Circuit module and semiconductor switch with a plurality of circuit modules which are connected in series

Abstract

The invention relates to a switch module for a semiconductor switch and to a switch made of a series circuit of such modules. The switch module according to the invention is formed of a first transistor (M3) having a source connection (source3), a control connection (Gate3), and a drain connection. Additionally, a second transistor (Q2) is provided, having a source connection, a control connection, and a drain connection, wherein the source connection is connected to the control connection (Gate3) of the first transistor (M3), and the drain connection is connected to the source connection (source3) of the first transistor (M3). Additionally, a connection is provided between the control connection of the second transistor (Q2) and a driver (V2). The invention allows a low-cost flexible implementation of an electronic interruption unit with an intrinsic short-circuit current limitation function.

Description

[0001]202300630 1 Description Circuit module and semiconductor switch with a plurality of series-connected circuit modules The invention relates to a circuit module, a semiconductor switch with a plurality of series-connected circuit modules, a power electronic switching or protective device with a semiconductor switch and a method for determining the short-circuit current limitation of a semiconductor switch according to the invention. A new development in low-voltage technology concerns the replacement of conventional electromechanical switches with so-called solid-state circuit breakers (SSCBs). Fig. 1 shows the basic structure of a typical SSCB. The main components of the SSCB are a power supply unit NT, a control unit SE, an electronic interruption unit EU and a mechanical isolating contact unit MK.SSCBs as miniature circuit breakers can implement virtually all the protective functions of conventional electromechanical circuit breakers in a single switch. Further advantages include switching speed, flexible control, and monitoring functions. However, high conduction losses are known to be a disadvantage of typical SSCBs. In recent years, increased efforts have therefore been made to reduce these conduction losses. One promising approach is the parallel connection of many unipolar components. In contrast to bipolar components, these have a nearly constant resistance in the on state (referred to below as RDSon, i.e., the resistance between drain and source in the on state). If the gate voltage on the power semiconductor is sufficiently high, this linearity is maintained up to the highest currents. This is shown in Fig.2 using a typical output characteristic field of an SI MOSFET (type designation IPT039N15N5). For various gate voltages V. GS (5V, 6V, 7V, 8V and 10V) is the drain current I0 flowing through the switch depending on the voltage between drain and source V DS Semiconductor switches are subject to limits regarding current carrying capacity. For example, for the MOSFET, whose characteristic field is shown in Fig. 1, the maximum permissible drain current according to the data sheet is 760 A. For sufficiently high gate voltages (in the example, already at V GS= 10V), the linearity between current and voltage, or a nearly constant resistance, remains up to currents at which the switch is destroyed. In other words, the power semiconductor in this case has no current limitation in a short circuit. It is thermally destroyed beforehand. This difficulty can be overcome in two ways. One possibility is to limit the gate voltage to values ​​at which the current remains within the permissible range. Fig. 3 shows a typical characteristic field R DSon as a function of the gate voltage of the MOSFET described in more detail above. The gate voltage can be lowered (in the example, for example, to 6 V), thereby forcing a limitation of the gate current to permissible values ​​(at 6 V to approximately 140 A – see Fig. 2). However, this measure results in a significant increase in the on-resistance R DSoneven during normal operation, and thus significantly higher conduction losses occur. The second option is to protect the switch with short-circuit current detection and shutdown, whereby the demands on the electronics become greater the lower the line inductance between the current source and the short circuit. This massively increases the costs for current measurement, threshold processing, and drivers, depending on the required dynamics. In the worst case, the design itself becomes a problem, since in reality it is difficult to specify a minimum possible lead inductance without having to install it as a discrete component in series with the load path, which in turn incurs significant costs and requires additional space. Thus, one finds oneself in a dilemma. Either one does not utilize the performance of the power semiconductor, or one accepts considerable additional expenditure for the electronics for short-circuit detection and shutdown.The object of the invention is to enable a low-cost and flexible implementation of an electronic interruption unit. This object is achieved by a circuit module according to claim 1, a semiconductor switch according to claim 13, a power electronic switching or protective device according to claim 25, and a method for determining the short-circuit current limitation of a semiconductor switch according to the invention according to claim 26. Advantageous further developments are specified in the subclaims. According to the invention, a circuit module for a semiconductor switch is proposed. This is formed with a first transistor having a source terminal, a control terminal, and a drain terminal.Here and in the following, the term “source terminal” refers to a source terminal or an emitter terminal, the term “control terminal” refers to a gate terminal or a base terminal, and the term “sink terminal” refers to a drain terminal or a collector terminal. In addition, the circuit module has a second transistor with a source terminal, a control terminal, and a drain terminal, the source terminal being connected to the control terminal of the first transistor and the drain terminal being connected to the source terminal of the first transistor. In addition, a connection is provided from the control terminal of the second transistor to a driver (which itself does not belong to the circuit module). 202300630 4 A central idea of ​​the invention is that a modular structure of a semiconductor switch can be achieved by series connection orCascading of circuit modules according to the invention can be realized, whereby the modules can be controlled by a single driver. This solution is low-complexity (only one driver), but can be scaled as required by changing the number of modules, i.e. it is also characterized by flexibility. By appropriately selecting the number of circuit modules and the driver voltage, short-circuit limitation can also be realized and set as required. The first transistor can be a unipolar transistor, e.g. a MOSFET. However, implementation using a bipolar transistor, e.g. an IGBT (Insulated-Gate Bipolar Transistor) with an anti-parallel protective diode (integrated or as an external freewheeling diode) is also possible. According to one embodiment of the circuit module according to the invention, the connection to the driver is formed by a conductor section into which a diode is introduced, which blocks in the direction of the driver.In addition, the connection can be formed with a conductor section into which a fuse is introduced. According to one embodiment of the circuit module according to the invention, the control terminal and the source terminal of the second transistor are connected to one another, and a diode which blocks current in the direction of the control terminal is arranged between the control terminal and the source terminal of the second transistor. According to one embodiment of the circuit module according to the invention, the control terminal and the drain terminal of the second transistor are connected to one another, and a resistor (preferably an ohmic resistor) is arranged between the control terminal and the drain terminal of the second transistor. According to one embodiment of the circuit module according to the invention, a voltage limiter is provided in parallel with the first transistor. A capacitive resistor can also be provided in parallel with the first transistor.According to a first alternative embodiment of the circuit module according to the invention, the control terminal and the source terminal of the first transistor are connected to one another, and a diode is arranged between the control terminal and the source terminal of the first transistor, which diode blocks in the direction of the control terminal. This diode is an optional feature, implemented, for example, by a Zener diode, which limits the maximum gate voltage or control terminal voltage. According to a second alternative embodiment of the circuit module according to the invention, the circuit module is formed with a third transistor, wherein the third transistor is of the same type as the first transistor and the first and third transistors are each directly connected to one another via the source terminal (i.e., are arranged practically in opposite directions).In this embodiment, the source terminal of the second transistor is connected to the control terminals of the first and third transistors, and the drain terminal of the second transistor is connected to the connection of the source terminals of the first and third transistors. The invention also relates to a semiconductor switch having a plurality of series-connected circuit modules according to the invention with a driver that is connected via the respective connections to the control terminals of the respective second transistors of the individual circuit modules. In particular, this semiconductor switch can be formed with exactly one driver. A resistor (preferably an ohmic resistor) can be provided between the driver and the connections to the control terminals of the respective second transistors of the individual circuit modules and the driver (ieThe resistor is then connected upstream of a branch to the various circuit modules. The semiconductor switch is not necessarily formed with completely identical circuit modules. For example, protective diodes and voltage limiters can be provided selectively only for the circuit modules where the specific design of the semiconductor switch requires it. Also, for example, the circuit module with the shortest distance to the driver can be formed without a second transistor. According to one embodiment, the semiconductor switch according to the invention is formed with a plurality of circuit modules connected in series, with two of the circuit modules being connected in series in opposite conduction directions (e.g., by connecting the source terminals).The semiconductor switch then preferably has an even number of circuit modules (greater than 4), wherein the first half of the circuit modules are connected in series one after the other with the same conducting direction and the second half of the circuit modules are connected in series one after the other with the opposite conducting direction. In this embodiment, an output of the driver can be connected to the connection of the two circuit modules connected in opposite conducting directions. According to a variant of this embodiment, the two circuit modules connected in opposite conducting directions are formed without a second transistor. The circuit modules can - possibly with the exception of the modules connected in opposite conducting directions - be designed with a diode between the control terminal and the source terminal of the first transistor, which diode blocks in the direction of the source terminal.In another embodiment, in which the circuit modules are formed with a third transistor, the semiconductor switch, when installed, has a defined circuit module that terminates the series connection of circuit modules on the load side, and the driver is arranged or looped between a connection to the connection of the source terminals of the first and third transistors of the load-side terminating circuit module and a connection to the connections to the control terminals of the respective second transistors of the individual circuit modules. In this embodiment, at least a third transistor of a first circuit module of the semiconductor switch and a first transistor of a second circuit module adjacent to the first circuit module can be integrated together as a bidirectional component. The semiconductor switch according to the invention allows the short-circuit current to be limited.For this purpose, the semiconductor switch is formed with a sufficient number of semiconductor modules to establish a predetermined upper limit for the short-circuit current. To establish the short-circuit current, the driver voltage of the semiconductor switch can then be adjusted in accordance with an upper limit for the short-circuit current. The invention also encompasses a power electronic switching or protective device with a semiconductor switch according to the invention, in which this semiconductor switch preferably ensures the switching function of the electronic interruption unit. “Power electronic switching or protective device” here means a device that implements a switching or protective function with the aid of power electronics. This applies to an SSCB. However, the invention is not limited to SSCBs, but can also be used in other devices (e.g. motor starters). In particularThe invention can also be used in switching and protective devices without a mechanical isolator. An application scenario without a neutral conductor, e.g., in IT networks (an option discussed for DC networks), is also conceivable. 202300630 8 The invention is described in more detail below using an exemplary embodiment. Fig. 1 shows the structure of an SSCB, Fig. 2 shows the output line field of a typical SI MOSFET, and Fig. 3 shows the characteristic field of the on-resistance R. Dsonas a function of the drain current at different gate-source voltages of a typical SI MOSFET, Fig. 4a-4c: circuit modules according to the invention with which a circuit according to the invention can be constructed, Fig. 5: a circuit according to the invention, Fig. 6: an example to illustrate the short-circuit limiting mode of operation of the circuit of Fig. 5, Fig. 7: output characteristic field of a MOSFET with a schematic representation of the linear region and the saturation region, Fig. 8a-8c: theoretical gate voltages of the individual MOSFETs of a circuit according to the invention for different driver voltages (assuming a uniform linear voltage drop at constant R DSon), Fig. 9: a further embodiment of a circuit according to the invention, Fig. 10: a switch-on process of the circuit from Fig. 9, Fig. 11: a switch-off process of the circuit from Fig. 9, and Fig. 12: a unidirectional GaN component and a bidirectional GaN component which can be used for a circuit according to the invention. 202300630 9 Fig. 1 shows an illustration of an SSCB for protecting a low-voltage electrical circuit. A grid-side neutral conductor connection NG, a grid-side phase conductor connection LG, a load-side neutral conductor connection NL and a load-side phase conductor connection LL are arranged in a housing GEH. An energy source is connected to the grid side GRID and a consumer is connected to the load side LOAD. The main components of the SSCB are a power supply unit NT, a control unit SE, an electronic interruption unit EU and a mechanical isolating contact unit MK.The control unit SE switches on the electronic interruption unit EU, which is formed, for example, with a pair of MOSFETs for switching the phase conductor, and sends an enable signal to the mechanical isolating contact unit. The mechanical isolating contact unit MK comprises contacts KKN, KKL for opening / closing the phase and neutral conductors. To record current and voltage values, a current sensor unit SI is provided in the path of the phase conductor, a first voltage sensor unit SU1 is provided for determining the voltage level between a mains-side connection point EUG and a load-side connection point EUL of the electronic interruption unit EU, and a second voltage sensor unit SU2 is provided for determining the voltage level between the mains-side neutral conductor connection NG and the mains-side phase conductor connection LG.A central idea of ​​the invention is to form a semiconductor switch from circuit modules connected in series. Fig. 4a shows an embodiment of such a circuit module. The module comprises a MOSFET M3 with a source terminal source3, a gate terminal Gate3 and a drain terminal and a PNP bipolar transistor Q2 with an emitter terminal, a base terminal and a collector terminal, wherein the emitter terminal is connected to the gate terminal Gate3 of the MOSFET M3 and the collector terminal is connected to the source terminal source3 of the MOSFET M3. The gate terminal Gate3 and the source terminal source3 of the MOSFET M3 are connected to one another, and between these terminals an (optional) diode D5 (preferably a Zener diode) is arranged, which blocks in the direction of the gate terminal Gate3.The base terminal and the emitter terminal of the PNP bipolar transistor Q2 are connected to one another, and a diode D4 is arranged in the connection, which blocks the conduction towards the base terminal. The base terminal of the PNP bipolar transistor Q2 is also connected to its collector terminal, with a resistor R5 looped into the connection. In addition, a connection from the base terminal of the PNP bipolar transistor Q2 to a driver V2 is provided. This can be seen, for example, in Fig. 5, which shows a semiconductor switch formed from series-connected modules with a driver V2. The driver V2 is connected to the PNP bipolar transistors Q1 - Q6 of six series-connected switch modules according to the invention. A diode D1, D6, D7, D12, D14 and D16 is inserted between the driver V2 and the base terminals of the PNP bipolar transistors Q1 – Q6, which blocks the direction of the driver V2.In this switch geometry, the semiconductor switch is formed from an even number of modules, with the first half of the circuit modules connected in series with the same conduction direction and the second half of the circuit modules connected in series with the opposite conduction direction. In Fig. 4a and Fig. 4b, the semiconductor circuit module is shown twice, with different conduction directions. The semiconductor switch according to Fig. 5 is therefore composed of half modules according to Fig. 4a and half modules according to Fig. 4b. The Zener diodes D5 and D18 in Fig. 5 are optional, as is the voltage limiter U1 (implemented by a TVS diode). In the middle, two modules with opposite conduction directions are connected in series. The driver 202300630 11 V2 is connected to the junction of the two circuit modules connected in opposite conduction directions (source).A resistor R2 or R6 is provided between this connection and the base terminals of the PNP bipolar transistors of the two circuit modules. In addition, a resistor R1 is inserted between the positive pole of the driver V2 and the connections of the switch modules with a forward direction. In addition, a capacitor C1 - C6 and a voltage limiter U1 - U6 (e.g. in the form of a suppressor diode or a varistor) are connected in parallel to each of the switch modules. A voltage V1 and a load R3 fed from this voltage are also shown. The following two points are relevant to the semiconductor switch structure according to Fig. 5: Firstly, this is a circuit for alternating current flow (AC or DC with both current flow directions). For unipolar current flow, only half of the circuit shown would be required (i.e. only the modules with transistors with a forward direction).On the other hand, the driver-related modules can in principle be designed without the transistors Q5 or Q6 for switching on. The elements D13, D14, D17 and R17 or D15, D16, D18 and R10 can then also be omitted, so that the modules then consist only of the MOSFETs M1 or M4. However, to ensure that all series-connected components are switched off as simultaneously as possible and to symmetrically control the switch-off behavior, it is advantageous to design these two modules in a similar way to the other one. With a suitable choice of driver voltage, the circuit shown here has intrinsic short-circuit current limitation, since a voltage drop depending on the load current develops across the series-connected components. 202300630 12 The following calculation example illustrates the idea behind this (see Fig. 6). In the figure, sizes are given at the top for a load current of 100A and at the bottom for a load current of 500A.This calculation example is based on the use of a MOSFET with a forward resistance RDSon of 3.9 mΩ, such as the Infineon MOSFET IPT039N15N5, which results in a drain-source voltage V. DS =i L *R DSon =100A*3.9mΩ=390mV. The drive voltage is 10V, which corresponds to the gate voltage V Gate1 of the MOSFET M1 (relative to the source or the marked "reference point gate unit"). The gate voltages of the MOSFETs M2 and M3 are reduced by the voltage drop at the MOSFET M1 or the MOSFETs M1 and M2, ie V Gate2 =V Gate1 -V DS =10V-0.39V=9.61V and V Gate3 =V Gate1 -2*V DS =10V-0.74V=9.22V (for identical MOSFETs M1-M3). For 500A, you get V DS =i L *R DSon =500A*3.9mΩ=1.95V and thus V Gate2 =8.05V and V Ga- te3=6.1V. Fig. 7 shows the linear region and the saturation region of a typical MOSFET. For different values ​​of the gate voltage, the current I flowing through the MOSFET is DS as a function of the voltage drop between drain and source. The boundary between the linear region and the saturation region is given by the fact that U DS =U GS -U th applies, where U th the threshold voltage U th is the value at which the MOSFET becomes conductive. The value of the current I DS , from which a MOSFET operates in the saturation range, depends on the gate voltage U GS and is lower the lower the gate voltage U GSIn the example in Fig. 6, the parameters are selected such that MOSFETs M1 and M2 (with gate voltages of 10V and 8.05V) (still) operate in the linear range, but MOSFET M3 with a gate voltage of 6.1V no longer does. This means that the on-resistance RDSon of MOSFET M3 is no longer approximately 3.9mΩ as with MOSFETs M1 and M2, but correspondingly higher. At a current of 100A, however, this series circuit can carry the current without a significant increase in the on-resistance RDSon occurring. At 500A, however, the topmost MOSFET in the series circuit is no longer in the linear range of its characteristic curve, as illustrated in Fig. 7. Thus, this MOSFET M3 builds up voltage at a current of 500A and reduces the driving voltage by its avalanche voltage or to the voltage of the associated voltage-limiting network (e.g. TVS diode with 120V limiting voltage).If the built-up counter voltage is equal to the driving voltage, then the current rise is zero, even in a short circuit. The switch arrangement intrinsically limits the current, and in a short circuit, also the short-circuit current. This is naturally accompanied by losses in the MOSFET and the overvoltage network – but the switch and the TVS diode can withstand this for a few µs, and this is precisely the time necessary to keep the requirements for short-circuit current detection and shutdown low or within an acceptable range. It would also be advantageous for the practical application of this circuit if the maximum short-circuit current could be adjusted, and as simply as possible. This is the case with this circuit. By changing the supply voltage of the gate unit V2, the maximum short-circuit current can be adjusted over a wide range. This is illustrated using the examples in Fig. 8a – 8c.The tables shown in these figures are again based on the use of a MOSFET with a forward resistance RDSon of 3.9 mΩ (in the linear range), such as the Infineon MOSFET IPT039N15N5. In the various tables, the drive voltage was changed from 9 V in Table 1 (Fig. 8a), to 10 V in Table 2 (Fig. 8b), and to 11 V in Table 3 (Fig. 8c). The individual MOSFETs or switch modules are numbered in the first column. The listing corresponds to an increasing distance to the driver, ie the data in the first row corresponds to the MOSFET closest to the driver (in 202300630 14 Fig. 5 e.g. MOSFET M1), the data in the second row to the following MOSFET (in Fig. 5 e.g. MOSFET M2) etc. Columns 2-5 list the gate voltages U. GSfor various load currents (50A, 100A, 200A, and 400A). The last row shows the total nominal on-resistance RDSon of the MOSFETs according to the number (i.e., the number according to the first column multiplied by the on-resistance RDSon of 3.9mΩ, e.g., 2*3.9mΩ = 7.8mΩ, 3*3.9mΩ = 11.7mΩ, etc.). For the values ​​shown for the gate voltages U GS Values ​​shown in larger font correspond to MOSFETs in the linear range and all values ​​shown in smaller font correspond to MOSFETs in the saturation range (also known as the pinch-off range for MOSFETs) or blocking range, ie the range with gate voltages below the threshold voltage U th (see Fig. 7 – U this approximately 3.8 V for the MOSFETs used in the calculation example), for which the resistance is then correspondingly increased (i.e. greater than 3.9 mΩ), as illustrated in Fig. 3. All MOSFETs with a gate voltage shown in smaller font will in reality build up a counter voltage. If the sum of the counter voltages is equal to the driving voltage, an equilibrium will be established and the resulting current increase in the short circuit is zero. The circuit thus actively and intrinsically limits the short-circuit current as a function of the applied driver voltage. Fig. 8a – Fig. 8c show that there are two parameters with which a short-circuit voltage limitation can be specified, namely the number of MOSFETs or circuit modules and the level of the driver voltage. One possible strategy is to limit the number of circuit modules for a coarse adjustment orto select a possible range of short-circuit voltage values ​​and to make a fine adjustment using the driver voltage. The inventive concept can be implemented in various ways in terms of circuitry. This is illustrated below using a further exemplary embodiment. 202300630 15 Fig. 4c shows another possible design of a circuit module according to the invention. A switch according to the invention can be constructed using switch modules of this type. This is shown in Fig. 9. The inventive series circuit in Fig. 9 comprises two circuit modules corresponding to Fig. 4c with a simple control circuit using only one driver circuit and only one necessary driver power supply. As with the switch in Fig. 5, there is only one driver power supply and also only one driver, symbolically represented in Fig. 9 by the pulse voltage source V2.The pulse voltage source V2 is connected via resistor R1 to two identically constructed functional units. The upper functional unit (corresponding to Fig. 4c) has a protective diode D6, via which resistor R1 is connected to the functional unit, and which only allows current to flow in the direction of the functional unit. Diode D6 is followed by a PNP bipolar transistor Q2, i.e., its emitter, base, and collector, with a further diode D4 connected to the emitter and a resistor R5 connected to the collector of the PNP bipolar transistor Q2. The emitter is connected to the gate terminal Gate3 of an N-channel metal-oxide-semiconductor field-effect transistor or N-channel MOSFET M3, and the collector is connected to the source terminal Source3 of the MOSFET M3.Connected in series with MOSFET M3 is another N-channel MOSFET M6 with an opposite conduction direction, with the gate terminal Gate3 and the source terminal Source3 of MOSFETs M3 and M6 corresponding to each other. The drain terminal Drain2 of MOSFET M6 is connected to another series-connected functional unit. Connected in parallel with MOSFETs M3 and M6 is an overvoltage protection or overvoltage limiter U1 (e.g., in the form of a suppressor diode or a varistor), which is connected to the drain terminals Drain3 and Drain2 of MOSFETs M3 and M2, respectively. The further functional unit has a structure identical to the first functional unit, wherein the elements D1, D2, R4, 202300630 16 Q1, Gate2, source2, M2, M7 and U2 of the second functional unit each correspond to the elements D6, D4, R5, Q2, Gate3, source3, M3, M6 and U1 of the first functional unit.The drain terminal of MOSFET M7 is connected to the load (load resistance RLoad), which is fed by the voltage V1, which drops across the functional units and the load resistance. The operation of the circuit shown in Fig. 9 is explained below. If the signal from the pulse source is V20V or negative (e.g. -15V), then 20V is applied to the Gate terminal against the source2 terminal, and 30V is applied to the Gate terminal against the source3 terminal. The series-connected functional units (MOSFETs) are therefore switched off. If a positive voltage is applied to the Drain3 terminal, MOSFETs M2 and M3 are off, while MOSFETs M6 and M7 are conductive (due to the freewheeling diode or body diode of the MOSFETs, or when using IGBTs, the anti-parallel diode is then mandatory). If a negative voltage is applied to the Drain3 terminal, MOSFETs M6 and M7 are off; MOSFETs M3 and M4 are then conductive. The following describes how to turn on the circuit shown in Fig. 9.If a positive voltage is now applied by driver V2, diodes D1 and D2 become conductive. At the gate connection Gate2 of MOSFETs M2 and M7 there is a positive voltage relative to the source connection Source2. If this voltage is greater than the threshold voltage of the MOSFETs, then they switch on. With a positive voltage between drain Drain2 and source Source2 of MOSFET M2, MOSFET M2 becomes conductive (MOSFET M7 conducts because of its body diode), and only the channel resistance RDSon remains between drain and source. If the load resistance RLast is much greater than the channel resistance RDSon, then the vast majority of the voltage across the load drops, the voltage drop across the resistor RDSon is very small and negligible for explaining the operation of this circuit 202300630 17. Thus the voltage across the MOSFET collapses, and the drain has the potential of the source.This means that the source of the upper switch (source3) now also has the potential of the source of the lower switch (source2). Diodes D6 and D4 become conductive, and the gate connection Gate3 becomes positive with respect to the gate connection Source3. MOSFETs M3 and M6 turn on. The entire path between the drain connection Drain3 and the load is now conductive. The series connection of MOSFETs is turned on. The progression of relevant signals during the turn-on process is described in more detail in Fig. 10. Applying a positive driver voltage first leads to a control signal at MOSFET M2 and, in quick succession, to a control signal at MOSFET M3. The MOSFETs turn on, allowing a load current to flow and the voltage across the switch to collapse (see Fig. 10). The turn-off process proceeds as described below.If driver V2 now outputs a voltage of 0V (or a voltage signal of -15V), then there is no longer a gate signal at diodes D1 and D2. PNP bipolar transistor Q1 switches on. This shorts the path between Gate2 and Source2 and discharges the gate capacitance of MOSFETs M2 and M7. MOSFETs M2 and M7 switch off (or become high-impedance). When there is a positive voltage at terminal Drain3, a voltage builds up across MOSFET M2, and when there is a negative voltage, a voltage builds up across MOSFET M7. The potential at terminal Source3 is now greater than the potential at terminal Source2. Diodes D6 and D4 now also block, PNP bipolar transistor Q2 switches on and discharges the gate capacitances of MOSFETs M3 and M6, causing them to also switch off. The series circuit becomes high-impedance, and the voltage drop across resistor RLast becomes negligible. Relevant signal curves during the switch-off process are shown in Fig. 11.The control signal at MOSFET M2 and, after a short time interval, that at MOSFET M3 are switched off, so that the MOSFETs are blocking. The load current is switched off and no significant voltage drop occurs across the load. The diodes D1 and D2 and the PNP transistor Q1 in the circuit shown in Fig. 9 can be omitted without affecting the circuit's operation (ultimately meaning: the lower stage can also have a completely normal driver). However, they are advantageous for switching off all components connected in series as simultaneously as possible. The design is modular. Fig. 4c shows the module, whereby the voltage limitation U1 can be omitted as long as the avalanche resistance of the components is sufficient to absorb the energy from overvoltages when switching on and off. The modules can now be connected in series, whereby the decoupling diode D6 must be connected to the driver output in each case, as already shown in Fig. 9 andfor the other embodiment is shown in Fig. 5. It is also possible to use this circuit for components that intrinsically have a common-drain structure, such as bidirectional GaN components. Referring to Fig. 9, the MOSFETs M2 and M6 would be merged into one component; any overvoltage limitation would then be located between Source3 and Source2; the rest of the circuit would remain the same. This circuit is also advantageous for a bidirectional GaN device in a single circuit, since it would elegantly solve the problem of having two gates at different potentials using the same approach, as shown in Fig. 12.

Claims

202300630 19 patent claims 1. Circuit module for a semiconductor switch, with - a first transistor (M3) with a source terminal (source3), a control terminal (Gate3) and a drain terminal, wherein -- the source terminal (source3) is a source terminal or an emitter terminal, the control terminal (Gate3) is a gate terminal or a base terminal and the drain terminal is a drain terminal or a collector terminal, - a second transistor (Q2) with a source terminal, a control terminal and a drain terminal, wherein -- the source terminal is connected to the control terminal (Gate3) of the first transistor (M3), -- the drain terminal is connected to the source terminal (source3) of the first transistor (M3), and -- a connection from the control terminal of the second transistor (Q2) to a driver (V2) is provided.Circuit module according to claim 1, characterized in that the first transistor (M3) is a unipolar transistor.

3. Circuit module according to one of claims 1 or 2, characterized in that the first transistor (M3) is a MOSFET or an IGBT with an anti-parallel protection diode.

4. Circuit module according to one of claims 1 to 3, characterized in that the second transistor (Q2) is a bipolar transistor.

5. Circuit module according to one of claims 1 to 4, characterized in that. 202300630 20 the connection is formed with a conductor section into which a diode (D6) is introduced, which blocks in the direction of the driver (V2).

6. Circuit module according to one of claims 1 to 5, characterized in that the connection is formed with a conductor section into which a fuse is introduced.

7. Circuit module according to one of claims 1 to 6, characterized in that - the control terminal and the source terminal of the second transistor (Q2) are connected to one another, and - a diode (D4) is arranged between the control terminal and the source terminal of the second transistor (Q2), which diode blocks in the direction of the control terminal.

8. Circuit module according to one of claims 1 to 7, characterized in that - the control terminal and the drain terminal of the second transistor (Q2) are connected to one another, and - a resistor (R5) is arranged between the control terminal and the drain terminal of the second transistor (Q2). 9.Circuit module according to one of claims 1 to 8, characterized in that a voltage limiter (U1) is provided in parallel with the first transistor (M3).

10. Circuit module according to one of claims 1 to 9, characterized in that a capacitive resistor (C1) is provided in parallel with the first transistor (M3).

11. Circuit module according to one of claims 1 to 10, characterized in that. 202300630 21 - the control terminal (Gate3) and the source terminal (source3) of the first transistor (M3) are connected to one another, and - a diode (D5) is arranged between the control terminal (Gate3) and the source terminal (source3) of the first transistor (M3), which diode blocks in the direction of the source terminal (source3). 12.Circuit module according to one of claims 1 to 11, characterized in that - the circuit module is formed with a third transistor (M6), wherein -- the third transistor (M6) is of the same type as the first transistor (M3) and the first and the third transistor are each directly connected to one another via the source terminal (source3), -- the source terminal of the second transistor (Q2) is connected to the control terminals (Gate3) of the first and third transistors (M3, M6), and -- the drain terminal of the second transistor (Q2) is connected to the junction of the source terminals (source3) of the first and third transistors (M3, M6).

13. A semiconductor switch comprising a plurality of series-connected circuit modules according to claims 1 to 12, comprising a driver (V2) connected via the respective connections to the control terminals of the respective second transistors (Q1, Q2, Q3, Q4, Q5, Q6) of the individual circuit modules. 14.Semiconductor switch according to claim 13, characterized in that the circuit module with the shortest distance from the driver is formed without a second transistor (Q2).

15. Semiconductor switch according to claim 13 or 14, characterized in that. 202300630 22 a resistor (R1) is provided between the connections to the control terminals of the respective second transistors (Q1, Q2, Q3, Q4, Q5, Q6) of the individual circuit modules and the driver (V2).

16. Semiconductor switch according to one of claims 13 to 15, characterized in that the semiconductor switch is formed with exactly one driver (V2).

17. Semiconductor switch according to one of claims 13 to 16, characterized in that - it has a plurality of series-connected circuit modules according to one of claims 1 to 11, and - two of the circuit modules are connected one after the other in opposite switching directions. 18.Semiconductor switch according to claim 17, characterized in that - it has an even number of circuit modules, - the first half of the circuit modules are connected in series with the same switching direction, and - the second half of the circuit modules are connected in series with the opposite switching direction.

19. Semiconductor switch according to claim 17 or 18, characterized in that an output of the driver (V2) is connected to the connection of the two circuit modules connected in opposite switching directions.

20. Semiconductor switch according to claim 19, characterized in that the two circuit modules connected in opposite switching directions are formed without a second transistor (Q2). 202300630 23 21. Semiconductor switch according to one of claims 17 to 20, characterized in that the circuit modules, with the exception of the respective last circuit module on the load side of the first and second half of the circuit modules according to claim 11, are designed with a diode (D5) between the control terminal (Gate3) and the source terminal (source3) of the first transistor (M3). 22.Semiconductor switch according to one of claims 13 to 16, characterized in that - it has a plurality of series-connected circuit modules according to claim 12, - the semiconductor switch, when installed, has a defined circuit module that terminates the series connection of circuit modules on the load side, and - the driver is arranged between a connection to the connection of the source terminals (source3) of the first and third transistors (M3, M6) of the load-side terminating circuit module and a connection to the connections to the control terminals of the respective second transistors (Q2, Q1) of the individual circuit modules. 23.Semiconductor switch according to claim 22, characterized in that at least a third transistor (M6) of a first circuit module of the semiconductor switch and a first transistor (M2) of a second circuit module adjacent to the first circuit module are integrated together as a bidirectional component.

24. Semiconductor switch according to one of the preceding claims 13 to 23, characterized in that - the semiconductor switch is designed to limit the short-circuit current, and - the semiconductor switch is formed with a number of semiconductor modules sufficient to establish a predetermined upper limit for the short-circuit current. 202300630 24 25. Power electronic switching or protection device with a semiconductor switch according to one of claims 13 to 24.

26. Method for determining the short-circuit current limitation of a semiconductor switch according to claim 24, characterized by determining the driver voltage of the semiconductor switch in accordance with an upper limit for the short-circuit current.

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