Electronic assembly

Abstract

The invention relates to an electronic assembly (100), comprising: - a switching device (102) for switching a main current path (103), wherein the switching device (102) comprises n series-connected semiconductor switching units (102.1, 102.2,..., 102.n), wherein n is a natural number excluding zero, - a voltage limiting device (114) connected in parallel with the switching device (102) and comprising at least one overvoltage protection component (107) and at least one diac (109) connected in series with the at least one overvoltage protection component (107), and - n surge arresters (110, 110.1, 110.2, ..., 110.n), wherein each one of the n surge arresters (110, 110.1, 110.2,..., 110.n) is connected in parallel with each one of the n semiconductor switching units (102.1, 102.2,..., 102.n) in a bijective relationship.

Description

[0001] Description

[0002] Electronic arrangement

[0003] The present invention relates to an electronic arrangement, an electrical switching device and a method.

[0004] US2021 / 0288636A1 (ABB Switzerland AG; Song et al.) September 16, 2021 describes in Fig. 4A a solid-state circuit breaker 400 (SSCB) which comprises a parallel connection of a semiconductor switching element 405 (e.g. MOSFET or IGBT) and a voltage clamping circuit 406 (MOSFET = metal oxide semiconductor field-effect transistor; IGBT = insulated-gate bipolar transistor) between a first terminal 401 and a second terminal 403. The voltage clamp circuit 406 comprises a series connection of a metal oxide varistor (= MOV) 407 and a TVS thyristor 411, wherein the MOV 407 is connected between the first terminal 401 and the TVS thyristor 411 and wherein the TVS thyristor 411 is designed such that it can selectively couple the MOV 407 to the second terminal 403 (TVS = Transient Voltage Suppression).The voltage clamp circuit 406 also includes a capacitor 409 connected between the first terminal 401 and the TVS thyristor 411. The technical effect of the voltage clamp circuit 406 is to protect the semiconductor switching element 405 from an undesirable overvoltage in the form of a damaging voltage spike 511; this overvoltage protection effect is illustrated in Figs. 5A and 5B.

[0005] A disadvantage of this known voltage clamp circuit 406 is that the capacitor 409 can negatively influence the behavior of the solid-state power switch 400.

[0006] There is therefore a need for improved overvoltage protection for a semiconductor switching device. This object is achieved according to the invention by an electronic arrangement having the features specified in claim 1, a switching device having the features specified in claim 7, and a method having the features specified in claim 8.

[0007] The electronic arrangement has a switching device which serves to switch a main current path, i.e. an electrical conductor between a voltage source and an electrical load. Under normal operating conditions, the main current path forms a current path of a load current (direct or alternating current) to an electrical load, which is also referred to as a consumer. This electrical conductor is also referred to here as a phase conductor. The phase conductor can be a conductor of a single-phase or multi-phase power line.

[0008] The switching device has n (n = 1, 2, 3, . . . ) semiconductor switching units connected in series. A semiconductor switching unit can be, for example, a power electronics switch (PE switch) comprising one or more semiconductor switching elements (e.g. IGBT or MOSFET). Each of the semiconductor switching units of the switching device can be switched by external control signals into a first state in which the semiconductor switching unit blocks current, or into a second state in which the semiconductor switching unit conducts current. To switch the main current path, the n semiconductor switching units of the switching device connected in series can each be controlled by external control signals such that the switching device blocks current or conducts current.

[0009] The switching device for switching a main current path can perform the switching function using a single semiconductor switching unit. However, it is also possible for the switching device for switching a main current path to perform the switching function using two or more semiconductor switching units. The technical effect of this latter configuration lies in the fact that the applied reverse voltage is distributed between the two or more semiconductor switching units, i.e. each of the two or more semiconductor switching units only has to be able to withstand a significantly lower reverse voltage than a single semiconductor switching unit to which the entire reverse voltage is applied. This is advantageous because the costs of a semiconductor switching unit are generally higher the higher the maximum voltage that may be applied to the semiconductor switching unit, provided that the on-resistance of the semiconductor switching unit remains constant.It may therefore be more cost-effective (e.g., approximately 20 to 30%) to construct the switching device with, for example, two semiconductor switching units, each of which may be applied with a maximum voltage of 600 V, rather than with a single semiconductor switching unit, to which a maximum voltage of 1200 V may be applied.

[0010] To interrupt a load circuit, i.e. to separate the feed and the load, semiconductor-based switching elements such as MOSFETs such as Si or SiC MOSFETs, transistors, IGBTs, triacs and thyristors can be used in an electrical switching device. These semiconductor-based switching elements have the advantage that they switch on quickly and can switch without wear. MOSFETs, transistors and IGBTs have the advantage that they can switch off electrical currents very quickly, which is important in the event of short circuits, for example. However, these semiconductor switches are sensitive in that they have a maximum blocking voltage. This limit specifies the maximum voltage that may be applied to the semiconductor switch. This limit must be observed in all cases, since the semiconductor switches only function reliably below the limit.If the topology of the circuit is such that it cannot be guaranteed that the limit value will be adhered to in every operating case, voltage limiting elements are connected in parallel to the semiconductor switch so that the voltage applied to the semiconductor switch does not exceed a defined value. The electronic arrangement also has a voltage limiting device connected in parallel to the switching device. The voltage limiting device, which is connected in parallel to the switching device, protects the switching device from harmful overvoltage. A common situation in which an overvoltage can occur is the switching device opening or closing an inductive circuit. Here and in the following, the term inductance is used as a generic term for inductive electrical and electronic components in the circuit, e.g.Electric motors, coils, transformers or electrical conductors (power lines). When a switching operation is carried out in a circuit, the inductance present in the circuit creates an overvoltage pulse at the switching device. An overvoltage must not exceed a maximum blocking voltage of the semiconductor switching units; this limit specifies the maximum voltage that may be applied to a semiconductor switching unit. As the switching device has n semiconductor switching units, which can generally be irreversibly damaged by even relatively small overvoltages, it is very important to protect the switching device from overvoltage. The voltage limiting device fulfils this task: it ensures that an occurring overvoltage does not exceed a threshold value above which damage to the switching device can occur.The voltage limiting device comprises a series connection of at least one overvoltage protection component and at least one diac.

[0011] A surge protection device, also known as an SPD (= Surge Protection Device), is an electrical device that protects other electrical components from voltage spikes. Typically, the surge protection device triggers at a specified voltage, which is approximately 1.2 to 2 times the nominal voltage. The surge protection device absorbs the voltage spike and dissipates the energy contained therein as heat. In addition to the at least one surge protection device, i.e. the actual energy absorber, at least one diac is connected in series. A diac, an acronym for "Diode for Alternating Current", is also called a bidirectional diode. The path between the two terminals of the diac only becomes conductive when the voltage across them reaches the breakdown voltage U Bo (breakover voltage) of the diac. The main advantage of this solution is that no control signal is required. A diac becomes conductive as soon as a certain voltage is exceeded across it.

[0012] The voltage limiting device is configured, through a clever selection of the at least one overvoltage protection component and the at least one diac, such that the voltage limiting device allows virtually no current to pass below a defined voltage threshold. Only when a voltage across the voltage limiting device exceeds this voltage threshold does the voltage limiting device allow current to pass. In this way, the applied voltage is reduced, and the overvoltage cannot rise significantly above the specified voltage threshold.

[0013] Unlike a TVS diode, once the diac's trigger voltage has been exceeded, only a small voltage (depending on the current) < 10 V drops across it, comparable to a diode characteristic. The power dissipated is correspondingly low, which is why the majority of the energy to be dissipated is dissipated in the overvoltage protection component. As soon as the energy has been dissipated to such an extent that the current through the series connection of the at least one overvoltage protection component and the at least one diac falls below the holding current (approx. 500 to 600 mA, depending on the type and trigger voltage), the at least one diac becomes high-impedance again and the voltage limitation or energy dissipation process is completed. The electronic arrangement also has n surge arresters.In this case, one of the n surge arresters is connected in parallel to one of the n semiconductor switching units of the switching device, so that there is a bij ective assignment between the n surge arresters and the n semiconductor switching units.

[0014] The invention is based on the finding that the n surge arresters provide additional degrees of freedom to safely and reliably protect a semiconductor switching device from an overvoltage that occurs. By wiring with the n surge arresters, it can be ensured that a voltage peak caused by an overvoltage that occurs is further reduced, since the surge arrester takes over part of the current in the initial moment the voltage peak occurs, until the voltage limiting device connected in parallel then takes over the current completely. This technical effect is achieved by the fact that the n surge arresters are designed in such a way that they have a significantly faster current take-over capacity than the voltage limiting device.

[0015] The electronics assembly can be part of an electrical switching device. An electrical switching device is used to supply an electrical consumer, also referred to as a "load," with electrical energy from a feed source, for example, an electrical power grid. Electrical consumers can essentially be divided into resistive electrical consumers, capacitive electrical consumers, and inductive electrical consumers, as well as hybrids thereof.

[0016] A current-carrying inductive load stores electrical energy, which leads to overvoltages after the load circuit is interrupted. Typically, a freewheeling path is provided to dissipate the stored energy: it forms a current path for the breaking current. If no freewheeling path is provided, other protective elements designed to dissipate the stored energy must be provided.

[0017] The object is further achieved according to the invention by an electrical switching device having an electronic arrangement according to the invention. The switching device can be an SSCB which controls the current flow through a phase line by means of a semiconductor switch. The SSCB can, among other things, assume an on state in which current flow through the semiconductor switch is enabled, and an off state in which current flow through the semiconductor switch is prevented. A change from the on state to the off state can be triggered by a fault in the phase line, e.g. a relatively low-strength overcurrent lasting for a longer period (overload) or a relatively high-strength overcurrent occurring rapidly (short circuit).

[0018] An electrical switching device is used to supply an electrical consumer, also known as a "load", with electrical energy from a feed-in source, for example from an electrical power grid, in a controlled manner. Electrical consumers can essentially be divided into resistive electrical consumers, capacitive electrical consumers and inductive electrical consumers, as well as hybrid forms thereof.

[0019] The object is further achieved according to the invention by a method for limiting an overvoltage using an electronic arrangement according to the invention. The method comprises a step in which a voltage is applied to the switching device for switching a main current path, the switching device comprising n semiconductor switching units connected in series, where n is a natural number excluding zero. The method comprises a step in which, when the overvoltage occurs, the current commutates from the switching device to the n surge arresters, one of the n surge arresters being connected in parallel to each of the n semiconductor switching units in a bi-jective assignment.The method comprises a step in which the overvoltage is reduced by the n surge arresters until the voltage limiting device connected in parallel to the switching device can completely take over the current, wherein the voltage limiting device comprises at least one overvoltage protection component and at least one diac connected in series with the at least one overvoltage protection component. The method comprises a step in which the current is commutated from the n surge arresters to the voltage limiting device. The method comprises a step in which the energy in the voltage limiting device is dissipated until the energy is dissipated to such an extent that the current through the voltage limiting device falls below a holding current of the diac; and the method comprises a step in which the current is commutated from the voltage limiting device to the main current path.

[0020] Advantageous embodiments and further developments of the invention are specified in the dependent claims.

[0021] According to a preferred embodiment, at least one of the n semiconductor switching units is formed by an interconnection of two or more of the following switching components: transistor, MOSFET, IGBT. In addition, the following switching components can also be used: BJT, GTO, MCT, IGCT, SiC switch, GaN switch, or any other type of HL-based switching element suitable for switching an electrical current, i.e. either allowing it to pass or blocking it (BJT = bipolar junction transistor; GTO = gate turn-off thyristor; MCT = MOS controlled thyristor; IGCT = integrated gate-commutated thyristor). Switching components forming a semiconductor switching unit can be coupled in series, parallel, anti-serial, anti-parallel or in a combination thereof.

[0022] According to a preferred embodiment, the surge protection component is a varistor, a gas discharge tube, or a spark gap. These surge components are characterized by their ability to absorb large amounts of energy. However, their response time, i.e., their ability to quickly transfer current, is limited.

[0023] A varistor, a portmanteau of the English term "variable resistor", is also known as a VDR (= Voltage Dependent Resistor). During normal operation, its electrical resistance is very high, but in the event of an overvoltage, its resistance drops almost instantly to a very low level. A common type of varistor is the metal oxide varistor (MOV), in which the resistance material is made of a metal oxide, e.g. zinc oxide (ZnO) or titanium dioxide (TiO2).

[0024] According to a preferred embodiment, at least one of the n surge arresters has a TVS diode or several TVS diodes connected in series. TVS diodes are characterized by a significantly faster current transfer capacity than metal oxide varistors. However, the energy absorbed is significantly smaller than that of metal oxide varistors, while simultaneously requiring a larger volume.

[0025] According to a preferred embodiment, a capacitor or a series circuit comprising a capacitor and a resistance component is connected across some or all of the one or more series-connected TVS diodes of at least one surge arrester. The resistance component, also referred to simply as a “resistor” below, is a component with a defined electrical resistance R. The capacitor has a defined electrical capacitance C. The capacitor has the advantage that it can improve the switching behavior of the TVS diodes. The parallel capacitor improves the commutation of the current to the TVS diode because the capacitor limits the voltage rise across the TVS diode. The resistance component has the advantage that it can improve the oscillation behavior of the electronic arrangement, for example by dampening unwanted oscillations that occur in the electronic arrangement.The series connection of a capacitor and a resistor component forms an RC element, which can limit electromagnetic interference.

[0026] In the following, the invention is explained using several embodiments with the aid of the accompanying drawing. It shows schematically and not to scale

[0027] Fig. 1 shows a first embodiment of the electronic arrangement;

[0028] Fig. 2 shows a second embodiment of the electronic arrangement, wherein the surge arrester has a TVS diode or two or more TVS diodes connected in series;

[0029] Fig. 3 shows a circuit with an electronic arrangement which has a TVS diode;

[0030] Fig. 4 shows a further embodiment of the electronic arrangement, wherein the switching device has two semiconductor switches;

[0031] Fig. 5 shows a further embodiment of the electronic arrangement, wherein the electronic arrangement additionally has a capacitor connected in parallel;

[0032] Fig. 6 shows a further embodiment of the electronic arrangement, wherein the switching device has two semiconductor switches and capacitors connected in parallel thereto;

[0033] Fig. 7 shows a further embodiment of the electronic arrangement, which represents an alternative design to the embodiment shown in Fig. 6; Fig. 8 shows a flowchart with the steps of the method according to the invention;

[0034] Fig. 9 a switching device;

[0035] Fig. 10 shows a circuit with an electronic arrangement which has at least two TVS diodes;

[0036] Fig. 11 shows a circuit with an electronic arrangement which has at least two TVS diodes and an RC element connected in parallel thereto;

[0037] Fig. 12 shows a further embodiment of the electronic arrangement, wherein the voltage limiting device comprises a series circuit of at least two varistors and at least two diacs; and

[0038] Fig. 13 shows a further embodiment of the electronic arrangement, wherein the four parallel current paths each have at least one corresponding component.

[0039] Fig. 1 shows an electronic arrangement 100. The electronic arrangement 100 has two terminals 101, 104, namely a first terminal 101 and a second terminal 104, with which the electronic arrangement 100 can be connected into an electrical circuit.

[0040] The electronic arrangement 100 has a main current path 103 between its first connection 101 and its second connection 104, in which main current path 103 a switching device 102 for switching the main current path 103 is arranged. For this purpose, the switching device 102 can switch between a current-conducting state and a current-blocking state. The switching device 102 has a semiconductor switching unit, which can be, for example, a transistor, a MOSFET, a triac or an IGBT. The electronic arrangement 100 also has, between its first connection 101 and its second connection 104, a parallel current path 108 running parallel to the main current path 103, in which parallel current path a voltage limiting device 114 is arranged. The voltage limiting device 114 has an overvoltage protection component 107 and a diac 109 connected in series with the overvoltage protection component 107.The overvoltage protection component 107 can be, for example, a varistor, a suppressor diode, a gas discharge tube or a spark gap.

[0041] The electronic arrangement 100 also has, between its first terminal 101 and its second terminal 104, a bypass current path 111 running parallel to the main current path 103 and parallel to the parallel current path 108, in which a surge arrester 110 is arranged. The surge arrester 110 can be one or more series-connected TVS diodes.

[0042] Fig. 2 shows an electronic arrangement 100 which corresponds to the electronic arrangement 100 shown in Fig. 1, wherein the overvoltage protection component 107 is designed as a varistor and the overvoltage arrester 110 is designed as n series-connected TVS diodes 112. 1, 112. 2, . . . , 112. n, where n is a natural number without zero.

[0043] Fig. 3 shows an electrical circuit with an electronic arrangement 100. The electrical circuit has a voltage source 118. The voltage source 118 can provide a direct voltage (DC) or an alternating voltage (AC). A first connection of the current source 118 is connected by means of an electrical conductor 113 to a first connection 101 of the electronic arrangement 100, which is designed according to Fig. 2. The second connection 104 of the electronic arrangement 100 is connected by means of the electrical conductor 113 to an electrical consumer 119, 120, also referred to as (electrical) load, which is symbolized by an electrical resistor 119 and an inductance 120. The circuit symbols of the electrical resistor 119 and the inductance 120 also include the ohmic and inductive properties of the electrical conductor 113 of the electrical circuit.From the electrical load 119, 120, the electrical conductor 113 runs back to the power source 118, where the electrical conductor 113 is connected to a second terminal of the power source 118. The term "inductance" refers to inductive electrical and electronic components of the circuit, such as coils, wires, or transformers.

[0044] The electronic arrangement 100 has, between its first terminal 101 and its second terminal 104, a main current path 103, a parallel current path 108 and a bypass current path 111, which run parallel to one another.

[0045] A switching device 102, 102.1 is arranged in the main current path 103, which can be switched on the main current path 103, which, during normal operation of the circuit, forms the current path of a load current flowing from the power source 118 to the electrical load 119, 120. The current-carrying conductor 113 is used to conduct the load current, a direct or alternating current, from the voltage source 118 to the electrical load 119, 120. The current-carrying conductor 113 can be a phase conductor of a single-phase or multi-phase circuit. To switch the load current, the switching device 102 can be switched by switching signals supplied externally to the switching device 102 into a first state in which the switching device 102, 102.1 is current-blocking, or into a second state in which the switching device 102, 102.1 is current-conducting. In the present embodiment, the switching device 102, 102.1 is formed by two transistors 117 connected to each other.

[0046] The electronics assembly 100 has a voltage limiting device 114 in the parallel current path 108, which comprises a series circuit 114 of a diac 109 and a varistor 107. The electronics assembly 100 has a surge arrester 110 in the bypass current path 111, which has a bidirectional TVS diode 112. 1.

[0047] The electronic arrangement 100 serves to supply the electrical load 119, 120 with electrical energy from the voltage source 118 in a controlled manner. The electronic arrangement 100 can be a component of an electrical switching device. A switching device with a semiconductor-based switching device can switch off electrical currents very quickly. Currents must be switched off, for example, in the event of short circuits. During the switching off process, a high overvoltage occurs at the switching device 102, which must be limited to safe values ​​by overvoltage limiting elements. The overvoltages are caused by the inductances present in the circuit.

[0048] Normally, when the switching device 102 is switched to conduct, the load current flows via the main current path 103. If the switching device 102 is now switched to block current, an overvoltage occurs in the circuit, from which the switching device 102, which contains semiconductor components such as transistors that can be easily damaged by an overvoltage, must be protected.

[0049] The voltage limiting device 114, connected in parallel with the switching device 102, becomes conductive when a voltage threshold defined by the component selection is exceeded, thereby limiting the voltage applied to the switching device 102. The voltage threshold can be defined not only by the selection of the diac 109 and the varistor 107, but also by other components of the circuit.

[0050] In this case, the voltage limiting device 114 has, in addition to the varistor 107, which acts as an energy absorber, a diac 109 in series. The main advantage of this voltage limiting device 114 is that it requires no control signal. A diac becomes conductive as soon as a certain voltage is exceeded across it. Unlike a TVS diode, only a small voltage (depending on the current) < 10 V drops across a diac after its ignition voltage is exceeded, comparable to a diode characteristic. The power converted is correspondingly low, which is why the majority of the energy to be dissipated is converted in the varistor 107. As soon as the energy in the circuit has been dissipated to such an extent that the current through the series connection of diac 109 and varistor 107 falls below the holding current (approx. 500 to 600 mA, depending on the type and ignition voltage), the diac 109 becomes high-impedance again and the process for limiting the voltage or to reduce energy is finished.In this case, the essential protective element can be a diode or another, similarly acting overvoltage protection component, e.g. a suppressor diode, a gas discharge tube or a spark gap, instead of the varistor 107.

[0051] By forming the voltage limiting device 114 by an overvoltage protection component 107 and a diac 109 connected in series with the overvoltage protection component 107, a further degree of freedom is gained: the actual inception voltage of the essential protection element, i.e. the overvoltage protection component 107, is extended by the inception voltage of the diac 109.

[0052] To increase performance, the electronic arrangement 100 has a further protective element in addition to the voltage limiting device 114: a TVS diode 112.1 connected in parallel with the voltage limiting device 114. This also makes it possible to utilize the advantages of a "stiffer characteristic curve" and "faster response time" of the TVS diode 112.1: the TVS diode 112.1 is characterized by a significantly faster current transfer capacity than the voltage limiting device 114 formed from varistor 107 and diac 109. In detail, this is as follows: at the beginning of the commutation process (load current commutates from the switching device 102 to the voltage limiting device 114), a small voltage peak occurs; this is due to the internal structure of the varistor 107. By additionally connecting the TVS diode 112.1, this voltage peak can be further reduced, since the TVS diode 112.1 initially takes over part of the load current until the voltage limiting device 114 then takes over the load current completely. This additional circuit with the TVS diode 112.1 is particularly useful when the voltage limiting device 114 has a varistor, since varistors generally exhibit a relatively slow current takeover.

[0053] Fig. 4 shows a further embodiment of the electronic arrangement. The switch device 102 has two series-connected semiconductor switches in the main current path 103.

[0054] 102.1 and 102.2. In the parallel current path 108, the voltage limiting device 114 has a varistor 107 and a diac 109 connected in series with the varistor 107.

[0055] In the bypass current path 111 there are two surge arresters 110.1,

[0056] 110.2, which are each connected in parallel to one of the two semiconductor switching units 102.1, 102.2, in a bi-directional arrangement between the surge arresters 110.1, 110.2 and the semiconductor switching units 102.1, 102.2. The surge arresters 110.1, 110.2 are each designed as an individual number of n series-connected TVS diodes 112.1, 112.2, ..., 112.n, where n is a natural number excluding zero. Compared to the embodiment shown in Fig. 3, unidirectional TVS diodes can preferably be used in the embodiment shown in Fig. 4.

[0057] Fig. 5 shows a further embodiment of the electronic arrangement corresponding to the electronic arrangement 100 shown in Fig. 2, wherein the electronic arrangement additionally has at least one capacitor 115 connected in parallel: A capacitor 115 or a series circuit comprising a capacitor 115 and a resistance component 116 is connected across a subset 112.1, 112.2, ..., 112.m-1 of the plurality of series-connected TVS diodes 112.1, 112.2, ..., 112.m-1, 112.m, 112.m+1, ..., 112.n of the surge arrester 110. The capacitor 115 can take over the current from the semiconductor switching unit 102 much faster than the TVS diodes. This allows the switching speed of the semiconductor switching unit 102 to be increased even further. In addition, the capacitor 115 limits the voltage rise across the semiconductor switching unit 192.The optional resistor component 116 is used to generate a vaporized behavior and reduces the risk of unwanted vibration excitation.

[0058] Fig. 6 shows a further embodiment of the electronic arrangement. The switch device 102 has two series-connected semiconductor switches in the main current path 103.

[0059] 102.1 and 102.2. In the parallel current path 108, the voltage limiting device 114 has a varistor 107 and a diac 109 connected in series with the varistor 107.

[0060] In the bypass current path 111 there are two surge arresters 110.1,

[0061] 110.2, which are each connected in parallel to one of the two semiconductor switching units 102.1, 102.2, in a bi ective assignment between the surge arresters 110.1, 110.2 and the semiconductor switching units

[0062] 102.1, 102.2. The surge arresters 110.1, 110.2 are each designed as an individual number of n or o TVS diodes 112.1, 112.2, ..., 112. n or

[0063] 112.1, 112.2, ..., 112.o, where n and o are natural numbers without zero.

[0064] In parallel to the surge arresters 110.1, 110.2 there is a series connection of a capacitor 115.1 or

[0065] 115.2 and an electrical resistor 116.1 or 116.2.

[0066] Capacitor 115.1 or 115.2 limits the voltage rise across semiconductor switching units 102.1, 102.2. Depending on the semiconductor used, a maximum voltage rise is specified that must not be exceeded to avoid damaging semiconductor switching units 102.1, 102.2. Electrical resistance 116.1 or 116.2 provides attenuation.

[0067] Fig. 7 shows a further embodiment of the electronic arrangement, which represents an alternative design to the embodiment shown in Fig. 6. The embodiment shown in Fig. 7 corresponds to the embodiment shown in Fig. 6, except for the following difference: while in the embodiment shown in Fig. 6 the series circuits of the capacitor 115.1 or 115.2 and the electrical resistor 116.1 or 116.2 are each connected across all TVS diodes of the associated surge arresters 110.1, 110.2, in the embodiment shown in Fig. 7 the series circuits of the capacitor 115.1 or 115.2 and the electrical resistor 116.1 or 116.2 each extend only across a subset of the TVS diodes of the associated surge arresters 110.1, 110.2.

[0068] Thus, the first series circuit of the capacitor extends

[0069] 115.1 and the electrical resistance 116.1 only via a subset of k-1 TVS diodes 112.1, 112.2, ..., 112, k-1 of the n TVS diodes 112.1, 112.2, ..., 112. k-1, 112. k, 112. k+1, ..., 112. n of the associated surge arrester 110.1.

[0070] And the second series connection of capacitor 115.2 and electrical resistor 116.2 extends only over a subset of h-1 TVS diodes 112.1, 112.2, ..., 112, h-1 of the o TVS diodes 112.1, 112.2, ..., 112. h-1, 112. h, 112. h+1, ..., 112.o of the associated surge arrester 110.2. The capacitors 115.1 and 115.2 can take over the current from the semiconductor switching units 102.1, 102.2 much faster than the TVS diodes 112. This allows the switching speed of the semiconductor switching units 102.1, 102.2 to be increased even further. In addition, the capacitors 115.1 and 115.2 limit the voltage rise across the semiconductor switching unit 102. The optional resistance components

[0071] 116.1 and 116.2 serve to generate a damped behavior and reduce the risk of unwanted vibration excitation.

[0072] Fig. 8 shows a flowchart with the steps of the method according to the invention for limiting an overvoltage using an electronic arrangement according to the invention.

[0073] In a first step 801, a voltage is applied to the switching device for switching a main current path. The switching device comprises n series-connected semiconductor switching units, where n is a natural number excluding zero. The current from the power source to the electrical load flows along the main current path through the switching device.

[0074] During a switching off process, the inductance present in the circuit creates an overvoltage at the switching device.

[0075] In a second step 802, when the overvoltage occurs, the current is commutated from the switching device 102 to the n surge arresters 110, 110.1, 110.2, ..., 110.n, wherein one of the n surge arresters 110, 110.1, 110.2, ..., 110.n is connected in parallel to one of the n semiconductor switching units 102.1, 102.2, ..., 102.n in a bijective assignment.

[0076] In a third step 803, the overvoltage is reduced by the n surge arresters 110, 110.1, 110.2, ..., 110.n, until the voltage limiting device 114 connected in parallel to the switching device 102 can completely accept the current. The voltage limiting device 114 has an overvoltage protection component 107 and a diac 109 connected in series with the overvoltage protection component 107. In a fourth step 804, the current is commutated from the n surge arresters 110, 110.1, 110.2, . . . , 110.n to the voltage limiting device 114.

[0077] To prevent the overvoltage occurring during a switch-off process from exceeding the maximum blocking voltage of the switching device, the voltage-limiting device 114 is connected in parallel with the switching device 102; this ensures that the voltage applied to the switching device never exceeds a defined value. For example, the voltage-limiting device can be designed as a voltage-limiting element which becomes conductive when a voltage defined by the selection of the voltage-limiting element, the so-called limiting value, is exceeded and thus prevents the voltage applied to the switching device from rising any further.

[0078] The magnetic energy stored in the circuit's inductance at the time of switching off must be essentially absorbed by the voltage limiting device and converted into heat during the switching off process, without overloading the device. Therefore, the dimensioning of the voltage limiting device depends primarily on the size of the inductance and the magnitude of the current to be switched off in the circuit.

[0079] In a fifth step 805 , the energy in the voltage limiting device 114 is reduced until the energy is reduced to such an extent that the current through the voltage limiting device ( 114 ) falls below a holding current of the diac .

[0080] In a sixth step 806, the current is commutated from the voltage limiting device 114 to the main current path 103.

[0081] Fig. 9 shows a switching device 900 with an electronic assembly 100. The switching device 900 has two terminals 901, 902, namely a first terminal 901 and a second terminal 902, with which the switching device 900 can be connected into an electrical circuit.

[0082] The switching device 900 has an electronic arrangement 100 according to the invention between its first terminal 901 and its second terminal 902.

[0083] The circuit has a voltage source 118. The voltage source 118 can provide a direct voltage (DC) or an alternating voltage (AC). A first terminal of the power source 118 is connected to the first terminal 901 of the switching device 900 by means of an electrical conductor 113. The second terminal 902 of the switching device 900 is connected by means of the electrical conductor 113 to an electrical load 119, 120, which is symbolized by an electrical resistor 119 and an inductance 120. From the electrical load 119, 120, the electrical conductor 113 runs back to the power source 118, where the electrical conductor 113 is connected to a second terminal of the power source 118.

[0084] Fig. 10 shows a circuit with an electronic arrangement 100, which has at least two TVS diodes 112.1, 112.2, ..., 112.n. With regard to the description of the circuit, reference is made to the circuit shown in Fig. 3: the circuit shown in Fig. 10 differs from the circuit shown in Fig. 3 exclusively in the design of the surge arrester 110. While in the circuit shown in Fig. 3 the surge arrester 110 is designed as a single TVS diode 112.1, in the circuit shown in Fig. 10 the surge arrester 110 is designed as a series connection of two or more TVS diodes 112.1, 112.2, ..., 112.n. This design can be particularly advantageous at high voltages U, since the voltage is distributed over the n series-connected TVS diodes: each individual TVS diode therefore only needs to provide a lower voltage, e.g.U / n, can therefore be more cost-effective than a single TVS diode, which must be able to carry the entire voltage U on its own.

[0085] However, a series connection of two or more TVS diodes can also simply be sensible or even necessary, as the maximum voltages of the diodes are limited at some point for different package sizes. For example, SMD TVS diodes can be used. Due to their size and weight, these diodes cannot be scaled arbitrarily in terms of voltage, as clearance and creepage distances must be maintained, and mechanical durability on the circuit board must also be guaranteed. For example, a typical SMC package has a maximum voltage of around 500 V; in this case, a series connection may be necessary. Furthermore, the energy is then also distributed, albeit only for the small voltage peak, but still a very high current.

[0086] Fig. 11 shows a circuit with an electronic arrangement 100, which has at least two TVS diodes 112.1, 112.2, ..., 112.n and an RC element 115, 116 connected in parallel thereto, formed by a series connection of a capacitor 115 and a resistor 116. With regard to the description of the circuit, reference is made to the circuit shown in Fig. 10: the circuit shown in Fig. 11 differs from the circuit shown in Fig. 10 only in the additional RC element 115, 116. The capacitor 115 has the advantage that it can improve the switching behavior of the TVS diodes 112.1, 112.2, ..., 112.n. The capacitor 115 connected in parallel to the TVS diodes 112.1, 112.2, ..., 112.n improves the commutation of the current to the TVS diodes 112.1, 112.2, ..., 112.n, since the capacitor 115 limits the voltage rise across the TVS diodes 112.1, 112.2, ..., 112.n.The resistance component 116 has the advantage that it can improve the oscillation behavior of the electronic arrangement 100, for example, by damping unwanted oscillations that occur in the electronic arrangement 100. The series connection of a capacitor 115 and a resistance component 116 forms an RC element, which can limit electromagnetic interference.

[0087] Fig. 12 shows a further embodiment of the electronic arrangement 100, wherein the voltage limiting device 114 is a series circuit of at least two varistors

[0088] 107.1, 107.2, ..., 107. n and at least two Diac 109.1,

[0089] 109.2, ..., 109. n. With regard to the description of the electronic arrangement 100, reference is made to the electronic arrangement shown in Fig. 1: the electronic arrangement shown in Fig. 12 differs from the electronic arrangement shown in Fig. 1 solely in the design of the voltage limiting device 114. While in the electronic arrangement shown in Fig. 1 the voltage limiting device 114 is formed by a series connection of a single overvoltage protection component 107, e.g. B. in the form of a varistor, and a single diac 109, in the electronic arrangement shown in Fig. 12 the voltage limiting device 114 is designed as a series connection of two or more varistors 107.1, 107.2, ..., 107. n and at least one diac 109.1, 109.2, ..., 109. n or as a series connection of at least one varistor 107.1, 107.2, ..., 107. n and two or more diacs 109.1, 109.2, ..., 109. n.This design can be particularly advantageous at high voltages U, since the voltage is distributed over the n series-connected components: each individual component (varistor and diac) only has to be able to withstand a lower voltage, and is therefore more cost-effective than a single component (varistor and diac), which has to be able to carry a significantly higher voltage on its own.

[0090] Fig. 13 shows a further embodiment of the electronic arrangement 100, wherein the four parallel current paths 103, 108, 111, 130 each have at least one corresponding component. The bracket symbols [...] next to the components in the respective current paths indicate that any number of further components can be arranged in the current path. Fig. 13 thus illustrates the wide variety of options available to the person skilled in the art for designing the electronic arrangement 100 to suit their needs. By selecting the number of components in the individual current paths 103, 108, 111, 130 and by selecting the properties of the individual components, the person skilled in the art can determine the behavior of the electronic arrangement 100 in order to ensure overvoltage protection of a semiconductor switching device 102.

Claims

Patent claims 1. Electronic arrangement (100) comprising - a switching device (102) for switching a main current path (103), wherein the switching device (102) comprises n series-connected semiconductor switching units (102.1, 102.2, ..., 102. n), where n is a natural number without zero, - a voltage limiting device (114) connected in parallel to the switching device (102), comprising at least one overvoltage protection component (107) and at least one diac (109) connected in series to the at least one overvoltage protection component (107), and - n surge arresters (110, 110.1, 110.2, ..., 110. n), wherein one of the n surge arresters (110, 110.1, 110.2, ..., 110. n) is connected in parallel to one of the n semiconductor switching units (102.1, 102.2, ..., 102. n) in a bijective assignment.

2. Electronic arrangement (100) according to claim 1, wherein at least one of the n semiconductor switching units (102.1, 102.2, ..., 102.n) is formed by an interconnection of two or more of the following switching components: transistor, MOSFET, IGBT.

3. Electronic arrangement (100) according to one of the preceding claims, wherein the overvoltage protection component (107) is a varistor, a gas discharge tube or a spark gap.

4. Electronic arrangement (100) according to one of the preceding claims, wherein at least one of the n surge arresters (110, 110.1, 110.2, ..., 110.n) has a TVS diode or a plurality of TVS diodes (112.1, 112.2, ..., 112.n, 112.o) connected in series.

5. Electronic arrangement (100) according to claim 4, wherein over a subset or over all of the one or more series-connected TVS diodes (112.1, 112.2, ..., 112.n, 112.o) of at least one surge arrester (110, 110.1, 110.2, ..., 110. n) a capacitor (115) or a series circuit of a capacitor (115) and a resistance component (116) is connected.

6. Switching device (900) with an electronic arrangement (100) according to one of claims 1 to 5.

7. A method for limiting an overvoltage using an electronic arrangement (100) according to one of claims 1 to 5, - applying (801) a voltage to the switching device (102) for switching a main current path (103), wherein the switching device (102) has n series-connected semiconductor switching units (102.1, 102.2, ..., 102.n), wherein n is a natural number without zero; - When the overvoltage occurs, commutating (802) the current from the switching device (102) to the n surge arresters (110, 110.1, 110.2, ..., 110. n), wherein in parallel to each of the n semiconductor switching units (102.1, 102.2, ..., 102.n) in a bijective assignment, one of the n surge arresters (110, 110.1, 110.2, ..., 110.n) is connected; - Reduction (803) of the overvoltage by the n surge arresters (110, 110.1, 110.2, ..., 110.n) until the voltage limiting device (114) connected in parallel to the switching device (102) can completely take over the current, wherein the voltage limiting device (114) has at least one overvoltage protection component (107) and at least one diac (109) connected in series to the at least one overvoltage protection component (107); - commutating (804) the current from the n surge arresters (110, 110.1, 110.2, ..., 110.n) to the voltage limiting device (114); - reducing (805) the energy in the voltage limiting device (114) until the energy is reduced to such an extent that the current through the voltage limiting device (114) falls below a holding current of the diac (109); and - Commutating (806) the current from the voltage limiting device (114) to the main current path (103).

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