Switches for safely switching a power supply

Abstract

A switch, particularly for switching direct currents, is proposed. This switch comprises circuit modules connected in series, each formed with at least one switching transistor, a control unit, and a current measuring device. A plurality of the circuit modules can be activated separately by the control unit. The current measuring device is connected to the control unit and is configured to transmit measured current values ​​to the control unit. The control unit is configured to selectively activate circuit modules according to the current values ​​measured and transmitted by the current measuring device. The switch according to the invention integrates functionalities for protecting the switch against excessive currents, which were conventionally implemented with additional external elements (especially pre-charging), and thus represents a more complex and compact solution.

Description

[0001] The invention relates to a switch which is designed for safe switching with regard to the load on components of the switch, and to a method for maintaining a power supply with such a switch.

[0002] Direct current (DC) networks are generally highly capacitive in industrial environments. However, connecting capacitive loads always causes a large compensating current. Particularly in DC applications such as intermediate circuits or DC networks, where multiple capacitors are connected together, the connecting current is significant and often exceeds the rated current by several times. Since this current would destroy components and trigger superimposed protection, this current must be limited. Limiting is typically achieved using a pre-charging resistor. However, this resistor is large, expensive, and requires cooling. To prevent the resistor and surrounding components from overheating, adequate ventilation must be ensured, which further increases the pre-charging effort. This resistor is switched on and off using separate switching elements, which must also be controlled.

[0003] In addition to the disadvantages outlined above, resistor precharging has another serious drawback. If the voltage builds up in the load zone, the driving voltage across the resistor decreases, and the precharging current decreases. Due to leakage currents in the load, the voltage difference across the resistor can never be zero. Therefore, the actual semiconductor switch must always be switched on at a certain voltage difference, allowing a certain (significantly smaller) inrush current to flow. WO 2020156689 A1 proposes a solution to this problem. Precharging is divided into two stages: 1st section: Pre-charging through resistance, as long as the voltage in the load zone is low and thus the voltage difference across the resistor and thus also the charging current is large (here the driving voltage is too high for a meaningful buck converter operation or clocked operation, but also for operation in the linear range). 2nd section: clocked operation of a solid-state switch after reaching a certain voltage level in the load zone (in this section the current through the load resistor would be very small because the driving voltage across the load resistor has become small).

[0004] Both sections require a separately controllable pre-charging resistor with a large thermal capacity so that the electrical losses occurring in the resistor do not lead to thermal destruction of the resistor.

[0005] The invention aims to provide an efficient and low-cost solution for safe switching with regard to the load on components of a switch used.

[0006] This object is achieved by a switch according to claim 1 and a method for a power supply according to claim 11.

[0007] A switch, in particular for switching direct currents, is proposed. This comprises series-connected circuit modules, each formed with at least one switching transistor (MOSFET, IGBT, BJT, etc.), a control unit (e.g., an MCU?), and a current measuring device (e.g., a current sensor formed with a shunt resistor, converter, or Hall probe). A plurality of the circuit modules are designed to be separately actively switchable by the control unit, i.e., to be placed in a state in which the switching transistor of the circuit module is switched on or can be switched on when a corresponding voltage is applied. This can also be realized by providing a separate driver for each circuit module, which is controlled separately. Preferably, however, the switch is constructed in a low-complexity manner that does not require a separate driver for each circuit module, which is described in more detail below.The current measuring device is connected to the control unit. The switch is designed to transmit measured current values ​​to the control unit, and the control unit is configured or programmed to selectively activate circuit modules based on current values ​​measured and transmitted by the current measuring device, e.g., when the transmitted current values ​​fall below a threshold value (possibly also in a suitably formed means, e.g., the RMS value or effective value of the current). The switch can be designed to switch in several consecutive stages (e.g., connecting one or two circuit modules per stage) until all circuit modules are activated. The stages are characterized by an increasing number of active circuit modules. With threshold switching, the same threshold value is then preferably, but not necessarily, used to connect the stages.

[0008] According to one embodiment of the switch according to the invention, a single driver is provided for a plurality of circuit modules (preferably for all circuit modules), which driver supplies voltage for switching on the switching transistors of the plurality of circuit modules. For this purpose, conductive connections or power connections from the driver to the circuit modules are provided, and for the selective activation of at least one circuit module of the plurality of circuit modules, a switching element (e.g., an optocoupler) is introduced into the connection between the driver and the circuit module, with which a current flow between the driver and the circuit module can be enabled or prevented.A hybrid switch geometry is also conceivable in which at least one circuit module is not controlled by the common driver, but by a dedicated driver, and for the selective activation of this circuit module, the switch is designed for a selective control of the associated driver by the control unit.

[0009] When designing the switch for step-through switching, a switch geometry with a driver for a plurality of switching modules can be configured so that active switching modules (possibly only one switching module) in the first stage cannot be activated separately (e.g., via an optocoupler), while the other switching modules can be activated separately. The first stage is then activated directly by the shared driver.

[0010] According to one embodiment of the switch according to the invention, it is formed with a plurality of series circuits of circuit modules arranged in parallel. The control unit can then be configured or programmed to selectively activate circuit modules in stages alternating between the plurality of series circuits (i.e., the circuit modules of two consecutive stages belong to different series circuits).

[0011] The inventive concept provides for relocating functionalities for protecting the switch against excessive currents, which were conventionally implemented with additional external elements (cf. WO 2020156689 A1), into the switch itself. This means that instead of additional external elements, the switch itself is designed for switching in such a way that the current does not reach values ​​that are dangerously high for the switch's electronics. This is achieved by forming the switch with multiple circuit modules and the switch-on behavior of the switch, i.e., measuring current values ​​by the current measuring device, transmitting the measured current values ​​to the control unit, and selectively activating circuit modules according to the current values ​​measured and transmitted by the current measuring device.

[0012] As an additional safeguard, the switch can be set to clocked operation if the transmitted current values ​​exceed a threshold value.

[0013] The switch according to the invention is therefore less complex and more efficient than conventional solutions. It can be manufactured, sold, and installed as an integral unit. This means that additional circuitry measures in the application environment are not required to protect the switch from high currents.

[0014] The circuit modules or switches used can be constructed as in the German patent application with the application number DE 10 2023 200 167.5.

[0015] There, a circuit module for a semiconductor switch is proposed. This is formed by a first transistor with a source terminal, a control terminal, and a drain terminal. 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. Furthermore, the circuit module has a second transistor with a source terminal, a control terminal, and a drain terminal, wherein the source terminal is connected to the control terminal of the first transistor and the drain terminal is connected to the source terminal of the first transistor. Furthermore, a connection is provided from the control terminal of the second transistor to a driver (which itself is not part of the circuit module).

[0016] A central idea of ​​the application with the application number DE 10 2023 200 167.5 is that a modular design of a semiconductor switch can be realized by connecting circuit modules according to the invention in series or cascading them, 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 specified as needed.

[0017] The first transistor can be a unipolar transistor, such as a MOSFET. However, it can also be implemented using a bipolar transistor, such as an IGBT (insulated-gate bipolar transistor) with an antiparallel protection diode (integrated or as an external freewheeling diode).

[0018] According to one embodiment of the circuit module, the connection to the driver is formed by a conductor section into which a diode is incorporated, which blocks current in the direction of the driver. Furthermore, the connection can be formed by a conductor section into which a fuse is incorporated.

[0019] According to one embodiment of the circuit module, the control terminal and the source terminal of the second transistor are connected to one another, and a diode is arranged between the control terminal and the source terminal of the second transistor, which diode blocks in the direction of the control terminal.

[0020] According to one embodiment of the circuit module, 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.

[0021] According to one embodiment of the circuit module, a voltage limiter is provided in parallel with the first transistor. A capacitive resistor can also be provided in parallel with the first transistor.

[0022] According to a first alternative embodiment of the circuit module, 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 blocks current toward 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.

[0023] According to a second alternative embodiment of the circuit module, 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 each other by the source terminal (i.e., 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 junction of the source terminals of the first and third transistors.

[0024] The German patent application with the application number DE 10 2023 200 167.5 also describes a semiconductor switch with a plurality of series-connected circuit modules 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 (i.e., the 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,Protection diodes and voltage limiters can be selectively provided only for the circuit modules where the specific design of the semiconductor switch requires it. For example, the circuit module with the shortest distance to the driver can also be designed without a second transistor.

[0025] According to one embodiment, this semiconductor switch is formed with a plurality of circuit modules connected in series, wherein two of the circuit modules are connected in series in opposite switching 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 switching direction and the second half of the circuit modules are connected in series one after the other with the opposite switching direction. In this embodiment, an output of the driver can be connected to the connection of the two circuit modules connected in opposite switching directions. According to a variant of this embodiment, the two circuit modules connected in opposite switching directions are formed without a second transistor. The circuit modules can - possibly.with the exception of modules connected in the opposite forward direction - be designed with a diode between the control terminal and the source terminal of the first transistor, which blocks in the direction of the source terminal.

[0026] In another embodiment, in which the circuit modules are formed with a third transistor, this 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 variant, 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.

[0027] The semiconductor switch in question allows for limiting the short-circuit current. For this purpose, the semiconductor switch is constructed with a sufficient number of semiconductor modules to establish a predefined upper limit for the short-circuit current. To determine the short-circuit current, the drive voltage of the semiconductor switch can then be adjusted according to the upper limit for the short-circuit current.

[0028] The invention is illustrated in more detail below using an exemplary embodiment. The figures show: Fig. 1A and Fig. 1B: two different possible geometries of a switch according to the invention, Fig. 2A and Fig. 2B: Circuit modules for a modular design of a switch with the geometry of Fig. 1B, Fig. 3: one with circuit modules acc. Fig. 2A and Fig. 2B constructed switch according to the invention, Fig. 4: Current and voltage curve during pre-charging by a switch with the structure of Fig. 3, where three MOSFETs connected in series are switched on in a staggered manner, Fig. 5: Current and voltage curve during a pre-charge when the driving voltage is applied all at once, Fig. 6: another example of a switch according to the invention, and Fig. 7: a method according to the invention.

[0029] Fig. 1A and Fig. 1B show two different possible geometries of a switch according to the invention. In both cases, the switch is formed with a control unit MCU and a current measuring device S(I), which transmits the measured current values ​​to the control unit MCU. The switch according to the invention is formed with circuit modules SM1-SM6, which can be switched on in stages. Fig. 1A and Fig. 1B, two switching modules are connected in each of the three stages S1-S3. The switching modules SM1-SM6 connected in a stage are identified by the stage affiliation S1-S3 in parentheses.

[0030] According to the geometry of Fig. 1A, a driver T is provided for each circuit module, which is activated by the control unit according to the stepped switching. The circuit modules with this geometry essentially correspond, for example, to a switching transistor or an antiparallel arrangement of two switching transistors.

[0031] However, the geometry of Fig. 1B, which requires a single driver T. This single driver is connected to all circuit modules SM1-SM6. The gradual activation of the circuit modules is achieved using switching elements OK (e.g., optocouplers) controlled by the MCU control unit. An example of this solution is described in more detail below.

[0032] The example of the switch solution according to Fig. 1B assumes a switch formed by circuit modules connected in series. Fig. Figure 2A shows a possible 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 each other, and between these terminals an (optional) diode D5 (preferably a Zener diode) is arranged, which blocks the conduction towards the gate terminal Gate3. The base terminal and the emitter terminal of the PNP bipolar transistor Q2 are connected to each other, 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.

[0033] In addition, a connection is provided from the base terminal of the PNP bipolar transistor Q2 to a driver V2 (see Fig. 3).

[0034] Fig. Figure 3 shows a switch according to the invention with series-connected circuit modules and 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 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. Fig. 2A and Fig. Figure 2B shows the circuit module twice, with different forward directions. The semiconductor switch shown in Figure 2B. Fig. 3 is therefore half made up of modules corresponding to Fig. 2A and half of modules corresponding Fig. 2B together. In the middle, two modules with opposite forward directions are connected in series. The driver V2 is connected to the junction of the two circuit modules connected in opposite 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. Also shown is a voltage V1 and a load R3 fed from this voltage.

[0035] For semiconductor switch construction acc. Fig. 3 The following two points are still relevant: Firstly, it 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 of a forward direction).

[0036] 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 and M4. However, to ensure the simultaneous switching off of all series-connected components, or to symmetrically balance the switching-off behavior, it is advantageous to design these two modules in a similar manner to the others.

[0037] With a suitable choice of the driver voltage, the circuit shown here has an intrinsic short-circuit current limitation, since a voltage drop depending on the load current develops across the components connected in series.

[0038] The circuit according to Fig. 3 thus represents a simple and cost-effective way to implement conduction losses through a series connection of power semiconductors or circuit modules formed by these power semiconductors. According to the invention, this circuit is expanded to include the possibility of separately connecting or disconnecting the MOSFETs M2, M3, M5, and M6 in this series connection.

[0039] Advantageously, this is done in a potential-separated manner, so that it can be easily connected to a microcontroller or similar device. Fig. 3, this is achieved by using suitable optocouplers U7–U10. The optocouplers are controlled by a suitable circuit (for each optocoupler, a voltage source V3–V6 and a resistor R12–R15 are shown for illustrative purposes). The optocouplers U7–U10 are each inserted between the driver V2 and the associated circuit module (more precisely, between the driver V2 and the respective diodes D1, D6, D7, and D12 connected upstream of the base terminals of the PNP bipolar transistors Q1–Q4).

[0040] A separate power supply for each individual gate signal of the circuit modules is thus not required. With a non-conductive optocoupler, the gate signal from driver V2 is not passed to the corresponding gate. When the optocoupler conducts, the path to the corresponding gate becomes low-impedance, and the corresponding power semiconductor is switched on.

[0041] The now available ability to individually switch on and off individual MOSFETs M2, M3, M5, and M6 in the series circuit enables a gradual increase in the driving voltage in the load zone and eliminates the disadvantages of the solution described in WO 2020156689 A1. For example, section 1 can be omitted there, since the driving voltage does not have to be switched on all at once. Thus, a precharge resistor is no longer required.

[0042] Fig. Figure 4 shows the current and voltage of the load zone during such a staggered precharge. The next MOSFET or circuit module (or Fig. 1B symmetrically two circuit modules or MOSFETs) are switched on when the pre-charging current drops below 2A. Fig. Figure 5 shows current and voltage during a conventional switch-on process.

[0043] If the peak value of the pre-charging current reaches a value that endangers the power semiconductors, it is of course possible to switch back to clocked operation, since the reduced driving voltage means that the requirements for the circuit's reaction time are lower than when the entire voltage is switched on at once.

[0044] The number of voltage levels can be further increased if a parallel connection of this circuit arrangement is considered, since it is possible to construct this series circuit with different blocking voltages. In the simplest case, TVS diodes with different breakdown voltages are used, but MOSFETs with different blocking voltages can also be installed. Such a parallel connection is Fig. 6. The circuit is equipped with a driver V1 and seven circuit modules according to Fig. 2A or Fig. 2B. The circuit modules each comprise a MOSFET (M1-M7), a PNP bipolar transistor (Q1-Q7), a diode (D3, D5, D9, D11, D17, D18, and D20) placed between the gate terminal and the source terminal of the MOSFET, a diode (D2, D4, D8, D10, D13, D15, and D19) placed between the base terminal and the emitter terminal of the PNP bipolar transistor, which blocks towards the base terminal, and a resistor (R4-R10) between the positive terminal of the driver V1 and the connections of the switch modules. A diode (D1, D6, D7, D12, D14, D16, and D21) is inserted between the driver V1 and the base terminals of the PNP bipolar transistors, blocking the direction of the driver V1. A TVS diode or suppressor diode (U1-U7) is also connected in parallel with the switch modules.

[0045] The left side of the circuit of Fig. 6 corresponds to the upper part of the circuit of Fig. 3 with the following differences - An additional circuit module is provided - No capacitors are shown parallel to the voltage limiters or TVS diodes (but can be provided)

[0046] This means that, with the exception of the module closest to driver V1, optocouplers U33, U55, and U77 are each inserted between driver V1 and the associated circuit module. Parallel to these (right side), three series-connected circuit modules with optocouplers U22, U44, and U66 are mounted. The optocouplers are controlled by a suitable circuit (for each optocoupler, a voltage source V2-V7 and a resistor R3 and R11-R15 are shown for illustrative purposes). The optocouplers are each arranged between driver V1 and the associated circuit module to ensure appropriate connection of the respective circuit module.

[0047] The circuit according to Fig. 6 is thus formed by a parallel connection of two series circuits of circuit modules, one of which comprises four circuit modules and the other of which comprises three. The TVS diodes are dimensioned so that the total blocking voltages or reverse voltages of both series circuits correspond to each other. In the example, 50V is dropped across TVS diodes U1 and U7 each, and 100V across all others, so that the total blocking voltage on both sides adds up to 300V.

[0048] When switching with the circuit according to Fig. 6, the driver signal V1 is first applied, turning on MOSFET M1. The blocking voltage of the left series circuit now drops by 50V to 250V. If the driving voltage, i.e. the voltage of the DC source, is 300V, it is now precharged with 50V. If the current drops below a specified value, MOSFET M2 is switched on with the help of the corresponding control signal and the associated optocoupler M22. The blocking voltage of the right series circuit now drops by 100V to 200V. The precharge voltage is now 100V and thus 50V higher than before MOSFET M2 was switched on. Then MOSFETs M3, M4, M5, M6, and M7 are switched on one after the other (MOSFET M7 is only needed to generate the same blocking voltage in the left series circuit as in the right series circuit). With each additional switch-on, the blocking voltage of the arrangement drops by a further 50V.This gives you a total of 6 voltage levels: 50V, 100V, 150V, 200V, 250V and 300V (full driving voltage, all switches on).

[0049] Fig. Figure 7 shows the sequence of a method according to the invention used in this case. In step S1, the switch receives a switch-on command. The driver is switched on by the control unit (step S2), thus activating the first stage (step S3). During the switch-on process, the current is continuously monitored (step 4) and checked to see whether it falls below a threshold value SW (step S5). If it falls below a threshold value SW, the next stage is switched on (step S6). Once the last stage has been switched on (query S7), the switch is fully switched on (step S8), and monitoring for the threshold value SW falling below can be terminated. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2020156689 A1 [0003, 0011, 0041] DE 10 2023 200 167.5 [0014, 0016, 0024]

Claims

[1] Switch, in particular for switching direct currents, comprising - circuit modules connected in series, each of which is formed with at least one switching transistor, - a control unit and - a current measuring device, wherein - a majority of the circuit modules can be activated separately by the control unit, - the current measuring device is connected to the control unit and is designed to transmit measured current values ​​to the control unit, and - the control unit is designed to carry out a selective activation of circuit modules in accordance with current values ​​measured and transmitted by the current measuring device. [2] Switch according to claim 1, characterized by , that - a single driver is provided for a plurality of circuit modules, which driver supplies voltage for switching on the switching transistors of the plurality of circuit modules, - conductive connections from the driver to the circuit modules are provided for this purpose, and - for the selective activation of at least one circuit module of the plurality of circuit modules, a switching element is introduced into the connection between the driver and the circuit module, with which a current flow between the driver and the circuit module can be enabled or prevented. or - a dedicated driver is provided for at least one circuit module, and - for the selective activation of the at least one circuit module, the switch is designed for selective control of the associated driver by the control unit. [3] Switch according to claim 2, characterized bythat the switching element is an optocoupler. [4] Switch according to one of the preceding claims, characterized by that the switch is designed to switch in several stages, wherein the stages are characterized by an increasing number of active switching modules. [5] Switch according to claim 4, characterized by that the circuit modules active at the first stage or the circuit modules active at the first stage cannot be switched to active mode separately, while the other circuit modules can be switched to active mode separately. [6] Switch according to claim 4 or 5, characterized by that the stages are characterized by the active switching of one or two circuit modules. [7] Switch according to one of the preceding claims, characterized bythat the control unit is designed to carry out a selective activation of circuit modules when the transmitted current values ​​fall below a threshold value. [8] Switch according to one of the preceding claims, characterized by that the control unit is designed to put the switch into clocked operation when the transmitted current values ​​exceed a threshold value. [9] Switch according to one of the preceding claims, characterized by that it is formed with several series circuits of circuit modules which are arranged parallel to each other. [10] Switch according to claim 9, characterized by that the control unit is designed to carry out a selective active switching of circuit modules in stages alternating between the several series circuits. [11] Method for switching a power supply with a switch according to one of claims 1 to 10, - Measuring current values ​​by the current measuring device, - Transmitting the measured current values ​​to the control unit, and - selective activation of circuit modules according to current values ​​measured and transmitted by the current measuring device. [12] Method according to claim 11, characterized by that the activation switching takes place in several stages until all circuit modules are activated, whereby the stages are characterized by an increasing number of active circuit modules. [13] Method according to one of claims 11 or 12, characterized by that a selective activation of circuit modules is carried out if the transmitted current values ​​fall below a threshold value. [14] Method according to one of claims 11 to 13, characterized by that the switch is put into clocked operation when the transmitted current values ​​exceed a threshold. [15] Method according to one of claims 11 to 14, characterized by , that - the switch is formed with several series circuits of circuit modules which are arranged in parallel to each other, and - a selective active switching of circuit modules is carried out in stages alternating between the several series circuits.

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