuit comprises several corresponding printed circuit boards.

[0026] The method, and thus also the control circuit, is expediently designed such that, if the current-carrying capacity of the semiconductor switch is less than a threshold value, an electrical voltage causing the isolating element to open is first applied to the first terminal. For example, the current-carrying capacity of the semiconductor switch is stored in the control circuit or is intrinsically predetermined based on the semiconductor switch used, or at least its type. The threshold value is adapted, for example, to the respective intended use of the hybrid switch, for example, a nominal current carried by the hybrid switch. Alternatively, the threshold value is, in particular, predetermined absolutely.After a time window following the opening of the isolating element, during which the arc is formed in particular in the isolating element, an electrical voltage causing the semiconductor switch to close is applied to the second terminal for a period of time. After the time period has elapsed, the application of this electrical voltage is discontinued and the semiconductor switch is preferably returned to the open state. The time period is comparatively short and in particular shorter than 1 ps. Advantageously, the time period is greater than 1 ms or at least 1 ns. The time window, however, is greater than the time period and in particular greater than 10 ms and preferably less than 10 ps.

[0027] Due to this design, the arc is initially formed when the current is interrupted. When the time window is over, the arc has a comparatively long length and the arc voltage, i.e. the electrical voltage required to maintain the arc, is comparatively high. If the semiconductor switch is now closed at least briefly, namely for the time period, the electrical current commutates from the main current path to the secondary current path. After the time period has elapsed, the semiconductor switch is opened again and the flow of electrical current via the secondary current path is interrupted. The electrical voltage now applied is not sufficient to reignite the arc, so that after a comparatively short period of time the hybrid switch is electrically non-conductive.The semiconductor switch conducts the electrical current only for the specified period of time, thus reducing the load on the semiconductor switch. This, along with the reduced current carrying capacity, makes it possible to use a comparatively cost-effective semiconductor switch.

[0028] For example, the control circuit has a third terminal for connection to an external voltage source. The third terminal is suitable, in particular provided and configured, for this purpose. At least some of the further components / parts of the control circuit are expediently connected to the third terminal in such a way that, during operation, they are supplied with electrical energy using the external voltage source, provided the external voltage source is connected to the third terminal. The method, and thus also the control circuit, are expediently designed such that, when an electrical supply voltage is applied to the third terminal, an electrical voltage causing the semiconductor switch to close is first applied to the second terminal. Subsequently, or at most simultaneously, an electrical voltage causing the isolating element to open is applied to the first terminal.Thus, the electrical current commutates from the main current path to the secondary current path when or before the isolating element is opened, which is why no arc is formed when the isolating element is opened. This reduces the load on the isolating element, and it can be selected comparatively cost-effectively, in particular without a possible arcing chamber. This temporal sequence of controlling the semiconductor switch and the isolating element expediently occurs only or at least also when the isolating element does not have a arcing chamber. Since power is supplied via the third terminal of the control circuit during operation, it is possible to select the time interval between the closing of the semiconductor switch and the opening of the isolating element essentially arbitrarily, or this occurs in particular depending on the semiconductor switch / isolating element used / connected.For example, in the case of a semiconductor switch which has a comparatively high current carrying capacity, the time interval is chosen to be longer.

[0029] Particularly preferably, the method, and thus also the control circuit, is designed such that, when no electrical supply voltage is applied to the third terminal, an electrical voltage causing the isolating element to open is first applied to the first terminal. Subsequently, i.e. at a time interval, an electrical voltage causing the semiconductor switch to close is applied to the second terminal. In particular, an electrical voltage arising across the isolating element due to the arc that forms is used to apply the electrical voltage causing the semiconductor switch to close to the second terminal. For example, an energy store is charged using the electrical voltage arising across the isolating element, and the corresponding electrical voltage is subsequently applied to the second terminal by means of the energy store.In particular, a constant period of time is formed between the opening of the isolating element and the closing of the semiconductor switch.

[0030] Due to this procedure, it is possible to supply the hybrid switch either with the external voltage source, thus enabling switching without the formation of an arc. However, it is also possible to use the hybrid switch in an installation situation in which no external voltage source is available. Even if, for example, a malfunction occurs and in particular an electrical line connected to the third terminal, by means of which the hybrid switch and the external voltage source are connected, breaks, the flow of electrical current via the hybrid switch is still reliably interrupted. Preferably, the control circuit has a fourth terminal for connection to a second semiconductor switch. The fourth terminal is suitable, in particular provided and configured, for this purpose.In the assembled state, the second semiconductor switch is electrically connected in series with the isolating element and is thus a component of the main current path. The method, and consequently also the control circuit, is expediently designed such that an electrical voltage causing the second semiconductor switch to open is applied to the fourth terminal when it has been detected that the second semiconductor switch is connected to the fourth terminal. Subsequently, an electrical voltage causing the isolating element to open is applied to the first terminal. Preferably, before the electrical voltage causing the second semiconductor switch to open is applied, an electrical voltage causing the semiconductor switch to close is applied to the second terminal. Thus, by means of the second semiconductor switch, a current flow via the main current path is interrupted, so that the electrical current commutates completely to the secondary current path.The electrical voltage subsequently accruing via the second semiconductor switch, i.e. the main current path, is comparatively low due to the closed semiconductor switch, so that only comparatively low losses occur in the second semiconductor switch and the load on the second semiconductor switch is comparatively low. Subsequently, in particular, an electrical voltage is applied to the second terminal such that the semiconductor switch is opened and thus the current flow via the hybrid switch is interrupted. The opening of the isolating element occurs in particular arbitrarily or at least independently of the opening of the semiconductor switch. If, on the other hand, it is detected that no second semiconductor switch is connected to the fourth terminal, in particular no electrical voltage is applied to it, or for example in this case the semiconductor switch is only closed after the isolating element has opened.

[0031] To detect whether the second semiconductor switch is connected to the fourth terminal, for example, a resistor provided at the fourth terminal is checked. Alternatively, a configuration is read out which has been stored, for example, using software, preferably in a memory. Alternatively, the configuration is stored by mechanical adjustment, for example by appropriately configuring a jumper plug or the like. In a further alternative, the corresponding electrical voltage causing the opening is first applied for detection, and if, for example, an electrical current flows, the application is maintained, since this only occurs when the second semiconductor switch is connected. Alternatively, the application of the corresponding electrical voltage is maintained regardless of whether an electrical current flows.Thus, it is not necessary to provide a corresponding sensor, which reduces the manufacturing costs of the control circuit.

[0032] Particularly preferably, the method, and thus the control circuit, is designed such that the timing is also adapted depending on a current state, in particular the current state of the control circuit and / or the isolating element / semiconductor switch used. In particular, the current state is first determined, for example using a theoretical model. Alternatively, the state is determined, for example, using measurement data provided via one or more of the possible sensor connections. For example, if the temperature of the semiconductor switch is elevated, further loading is avoided and, for example, it is always left in the closed state. In this case, only the isolating element is opened, which is why the duration during which the electrical current still flows is comparatively long.

[0033] The hybrid switch has a main current path with a isolating element and a secondary current path connected in parallel to the main current path with a semiconductor switch. The isolating element is, for example, a mechanical switch, such as a relay or contactor. Alternatively, the isolating element is designed, for example, in the manner of a plug. In particular, the isolating element is designed such that when opened, i.e. when the ohmic resistance increases, a mechanical separation of two contacts occurs, through which an electrical current flows when closed, with the two contacts mechanically abutting one another. The semiconductor switch is expediently connected to a power semiconductor switch, for example an IGBT or MOSFET.

[0034] The hybrid switch further comprises a control circuit with a first terminal to which the isolating element is connected. In addition, the control circuit has a second terminal to which the semiconductor switch is connected. For example, the semiconductor switch / isolating element is detachably connected to the respective terminal, which is designed in particular in the manner of a plug. Alternatively, the semiconductor switch and / or the isolating element is soldered to the respective terminal or electrically contacted in another way. The two terminals are designed according to the isolating element / semiconductor switch, and via this, in particular, a respective electrical voltage can be applied to the isolating element and the semiconductor switch, so that they are controlled by the control circuit.Thus, it is possible to change a (switching) state of the semiconductor switch / isolating element by means of the control circuit and, in particular, to transfer it from an open to a closed state and vice versa.

[0035] The control circuit is provided and configured to perform a method in which a request to interrupt a current flow through the hybrid switch is detected. In other words, the request specifies that an electrical current flowing through the hybrid switch is to be interrupted. The timing of an electrical voltage applied to each of the two terminals is selected depending on the isolating element connected to the first terminal and the semiconductor switch connected to the second terminal.

[0036] In particular, the hybrid switch is used in a direct current circuit, and the method is carried out in particular for interrupting direct current. For example, the hybrid switch, in its assembled state, is a component of industrial automation, street lighting, a ship's on-board power system, electrified aviation, railway infrastructure, or the railway drive of an isolated grid in the private home, an energy generator, a greenhouse, or is used in the field of electromobility, for example, in a motor vehicle, in agriculture, or in a construction vehicle. In particular, the hybrid switch is suitable, expediently provided, and configured for this purpose.

[0037] The further developments and advantages explained in connection with the control circuit can also be transferred analogously to the method / the hybrid switch / the use and to each other and vice versa.

[0038] An embodiment of the invention is explained in more detail below with reference to a drawing. In the drawings:

[0039] Fig. 1 schematically shows a hybrid switch with a control circuit, and Fig. 2 shows a method carried out by the control circuit.

[0040] Corresponding parts are provided with the same reference numerals in all figures.

[0041] Figure 1 shows a simplified schematic of a hybrid switch 2 used in a direct current circuit 4. The hybrid switch 2 has two terminals 6, each connected to a line 8 of the direct current circuit 4. The direct current circuit 4 is a component of a railway infrastructure, and by means of it, i.e., via the lines 8, an electrical current of over 50 A is carried during normal operation, with an electrical voltage with respect to a ground (not shown in detail) being greater than 300 V.

[0042] The hybrid switch 2 has a main current path 10, which is connected between the two terminals 6 and which is bridged by a secondary current path 12. A sensor 14 is connected between one of the terminals 6 and the main current path 10, and consequently also between this terminal 6 and the secondary current path 12, or is at least assigned to the part of a current line located there, by means of which the main current path 10 and the secondary current path 12 are electrically contacted with this terminal 6. The sensor 14 is a current sensor, by means of which the electrical current flowing between the terminals 6 can be measured. In summary, the two terminals 6 are electrically connected by means of the main current path 10 and the secondary current path 12.

[0043] The auxiliary current path 12 has a semiconductor switch 16. This is designed as an IGBT or MOSFET and is introduced into the auxiliary current path 12 in such a way that it can be used to create or interrupt an electrical current flow via the auxiliary current path 12. For this purpose, it is possible to bring the semiconductor switch 16 into the closed state, so that the electrical resistance provided by the semiconductor switch 16 is essentially negligible. It is also possible to open the semiconductor switch 16, i.e. to switch it to a current-blocking state so that it is electrically non-conductive. In this case, the electrical resistance provided by the semiconductor switch 16 is comparatively large. It is also possible to bring the semiconductor switch 16 into a state in which it is not fully controlled.In this case, an electrical resistance of between 5 ohms and 200 ohms is provided by means of the semiconductor switch 16, so that the electrical current conducted by means of the semiconductor switch 16 is limited.

[0044] The state of the semiconductor switch 16 is adjusted by applying an electrical voltage to a control input 18 of the semiconductor switch 16, which is connected to a second terminal 20 of a control circuit 22. Thus, it is possible to control the semiconductor switch 16 by means of the control circuit 22, and the switching state, i.e., whether the semiconductor switch 16 is electrically conductive or electrically non-conductive, is adjusted by applying a corresponding electrical voltage to the second terminal 20. Consequently, the control circuit 22 adjusts whether an electrical current flow is possible between the two terminals 6 via the secondary current path 12. The main current path 10 has a separating element 24 in the form of a mechanical switch, namely a relay or the like.The separating element 24 can also be placed in a closed or an open state, wherein in the closed state an electrical current flow via the separating element 24 is possible. For this purpose, the separating element 24 has a mechanical part 26 which is electrically contacted with the other components of the main current path 10. The mechanical part 26 comprises, for example, a moving contact which can be moved relative to a fixed contact. If the two contacts are in contact with one another, an electrical current flow via the main current path 10 is possible. If, however, the contacts are spaced apart, an electrical current flow via the main current path 10 is prevented. In addition, the separating element 24 has an electrical part 28, by means of which a movement of the mechanical part 26 is caused so that it is either in the electrically conductive or in the electrically non-conductive state.The electrical part 28 comprises, for example, a coil for generating a magnetic field when needed. The electrical part 28 is electrically connected to a first terminal 30 of the control circuit 22. If a corresponding electrical voltage is applied to the first terminal 30, the electrical part 28 is operated accordingly, so that the mechanical part 26 is actuated. Consequently, by applying a corresponding electrical voltage to the first terminal 30, the state of the separating element 24 is changed.

[0045] A second semiconductor switch 32, which has a further control input 34, is electrically connected in series with the isolating element 24. This is electrically connected to a fourth terminal 36 of the control circuit 22, so that the switching state of the second semiconductor switch 32 is set by applying a corresponding electrical voltage to the fourth terminal 36. The control circuit 22 further comprises a sensor terminal 38, to which the sensor 14 is connected, so that the measurement data generated by the sensor 14, in particular an electrical voltage corresponding to the electrical current conducted between the terminals 6, is provided there. The control circuit 22 also comprises a third terminal 40, to which an external voltage source is connected.An electrical supply voltage, namely a DC voltage of 12 V, is provided by the external voltage source, and the supply voltage applied to the third terminal 40 is used to power the other components of the control circuit 22, i.e., also for a simplified schematic circuit 42 of the control circuit 22. The circuit 42 comprises several discrete electrical components (not shown individually), such as electrical coils, capacitors, and resistors. The control circuit 22 also includes a computer 44 in the form of a programmable microprocessor and a storage medium in the form of a memory 46. A computer program product 48 is stored in the memory 46.

[0046] Here, circuitry 42 is constructed such that a method 50 illustrated in Figure 2 is at least partially carried out by means of it. The computer program product 48 also comprises a plurality of instructions which, when the program is executed by the computer 44, cause the computer 44 to carry out at least parts of the method 50. In other words, part of the method 50 is carried out by means of the circuitry 42, and another part is carried out by means of the computer 44 using the computer program product 48. Thus, the control circuit 22 is provided and configured to carry out the method 50, and the hybrid switch 2 is operated at least partially according to the method 50.

[0047] In a variant or installation situation of the hybrid switch 2 not shown in detail, the third terminal 30 is not connected to the external voltage source and / or the sensor 14 is not present. It is also possible for the second semiconductor switch 32 to be omitted. Furthermore, it is possible to replace the isolating element 24, which is shown here as a relay, with a different mechanical switching element. It is also possible to replace the semiconductor switch 16, namely the MOSFET or IGBT, with another MOSFET or IGBT or, for example, with a GTO. In these variants, however, the control circuit 22 is always constructed the same. The method 50 is carried out when an electrical current is conducted via the hybrid switch 2. In this case, the isolating element 24 is in the electrically conductive state, i.e., closed. Likewise, the second semiconductor switch 32 is closed, and the semiconductor switch 16 is open.

[0048] In the method 50, in a first work step 52, a request 54 to interrupt a current flow via the hybrid switch 2 is detected. The request 54 is received, for example, via a data input (not shown in detail) of the control circuit 22, which is connected to a line. The line is connected to a control unit (not shown in detail) of the DC circuit 4. Alternatively, the request 54 is generated by means of a manual switch that is incorporated into a housing of the hybrid switch 2 and is electrically connected to the control circuit 22, for example, to the data input (not shown in detail). In a further alternative, the request 54 is generated by the control circuit 22 itself, namely based on the measurement data provided by the sensor 14.Here, the request 54 is generated when the electrical current conducted through the hybrid switch 2, i.e., the electrical current flowing between the two terminals 6, exceeds a certain limit. Thus, the hybrid switch 2 functions like a circuit breaker.

[0049] In addition, in the first work step 52, a current state 56 of the hybrid switch 2 is determined. This check determines how often the two semiconductor switches 16, 32 were actuated within a previous period of time. Heat loss occurs with each switching operation of the respective semiconductor switch 16, 32. If the number of switching operations is greater than a certain value, i.e. the respective semiconductor switch 16, 32 has been actuated more than the certain value within the period of time, it is assumed that state 56 represents an overload of the hybrid switch 2. In this case, only the isolating element 24 is subsequently opened, for which purpose a corresponding electrical voltage is applied to the first terminal 30. Due to the applied electrical voltage, the mechanical part 26 is actuated and the isolating element 24 is transferred to the electrically non-conductive state.In one embodiment of the isolating element 24, the mechanical part 26 comprises a spring by means of which a force is exerted between the two contacts, i.e. the fixed contact and the moving contact, which leads to a spacing of the two contacts. In order for the isolating element 24 to be electrically conductive, it is necessary that a force is exerted by means of the electrical part 28 by means of which the force provided by the spring is compensated. In particular, the isolating element 24 is designed as a monostable switching device. To open the isolating element 24, an electrical voltage of 0 V is applied to the first terminal 30. In another embodiment of the isolating element 24, however, an adapted electrical voltage is applied, which also leads to an opening.

[0050] After the isolating element 24 is opened, it is possible for an arc to form in the isolating element 24 due to the applied electrical voltage and the conducted electrical current. This arc only extinguishes after a comparatively long period of time, so that the current flow through the hybrid switch 2 is interrupted. With this type of actuation of the hybrid switch 2, the electrical current flow continues for a comparatively long period of time, but no additional load is placed on the semiconductor switches 16, 32.

[0051] If, when determining state 56, it was determined that there is no overload of the two semiconductor switches 16, 32, normal operation of the hybrid switch 2 is possible. In this case, a check is carried out to determine whether an electrical supply voltage is present at the third terminal 40. For example, no electrical supply voltage is present at the third terminal 40 because the external voltage source is not connected, or because a cable used to connect the external voltage source is damaged or broken.

[0052] If no electrical supply voltage is applied to the third connection 40, a second work step 58 is carried out. Since no electrical supply voltage is present, there is no power supply to the computer 44 either, so that the second work step 48 is carried out essentially on the basis of the circuitry 42. In the second work step 58, the isolating element 24 is first opened so that the arc is created. As a result, an electrical voltage is generated via the isolating element 24 or the entire main current path 10, which is used to power the circuitry 42. Furthermore, an energy storage device, such as a capacitor, is charged in the process. In a further development, the resulting electrical voltage is also used to power the computer 44, so that the second work step 58 is carried out partly by means of the computer 44.

[0053] To open the separating element 24, the appropriate electrical voltage is applied to the first terminal 30, for example, 0 V, so that no force applied by the spring or the like is compensated, particularly by the electrical part 28. Consequently, the mechanical part 26 is moved into a position in which the two contacts are spaced apart from each other.

[0054] Once the energy storage device has been sufficiently charged, an electrical voltage is applied to the second terminal 20, causing the semiconductor switch 16 to close. As a result, the electrical current commutates from the main current path 10 to the secondary current path 12, so that the arc formed in the isolating element 24 collapses and no further electrical current is carried via the main current path 10. Thus, the control circuit 22 is no longer supplied due to the arc, but only via the energy storage device. After a period of time, the application of the electrical voltage to the second terminal 20 is terminated, thus opening the semiconductor switch 16 again. Therefore, the flow of electrical current via the secondary current path 12 is interrupted.In this case, the electrical voltage applied between the terminals 6 is insufficient to reignite the arc due to the gas in the isolating element 24 having cooled in the meantime, and the current flow via the hybrid switch 2 is prevented. The method 50 is then terminated. The period of time for which the semiconductor switch 16 is electrically conductive is tailored to the respective isolating element 24 and semiconductor switch 16 used. Thus, for different isolating elements 24 and different semiconductor switches 16 used, a different period of time is used, which is in each case such that the arc is not reignited. In each case, the period of time between the detection of the request 54 and the point in time at which the hybrid switch 2 no longer carries electrical current is minimal.

[0055] If, however, the electrical supply voltage is applied to the third terminal 40, a third work step 60 checks the current carrying capacity of the semiconductor switch 16 and compares it with a threshold value. The threshold value corresponds to the value of the currently flowing electrical current provided by the sensor 14, and the current carrying capacity is determined based on the connection diagram of the semiconductor switch 16 at the second terminal 20. Alternatively, the current carrying capacity is stored in the memory 46 when the semiconductor switch 16 is connected, i.e., during assembly.

[0056] If the current carrying capacity is lower than the threshold value, a fourth work step 62 is carried out. In this step, an electrical voltage which opens the isolating element 24 is first applied to the first terminal 30, causing it to open and the arc to form in the isolating element 24. After a subsequent time window of 1 ps, an electrical voltage which closes the semiconductor switch 16 is applied to the second terminal 20 for a period of time, namely 500 ms. Due to the electrically conductive secondary current path 12, the electrical current commutates from the main current path 10 to the secondary current path 12, which is why the arc formed in the isolating element 24 is extinguished. The time window and the time period are selected such that after the time period, the electrical voltage applied between the terminals 6 is insufficient to reignite the arc.Due to the comparatively short period of time for which the electrical current is conducted by means of the semiconductor switch 16, its load is comparatively low, so that despite the comparatively low current-carrying capacity, no damage to the semiconductor switch 16 occurs. In the fourth work step 62, the period of time for which the semiconductor switch 16 is closed is shortened compared to the period during which the semiconductor switch 16 is conductive in the second work step 58, whereas in the second work step 58, the separating element 28 is electrically conductive for a shorter time than in the fourth work step 62, and thus the arc lasts for a shorter time.

[0057] If the current-carrying capacity of semiconductor switch 16 is greater than the threshold value, a fifth step 64 is performed. This step checks whether the second semiconductor switch 32 is connected to the fourth terminal 36. If it is detected that the second semiconductor switch 32 is not connected, for example, because the connection is broken or because the second semiconductor switch 32 is not present, a sixth step 66 is performed.

[0058] In this, an electrical voltage is applied to the second terminal 20, which leads to the closing of the semiconductor switch 16. The electrical current thus commutates at least partially to the secondary current path 12. Following this, an electrical voltage is applied to the first terminal 30, which leads to the opening of the isolating element 24. The remaining electrical current via the main current path 10 is thus interrupted, whereby the electrical current flow between the terminals 6 via the secondary current path 12 still exists. When the isolating element 24 opens, no arc is formed, or it extinguishes essentially immediately. The semiconductor switch 16 is opened again after a preselected period of time, for which purpose a corresponding electrical voltage is applied to the second terminal 20.The time period between the closing of the semiconductor switch 16 and the opening of the isolating element 24, and the period of time that the semiconductor switch 16 remains in the closed state, are adapted to the respective semiconductor switch 16 and isolating element 24 used. For this purpose, the isolating element 24 and the semiconductor switch 16 used are stored, for example, in the memory 46 during assembly, or the configuration can be retrieved using a connector configuration and / or a connection diagram at the respective connection 20, 30. The time period and the period are always selected such that, after the opening of the semiconductor switch 16, no electrical current is carried by the hybrid switch 2. The period of time between the execution of the first work step 52 and the point in time at which no electrical current is carried by the hybrid switch 2 is minimal.

[0059] If it has been detected that the second semiconductor switch 32 is connected to the fourth terminal 36, a seventh work step 68 is carried out. In this seventh step 68, an electrical voltage which causes the semiconductor switch 16 to close is also applied to the second terminal 20. The electrical current thus begins to commutate to the secondary current path 12. Essentially immediately after the semiconductor switch 16 has been closed, an electrical voltage which causes the second semiconductor switch 32 to open is applied to the fourth terminal 36, so that the electrical current flow via the main current path 10 is interrupted. Subsequently, an electrical voltage which causes the isolating element 24 to open is applied to the first terminal 30. Since no electrical current flows via the main current path 10 anymore, no arc is formed.Furthermore, an electrical voltage is applied to the second terminal 20 at essentially the same time, causing the semiconductor switch 16 to open. With this procedure, the time period between the execution of the first work step 52 and the point in time until no more electrical current flows through the hybrid switch 2 is comparatively short. The time period between the opening of the semiconductor switch 16 and the closing of the second semiconductor switch 32 is adapted to the respective semiconductor switches 16, 32 used.

[0060] In summary, in method 50, the timing in which a corresponding electrical voltage is applied to each of the terminals 20, 30, 36 is selected depending on the respective isolating element 24 used, as well as the semiconductor switches 16, 32, and also the applied supply voltage. The timing is also adapted depending on the current state 56. The invention is not limited to the exemplary embodiment described above. Rather, other variants of the invention can also be derived therefrom by a person skilled in the art without departing from the subject matter of the invention. In particular, all of the individual features described in connection with the exemplary embodiment can also be combined with one another in other ways without departing from the subject matter of the invention.

[0061] List of reference symbols

[0062] 2 hybrid switches

[0063] 4 DC circuit

[0064] 6 Connection

[0065] 8 Line

[0066] 10 Main current path

[0067] 12 bypass path

[0068] 14 Sensor

[0069] 16 semiconductor switches

[0070] 18 Control input

[0071] 20 second connection

[0072] 22 Control circuit

[0073] 24 Separator

[0074] 26 mechanical part

[0075] 28 electrical part

[0076] 30 first connection

[0077] 32 second semiconductor switch

[0078] 34 additional control input

[0079] 36 fourth connection

[0080] 38 Sensor connection

[0081] 40 third connection

[0082] 42 Interconnection

[0083] 44 computers

[0084] 46 storage

[0085] 48 Computer program product

[0086] 50 procedures

[0087] 52 first step

[0088] 54 Request

[0089] 56 Condition

[0090] 58 second step

[0091] 60 third step

[0092] 62 fourth step fifth step sixth step seventh step

Claims

Claims 1. Control circuit (22) of a hybrid switch (2), which comprises a main current path (10) with a separating element (24) and a secondary current path (12) connected in parallel to the main current path (10) with a semiconductor switch (16), which has a first connection (30) for the separating element (24) and a second connection (20) for the semiconductor switch (16), and which is provided and configured to carry out a method (50), in which - a request (54) to interrupt a current flow via the hybrid switch (2) is detected, and - a time sequence of an electrical voltage applied to the two terminals (20, 30) is selected as a function of the isolating element (24) connected to the first terminal (30) and the semiconductor switch (16) connected to the second terminal (20).

2. Control circuit (22) according to claim 1, characterized in that the method (50) is designed such that, if a current-carrying capacity of the semiconductor switch (16) is less than a threshold value, first an electrical voltage causing the opening of the isolating element (24) is applied to the first terminal (30), and that after a subsequent time window, an electrical voltage causing the closing of the semiconductor switch (16) is applied to the second terminal (20) for a period of time.

3. Control circuit (22) according to claim 1 or 2, characterized by a third terminal (40) for connection to an external voltage source, wherein the method (50) is designed such that, when an electrical supply voltage is applied to the third terminal (40), first a voltage causing the closing of the semiconductor switch (16) electrical voltage is applied to the second terminal (20) and then an electrical voltage causing the opening of the separating element (24) is applied to the first terminal (30).

4. Control circuit (22) according to claim 3, characterized in that the method (50) is designed such that, when no electrical supply voltage is applied to the third terminal (40), first an electrical voltage causing the opening of the isolating element (24) is applied to the first terminal (30) and then an electrical voltage causing the closing of the semiconductor switch (14) is applied to the second terminal (20).

5. Control circuit (22) according to one of claims 1 to 4, characterized by a fourth terminal (36) for connection to a second semiconductor switch (32) which is electrically connected in series with the isolating element (24), wherein the method (50) is designed such that, when it has been detected that the second semiconductor switch (32) is connected to the fourth terminal (36), first an electrical voltage causing the second semiconductor switch (32) to open is applied to the fourth terminal (36) and then an electrical voltage causing the isolating element (24) to open is applied to the first terminal (30).

6. Control circuit (22) according to one of claims 1 to 5, characterized in that the method (50) is designed such that the time sequence is adapted as a function of a current state (56).

7. Hybrid switch (2) comprising a main current path (10) with a separating element (24) and a secondary current path (12) connected in parallel to the main current path (10) with a semiconductor switch (16) and a control circuit (22) according to one of claims 1 to 6, wherein the first The isolating element (24) is connected to the first terminal (30) and the semiconductor switch (16) is connected to the second terminal (20).

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