Method for operating a hybrid switch, and hybrid switch

Abstract

The invention relates to a method (28) for operating a hybrid switch (10) comprising a main current path (14) with a isolating element (16) and a secondary current path (22) connected in parallel to the main current path (14) with a semiconductor switch (26). According to the method (28), the isolating element (16) is opened, and an electrical parameter (20) of the main current path (14) is determined. A current flow through the semiconductor switch (24) is adjusted depending on the parameter (20). The invention further relates to a hybrid switch (10) for this purpose.

Description

[0001] The invention relates to a method for operating a hybrid switch and to a hybrid switch itself. The hybrid switch has a main current path with a disconnecting element and a secondary current path connected in parallel to the main current path with a semiconductor switch.

[0002] WO 2010 / 108565 A1 discloses a hybrid switch (hybrid disconnect switch) comprising a mechanical switch or disconnecting element and semiconductor electronics connected in parallel to it, which includes a semiconductor switch, preferably an IGBT. The semiconductor electronics have no additional power source and are current-blocking when the mechanical switch is closed, i.e., practically current- and voltage-free. To interrupt the current via the hybrid switch, the mechanical switch is opened, which may generate an arc. The energy of the arc generated when the mechanical switch opens is used by the semiconductor electronics, which are connected to the mechanical switch in such a way that when the mechanical switch opens, the arc voltage across it (due to the arc) makes the semiconductor switch conductive.

[0003] As soon as the semiconductor switch is energized, the electric current commutates from the mechanical switch to the semiconductor switch. The corresponding arc voltage or current also charges an energy storage device in the form of a capacitor, which provides the control voltage for the semiconductor electronics. Once the electric current has commutated to the semiconductor switch, the arc extinguishes, and the charging process of the energy storage device is complete. An ionized gas, generated by the arc, is present 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 energized. After the timer expires, the semiconductor switch is switched off again.Instead of using the timer, for example, the duration is determined based on the state of charge of the energy storage device.

[0004] If the duration is chosen too short, it is possible that, due to the ionized gas still present between the contacts of the mechanical switch and the applied electrical voltage, an arc will reignite, causing an electric current to flow through the mechanical switches again. Therefore, the duration is usually chosen to be relatively long, assuming that the ionized gas will have sufficiently dissipated after this time and / or the distance between the contacts of the mechanical switch is large enough to prevent the arc from reigniting.

[0005] Since the duration is used for all applications of the hybrid switch, it is further increased, even though a shorter duration would have sufficed in each specific application. During this time, an unwanted current continues to flow through the hybrid switch, which can lead to further undesired operation and potentially damage to the components energized by the hybrid switch and / or endanger people.

[0006] A method for operating a hybrid switch is known from US 2010 / 254046 A1. The mechanical switch detects an arc current. The semiconductor switch remains in the electrically closed state until the arc is extinguished.

[0007] The invention is based on the objective of specifying a particularly suitable device for operating a hybrid switch and a particularly suitable hybrid switch, wherein a safe current interruption is expediently achieved, and in particular a switching time is reduced.

[0008] With regard to the method, this problem is solved according to the invention by the features of claim 1 and with regard to the hybrid switch by the features of claim 8. Advantageous embodiments and further developments are the subject of the dependent claims.

[0009] The method serves to operate a hybrid switch, which is a disconnecting device, i.e., a switching unit. The method is particularly useful for interrupting the current via the hybrid switch, preferably a direct current interruption. In other words, the method interrupts the flow of electrical current between a direct current source and an electrical device. The hybrid switch is, for example, unidirectional or bidirectional. For instance, the electrical voltages switchable by the hybrid switch, preferably the respective nominal voltage, are between 200 V and 3 kV, and particularly 220 V, 400 V, 650 V, 1000 V, or 1500 V.

[0010] The hybrid switch has a main current path, which is formed between, or at least connected to, two terminals of the hybrid switch. These two terminals serve primarily for contacting other components of an electrical circuit, such as conductors or busbars, and are formed, for example, by means of terminals or plugs. The main current path has a disconnecting element that can be actuated. This element can be closed, in which the main current path has low resistance, allowing current to flow between the two ends of the main current path, preferably between the two terminals. InIn 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 that an increased ohmic resistance prevails. Advantageously, the isolating element is a galvanically isolating component when open. The isolating element is advantageously a mechanical switch, such as a relay, contactor, or connector, or at least includes one of these. Alternatively, the isolating element is designed as a surge protector. The surge protector specifically includes a spark gap, also known as a gas discharge tube (GDT), or at least incorporates one.The separating element is expediently electrically actuated, and / or in particular suitable, preferably provided and equipped, to perform a galvanic separation of the main current path when opening, i.e. when moving into the open state.

[0011] The hybrid switch also features a bypass path that includes a semiconductor switch. Specifically, the semiconductor switch is connected in parallel to the isolating element, so that the isolating element is bypassed by the semiconductor switch. Alternatively, for example, other components of the main current path may also be bypassed by the semiconductor switch. If the isolating element has or consists of a gas discharge tube, its opening is equivalent to the formation of an electric arc.

[0012] The semiconductor switch is advantageously a power semiconductor switch and preferably a field-effect transistor, such as a MOSFET, IGBT, or GTO. In particular, during normal operation, i.e., when current is to flow through the hybrid switch, the semiconductor switch is current-blocking and is controlled accordingly. Thus, the electrical losses of the hybrid switch during operation are comparatively low.

[0013] This method is used in particular to interrupt the current via the hybrid switch. The process begins with opening the isolating element. Opening the element increases the electrical resistance of the main current path. It is possible for an arc to form within the isolating element, especially between two switching contacts spaced apart when opened, allowing current to continue flowing through the main current path. However, this significantly increases the electrical resistance of the main current path and, consequently, the voltage drop across it.

[0014] InIn a subsequent step, an electrical parameter of the main current path is determined. This electrical parameter is particularly variable over time and dependent on the current state of the hybrid switch. In other words, in subsequent iterations of the process, even with the same hybrid switch, the electrical parameter will differ and / or change after the disconnect element is opened.

[0015] InIn a further step, the current flow through the semiconductor switch is adjusted according to a specific parameter. Specifically, a corresponding voltage is applied to a control input of the semiconductor switch to adjust the current flow. During adjustment, the current flow through the semiconductor switch is initiated, terminated, reduced, or increased, thus also altering the portion of the current flowing through the hybrid switch that is routed via the main current path. The current flow is adjusted, for example, using a binary approach, either initiating or interrupting it. In this case, the semiconductor switch is fully energized. Alternatively, the semiconductor switch is partially energized, so that it exhibits a resistance that is neither low nor high, allowing an electric current to flow through it.For example, when adjusting the current flow, a duration is set during which the semiconductor switch is energized, i.e., the point in time at which the semiconductor switch is switched to the non-conductive state, or the point in time at which the semiconductor switch becomes energized is set. Preferably, for example, due to the adjustment of the electrical current flow or due to further control in another operation, the semiconductor switch is switched to the non-conductive state after a certain period of time, where this period corresponds, for example, to the duration mentioned above.

[0016] This method adjusts the current flow through the semiconductor switch according to the current situation during each switching operation, i.e., each desired current interruption. This makes it possible to reduce the duration for which an electric current remains through the semiconductor switch after the isolating element opens, while simultaneously preventing the arc from reigniting in the isolating element after the semiconductor switch opens. Alternatively, or in combination, the current flow can be adjusted to shorten the duration for which an arc remains in or across the isolating element after opening. Alternatively, or in combination, it is possible to reduce the amount of electric current remaining through the hybrid switch after the isolating element opens, particularly by reducing the conductivity of the semiconductor switch, while still allowing it to conduct current.In other words, the semiconductor switch is not fully engaged.

[0017] This procedure ensures that an electrical load, i.e., a component, operated by the hybrid switch continues to be powered, i.e., supplied with electrical current, only for a relatively short period and / or with a relatively low electrical energy after the disconnecting element has opened. This prevents the arc from reigniting above or within the disconnecting element, thus ensuring a reliable current interruption after the process is complete. The duration and electrical energy are adapted to the specific application, allowing them to be set to the minimum necessary. This enhances safety.

[0018] The setting of the semiconductor switch, in particular the application of a control voltage to enable / set current flow through it, and / or the determination of the electrical characteristic, is carried out, for example, by means of electronics, especially a control circuit, which is operated, for example, by an external power source. Alternatively or in combination with this, the electronics are at least partially powered by an electrical voltage applied across the isolating element. This simplifies the assembly of the hybrid switch and increases its robustness. For example, the hybrid switch comprises only the main current path and the secondary current path. Alternatively, the hybrid switch also includes interference suppression circuitry connected in parallel to the main current path, the secondary current path, or between the terminals. In particular, the interference suppression circuitry includes or is formed using a varistor.The interference protection circuitry is used in particular to prevent an overvoltage from being applied to the disconnecting element and / or the semiconductor switch, which would lead to their destruction.

[0019] Alternatively or in combination with this, the hybrid switch expediently includes a further isolating element that is electrically connected in series with the main current path and the secondary current path. This element opens, in particular, as soon as there is no longer any electrical current flow through the main current and the secondary current path. Thus, it is possible to achieve galvanic isolation using the hybrid switch. For example, the further isolating element, or an additional isolating element, is at least partially integrated into the secondary current path so that galvanic isolation can also occur there.

[0020] For example, a hybrid switch is a component of a circuit breaker, used to protect a component of the electrical circuit during operation, such as an (electrical) line or a connected component, i.e., a load. In other words, the hybrid switch is either part of a miniature circuit breaker (MCB) or a device circuit breaker. Alternatively, the hybrid switch can be, for example, a manual switch for interrupting the current flow through the associated circuit, such as an emergency stop switch.

[0021] For example, the electrical parameter is measured only once, and the current flow is adjusted accordingly. The current flow can be constant or time-varying. For instance, the adjustment is made such that the corresponding current flow occurs at least once or briefly. Preferably, the adjustment is made such that the current flow is present for a specific duration and then terminates. In other words, the duration of the current flow through the semiconductor switch is adjusted based on the (electrical) parameter. After the specified duration, the semiconductor switch is, in particular, current-blocking. The parameter used for the adjustment is advantageously such that a re-ignition of the arc in the disconnecting element after the semiconductor switch opens is prevented.Thus, the hybrid switch is only energized for a comparatively short period of time, which includes the duration during which the semiconductor switch is energized, ensuring that the arc does not reignite afterwards.

[0022] For example, the electrical parameter is measured using a sensor that is assigned to the main current path. Alternatively, the electrical parameter is determined, for example, based on other operating data of the hybrid switch, whereby the operating data is measured. For example, the electrical parameter is determined essentially simultaneously with the opening of the isolating element or at a specific time interval after the opening of the isolating element. For example, the electrical parameter is determined only once. Alternatively, the electrical parameter is determined several times, especially if it is time-varying. It is advantageous that the current flow is adjusted accordingly after each determination of the electrical parameter, so that the current flow is adapted.In particular, the electrical parameter is determined at specific time intervals, which may vary or, preferably, remain constant, thus simplifying the execution of the method. Advantageously, the electrical parameter is determined essentially continuously, and the current flow is adjusted and, for example, varied accordingly.

[0023] The electrical parameter is preferably regulated to a setpoint by adjusting the current flow. In this process, the semiconductor switch is not fully energized, so its resistance is not always comparatively low; instead, it is varied. For example, the setpoint may be constant or change over time. Specifically, the setpoint is chosen such that the resulting behavior of the hybrid switch prevents or interrupts the formation of an arc across the separating element. Furthermore, the setpoint is advantageously configured to minimize the current flow. In this way, the electrical energy passed through the hybrid switch after the separating element opens is comparatively low, while still reliably preventing the formation of an arc.For example, the regulation occurs essentially immediately after the separating element opens. Alternatively, the current flow through the semiconductor switch is initially set to its maximum for a specific duration, for which the electrical resistance of the semiconductor switch is set to the lowest possible value. In other words, the semiconductor switch is initially fully engaged. Only then is the current flow adjusted so that the electrical parameter corresponds to the target value. This ensures that after the separating element opens, the electrical current is fully commutated to the semiconductor switch, thus reliably extinguishing the arc formed in the separating element. Deionization of the gas present in the separating element also occurs during this process.

[0024] For example, the electrical characteristic is measured when the semiconductor switch is closed. For instance, the semiconductor switch might be fully conducting, thus providing the lowest possible electrical resistance. Alternatively, the semiconductor switch might have a certain, non-negligible resistance, allowing an electric current to flow, but this current is limited by the resistance. For example, the semiconductor switch might be closed (i.e., current-carrying) when the separating element is opened, such as during opening, immediately after opening, or within a specific time window thereafter.Alternatively, the semiconductor is closed, for example, before the separating element is opened, so that the electric current from the separating element is at least partially commutated to the semiconductor switch and thus to the bypass path. In this way, the formation of an arc in the separating element when it opens is essentially prevented from the outset.

[0025] The electrical parameter is preferably compared with a first threshold value, advantageously being determined when the separating element is open. During the determination, the main current path is suitably no longer current-carrying, and any arc in the separating element has already extinguished. For example, the electrical parameter is determined continuously or at least at certain discrete time intervals. The comparison specifically checks whether the electrical parameter exceeds or falls below the first threshold value, or preferably whether the electrical parameter is greater or less than the first threshold value. Depending on the comparison of the electrical parameter with the first threshold value, the semiconductor switch is opened.The comparison, and in particular the type of comparison, and / or the initial threshold are adjusted in such a way that when the semiconductor switch opens as a result, i.e., when it switches to the blocking state, the arc in the disconnecting element cannot be (re)ignited. Suitablely, ignition is no longer possible due to the prevailing conditions.

[0026] The first threshold and the comparison are adapted to the specific electrical parameter used. For example, the electrical parameter corresponds to a conductance of the main current path, and the semiconductor switch opens when the electrical parameter is less than the first threshold. If the electrical parameter corresponds to an electrical resistance, preferably an impedance, of the main current path, the semiconductor switch opens when the electrical parameter is greater than the first threshold.

[0027] In summary, once the comparison determines that reigniting the arc is no longer possible, the current flow through the semiconductor switch is interrupted and adjusted accordingly. In other words, the semiconductor switch is controlled so that it is no longer conducting current. Thus, with a suitable choice of the initial threshold and the electrical parameters used, the electrical current flowing through the hybrid switch can be terminated relatively quickly and reliably. For example, the semiconductor switch is fully conducted until it opens, resulting in a comparatively low resistance. Alternatively, the electrical current flow through it is at least partially limited.

[0028] Alternatively, or in combination with this, the electrical parameter is measured with the semiconductor switch open, i.e., when the current flow through it is interrupted. The semiconductor switch closes when the electrical parameter reaches a second threshold value. Thus, the electrical parameter is measured when an arc is present in the separating element. For example, the semiconductor switch is left open after the separating element has been opened, or it is first closed and then opened. Due to the comparatively high conductivity of the semiconductor switch, i.e., comparatively low resistance, the arc across the separating element initially collapses, resulting in deionization and cooling of the separating element.When the semiconductor switch is subsequently opened, the arc reignites, with an increased electrical voltage required to maintain / ignite the arc in the separating element. The amount of ionized gas present is reduced, and less is regenerated.

[0029] When the electrical parameter reaches the second threshold, i.e., exceeds or falls below it, the semiconductor switch closes. Consequently, the electric current commutates from the main current path to the secondary current path, and the arc present in the switching element extinguishes, whether it was generated immediately after opening or reignited. In particular, the electrical parameter then changes relatively rapidly. Preferably, after the semiconductor switch closes and / or the electrical parameter changes, the semiconductor switch is reopened essentially immediately. The time of reopening is determined, for example, based on the newly determined electrical parameter, or it occurs within a specific time window after the time the semiconductor switch closes.The second threshold is expediently chosen such that, after closing and subsequently opening the semiconductor switch, ignition of the arc in the separating element does not occur.

[0030] In summary, this variant initially maintains the arc across the separating element, during which time the electrical voltage required to sustain the arc increases. The semiconductor switch is closed for a relatively short period to extinguish the arc, and the closing time is chosen such that the arc will not reignite when the semiconductor switch is reopened. The second threshold value and the electrical parameters are selected accordingly. With this approach, the arc persists for a longer time. However, the electrical energy, current, and / or voltage transmitted through the semiconductor switch are comparatively low, thus reducing the load on the semiconductor switch. Consequently, a relatively inexpensive semiconductor switch can be used.

[0031] The electrical conductivity of the main current path is used as an electrical parameter, or the electrical parameter is at least based on it. For this purpose, for example, an electric current carried by the complete hybrid switch and / or an electric current carried via the bypass is measured, and the conductivity is determined from this.

[0032] A particularly preferred electrical parameter is an electrical voltage that appears across another component of the main current path, which is connected in series with the isolating element. Here, the semiconductor switch advantageously bridges the series connection of the isolating element and the other component. When an arc is formed in the isolating element, an electric current flows through the main current path, so that a specific electrical voltage appears across the other component. In particular, the isolating element is limited by a Zener diode and / or a diode, or by a series connection of a Zener diode, a diode, and / or a resistor, wherein the reverse bias of the two diodes is opposite. Once the arc in the isolating element has extinguished, this ensures, in particular, that an electrical voltage continues to appear across the other component.Based on the electrical voltage across the other component, it is possible to deduce the electrical current carried through the main current path and / or the conductivity of the main current path, which is still present due to the ionized gas when the separating element is open. Thus, the measured electrical voltage allows us to determine whether the arc can be reignited.

[0033] For example, a resistor is used as an additional component, where the additional component is, for example, an ohmic resistor and / or a shunt-type resistor. Thus, the resulting electrical voltage corresponds to the electrical current carried through the main current path, and this can, for example, be used for further evaluations or other control of the hybrid switch.

[0034] A switching element is particularly preferred as an additional component. This additional component is advantageously controlled to achieve a specific electrical parameter. In particular, the control signal defines a range within which the respective electrical parameter can be located. Preferably, the switching element is opened for this purpose, and an electric arc may also form within it. For example, the switching element is or comprises a semiconductor switch or a mechanical switch, such as a relay. For example, the switching element and the isolating element are formed by means of a common double switch, which simplifies the design. In this way, the switching element and the isolating element are always actuated essentially simultaneously, which simplifies the control signal. Alternatively, the switching element and the isolating element are two separate components.Advantageously, the switching element is bypassed, for example, by means of additional elements such as a resistor, a capacitor, a diode, a Zener diode, or several of these elements connected in parallel. The resistor, capacitor, diode, and / or Zener diode are integral components of the circuit, separate from it, but the switching element is bypassed by them. Because of these elements, an electrical voltage is present across the switching element even when it is open. These elements also ensure that as long as electrical conductivity exists in the main current path, the electrical parameter does not disappear, allowing the current flow to be adjusted and / or appropriate control to be implemented.

[0035] InIn this further development, an electrical parameter used is the electric current induced in the main current path. The induced electric current is measured qualitatively or quantitatively, or at least by a corresponding quantity. If the separating element is open and there is no longer an arc in the separating element, ionized gas may still be present, through which the electric current induced in the main current path is conducted. If deionization is sufficiently advanced, however, no electric current can be induced in the main current path, or at least the amount is reduced. Thus, it is possible to infer the conductivity of the main current path from the induced electric current. Due to inductive coupling, this has essentially no impact on the normal operation of the hybrid switch.

[0036] To induce the electric current, the main current path expediently includes an electrical coil, which is hereinafter also referred to as the first coil. The first coil is electrically connected in series with the isolating element. The first coil is inductively coupled to another electrical coil, which is hereinafter also referred to as the second coil. In particular, the two (electrical) coils are formed by means of a common transformer. For example, a predetermined electric current is passed through the second coil at specific intervals, and the amount of energy transferred to the first coil and thus into the main current path is measured. From this, the induced electric current is determined.

[0037] The hybrid switch has a main current path with a disconnecting element and a secondary current path connected in parallel to the main current path with a semiconductor switch. The disconnecting element is, for example, a mechanical switch such as a relay or contactor. Alternatively, the disconnecting element is designed, for example, like a plug. In particular, the disconnecting element is designed such that when it opens, i.e., when the ohmic resistance increases, a mechanical separation occurs between two contacts, through which an electrical current flows when the two contacts are in mechanical contact. The semiconductor switch is expediently a power semiconductor switch and, for example, an IGBT or MOSFET.

[0038] The hybrid switch is operated according to a method in which the isolating element is opened. An electrical parameter of the main current path is determined, and the current flow through the semiconductor switch is adjusted depending on this parameter. For example, the hybrid switch includes a control unit that is suitable, and in particular designed and configured, to carry out the method. The control unit includes or appropriately forms a drive circuit for the semiconductor switch and / or the isolating element. For example, the control unit is powered by an external energy source. Alternatively, the control unit is powered via the main current path, for example, by an electrical voltage applied across the isolating element.In another alternative, the process is carried out using a suitable interconnection of several discrete elements, advantageously without an external power source. This increases robustness and simplifies the assembly of the hybrid switch.

[0039] In particular, the hybrid switch is used in a direct current circuit, and the method is especially used for direct current interruption. For example, in its installed state, the hybrid switch is a component of industrial automation, street lighting, a ship's electrical system, electrified aviation, railway infrastructure or traction, an island grid in a private household, a power 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, appropriately designed, and configured for this purpose.

[0040] For example, the hybrid switch is formed solely by means of the main current path and the secondary current path, as well as any control unit. However, the hybrid switch particularly preferably includes an interference suppression circuit connected in parallel to the main current path or at least to the isolating element and / or the semiconductor switch. This circuit is used, in particular, to limit overvoltages. The interference suppression circuit preferably includes a varistor or is formed by means of one.

[0041] A field-effect transistor, such as a MOSFET, is particularly preferred as the semiconductor switch. In this case, the drain and gate are electrically connected by a series circuit consisting of a diode and a Zener diode, with opposite reverse bias. Alternatively, the gate and source are electrically connected by a series circuit. Specifically, this series connection implements an active clamping circuit. Thus, when a minimum voltage is applied, which occurs particularly after the disconnect element opens and the arc forms, the semiconductor switch is switched to an electrically conductive state.

[0042] For example, the necessary additional component is also present. Preferably, this is bridged by means of a series connection of the diode and the Zener diode. Preferably, the series connection is connected to the control input (gate) of the semiconductor switch. This increases the response time for switching on the semiconductor switch after opening the isolating element, which simplifies control. Furthermore, no additional power supply is required.

[0043] Alternatively or in combination with this, the hybrid switch comprises an electrical (first) coil that is electrically connected in series with the disconnecting element. The first coil is inductively coupled to a second coil, with both coils conveniently assigned to a common transformer, which simplifies manufacturing. By energizing the second coil, namely by applying an alternating voltage, it is possible to induce an electric current in the main current path. Furthermore, due to the inductive coupling with other components of the transformer, it is possible to determine an electric current carried in the main current path.

[0044] Advantageously, the second coil is part of a resonant circuit that also includes a capacitor. If the main current path is electrically conductive, and it is therefore possible to induce an electric current in it, the quality factor of the resonant circuit is comparatively poor. Conversely, if no electric current can be induced, the quality factor of the resonant circuit is comparatively high. Advantageously, the resonant circuit is operated at its natural frequency, which reduces energy consumption. In particular, the energy supplied to the resonant circuit is determined, and the conductivity of the main current path is calculated based on this.

[0045] Furthermore, the invention also relates to the use of such a hybrid switch for carrying out the method and / or as a protective switch.

[0046] The further training and advantages explained in connection with the procedure can also be applied analogously to the hybrid switch / its use and to each other, and vice versa.

[0047] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. The drawing shows: Fig. 1 schematically shows a circuit with a hybrid switch, Fig. 2 a method for operating the hybrid switch, Fig. 3 a simplified circuit diagram of the hybrid switch comprising a further component, and Fig. 4 a modification of the hybrid switch comprising the further component, Figs. 5-9 each show an embodiment of the further component, Fig. 10 a simplified circuit diagram of a further embodiment of the hybrid switch, Fig. 11 a simplified circuit diagram of a final embodiment of the hybrid switch, and Fig. 12 a more detailed circuit diagram of the hybrid switch according to Fig. 11 .

[0048] Corresponding parts are marked with the same reference symbols in all figures.

[0049] In Figure 1 A simplified schematic representation shows a circuit 2 comprising an (electrical) power source 4. The power source 4 provides a DC voltage of 650 V. The power source 4 is connected to a load 8 via several conductors 6, and the electric current flowing through the conductors 6 during normal operation is greater than 5 A and is a direct current.

[0050] Depending on the application of circuit 2, the power source 4 and the load 8 are adapted. For example, circuit 2 is a component of a motor vehicle, such as a land-based vehicle. This vehicle could be a commercial vehicle, a passenger car, construction equipment, or agricultural machinery. In this case, power source 4 is provided, for example, by a high-voltage battery or a rectifier. Alternatively, the motor vehicle could be a rail vehicle, and power source 4 could be provided, for example, by a pantograph or similar device. In Another alternative is a motor vehicle, an aircraft, or a ship. In each case, a main drive is used as load 8. Alternatively, the circuit 2 is stationary, and the power source 4 is, for example, a power grid or a local energy storage device. Load 8 is, for example, an inverter or an actuator.

[0051] A hybrid switch 10 is installed in one of the lines 6, by means of which a current flow between the power source 4 and the load 8 can be interrupted. For this purpose, the hybrid switch 10 is, for example, manually operated, or the hybrid switch 10 is a component of a device for protecting the power source 4, the load 8, or the lines 6, and is, for example, a circuit breaker. The hybrid switch 10 has two terminals 12, each of which is electrically contacted with a portion of one of the corresponding lines 6.

[0052] A main current path 14 extends between the two terminals 12 and includes a isolating element 16. The isolating element 16 is an electrically actuated mechanical switch, such as a relay. The isolating element 16 can be opened and closed, and in the closed state, the two terminals 12 are electrically connected to each other via the main current path 14 with low resistance. When the isolating element 16 is open, the main current path 14 is galvanically isolated, and if the electrical voltage applied between the terminals 12 is sufficiently low, no electrical current can flow through the main current path 14. A unit 18 is associated with the main current path 14, which allows an electrical parameter 20 of the main current path 14 to be determined. The unit 18 is, for example, a component of the main current path 14 or mechanically and / or electrically separated from it.

[0053] Furthermore, the hybrid switch 10 has a bypass path 22 which includes a semiconductor switch 24. The bypass path 22 also extends between the two terminals 12, and the isolating element 16 and the semiconductor switch 24 are therefore electrically connected in parallel. The semiconductor switch 24 is, for example, designed as an IGBT or MOSFET. By appropriately controlling the semiconductor switch 24, namely by applying a corresponding control voltage, it is possible to bring the semiconductor switch 24 into an electrically conductive state, which is also referred to as the closed state. In this case, the semiconductor switch 24 is fully conducting, and the resulting electrical resistance is minimal.It is also possible to put the semiconductor switch 24 into an electrically non-conductive state, also known as the open state, in which the electrical resistance is increased to a maximum. However, it is also possible to choose an average value for the electrical resistance between the minimum and the maximum, so that the semiconductor switch 24 has an increased electrical resistance, but one that is lower than the maximum. In this case, current flow through the semiconductor switch 24 and thus through the bypass path 22 is possible in principle, although the current intensity is limited due to the existing electrical resistance.

[0054] The hybrid switch 10 has a control unit 26, which includes a control circuit (not shown) for the isolating element 16 and the semiconductor switch 24. This circuit allows a corresponding (control) voltage to be applied to the isolating element 16 and the semiconductor switch 24, respectively, which determines the open or closed state. The control unit 26 is suitable, designed, and configured to operate a Figure 2The illustrated method 28 is used to operate the hybrid switch 10. Method 28 is executed when an electrical current between the power source 4 and the load 8 needs to be interrupted. In other words, method 28 serves to interrupt the current via the hybrid switch 10. Thus, method 28 is used to terminate normal operation, in which an uninterrupted current flow from the power source 4 to the load 8 via the hybrid switch 10 is intended. During normal operation, the isolating element 16 is closed, so that the two terminals 12 of the hybrid switch 10 are electrically connected to each other via the main current path 14 with low resistance. The semiconductor switch 24, on the other hand, is electrically non-conductive and therefore open, so that no electrical losses occur there.

[0055] In a first step 30 of the process 28, the isolating element 16 is opened, i.e., placed in the electrically non-conductive state. Due to the electric current carried by the hybrid switch 10 and the electrical voltage present between the terminals 12 because of the now open isolating element 16, it is possible for an arc 32 to form in the isolating element 16, so that an electric current continues to flow via the main current path 14. When the isolating element 16 is opened, the semiconductor switch 24 is placed in the electrically conductive state, for example, essentially simultaneously or at an earlier or later time, so that the electric current carried by the main current path 14 is commutated to the secondary current path 22.In this case, the arc 32 is extinguished, or it may not be formed if the semiconductor switch 24 was already in the electrically conductive state when the separating element 16 was opened.

[0056] In a second step 32, the electrical parameter 20 of the main current path 14 is determined using unit 18. For example, the electrical parameter 20 can be measured directly using unit 18. Alternatively, the electrical parameter 20, which is also simply referred to as the parameter, can be derived from measurement data and determined in this way. The electrical parameter 20 is time-varying and changes, in particular, depending on the portion of the electric current flowing between the terminals 12 or at least via the main current path 14. Alternatively, or in combination, the parameter 20 changes depending on an electric voltage at least partially applied via the main current path 14 or at least on the conductivity of the main current path 14.The electrical parameter 20 also changes in particular depending on the arc 32, for example depending on its presence and / or the electrical voltage required to hold it and / or the electric current carried by means of the arc 32.

[0057] Depending on the determined parameter 20, a current flow through the semiconductor switch 24 is set. To set the current flow through the semiconductor switch 24, the electrical resistance of the semiconductor switch 24 is adjusted or set accordingly.

[0058] The process is completed with a third step 34. In this step, if this has not already occurred in the second step 32, the semiconductor switch 24 is opened, thus preventing any further electrical current flow through it. In a variant not shown in detail, another isolating element, which is electrically connected in series with both the main current path 14 and the secondary current path 22, and thus between these and one of the terminals 12, is also opened. This additional isolating element is a relay or contactor, so that when the additional isolating element is opened, the two terminals 12 are galvanically isolated. Since no current flowed through the hybrid switch 10 prior to this, no arc is generated when the additional isolating element is opened, and the opening does not occur under load.

[0059] In Figure 3Figure 10 shows a simplified circuit diagram of a variant of the hybrid switch 10. The isolating element 16 is designed as a relay and is electrically connected in series with another component 36, which is also part of the main current path 14. The hybrid switch includes a voltage sensor 38, which is part of an auxiliary current path 40 by means of which the other component 36 is bypassed. The voltage sensor 38 can detect the electrical voltage across the other component 36. In a variant not shown in detail, the voltage sensor 38 is integrated into the other component 36 or, for example, is not present. The voltage sensor 38 and the other component 36 are connected to the control unit 26 via signaling and electrical connections, and these together form at least part of the unit 18.

[0060] A control input 42 of the semiconductor switch 24 is connected to the control unit 26, enabling the semiconductor switch 24 to be controlled by the control unit 26. The control unit 26 also controls the isolating element 16 (not shown in detail). The control unit 26 is electrically connected to a power source 46, which supplies current to the control unit 26. The electrical energy supplied by the power source 46 is then directed, as needed, to the isolating element 16, the semiconductor switch 24, the other component 36, and the voltage sensor 38. The power source 46 is implemented, for example, by means of a connection to a power supply network that is independent of the circuit 2.

[0061] The series connection consisting of the isolating element 16 and the further component 36 is bridged by the semiconductor switch 24. Furthermore, the series connection, and therefore also the main current path 14 and the secondary current path 22, is bridged by an interference suppression circuit 44. The interference suppression circuit 44 includes a varistor and is formed by means of it. The interference suppression circuit prevents the formation of an electrical overvoltage on the main current path 14 and the secondary current path 22, which could otherwise lead to the destruction of the individual components.

[0062] When operating this embodiment of the hybrid switch 10, i.e., when carrying out the method 28, the electrical voltage across the additional component 36 of the main current path 14, measured by the voltage sensor 38, is used as the electrical parameter 10. In the first operating step 30, the semiconductor switch 24 closes after or simultaneously with the opening of the separating element 16. As a result, the electrical current commutates to the bypass path 22, and the arc 32 extinguishes. However, due to the arc 32, ionized gas was formed in the separating element 16, which is why the main current path continues to exhibit an electrical conductivity, albeit reduced. Consequently, an electrical voltage develops between the two ends of the main current path 14, and thus also across the additional component 36, even though no current flows through the main current path 14.The electrical voltage, i.e., the parameter 20, decreases as the deionization of the gas in the separating element 16 progresses. Furthermore, the applied electrical voltage, i.e., the parameter 20, depends on the electrical voltage applied between the terminals 12.

[0063] In the second step 32, the current flow through the semiconductor switch 24 is adjusted such that the electrical parameter 20, i.e., the electrical voltage applied across the other component 36, corresponds to a target value. In other words, the electronic parameter 20 is regulated to the target value by adjusting the current flow. The target value, i.e., the electrical voltage, is such that when applied to the other component 36, the electrical voltage applied in this case to the separating element 16 does not cause the arc 32 to ignite.

[0064] To ensure that the electrical parameter 20 corresponds to the target value, the semiconductor switch 24 is energized, whereby the electrical current carried by the bypass path 22 is limited, so that initially the full voltage supplied by the power source 4 is not present between the terminals 12. For this purpose, a correspondingly adjusted electrical voltage is applied to the control input 42. Due to the ongoing deionization of the gas in the separating element 16, as the arc 32 is no longer present, the electrical conductivity of the main current path 14 decreases, and thus the electrical voltage across the further component 36 decreases. This is compensated for by regulating the current flow via the semiconductor switch 24, and the electrical voltage, i.e., parameter 20, is again adjusted to the target value. For this purpose, the current flow through the semiconductor switch 24 is reduced, so that the electrical voltage between the terminals 12 increases.Consequently, the electrical parameter 20 again assumes the target value, although the current flow through the hybrid switch 10 is lower. In summary, in order for the electrical parameter 20 to correspond to the target value, it is necessary to increase the electrical voltage between the terminals 12 due to the deionization of the gas in the separating element 16, for which the conductivity of the semiconductor switch 24 is reduced.

[0065] This continues until the semiconductor switch 24 is fully open, so that the electrical voltage between terminals 12 corresponds to the setpoint. Further deionization prevents any further adjustment of the control. Thus, even with the semiconductor switch 24 fully open, the electrical parameter 20 can no longer reach the setpoint because the conductivity of the main current path 14 has decreased too much. Consequently, the current flow through the hybrid switch 10 ceases completely. Following this, the third step 34 is executed, and the process 28 is terminated.

[0066] In another embodiment, in the first step 30, the semiconductor switch 24 is also closed after or simultaneously with the opening of the isolating element 16, so that the electric current is commutated to the bypass path 22. The semiconductor switch 24 is then fully conducting. In other words, the electrical resistance of the semiconductor switch 24 is reduced to a minimum, for which a corresponding electrical voltage is applied to the control input 42. Due to the deionization in the isolating element 16, the electrical voltage across the further component 36 decreases, and the electrical parameter 20 is reduced. The electrical parameter 20 is compared with a first threshold value by means of the control unit 26. As soon as the electrical parameter 20 reaches or falls below the first threshold value, the semiconductor switch 24 is opened in the second step 32.

[0067] The first threshold is chosen such that, given the reduced conductivity of the separating element 16 and the main current path 14, the arc 32 will not reignite. This first threshold essentially corresponds to the value at which, in the above variant of method 28, the target value can no longer be reached despite the semiconductor switch 24 being fully open. Specifically, the target value used there is adopted as the first threshold.

[0068] When combining these two variants, the setpoint is chosen to be slightly lower, and a corresponding control is implemented. As soon as the electrical parameter 20 reaches the setpoint, the control is terminated and the semiconductor switch 24 is opened. In summary, the electrical parameter 20 is thus measured with the semiconductor switch 24 closed, and depending on a comparison with the first threshold value—namely, when the electrical parameter falls below the first threshold value—the semiconductor switch 24 is opened.

[0069] In another alternative, in the first work step 30 the semiconductor switch 24 is not closed initially, so that the arc 32 continues to exist.

[0070] However, due to the opening contacts of the separating element 16, the electrical voltage across the separating element 16, and thus also between the terminals 12, increases. Consequently, depending on the additional component 36 used, the electrical voltage across the additional component 36 changes. It is possible for the electrical voltage to increase or decrease.

[0071] At least in the second step 32, the electrical parameter 20 is measured with the semiconductor switch 24 open. If the electrical parameter 20 reaches a second threshold value, i.e., if the electrical voltage across the additional component 36 is greater or less than, or exceeds, the second threshold value (depending on the additional component 36 used), the semiconductor switch 24 is closed. Only then does the electrical current commutate from the main current path 14 to the secondary current path 22, thus extinguishing the arc 32. The current flow through the semiconductor switch 24 is therefore controlled depending on the parameter 20, namely, it is initiated as soon as the electrical parameter 20 reaches the second threshold value.

[0072] The second threshold is chosen such that if the semiconductor switch 24 is subsequently opened again and thus the electrical voltage now present between the terminals 12 is applied to the main current path 14, this voltage is not sufficient to reignite the arc 32.

[0073] As soon as the semiconductor switch 24 is closed and the arc 32 is extinguished, the third step 34 is carried out essentially immediately, and the semiconductor switch 24 is opened again. Since the arc 32 cannot be reignited, the current flow via the hybrid switch 10 is thus interrupted. In this variant of the method 28 and the hybrid switch 10, the semiconductor switch 24 serves to terminate the arc 32 when the electrical voltage applied between the terminals 12 is insufficient to reignite it because the switching contacts of the isolating element 16 are too far apart. Consequently, a comparatively low-power semiconductor switch 24 can be used.

[0074] In the conversion process, during the first step 30, the semiconductor switch 24 is closed for a short period of time when the separating element 16 is opened. The period during which the semiconductor switch 24 is closed is relatively short, so that the arc 32 reignites upon subsequent opening. However, in this variant, a brief deionization or other cooling already occurs in the separating element 14, so that the electrical voltage required to maintain the arc is already increased. Consequently, it is possible to choose a lower second threshold value.

[0075] In Figure 4 A modification of the hybrid switch 10 is shown, wherein the bypass path 22 with the semiconductor switch 24, the main current path 14 with the isolating element 16 and the further component 36 and the interference protection circuit 44 and their respective interconnection are not changed.

[0076] The control input 42 of the semiconductor switch 24, however, is electrically contacted via a series circuit 48 consisting of a diode 50 and a Zener diode 52 with one of the terminals 12, namely the one to which the further component 36 is also directly electrically contacted. The reverse bias of the diode 50 and the Zener diode 52 are opposite to each other.

[0077] The auxiliary current path 40 no longer includes the current sensor 38, but instead comprises a series circuit 48 with the corresponding diode 50 and the Zener diode 52. The power source 46 is connected to the auxiliary current path 40 on the side facing terminal 12. The power source 46 is further connected via a first resistor 54 to the remaining end of the auxiliary current path 40 and thus also to the main current path 14 between the isolating element 16 and the other component 36. Therefore, the electrical potential for the auxiliary current path 40 is at least partially determined by the power source 46, i.e., the electrical voltage across the other component 36.

[0078] The control unit 26 is also connected to the main current path 14 between the isolating element 16 and the further component 36 via another of the series circuits 48 and a second resistor 56, which are electrically connected in series, and thus to one end of the auxiliary current path 40. Furthermore, the control unit 26, which is still electrically contacted with the control input 42 of the semiconductor switch 24, is electrically connected to the remaining terminal 12 via another of the series circuits 48, which is electrically connected in series with a third resistor 58. The construction of all series circuits 48 with the respective diode 50 and the Zener diode 52, whose reverse biases are opposed to each other, is identical. However, these circuits can exhibit different reverse voltages, particularly in different series circuits 48.

[0079] Due to the circuit configuration, the electrical voltage across the additional component 36 is no longer measured directly in this variant. However, if the electrical voltage across the additional component 36 exceeds a certain value, the semiconductor switch 24 is switched to electrical conductivity almost immediately due to the circuit configuration, which is of the type known as "active clamping," thus reducing the reaction time for switching on the semiconductor switch 24. Because of the circuit configuration of the control unit 26, the electrical voltage across the additional component 36 can be determined, enabling, for example, control. At the very least, it is possible to adjust the current flow through the semiconductor switch 24 depending on the electrical parameter 20.

[0080] In Figure 5A first embodiment of the further component 36 is shown. This component is designed as an ohmic resistor and thus has a constant electrical resistance. It is possible to integrate the current sensor 38 into the further component 36, so that it is a shunt, by means of which, in particular, the electric current flowing through the main current path 14 can be measured. In this variant, the electrical parameter 20 is preferably detected when the semiconductor switch 24 is open, and the semiconductor switch 24 is closed when the electrical parameter 20 reaches the second threshold value.

[0081] In the Figure 6 and 7 In each case, a further embodiment of the additional component 36 is shown. In both cases, the additional component 36 is a switching element 60, wherein in Figure 6 The switching element 60 is a semiconductor switch, such as a MOSFET. Figure 7The switching element 60, and thus also the further component 36, is designed as a mechanical switch. It is possible for the mechanical switch, which is designed in particular like a relay, to be separate from the isolating element 16. However, it is also possible to provide the switching element 60 and the isolating element 16 by means of a common unit, namely a double switch, so that during operation the isolating element 16 and the further component 36 are actuated essentially simultaneously.

[0082] In the depicted variants, the switching element 60 is controlled during the execution of the method 28 in such a way that a certain electrical parameter 20 is achieved, namely that the electrical parameter 20 does not fall below a minimum voltage. For example, the mechanical switch is controlled in such a way that an additional arc is generated via it when it opens.

[0083] In the Figures 8 and 9In the illustrated variants, the additional component 36 each includes the switching element 60, which is designed as a semiconductor switch or as a mechanical switch. The respective switching element 60 is bridged by a fourth resistor 62, a capacitor 64, and a second Zener diode 66. This ensures that the electrical voltage across the additional component 36, i.e., the electrical parameter 20, always has a minimum value. When using such an additional component 6, the first and second threshold values ​​are adjusted accordingly.

[0084] In Figure 10Another embodiment of the hybrid switch 10 is shown, in which the additional component 36 is designed as a switching element 60, which is mechanically combined with the isolating element 16 to form a double switch. The interference suppression circuit 44 is also present and remains unchanged. The auxiliary current path 22 with the semiconductor switch 24 is still present, with the control input 42 of the semiconductor switch 24 being electrically connected via one of the series circuits 48 to one of the outputs 12, namely the one that is also connected to the auxiliary current path 40. A fifth resistor 68 and a second capacitor 70 are connected in parallel to this series circuit 48. The auxiliary current path 40 has only a sixth resistor 72, by means of which the additional component 36 is bypassed, and by means of which the minimum voltage drop across it is determined.

[0085] The control input 42 of the semiconductor switch 24 is also connected to the main current path 14 between the isolating element 16 and the further component 36 via one of the series circuits 48 and the second resistor 56, which are electrically connected in series. Optionally, the control input 42 is connected to the remaining terminal 12 via one of the series circuits 48 and the third resistor 58.

[0086] In this variant of the hybrid switch 10, the control unit 26 is not present as a separate unit, but is formed by the interconnection. A power source 46 is also not required and is omitted. As soon as the isolating element 16 is opened, the other component 36, i.e., the switching element 60, is also opened. Due to the connection of the control input 42 of the semiconductor switch 24 with at least one of the terminals 12 in the manner of so-called "active clamping," an electrical voltage is present at the control input 42, so that the semiconductor switch 24 is electrically conductive. This voltage is at least partially determined by the sixth resistor 72 and changes depending on the electrical voltage across the switching element 60, which represents the electrical parameter 20.In other words, the electrical parameter 20 is regulated to the target value due to the circuit configuration, whereby this is at least partially predetermined by the sixth resistor 72. Thus, a variant of the procedure 28 is carried out due to the circuit configuration.

[0087] In Figure 11A further embodiment of the hybrid switch 10 is shown in simplified form, comprising the main current path 14 extending between the terminals 12, to which the secondary current path 22 with the semiconductor switch 24 is connected in parallel. The interference suppression circuit 44 is not shown and is omitted in a variant not shown in detail. The control unit 26 is also not shown. A first coil 74 is inserted into the main current path 14 and is electrically connected in series with the isolating element 16. The first coil 74 is inductively coupled to a second coil 76, with the two coils 74, 76 being part of a common transformer 78. Due to the inductive coupling, an alternating voltage is induced in the other coil 74, 76 when an alternating current is passed through one of the two coils 74, 76.In other words, the two coils 74, 76 are electrical coils, each formed by means of an electrical conductor wound on a common soft magnetic core, so that inductive coupling is realized.

[0088] The second coil 74 is a component of a resonant circuit 80, which is galvanically isolated from the current path 14 and the bypass path 22, and which has a capacitance 82 in the form of a capacitor. The resonant circuit 80 is operated by means of a control unit 84, which maintains the resonant circuit 80 at its natural resonant frequency, determined by the second coil 76 and the capacitance 82. The control unit 84 applies a corresponding alternating voltage to the capacitance 82, or second coil 76, which corresponds to the natural frequency of the resonant circuit 80. The control unit 84 also compensates for electrical losses resulting from a deterioration in the quality factor of the resonant circuit 80. In other words, the control unit 84 ensures that the energy present in the resonant circuit 80 during operation is always constant, regardless of the losses of the resonant circuit 80.

[0089] In the first step 30 of the process 28, the separating element 16 is opened and the semiconductor switch 24 is closed. This initially creates the electric arc 32, which subsequently extinguishes. Due to the electric arc 32, ionized gas is present in the separating element 16, so that the main current path 14 continues to exhibit (electrical) conductivity. In the second step 32, the control unit 84 is used to start operating the resonant circuit 80, causing an alternating current to flow through it. This induces an alternating voltage in the first coil 74. As long as the main current path 14 still exhibits electrical conductivity, the induced alternating voltage leads to a current flow in the main current path 14, and electrical energy stored in the first coil 74 is coupled out. This energy originated from the resonant circuit 80. In other words, electrical energy flows out of the resonant circuit 80.Thus, the quality of the resonant circuit 80 is comparatively low, and by means of the control unit 84 a comparatively large amount of energy is introduced back into the resonant circuit 80 so that it has a constant energy content.

[0090] The supplied energy corresponds to the electric current induced in the main current path 14 and is used as the electrical parameter 20. In other words, the electric current induced in the main current path 14 is used as the electrical parameter. The control unit 84 and the resonant circuit 80 are designed such that the maximum supplied electrical energy, even at maximum electrical conductivity of the main current path 14, is less than 1 W, so that the total electrical losses occurring during operation of the hybrid switch 10 are comparatively low.

[0091] If the conductivity of the main current path 14 decreases, the electric current resulting from the alternating voltage induced in the first coil 74 is reduced, which is why the energy coupled out of the resonant circuit 80 is also reduced. If the main current path 14 has no electrical conductivity at all, the electric current induced in the main current path 14 is essentially 0 A, and the control unit 84 merely compensates for electrical losses occurring in the resonant circuit 80 itself.

[0092] The electrical parameter 20 is compared with the first threshold value adapted to this application. The first threshold value is adjusted such that if the electrical parameter 20 falls below this threshold, the electrical conductivity of the main current path 14 is so low that opening the semiconductor switch 24 does not reignite the arc 32. However, the main current path 14 still retains a slight conductivity, which is why the threshold is crossed relatively quickly after the first operating step 30. Therefore, in the second operating step 32, the semiconductor switch 24 is opened when the electrical parameter 20 falls below the first threshold value.

[0093] Alternatively, when the semiconductor switch 24 is open, i.e., when the arc 32 exists, an electric current is induced in the main current path 14, and this is used as a parameter 20. Since an electric current is already flowing through the main current path 14, the saturation of the core of the transformer 78 is altered, so that, depending on the current flow direction in the resonant circuit 80, electrical energy is extracted. If the electrical parameter 20 falls below the second threshold value, which is adjusted accordingly, the semiconductor switch 24 is closed, so that the electric current flow is commutated from the main current path 14 to the secondary current path 22. Subsequently, the semiconductor switch 24 is opened again. The second threshold value is adjusted such that the arc 32 does not reignite.

[0094] In Figure 12A circuit of this variant of the hybrid switch 10 is shown, essentially depicting the resonant circuit 80 and the control unit 84. The control unit 84 is supplied with electrical voltage via the power source 46. Three transistors 86 are present, connected to a first control resistor 88 and a second control resistor 90 in such a way that an electrical current flowing through the first control resistor 88 must also flow through the second control resistor 90. Two of the transistors 86 and the second control resistor 90 are electrically connected in series between the two potentials of the power source 46. The remaining transistor 86, the first control resistor 88, and a control capacitor 91 are also electrically connected in series between the two potentials of the power source 46.

[0095] Thus, the voltage drop across the second control resistor 90 is proportional to the charging current of the capacitor 82. This voltage is smoothed by an RC filter connected in parallel to the two series-connected transistors 86, and consisting of a third capacitor 92 and a seventh resistor 94. The smoothed voltage is passed to the sensor input of a voltage regulator 96, which switches off as soon as the measured voltage rises above 2.5V, and which is connected in series with an eighth resistor 98 between the two potentials of the power source 46.

[0096] An electrical series circuit consisting of a ninth resistor 100 and a fourth capacitor 102 is connected between the two potentials of the energy source 46. A third Zener diode 104 is connected in parallel to this series circuit. During operation, the fourth capacitor 102 is charged via the ninth resistor 100, with the charging voltage limited by the third Zener diode 104. Due to the circuit configuration, the charging voltage is applied to the gate of a first MOSFET 106 and to the gate of a second MOSFET 108. If the voltage at the source of the respective MOSFET 106 or 108 is lower than at the gate, the respective MOSFET 106 or 108 has a low resistance.

[0097] Parallel to the control capacitor 91, a series connection consisting of a third coil 110 and a third MOSFET 112, as well as a series connection consisting of a fourth coil 114 and a fourth MOSFET 116, is connected. The resonant circuit 80 is connected between the third coil 110 and the fourth coil 114, and also between the third MOSFET 112 and the fourth MOSFET 114.

[0098] In parallel with the third MOSFET 112, an electrical circuit consisting of a fifth capacitor 118 and a tenth resistor 120 is connected in series. The fifth capacitor 118 is bypassed by a second diode 122, through which the third coil 110 is electrically connected to the first MOSFET 106. The first MOSFET 106 is connected to the gate of the fourth MOSFET 116 via an eleventh resistor 124. In parallel with the fourth MOSFET 116, an electrical circuit consisting of a sixth capacitor 126 and a twelfth resistor 128 is connected in series. The sixth capacitor 126 is bypassed by a third diode 130, through which the fourth coil 114 is electrically connected to the second MOSFET 108. The second MOSFET 108 is connected to the gate of the third MOSFET 112 via a thirteenth resistor 132.

[0099] The gate of the third MOSFET 112 is connected to one of the electrical potentials of the power source 46 via an electrical series connection consisting of the thirteenth resistor 132 and a fourth Zener diode 134. The gate of the third MOSFET 112 is connected to the other electrical potential of the power source 46 via an electrical series connection consisting of the thirteenth resistor 132, a fourteenth resistor 136, and the ninth resistor 100.

[0100] The gate of the fourth MOSFET 116 is connected to one of the electrical potentials of the power source 46 via an electrical series connection consisting of the eleventh resistor 124 and a fifth Zener diode 138. The gate of the fourth MOSFET 116 is connected to the other electrical potential of the power source 46 via an electrical series connection consisting of the eleventh resistor 124, a fifteenth resistor 140, and the ninth resistor 100.

[0101] Consequently, the electrical voltage is switched via the resonant circuit 80 to the third and fourth MOSFETs 112 and 116 by means of the fifth capacitor 118 and the sixth capacitor 126, as well as the first and second MOSFETs 106 and 108. This makes it possible to switch the third and fourth MOSFETs 112 and 116 close to their voltage zero crossing, thus keeping switching losses low.

[0102] The fourth and fifth coils 110, 114 prevent a short circuit when the third and fourth MOSFETs 112, 116 switch on and feed the absorbed energy back into the resonant circuit 80. Since the branches are capacitively connected via the fifth capacitor 118 and the sixth capacitor 126, continuous conduction of the third and fourth MOSFETs 112, 116 is reliably prevented. Reliable blocking of the third and fourth MOSFETs 112, 116 is ensured by the second and third diodes 122, 130, respectively. To ensure the circuit starts up, the gates of the third and fourth MOSFETs 112, 116 are pre-charged with approximately their respective threshold voltages by means of the voltage dividers formed by the twelfth and fourteenth resistors 128, 136 and the tenth and fifteenth resistors 120, 140, respectively. As a result, the third and fourth MOSFETs 112, 116 operate in the manner of an amplifier until the resonant circuit 80 reaches its operating voltage.

[0103] The energy supplied to the resonant circuit 80 is drawn from the control capacitor 91, which is recharged via the first control resistor 88. Since the energy consumption is primarily determined by the quality factor / load of the resonant circuit 80, in addition to a basic requirement, the electrical parameter 20 can be directly determined from the current consumption. The first control resistor 88 serves to limit the power consumption of the resonant circuit 80 and prevents damage to the transistors 86. Additionally, this prevents significant power input via the transformer 78 to the ionized gas present in the separating element 16 and / or the arc 32. To increase the sensitivity, the winding ratio of the two coils 74, 76 can be adjusted, or the operating voltage of the resonant circuit 80 can be increased. Reference symbol list

[0104] 2 Circuit 4 Power source 6 Conductors 8 Load 10 Hybrid switch 12 Connection 14 Main current path 16 Isolating element 18 Unit 20 Electrical characteristic 22 Auxiliary current path 24 Semiconductor switch 26 Control unit 28 Procedure 30 First step 32 Second step 34 Third step 36 Additional component 38 Voltage sensor 40 Auxiliary current path 42 Control input 44 Interference suppression circuit 46 Power source 48 Series circuit 50 Diode 52 Zener diode 54 First resistor 56 Second resistor 58 Third resistor 60 Switching element 62 Fourth resistor 64 Capacitor 66 Second Zener diode 68 Fifth resistor 70 Second capacitor 72 Sixth resistor 74 First coil 76 Second coil 78 Transformer 80 Resonant circuit 82 Capacitance 84 Control unit 86 Transistor 88 First control resistor 90 Second control resistor 91 Control capacitor 92 Third capacitor 94 Seventh resistor 96 Voltage regulator 98 Eighth resistor 100 Ninth resistor 102 Fourth capacitor 104 Third Zener diode 106 First MOSFET 108 Second MOSFET 110 ThirdCoil 112 third MOSFET 114 fourth coil 116 fourth MOSFET 118 fifth capacitor 120 tenth resistor 122 second diode 124 eleventh resistor 126 sixth capacitor 128 twelfth resistor 130 third diode 132 thirteenth resistor 134 fourth Zener diode 136 fourteenth resistor 138 fifth Zener diode 140 fifteenth resistor

Claims

1. Method (28) for operating a hybrid switch (10), which has a main current path (14) comprising an isolating element (16), and an auxiliary current path (22), connected in parallel with the main current path (14), comprising a semiconductor switch (26), in which - the isolating element (16) is opened, - an electrical characteristic variable (20) of the main current path (14) is ascertained, characterized in that the electrical characteristic variable (20) is based on or corresponds to an electrical conductivity of the main current path (14), and wherein - a current flow via the semiconductor switch (24) is adjusted depending on the characteristic variable (20).

2. Method (28) according to Claim 1, characterized in that the electrical characteristic variable (20) is regulated to a target value by adjusting the current flow.

3. Method (28) according to Claim 1 or 2, characterized in that the electrical characteristic variable (20) is recorded when the semiconductor switch (24) is closed, and in that the semiconductor switch (24) is opened depending on a comparison of the electrical characteristic variable (20) with a first threshold value.

4. Method (28) according to one of Claims 1 to 3, characterized in that the electrical characteristic variable (20) is recorded when the semiconductor switch (24) is open, and in that the semiconductor switch (24) is closed when the electrical characteristic variable (20) reaches a second threshold value.

5. Method (28) according to one of Claims 1 to 4, characterized in that a voltage present across a further component (36) of the main current path (14) that is electrically connected in series with the isolating element (16) is used as the electrical characteristic variable (20).

6. Method (28) according to Claim 5, characterized in that a switching element (60) that is actuated in order to achieve a certain electrical characteristic variable (20) is used as the further component (36).

7. Method (28) according to one of Claims 1 to 4, characterized in that an electric current induced in the main current path (14) is used as the electrical characteristic variable (20).

8. Hybrid switch (10), which has a main current path (14) comprising an isolating element (16), and an auxiliary current path (22), connected in parallel with the main current path (14), comprising a semiconductor switch (24), and which is operated according to a method (28) according to one of Claims 1 to 7.

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